Life cycle analysis has a static character, which represents a problem of applicability in forestry, because forestry is determined by works in space and time and thus has a dynamic character. There is a big difference between the duration and physical activity between the chain cycles of industrial products and production chains in forestry so there is a the need to develop a modelling approach that will enable the creation and collection of representative

Empirical models - modelling is based on an analysis of existing data. Inventory based

 Process based models - development modelling with prediction of future events, taking into account any changes in the production process. Nonlinear effects can be taken into consideration by using corresponding productivity models or other process

For modelling it is essential that complex dynamic models are simplified in an appropriate way and as such are used in the analysis of the life cycle. Depending on forest management

For even aged forests a modelled period (determined by the length of rotations) is

Berg (1998) presented how different ways of data collection can give considerable differences in results, which may or may not be dependent on physical factors. Data were

1. Statistics regarding actual work volume (area in hectares, cubic meters of harvested

2. Operational data or work study data about production efficiency and fuel consumption

Another approach was also tried and data were collected from vast forest area during oneyear work operations. Records were kept of all recourses allotted to that area in order to deliver the timber that was transported from the area. During collection, data was sorted

2. Measurements and constants (for example actual wood volume produced with actual

Author claims that discrepancies occurred due to several reasons. Gross data did not cover all the measurements performed, problems occurred between boundary operations and

1. Measurements of actual consumption of fossil fuel and actual delivery of timber.

machine hours, but with a measured constant of fuel/machine hour).

3. Local averages of data concerning equipment of the specific area.

authors propose the rotation (management) period to be determined in two ways:

The modelling can use these types of data (Karjalainen et al., 2001).:

For selection forests it is proposed to use a period of 120 years.

timber or tonne per kilometre of made wood transport).

modelling is based on knowledge of the past and present situation.

It is obvious that many data is not available.

**2.3 Data availability**

models. Hybrid models

proposed;

produced from two kinds of sources:

per work or time unit.

according to four origins:

4. General averages

data for the accurate analysis.

secondary transport, logging and stand treatment appeared and there was different data quality depending on data origin. Data from contractors were seldom available or not certified according to ISO standards. Available emission factors in literature were not appropriate with respect to fuels and engines used.

Berg and Karjalainen (2000) revealed the importance to depend on the origin and quality of data. In their study which was based on data of environmental loads from forest operations in Sweden and Finland in the late 1980s and early 1990s, the authors have compared records of CO2 emissions from logging operations, transport of timber to industry and some silvicultural activities. Even though harvested volumes in both countries were similar, together with operational conditions (terrain difficulty and level of mechanization in thinnings were the only differences) and machine types used in logging, mixed origin of data caused mistakes in calculating energy consumption. Two types of data were available, either from time-studies or data from follow-up routines.

Athanassiadis (2000) reported of difficulty to get specific data from the industry due to confidentiality problems. Author in his study summarizes the results from four separate studies on energy and resource consumption and emissions during the life cycle phases of harvesters and forwarders in the cut-to-length harvesting systems. Energy input during operations was 82 MJ/m3, 11% was due to energy consumption during the production phase of the fuel. Exhaust emissions varied considerably depending on the kind of fuel that was examined (rapeseed methyl ester, environmental class 1 and environmental class 3 diesel fuels) and on whether emissions produced during the production phase of the fuels were taken onto consideration. It was also estimated that 35 l/1000 m3 of chainsaw oil was used for felling and crosscutting while hydraulic oil spillage from both harvesters and forwarders was 20 l/1000 m3. 52% of the forwarder's mass was replaced during its operational lifetime, 56% of mass for single-grip harvester and 50% of mass for two-grip harvester. About 6% of the machinery's life cycle energy consumption was due to activities connected with the production of the vehicles; raw material acquisition and intermediate processing, fabrication of individual components, assembly of the vehicles and associated transports.

McManus et al. (2004) analyzed the life cycle of mineral oil and BIO (rapeseed) oil used in mobile hydraulic systems (Table 6). The authors note that the use of BIO oil is a relatively new process and that it is difficult to obtain accurate input data. In most emissions occurring in the production of both types of oil, emissions of pollutants at production of BIO oil exceed those in production of mineral oil, except in greenhouse gas emissions. Authors further conclude that although it is not always better to use the BIO (negative impact on parts of the hydraulic system - seals and hoses), production of mineral oil is by itself volatile because mineral oil is a derivative of non-renewable resources.

Schwaiger and Zimmer (2001) collected data from 12 European countries (data from Croatia was included from the study of Beuk et al. 2007) participating in the COST Action E9 "LCA of Forestry and Forest Products" (Figures 4, 5, 6). The study is restricted to the forest operations "harvesting" and "extraction" due to the lack of available data for all other forest processes such as "scarification", "stand establishment", "tending and seeding", "clearing" or "use of pesticides", "forest road construction and maintenance", "delimbing", "debarking" etc. Quantity and quality of information available varied

Forestry and Life Cycle Assessment 151

In order to create standardized and representative data suitable for comparison, harvesting was divided to felling and timber transport (Figure 5). Timber transport was further divided

Fig. 5. Removal structure and mechanization level of felling and processing

Mechanization level of timber harvesting and processing in these countries should be compared with respect to the proportion of tree species in the growing stock, type of forest management, terrain (the influence of terrain slope, surface barriers and the load-bearing

Austria 17.0 3.5 9.8 69.7 – Denmark 40.0 – – – 60.0 Finland 33.2 – 4.7 54.3 7.8 France 10.2 – 16.2 73.6 – Germany 4.3 29.6 26.1 40.0 – Greece – – – – – Ireland – – – 35.0 65.0 Italy 7.6 – 27.4 59.9 5.1 Norway 7.0 2.0 – 91.0 – Slovenia 32.6 – – 64.9 2.4 Sweden 3.4 – 8.0 49.2 39.4 Switzerland 5.0 1.0 62.0 29.0 3.0 Croatia 76.0 19.7 – 4.3 –

Corporation forests

%

Private forests

Company forests

State

State forests

Table 7. Distribution of forest ownership

to timber extraction and remote transport (Figure 6)

Federal forests

considerably. Data, such as felling, increment, forest area, etc., are available in all countries and performance data on forest operations were not often available (e.g. transport distances were assumed ...). In countries such as Austria, Finland, Switzerland and Sweden larger amounts of data were available at the national level. However, it should be noted that in none of the analyzed countries secondary forest products (in the lifecycle analysis) were not mentioned and no differences was made between the timber harvested in thinnings or in final fellings (clear cuts).

Table 6. Normalized data for the production of 1 kg of mineral and rapeseed BIO oil

Fig. 4. Data of forest land, increment and removal

Authors claim that data availability depended on forest ownership (Table 7) because data from private and company forests were often incomplete.

considerably. Data, such as felling, increment, forest area, etc., are available in all countries and performance data on forest operations were not often available (e.g. transport distances were assumed ...). In countries such as Austria, Finland, Switzerland and Sweden larger amounts of data were available at the national level. However, it should be noted that in none of the analyzed countries secondary forest products (in the lifecycle analysis) were not mentioned and no differences was made between the timber

Category Total people emission equivalents

Greenhouse gases 2.73 \*10-4 2.30\*10-5 Ozone-depleting gases 9.61\*10-12 4.59\*10-10 Acidification 3.41\*10-5 2.91\*10-5 Eutrophication 9.89\*10-6 2.68\*10-5 Heavy metals 9.23\*10-6 6.90\*10-6 Carcinogens 1.49\*10-10 5.99\*10-9 Winter smog 1.91\*10-5 1.03\*10-5 Summer smog 8.96\*10-10 2.67\*10-5 Pesticides 0 1.48\*10-5 Energy 3.73\*10-5 3.89\*10-5 Solid waste 0 0

Table 6. Normalized data for the production of 1 kg of mineral and rapeseed BIO oil

Authors claim that data availability depended on forest ownership (Table 7) because data

Mineral oil BIO rapeseed oil

harvested in thinnings or in final fellings (clear cuts).

Fig. 4. Data of forest land, increment and removal

from private and company forests were often incomplete.

Table 7. Distribution of forest ownership

In order to create standardized and representative data suitable for comparison, harvesting was divided to felling and timber transport (Figure 5). Timber transport was further divided to timber extraction and remote transport (Figure 6)

Fig. 5. Removal structure and mechanization level of felling and processing

Mechanization level of timber harvesting and processing in these countries should be compared with respect to the proportion of tree species in the growing stock, type of forest management, terrain (the influence of terrain slope, surface barriers and the load-bearing

Forestry and Life Cycle Assessment 153

forest roads), the greatest attention was on relative fuel consumption due to the volume of

Felling and processing Chainsaw (Stihl 026) Fedrau (2000) 4.00 1.50 0.28 3150 0.02 6.91 Chainsaw (Stihl 036) Fedrau (2000) 8.00 2.40 0.23 3150 0.02 6.91 Chainsaw (Stihl 026/036) Fedrau (2000) 6.00 2.00 0.24 3150 0.02 6.91

Timber transport Animal (horse) FPP(1991) 1.50 – – – – – Skidder (Mahler Unifant) Fedrau (2000) 7.00 6.00 0.64 3455 2.20 5.23

Yarder (Sincrofalke) Winkler (1997) 6.00 7.20 0.90 3455 2.20 5.23

Truck (MAN) Frischnecht (1995) – 4.00 3180 0.10 0.20

Fuel consumption

The total amount of pollutants disposed into the environment during forest operations is directly linked with the consumption of fossil fuels. Table 10 shows the estimated fuel

kg/m3 \* 100 km t

Table 8. Productivity, fuel consumption and amount of exhaust gasses in harvesting

Austria 1.47 38 Denmark 1.28 48 Finland 1.16 56 Germany 1.42 40 Greece 1.47 24 Ireland 1.43 40 Italy 1.42 44 Norway 1.28 50 Slovenia 1.42 40 Sweden 1.14 60 Switzerland 1.42 40

consumption

Knechtle (1997) 13.00 11.30 0.77 3455 2.20 5.23

Knechtle (1997) 17.00 9.80 0.43 3455 2.20 5.23

(1989) 1.50 – – – – –

Allowed weight

m3/h l/h kg/m3 g/kg fuel

Exhaust gasses CO2 N2O CH4

(producer) Reference Productivity Fuel

transported wood (Table 9).

Means of work

Harvester (Timberjack

Forwarder (Timberjack

Log line (Leykam) Trzesniowski

Country

Table 9. Fuel consumption and total allowed weight of trucks

consumption in European countries in different harvesting operations.

Source: Schwaiger i Zimmer (2001)

1270)

810B)

operations

capacity of forest vehicles) and to the relationship between incomes gained in timber felling (Figure 4).

Fig. 6. Structure of timber extraction and further transport

On the choice of extraction vehicles used, the above-mentioned terrain factors and certainly the level of road openness was crucial which has led to significant performance differences in the primary timber transport between European countries (Figure 5).

Remote (secondary) timber transport for all European countries mainly relies on the transport of timber by trucks (> 75%).

Shares of transport by rail and water in some European countries are related to the existence of a network of railroads and their affiliation with the international transport corridors, or the existence of navigable waterways.

In analyzing life cycle, except general information related to individual forestry (Figures 3, 4 and 5), the environmental assessment is required and the data on productivity, fuel consumption and the amount of discharged pollutants are an integral part of each harvesting systems (Table 8).

Transport of timber with trucks significantly affects the life cycle analysis, because fuel consumption and exhaust (GHG) emissions depend on the distance of transport and vehicle type. It should be noted that legal restrictions vary considerably within European countries (Table 9), and that the total number of axles affect considerably on the permissible weight of the vehicle and trailer. Fuel consumption per kilometre for trucks depends on the type and age of the vehicle, its total weight and the distance of timber transportation. However, due to lack of data on the structure of passed kilometres, depending on the type of road (public,

capacity of forest vehicles) and to the relationship between incomes gained in timber felling

On the choice of extraction vehicles used, the above-mentioned terrain factors and certainly the level of road openness was crucial which has led to significant performance differences

Remote (secondary) timber transport for all European countries mainly relies on the

Shares of transport by rail and water in some European countries are related to the existence of a network of railroads and their affiliation with the international transport corridors, or

In analyzing life cycle, except general information related to individual forestry (Figures 3, 4 and 5), the environmental assessment is required and the data on productivity, fuel consumption and the amount of discharged pollutants are an integral part of each

Transport of timber with trucks significantly affects the life cycle analysis, because fuel consumption and exhaust (GHG) emissions depend on the distance of transport and vehicle type. It should be noted that legal restrictions vary considerably within European countries (Table 9), and that the total number of axles affect considerably on the permissible weight of the vehicle and trailer. Fuel consumption per kilometre for trucks depends on the type and age of the vehicle, its total weight and the distance of timber transportation. However, due to lack of data on the structure of passed kilometres, depending on the type of road (public,

Fig. 6. Structure of timber extraction and further transport

transport of timber by trucks (> 75%).

the existence of navigable waterways.

harvesting systems (Table 8).

in the primary timber transport between European countries (Figure 5).

(Figure 4).

forest roads), the greatest attention was on relative fuel consumption due to the volume of transported wood (Table 9).

Source: Schwaiger i Zimmer (2001)

Table 8. Productivity, fuel consumption and amount of exhaust gasses in harvesting operations

Table 9. Fuel consumption and total allowed weight of trucks

The total amount of pollutants disposed into the environment during forest operations is directly linked with the consumption of fossil fuels. Table 10 shows the estimated fuel consumption in European countries in different harvesting operations.

Forestry and Life Cycle Assessment 155

Use of materials at the end of the life cycle - materials recovery and recycling with reuse

The greatest impact on the environment throughout the life cycle of both vehicles had a period of vehicle use (Figure 8). Period of vehicle use should be perceived by the two parameters known in the cost calculations of machine work: 1) normal use of the vehicle corresponds to the number of operating hours during which the operating cost per hour does not increase due to increased maintenance costs (for the harvester and forwarder it is usually 10 000 operating hours), 2) during the obsolescence of the vehicle which corresponds to the greatest time period in years when the use of the vehicle is still economical, and after which comes technological obsolescence (corrosion, fatigue) and reduction of operational safety (for the harvester and forwarder it is usually 10 years).

 The most important pollutants are vehicle exhaust gasses, carbon dioxide (as the most important greenhouse gas that affects global warming), nitrogen oxides (as one of the causes of acid rain), and as well as sulphur oxides (cause

The environmental benefit of each product is presented with the possibility for recycling or reuse of materials at the end of its life cycle. Recycling must be primarily technologically feasible, and economically viable. The rate of vehicle recycling at the end of its period of use is determined by the ratio of the mass of materials that can be recycled and the total mass of the vehicle. According to EU Directive 2000/53/EC, the rate of recovery at the end of the period of use of vehicles must be at least 80% (i.e. 85% when reusable parts of the machine are taken into account). Till the year 2015 the prescribed recycling rate will be 85% (i.e. 95%

of parts and storage of non-recyclable materials.

Fig. 7. Environmental suitability of some harvesting technologies

when reusable parts of the machine are taken into account).

respiratory diseases).

Table 10. Estimated fossil fuel input for harvesting operations

Authors conclude that the forest data availability in European countries differs significantly. While data of forest land use (ha), distribution of tree species (%), growing stock, increment and harvested volume (m3) are available in all countries, specific data and information on different forest operation are rather small.

Heinimann et al. (2006) state that since the introduction of ISO 14 030 environmental impact awareness became more present, but there is still nevertheless a small number of prepared and/or published studies with forestry topics. The same author explores the environmental benefits of certain harvesting operations with respect to energy consumption, carbon dioxide emission, as well as carbon sequestration. Determines the energy consumption in the range of 0.12 to 0.62 MJ/kg, which is only 0.5 – 3.7% of energy gained form forest biomass production. The CO2 emissions amounted to 0.005 to 0.032 kg/kg of forest biomass, for which from 0.005 to 0.018 kg of forest biomass must be produced which would lead to carbon sequestration in trees. Although it was previously thought that felling and processing of wood with a chainsaw (motor-manual cutting) is more environmentally friendly, it was proved by the author that completely mechanized felling and processing (harvester-forwarder system) of short wood has the same impact on the environment (Figure 7).

Data on the life cycle of machines used in forestry can also be obtained from some manufacturers. Timberjack (John Deere Group member) in its "environmental label" provides information about the environmental impact of harvester Timberjack 770 and Timberjack 1410 forwarders throughout their life cycle (Figure 8), which is divided into these five periods:

Country Felling and processing Timber extraction Further transport Total

Austria 0.31 0.59 3.68 4.60 Denmark 0.51 0.46 1.28 2.30 Finland 0.73 0.36 2.08 3.20 Germany 0.40 0.58 1.42 2.40 Greece 0.28 0.45 5.89 6.60 Ireland 0.75 0.48 1.98 3.20 Italy 0.24 0.64 0.86 1.70 Norway 0.60 0.47 1.41 2.50 Slovenia 0.24 0.62 0.99 1.90 Sweden 0.77 0.43 2.08 3.30 Switzerland 0.25 0.58 1.22 2.00

Authors conclude that the forest data availability in European countries differs significantly. While data of forest land use (ha), distribution of tree species (%), growing stock, increment and harvested volume (m3) are available in all countries, specific data and information on

Heinimann et al. (2006) state that since the introduction of ISO 14 030 environmental impact awareness became more present, but there is still nevertheless a small number of prepared and/or published studies with forestry topics. The same author explores the environmental benefits of certain harvesting operations with respect to energy consumption, carbon dioxide emission, as well as carbon sequestration. Determines the energy consumption in the range of 0.12 to 0.62 MJ/kg, which is only 0.5 – 3.7% of energy gained form forest biomass production. The CO2 emissions amounted to 0.005 to 0.032 kg/kg of forest biomass, for which from 0.005 to 0.018 kg of forest biomass must be produced which would lead to carbon sequestration in trees. Although it was previously thought that felling and processing of wood with a chainsaw (motor-manual cutting) is more environmentally friendly, it was proved by the author that completely mechanized felling and processing (harvester-forwarder system) of short wood has the same impact on the environment

Data on the life cycle of machines used in forestry can also be obtained from some manufacturers. Timberjack (John Deere Group member) in its "environmental label" provides information about the environmental impact of harvester Timberjack 770 and Timberjack 1410 forwarders throughout their life cycle (Figure 8), which is divided into these five periods:

Extraction of raw materials - the impact on the environment during the manufacture of

Production of the vehicle - the impact on the environment in the development and

Use of vehicles - dumping pollutants into the environment due to the consumption of

Vehicle maintenance and repairs - the environmental impact of disposal and recycling

preparation of the vehicle (determined by ISO 14001);

of old oil, tires and other vehicle parts;

Table 10. Estimated fossil fuel input for harvesting operations

different forest operation are rather small.

(Figure 7).

steel, cast iron, rubber ...

fuels and lubricants;

kg fuel/m3

 Use of materials at the end of the life cycle - materials recovery and recycling with reuse of parts and storage of non-recyclable materials.

Fig. 7. Environmental suitability of some harvesting technologies

The greatest impact on the environment throughout the life cycle of both vehicles had a period of vehicle use (Figure 8). Period of vehicle use should be perceived by the two parameters known in the cost calculations of machine work: 1) normal use of the vehicle corresponds to the number of operating hours during which the operating cost per hour does not increase due to increased maintenance costs (for the harvester and forwarder it is usually 10 000 operating hours), 2) during the obsolescence of the vehicle which corresponds to the greatest time period in years when the use of the vehicle is still economical, and after which comes technological obsolescence (corrosion, fatigue) and reduction of operational safety (for the harvester and forwarder it is usually 10 years).

 The most important pollutants are vehicle exhaust gasses, carbon dioxide (as the most important greenhouse gas that affects global warming), nitrogen oxides (as one of the causes of acid rain), and as well as sulphur oxides (cause respiratory diseases).

The environmental benefit of each product is presented with the possibility for recycling or reuse of materials at the end of its life cycle. Recycling must be primarily technologically feasible, and economically viable. The rate of vehicle recycling at the end of its period of use is determined by the ratio of the mass of materials that can be recycled and the total mass of the vehicle. According to EU Directive 2000/53/EC, the rate of recovery at the end of the period of use of vehicles must be at least 80% (i.e. 85% when reusable parts of the machine are taken into account). Till the year 2015 the prescribed recycling rate will be 85% (i.e. 95% when reusable parts of the machine are taken into account).

Forestry and Life Cycle Assessment 157

Fig. 10. Environmental impact throughout different life cycle phases of a slash bundler and

larger task than assumed. Even if there is a good knowledge of the total emissions and the energy demand of the factory, the processes are often integrated and there are problems allocating different emissions to the products. In addition to the internal problems of finding the correct data from the manufacturing processes there are problems to procure data from the processing of raw materials (forest products and chemicals). Author further claims that some pulp and paper companies have established their own expertise in the field of LCA on

 LCA may be used in the process to select the most environmentally friendly product. It is emphasised that it may be difficult to get a just result from such comparisons because

different system boundaries in the assessment will lead to different answers; LCA may be used as a tool to identify the points in the production process which gives the highest environmental impacts and where the potential improvement is the highest;

Fig. 9. Harvester and forwarder recyclability rate

the corporate level and have their own LCA strategy:

LCA is seen as a useful tool in the development of the new products;

its recyclability rate

Fig. 8. Environmental impact throughout different life cycle phases of harvester and forwarder

Source: Timberjack (2002)

Table 11. Pollutions during harvester and forwarder life cycle

At the end of the period of use, the harvester waste (un-recyclable materials) is less than 8% of the total mass, and forwarder waste is even smaller, only 4% of the total vehicle's mass (Figure 9).

The VTT Technical Research Centre of Finland applied the LCA method in a study to determine the most significant environmental impacts of the Timberjack 1490D slash bundler. In the LCA study of the slash bundler, environmental impact is divided into five phases:

The total emissions of carbon dioxide is 727 001 kg where 88% of the total carbon dioxide emissions occur during entire life cycle of the slash bundler. Nitrogen oxide emissions amount to 4881 kg during the slash bundler's life cycle (96% during usage phase). 1402 kg of sulphur oxides are generated (84% during usage phase) and 246 kg of particulate emissions are generated during the usage phase. Slash bundler is built on forwarder chassis, to which is attached the bundler component and the automation that drives its usage, so the recyclability rate is the same as for forwarders (Fig.10).

Økstad (1995) states that common experiences for paper and pulp industry in Norway with LCA projects in gathering data, from the production process and the raw materials, is much

Fig. 8. Environmental impact throughout different life cycle phases of harvester and forwarder

Total During

Harvester 499 000<PHONE_NUMBER> 5 293 624 523 284 256 Forwarder 509 100<PHONE_NUMBER> 4 206 713 523 232 209

At the end of the period of use, the harvester waste (un-recyclable materials) is less than 8% of the total mass, and forwarder waste is even smaller, only 4% of the total vehicle's mass (Figure 9). The VTT Technical Research Centre of Finland applied the LCA method in a study to determine the most significant environmental impacts of the Timberjack 1490D slash bundler. In the LCA study of the slash bundler, environmental impact is divided into five phases:

The total emissions of carbon dioxide is 727 001 kg where 88% of the total carbon dioxide emissions occur during entire life cycle of the slash bundler. Nitrogen oxide emissions amount to 4881 kg during the slash bundler's life cycle (96% during usage phase). 1402 kg of sulphur oxides are generated (84% during usage phase) and 246 kg of particulate emissions are generated during the usage phase. Slash bundler is built on forwarder chassis, to which is attached the bundler component and the automation that drives its usage, so the

Økstad (1995) states that common experiences for paper and pulp industry in Norway with LCA projects in gathering data, from the production process and the raw materials, is much

usage

Gaseous and particulate emission CO2 NOX, NO2 SOX, SO2 Particulates

kg

Total During

usage

Total During

usage

Vehicle type

Source: Timberjack (2002)

1. Production of materials, 2. Manufacturing of the machine,

4. Maintenance and repairs, 5. Post-use disposal.

3. Usage,

Total During

usage

Table 11. Pollutions during harvester and forwarder life cycle

recyclability rate is the same as for forwarders (Fig.10).

Fig. 9. Harvester and forwarder recyclability rate

Fig. 10. Environmental impact throughout different life cycle phases of a slash bundler and its recyclability rate

larger task than assumed. Even if there is a good knowledge of the total emissions and the energy demand of the factory, the processes are often integrated and there are problems allocating different emissions to the products. In addition to the internal problems of finding the correct data from the manufacturing processes there are problems to procure data from the processing of raw materials (forest products and chemicals). Author further claims that some pulp and paper companies have established their own expertise in the field of LCA on the corporate level and have their own LCA strategy:

Forestry and Life Cycle Assessment 159

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Athanassiadis, D., (2000). Resource consumption and emissions induced by logging

Berg, S. and Karjalainene, T. (2000). Comparision of emissions from forest operations in

Beuk, D., Ž. Tomašić, D. Horvat, (2007). Status and development of forest harvesting

Cowell, S. J., & Clift, R. (2000). A Methodology for Assessing Soil Quantity and Quality in

De Feyter, S., (1995). Handling of the Carbon Balance of Forest in LCA. *Proceedings of the*

Frühwald, A., (1995). LCA – A Challenge for Forestry and Forest Products Industry.

Guineé, J., L. van Oers, A. de Koning, W. Tamis, (2006). Life Cycle Approaches for

Grasser, C. (1994). Ökoinventare für Energiesysteme. *Grunlagen für den ökologische Vergleich*

Häkkinen, T. and Mäkelä, K. (1996). Environemtal adaption of concrete. Environmental

Heinimann, H. R., A. Wollenmann, R. Knechtle, (2006). Life Cycle Approaches for

Jungmeier, G., (2003). System Analysis of Forestry, Forest products and Recovered Wood.

Action E9 and E31, PPT, September 30 – October 1, Österund, Sweden. Karjalainene, T., T. Apnesth, P. Esser, L. Finér, G. Jungmeier, B. Košir, K. E. Kvist, J. M.

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*Industry*, May 3–5, 1995, Hamburg, Germany, pg. 37–43.

*products*. Technical annex, April 11, 1997, Bruxelles, Belgium.

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Espooo/Finland, Dipoli 27-29 March 2000.

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poster presentation.

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Finland and Sweden. *Presentation at COST Action E9*, Mid-term Seminar in

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*International Workshop: Life-Cycle Analysis – A Challenge for Forestry and Forest*

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Conservation Agriculture, Part I: A definition study for data analysis. *CML report 171*, June 2006, Universiteit Leiden, ISBN-10: 90-5191-148-3, Leiden, Netherlands, pg. 1–67.

*van Energiesystemen und der Einbezug van Energiesystemen in ökobilanzen für die*

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**4. References**

63–82.

 Having carried out LCA of their own products gives the industry much better "cards on hand" in the communication with local and national environmental authorities.

Some companies have taken the challenge and initiated their own work to collect data and carry out LCA of their activities and products, while others have a more reluctant attitude towards the method and have the opinion that the method is not fully developed to be used as a tool for industry. Author concludes that LCA is a useful tool in the development of new products and it may be used in the process of selecting the most environmentally friendly product or for highlighting points in the production process which give the highest environmental impact. In some cases LCA will be required in the licensing process of discharge permits.

#### **3. Conclusion**

Life cycle assessment is a very complex tool in the process of assessing the environmental impact of a product. To be successfully developed, high quality data sources are required that will contain all the inputs and outputs of different materials used, energy consumption and the amount of pollutants and emissions produced during:

For forestry, the life cycle assessment is particularly difficult due to the long production process of raw materials, primarily wood (length of rotation period), and because of the high spatial and temporal impact forests have on the environment. As the life cycle assessment is a static and not a dynamic tool of environmental impact, many experts believe that the spatial and temporal aspects should be excluded from the assessment itself. However, the life cycle assessment related to forestry and its products makes such exclusion impossible. Forests not only have an important social impact, but they store large amounts of carbon (carbon sequestration), protect soil and water resources, ensure biodiversity, produce oxygen, etc., thus affecting the global climate. These are beneficial functions of forests that can not and should not be ignored when dealing with life cycle assessment in forestry. On the other hand, the question of how to include all forest management activities (from silviculture to forest protection and harvesting) could be involved in the life cycle assessment of forest products.

Life cycle assessment is a good tool for determining the effects of each product (and manufacturing processes in which the product is being produced) on the environment, especially today when there is more and more awareness of environmentally friendly technologies, renewable energy and eco-efficiency. The greatest use of life cycle assessment tool in forestry, from the aspect of timber harvesting, is in comparing different harvesting systems for selecting environmentally friendly versions.

Due to the lack of quality data sources, and conversion between a static to a dynamic character of the life cycle assessment, requires further research and improvement of this otherwise useful, but very complex tool in assessing the environmental acceptability of products and production processes.

#### **4. References**

158 Global Perspectives on Sustainable Forest Management

 Having carried out LCA of their own products gives the industry much better "cards on hand" in the communication with local and national environmental authorities.

Some companies have taken the challenge and initiated their own work to collect data and carry out LCA of their activities and products, while others have a more reluctant attitude towards the method and have the opinion that the method is not fully developed to be used as a tool for industry. Author concludes that LCA is a useful tool in the development of new products and it may be used in the process of selecting the most environmentally friendly product or for highlighting points in the production process which give the highest environmental impact. In some cases LCA will be required in the licensing process of

Life cycle assessment is a very complex tool in the process of assessing the environmental impact of a product. To be successfully developed, high quality data sources are required that will contain all the inputs and outputs of different materials used, energy consumption

For forestry, the life cycle assessment is particularly difficult due to the long production process of raw materials, primarily wood (length of rotation period), and because of the high spatial and temporal impact forests have on the environment. As the life cycle assessment is a static and not a dynamic tool of environmental impact, many experts believe that the spatial and temporal aspects should be excluded from the assessment itself. However, the life cycle assessment related to forestry and its products makes such exclusion impossible. Forests not only have an important social impact, but they store large amounts of carbon (carbon sequestration), protect soil and water resources, ensure biodiversity, produce oxygen, etc., thus affecting the global climate. These are beneficial functions of forests that can not and should not be ignored when dealing with life cycle assessment in forestry. On the other hand, the question of how to include all forest management activities (from silviculture to forest protection and harvesting) could be involved in the life cycle

Life cycle assessment is a good tool for determining the effects of each product (and manufacturing processes in which the product is being produced) on the environment, especially today when there is more and more awareness of environmentally friendly technologies, renewable energy and eco-efficiency. The greatest use of life cycle assessment tool in forestry, from the aspect of timber harvesting, is in comparing different harvesting

Due to the lack of quality data sources, and conversion between a static to a dynamic character of the life cycle assessment, requires further research and improvement of this otherwise useful, but very complex tool in assessing the environmental acceptability of

and the amount of pollutants and emissions produced during:

discharge permits.

**3. Conclusion**

1. Extraction of raw materials, 2. Product production, 3. Time of product usage, 4. Possible recycling and re-use, 5. Final disposal of waste.

assessment of forest products.

products and production processes.

systems for selecting environmentally friendly versions.

**10**

 *USA*

**Wildlife Forestry**

*Patuxent Wildlife Research CenterVicksburg, Mississippi*

Wildlife forestry is management of forest resources, within sites and across landscapes, to provide sustainable, desirable habitat conditions for all forest-dependent (silvicolous) fauna while concurrently yielding economically viable, quality timber products. In practice, however, management decisions associated with wildlife forestry often reflect a desire to provide suitable habitat for rare species, species with declining populations, and exploitable (i.e., game) species. Collectively, these species are deemed priority species and they are assumed to benefit from habitat conditions that result from prescribed silvicultural

Early wildlife conservation efforts largely focused on controlling indiscriminate slaughter of wildlife by restricting the season or sex of harvested species (Graham, 1947). Subsequent conservation efforts targeted increased protection of populations through creation of sanctuaries or reserves (Knight, 1999), such as national parks and wildlife refuges, within which harvest of wildlife was prohibited or greatly restricted. Typically parks and wildlife reserves were located in areas with abundant wildlife populations, and therefore, little emphasis was placed on active management to improve or maintain

In his description of a "land ethic" in which people are members of the natural community, Leopold (1949) indicated the appropriateness of habitat alteration and management to aid the continued existence of wildlife species. His philosophical principles were succinctly stated as "*A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic*

Anthropogenic alteration of forest habitat for the benefit wildlife species has long been practiced, particularly with regard to intentional use of fire (Bonnicksen, 2000, Ford et al., 2002). Even so, active manipulation of forest structure to purposefully enhance wildlife habitat has been slow to evolve. Most early efforts regarding habitat alteration focused on providing suitable escape cover, foraging habitat, or distinct habitat features (e.g., nest sites) for game species. Within forested landscapes, improving wildlife habitat often meant increasing local heterogeneity and providing more forest edge habitat. However, increased knowledge of the possible negative effects associated with forest edges, such as greater predation and nest parasitism rates, has called into question the practice of providing

**1. Introduction**

management actions.

suitable habitat.

*community. It is wrong when it tends otherwise*."

Daniel J. Twedt *U.S. Geological Survey*

www.iso.org

www.admin.cam.ac.uk

## **Wildlife Forestry**

Daniel J. Twedt

*U.S. Geological Survey Patuxent Wildlife Research CenterVicksburg, Mississippi USA*

#### **1. Introduction**

160 Global Perspectives on Sustainable Forest Management

Lox, F. (1994). Milieubalans van vouwkarton. Vrije Universiteit Brussels, in opracht van Pro

Mcmanus, M. C., G. Hammond, C. R. Burrows, (2004). Life-cycle Assessment of Mineral and

Mroueh, U. M., P. Eskola, J. Laine-Ylijoki, K. Wellman, E. M. M. Juvankoski, A.

Nabuurus, G., J. and Mohren G., M., J. (1993). Carbon fixation through forestation activities.

Økstad, E., (1995). Experience with LCA in the pulp, paper and packaging industry in

Timberjack, (2002*): Green forest machines for sustainable development – Environmental Declaration.* Timberjack – A John Deere Company, Tampere, Finland, 12 pages. Thoroe, C., J. Schweinle, (1995). Life Cycle Analysis in Forestry. *Proceedings of the*

Wollenmann, R., (2006). Balancing Carbon Emission and Sequestration Fluxes of Forest Land

ISBN-10: 90-5191-148-3, Leiden, Netherlands, poster presentation.

17/2000, ISBN 951-726-633-2, Helsinki, Finland, 59 pages.

and Nature Research (IBN-DLO), Arnhem/Wageningen.

paper 10, : 952-9844-92-1, Joensuu, Finland, pg. 33–53.

ISBN<PHONE_NUMBER>, London, UK, 166 pages.

www.iso.org

www.admin.cam.ac.uk

Rapeseed Oil in Mobile Hydraulics Systems. *Journal of Industrial Ecology*, 7(3–4):

Ruotoistenmäki, (2000). Life Cycle Assessment of Road Construction. *Finnra report*,

*A study of the carbon sequestration potential of selected forest types*. Institute for Forestry

Norway. *Proceedings of the International Workshop: Life-Cycle Analysis – A Challenge for Forestry and Forest Industry*, May 3–5, 1995, Hamburg, Germany, pg. 141–149. Ranta, J., Wahlström, M., Rouhomäki, J., Häkkinen, T. and Lindroos, P. (1987). Desulphurisation products of coal combustion plants. *VTT Research Notes 741*. Espoo, 140 pages. Schwaiger, H., B. Zimmer, (2001). A comparison of Fuel Consumption and Greenhouse Gas

Emissions from Forest Operations in Europe. *Energy, Carbon and Other Material Flows in the Life Cycle Assessment of Forestry and Forest Products.* Achievements of the working group 1 of the COST action E9, European Forest Institute, Discussion

*International Workshop: Life-Cycle Analysis – A Challenge for Forestry and Forest Industry*, May 3–5, 1995, ISBN: 952-9844-16-6, Hamburg, Germany, pg. 15–24. Virtanen, Y. and Nilsson, S. (1993). Environmental impacts of waste paper recycling.

International Institute for Applied Systems Analysis, Earthscan Publications Ltd,

Based on LCI – approach. ). Life Cycle Approaches for Conservation Agriculture, Part I: A definition study for data analysis. *CML report 171*, June 2006, Universiteit Leiden,

Carton België, draft, april 1994.

163–177, ISSN: 1530-9290.

Wildlife forestry is management of forest resources, within sites and across landscapes, to provide sustainable, desirable habitat conditions for all forest-dependent (silvicolous) fauna while concurrently yielding economically viable, quality timber products. In practice, however, management decisions associated with wildlife forestry often reflect a desire to provide suitable habitat for rare species, species with declining populations, and exploitable (i.e., game) species. Collectively, these species are deemed priority species and they are assumed to benefit from habitat conditions that result from prescribed silvicultural management actions.

Early wildlife conservation efforts largely focused on controlling indiscriminate slaughter of wildlife by restricting the season or sex of harvested species (Graham, 1947). Subsequent conservation efforts targeted increased protection of populations through creation of sanctuaries or reserves (Knight, 1999), such as national parks and wildlife refuges, within which harvest of wildlife was prohibited or greatly restricted. Typically parks and wildlife reserves were located in areas with abundant wildlife populations, and therefore, little emphasis was placed on active management to improve or maintain suitable habitat.

In his description of a "land ethic" in which people are members of the natural community, Leopold (1949) indicated the appropriateness of habitat alteration and management to aid the continued existence of wildlife species. His philosophical principles were succinctly stated as "*A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong when it tends otherwise*."

Anthropogenic alteration of forest habitat for the benefit wildlife species has long been practiced, particularly with regard to intentional use of fire (Bonnicksen, 2000, Ford et al., 2002). Even so, active manipulation of forest structure to purposefully enhance wildlife habitat has been slow to evolve. Most early efforts regarding habitat alteration focused on providing suitable escape cover, foraging habitat, or distinct habitat features (e.g., nest sites) for game species. Within forested landscapes, improving wildlife habitat often meant increasing local heterogeneity and providing more forest edge habitat. However, increased knowledge of the possible negative effects associated with forest edges, such as greater predation and nest parasitism rates, has called into question the practice of providing

Wildlife Forestry 163

Fig. 1. Characterization of wildlife forestry silvicultural methodology.

Silviculture is the manipulation of the establishment, growth, composition, and quality of forest vegetation to achieve management objectives. Historically a primary objective on managed forest lands has been to maximize financial returns from production of forest

**2. Forest management**

increased heterogeneity within forested landscapes. At the same time, a desire to provide habitat for specific species that may require specialized habitat conditions, as is the case for some endangered and threatened species as well as other charismatic megafauna with widespread public support, has prompted development of habitat management prescriptions designed to improve forest habitat conditions for specific species (Wilson et al., 2007).

Partly in response to what has been perceived as management for single-species, but also to advocate a desire to prevent future population declines of common species, recent emphases in wildlife conservation have been placed on the development of comprehensive, eco-regional, conservation plans whose scope encompasses multiple species or the entirety of a species-group. This approach gained momentum with the North American Waterfowl Management Plan (1986) which identified conservation actions intended to return waterfowl populations to their former abundance and distribution. Subsequently, this basic concept has been expanded to other species groups such as songbirds (Rich et al., 2004), reptiles and amphibians (Bailey et al., 2006), and shorebirds (Brown et al., 2001), as well as other species groups. Although these conservation plans differ markedly with regard to their recommendations for habitat management, many of these conservation plans advocate use of prophylactic management prescriptions to enhance or maintain suitable habitat conditions for priority wildlife species. Indeed, most conservation plans recognize the need for alteration of habitat and landscapes via management actions so as to attain the desired distribution, abundance, and viability of priority wildlife species.

Before managers can provide appropriate forest habitat for priority wildlife, the landscape and site characteristics that contribute to viable populations of these species must be identified. Preferably, those forest habitat characteristics identified can be quantified via standard measurement protocols. If possible, the desired or acceptable range of values should be determined, and either quantitatively or qualitatively stated, for each of these characteristics. In addition, a threshold value for each characteristic should be determine, that if exceeded would justify prescription of management actions to return site characteristics within the desired range (Fig. 1).

Because wildlife forestry silviculture does not target optimal production of forest products, many forest management practitioners (i.e., foresters) have been reluctant to adopt these alternative silvicultural practices. Indeed, these concerns may be justified, as desired stand conditions may include less then fully stocked stand densities, retention of some economically mature trees, maintaining species diversity which includes less merchantable tree species, and preservation of less vigorous (decadent) trees. However, at present we lack credible, long-term economic data to suggest that development and maintenance of quality forest habitat for priority wildlife species will result in a sacrifice in timber production or quality. Regardless of these overarching financial concerns, silvicultural management actions prescribed to enhance desirable forest habitat conditions for priority wildlife species are expected to be commercially viable. Maintaining the long-term commercial viability of prescribed silviculture is import, because without sufficient financial returns, needed management actions will not be undertaken.

increased heterogeneity within forested landscapes. At the same time, a desire to provide habitat for specific species that may require specialized habitat conditions, as is the case for some endangered and threatened species as well as other charismatic megafauna with widespread public support, has prompted development of habitat management prescriptions designed to improve forest habitat conditions for specific species (Wilson et

Partly in response to what has been perceived as management for single-species, but also to advocate a desire to prevent future population declines of common species, recent emphases in wildlife conservation have been placed on the development of comprehensive, eco-regional, conservation plans whose scope encompasses multiple species or the entirety of a species-group. This approach gained momentum with the North American Waterfowl Management Plan (1986) which identified conservation actions intended to return waterfowl populations to their former abundance and distribution. Subsequently, this basic concept has been expanded to other species groups such as songbirds (Rich et al., 2004), reptiles and amphibians (Bailey et al., 2006), and shorebirds (Brown et al., 2001), as well as other species groups. Although these conservation plans differ markedly with regard to their recommendations for habitat management, many of these conservation plans advocate use of prophylactic management prescriptions to enhance or maintain suitable habitat conditions for priority wildlife species. Indeed, most conservation plans recognize the need for alteration of habitat and landscapes via management actions so as to attain the desired distribution, abundance,

Before managers can provide appropriate forest habitat for priority wildlife, the landscape and site characteristics that contribute to viable populations of these species must be identified. Preferably, those forest habitat characteristics identified can be quantified via standard measurement protocols. If possible, the desired or acceptable range of values should be determined, and either quantitatively or qualitatively stated, for each of these characteristics. In addition, a threshold value for each characteristic should be determine, that if exceeded would justify prescription of management actions to return site

Because wildlife forestry silviculture does not target optimal production of forest products, many forest management practitioners (i.e., foresters) have been reluctant to adopt these alternative silvicultural practices. Indeed, these concerns may be justified, as desired stand conditions may include less then fully stocked stand densities, retention of some economically mature trees, maintaining species diversity which includes less merchantable tree species, and preservation of less vigorous (decadent) trees. However, at present we lack credible, long-term economic data to suggest that development and maintenance of quality forest habitat for priority wildlife species will result in a sacrifice in timber production or quality. Regardless of these overarching financial concerns, silvicultural management actions prescribed to enhance desirable forest habitat conditions for priority wildlife species are expected to be commercially viable. Maintaining the long-term commercial viability of prescribed silviculture is import, because without sufficient financial returns, needed management actions will not

al., 2007).

and viability of priority wildlife species.

characteristics within the desired range (Fig. 1).

be undertaken.

#### **2. Forest management**

Silviculture is the manipulation of the establishment, growth, composition, and quality of forest vegetation to achieve management objectives. Historically a primary objective on managed forest lands has been to maximize financial returns from production of forest

Wildlife Forestry 165

between managed and natural forest stands are exacerbated over time, as natural stands approach climax or 'old-growth' conditions while intensively managed forests are

To mitigate the detrimental effects of forest management on priority wildlife species, recommendations have been made to increase the length of production cycles, thereby allowing increased time for development of heterogeneous forest structure (Kerr, 1999). Unfortunately, small increases in rotation lengths provide little opportunity for increased complexity of forest structure within these stands – and periodic, complete harvest and stand regeneration thwart retention of forest structure over time. Similarly, forest managers have argued that temporal and spatial dispersion of clear-cuts throughout landscapes will provide continual availability of wildlife habitat – albeit at different locations. Although early-successional habitat may be continuously afforded via such dispersion, few of the other benefits conferred by increased forest structural heterogeneity, such as emergent or

Increased recognition of the structural and ecological deficiencies within productionoriented forests has spurred interest in and development of alternative silviculture (Franklin, 1989). Alternative silviculture has been especially valuable for stands where management objectives are not solely financial but where stewardship objectives include preservation of regional biodiversity, enhancement of wildlife habitat, maintaining

Alternative silvicultural methods developed for use in many forest types have been based on identification and quantification of natural disturbance regimes, with subsequent implementation of silvicultural methods intended to emulate these disturbances (Mitchell et al., 2002, 2006; Palik et al., 2002). For many forest types, emulation of natural disturbance regimes includes small-scale disturbances implemented via single-tree and patch-cut harvests (Franklin et al., 2007, North and Keeton, 2008). If successfully implemented, emulation of natural disturbance regimes should promote natural stand development and succession. Unfortunately, natural stand development and concurrent successional changes may conflict with landowner objectives if succession results in changed species composition or reduced financial returns. Moreover, strict adherence to silvicultural regimes that mimic natural disturbance may not be necessary to maintain biodiversity or to provide desired

Another common alternative silviculture has been inspired by the desire to achieve forest structure reminiscent of old-growth forest (Bauhus et al., 2009). Although the structure of old-growth forest varies among forest types (Hayward, 1991), common attributes generally include increased vertical heterogeneity via a multi-layered canopy, increased horizontal heterogeneity associated with canopy gaps and different regeneration cohorts, the presence of large trees that are often in older-age classes, abundant snags (standing dead trees) or senescent trees, and large diameter downed woody debris (Bauhus et al., 2009, Keeton, 2006). Myriad ecological benefits, including increased biodiversity, have been ascribed to old-growth forests (Lindenmayer and Franklin, 2002). As such, forest reserve lands have been designated (e.g., wilderness areas and parks) which afford unfettered, natural development of these characteristics. However, on lands with timber production as an objective, even if not the sole objective, implementation of production cycles that span hundreds of years is not likely to occur. In addition, merely increasing the length of

landscape aesthetics, or providing increased recreational opportunities.

repeatedly regenerated.

senescent legacy trees, are realized.

wildlife habitat (Palik et al., 2002).

products such as timber and wood pulp. Production-oriented silviculture has focused on reducing the length of production cycles between stand regeneration and harvest while concurrently maximizing wood product yields. Reduction of production cycles (i.e., rotation length) tends to lessen the time regenerating forests are in early seral habitats, and consequently the size and age of shrubs and there their likelihood of persistence within subsequent seral stages is reduced (Hagar, 2004). Often production-forestry objectives favored a limited number of tree species due to their high economic value or growth potential. Concomitantly, to increase growth and yield of desired trees, other species with lesser economic value, as well as congeneric competitors, were culled. These actions result in increased spatial homogeneity within managed stands. The apogee of this trend towards increased spatial regularity is expressed within planted plantation forests. Climate, soils, species, and other factors affect the optimal length of production cycles within productionoriented forests (Lindenmayer et al., 1999). Thus, rotation periods within plantations vary markedly from rotations of up to 150 years to as few as 10 years. Notably, recent developments and increased advocacy of short-rotation woody coppice systems for use in biomass production have further compressed the length of production cycles to <4 years (Tubby and Armstrong, 2002).

Even in non-plantation forest management systems, historical forest management practices, especially those focused on timber or pulpwood production, have often resulted in relatively homogeneous mature forest conditions. This homogeneity has been exacerbated by environmental changes that limit natural disturbances within forest stands (e.g., fire suppression). When these homogenous forests are managed using even-aged silviculture, during which all or most trees are harvested and the entire stand regenerated, successional 'boom and bust' conditions are dispersed throughout landscapes. The forest conditions resulting from even-aged management (e.g., clear cuts) are temporarily favorable for some species, specifically benefiting species that exploit early-successional forest habitat (Askins, 2001, Hunter et al., 2001). Even so, these early-successional habitats are transitory and are followed by an extended period of stand development (stem exclusion and understory reinitiation; Oliver and Larson, 1996) during which the homogeneous, closed-canopy forest structure with sparse understory vegetation offers attraction (forage or cover) primarily for common (non-priority) forest wildlife species. Indeed, the abundance of homogeneous, closed canopy forests with sparse understory cover that have resulted from historical silvicultural practices may have contributed to why species for which these habitat conditions are suitable are considered common and are not priority species in need of management actions to increase their abundance. In addition, the altered (often depauperate) species compositions that have resulted from selective harvest and culling during past management practices may amplify the potential for catastrophic damage from outbreaks of insects or diseases or limit the seasonality of mast crops that are exploited by wildlife.

In contrast to the relatively short periodicity of production-oriented silviculture and the periodic boom-bust cycles associated with even-aged silviculture, natural successional processes within forests may require hundreds, or potentially a thousand, years to achieve complete replacement via small-scale disturbance or as the duration between catastrophic stand-replacement events. Owing to differences in their successional development, structural and ecological characteristics within production-oriented managed forests and in forests managed using even-aged silviculture are manifestly different from those same characteristics within natural forests (Seymour and Hunter, 1999). Ecological differences

products such as timber and wood pulp. Production-oriented silviculture has focused on reducing the length of production cycles between stand regeneration and harvest while concurrently maximizing wood product yields. Reduction of production cycles (i.e., rotation length) tends to lessen the time regenerating forests are in early seral habitats, and consequently the size and age of shrubs and there their likelihood of persistence within subsequent seral stages is reduced (Hagar, 2004). Often production-forestry objectives favored a limited number of tree species due to their high economic value or growth potential. Concomitantly, to increase growth and yield of desired trees, other species with lesser economic value, as well as congeneric competitors, were culled. These actions result in increased spatial homogeneity within managed stands. The apogee of this trend towards increased spatial regularity is expressed within planted plantation forests. Climate, soils, species, and other factors affect the optimal length of production cycles within productionoriented forests (Lindenmayer et al., 1999). Thus, rotation periods within plantations vary markedly from rotations of up to 150 years to as few as 10 years. Notably, recent developments and increased advocacy of short-rotation woody coppice systems for use in biomass production have further compressed the length of production cycles to <4 years

Even in non-plantation forest management systems, historical forest management practices, especially those focused on timber or pulpwood production, have often resulted in relatively homogeneous mature forest conditions. This homogeneity has been exacerbated by environmental changes that limit natural disturbances within forest stands (e.g., fire suppression). When these homogenous forests are managed using even-aged silviculture, during which all or most trees are harvested and the entire stand regenerated, successional 'boom and bust' conditions are dispersed throughout landscapes. The forest conditions resulting from even-aged management (e.g., clear cuts) are temporarily favorable for some species, specifically benefiting species that exploit early-successional forest habitat (Askins, 2001, Hunter et al., 2001). Even so, these early-successional habitats are transitory and are followed by an extended period of stand development (stem exclusion and understory reinitiation; Oliver and Larson, 1996) during which the homogeneous, closed-canopy forest structure with sparse understory vegetation offers attraction (forage or cover) primarily for common (non-priority) forest wildlife species. Indeed, the abundance of homogeneous, closed canopy forests with sparse understory cover that have resulted from historical silvicultural practices may have contributed to why species for which these habitat conditions are suitable are considered common and are not priority species in need of management actions to increase their abundance. In addition, the altered (often depauperate) species compositions that have resulted from selective harvest and culling during past management practices may amplify the potential for catastrophic damage from outbreaks of insects or diseases or limit the seasonality

In contrast to the relatively short periodicity of production-oriented silviculture and the periodic boom-bust cycles associated with even-aged silviculture, natural successional processes within forests may require hundreds, or potentially a thousand, years to achieve complete replacement via small-scale disturbance or as the duration between catastrophic stand-replacement events. Owing to differences in their successional development, structural and ecological characteristics within production-oriented managed forests and in forests managed using even-aged silviculture are manifestly different from those same characteristics within natural forests (Seymour and Hunter, 1999). Ecological differences

(Tubby and Armstrong, 2002).

of mast crops that are exploited by wildlife.

To mitigate the detrimental effects of forest management on priority wildlife species, recommendations have been made to increase the length of production cycles, thereby allowing increased time for development of heterogeneous forest structure (Kerr, 1999). Unfortunately, small increases in rotation lengths provide little opportunity for increased complexity of forest structure within these stands – and periodic, complete harvest and stand regeneration thwart retention of forest structure over time. Similarly, forest managers have argued that temporal and spatial dispersion of clear-cuts throughout landscapes will provide continual availability of wildlife habitat – albeit at different locations. Although early-successional habitat may be continuously afforded via such dispersion, few of the other benefits conferred by increased forest structural heterogeneity, such as emergent or senescent legacy trees, are realized.

Increased recognition of the structural and ecological deficiencies within productionoriented forests has spurred interest in and development of alternative silviculture (Franklin, 1989). Alternative silviculture has been especially valuable for stands where management objectives are not solely financial but where stewardship objectives include preservation of regional biodiversity, enhancement of wildlife habitat, maintaining landscape aesthetics, or providing increased recreational opportunities.

Alternative silvicultural methods developed for use in many forest types have been based on identification and quantification of natural disturbance regimes, with subsequent implementation of silvicultural methods intended to emulate these disturbances (Mitchell et al., 2002, 2006; Palik et al., 2002). For many forest types, emulation of natural disturbance regimes includes small-scale disturbances implemented via single-tree and patch-cut harvests (Franklin et al., 2007, North and Keeton, 2008). If successfully implemented, emulation of natural disturbance regimes should promote natural stand development and succession. Unfortunately, natural stand development and concurrent successional changes may conflict with landowner objectives if succession results in changed species composition or reduced financial returns. Moreover, strict adherence to silvicultural regimes that mimic natural disturbance may not be necessary to maintain biodiversity or to provide desired wildlife habitat (Palik et al., 2002).

Another common alternative silviculture has been inspired by the desire to achieve forest structure reminiscent of old-growth forest (Bauhus et al., 2009). Although the structure of old-growth forest varies among forest types (Hayward, 1991), common attributes generally include increased vertical heterogeneity via a multi-layered canopy, increased horizontal heterogeneity associated with canopy gaps and different regeneration cohorts, the presence of large trees that are often in older-age classes, abundant snags (standing dead trees) or senescent trees, and large diameter downed woody debris (Bauhus et al., 2009, Keeton, 2006). Myriad ecological benefits, including increased biodiversity, have been ascribed to old-growth forests (Lindenmayer and Franklin, 2002). As such, forest reserve lands have been designated (e.g., wilderness areas and parks) which afford unfettered, natural development of these characteristics. However, on lands with timber production as an objective, even if not the sole objective, implementation of production cycles that span hundreds of years is not likely to occur. In addition, merely increasing the length of

Wildlife Forestry 167

Fig. 2. Potential distribution of legacy elements after application of alternative silviculture, differing in quantity of retained canopy cover (a, b) or dispersion of retained elements (c, d).

Loss of diversity within landscapes is often a reflection of the increased homogeneity within forest stands. Although forest structure within a landscape ranges from regenerating stands to mature merchantable stands, these stands may be monotypic in species composition and physical structure. In addition, ensuring appropriate size of habitat patches and maintaining connectivity among these patches is critical to sustaining viable wildlife populations within landscapes (Franklin and Forman, 1987). Although the appropriate patch size is dependent upon the species under consideration, increased fragmentation tends to disrupt dispersion of fauna and flora and when habitat area is reduced without appropriate connectivity, extirpation of some species can result (MacArthur and Wilson, 1967). Finally, maintaining landscapes capable of sustaining viable wildlife populations requires that evaluation, planning, and management decisions reflect the temporal processes inherent in the ecosystem. Four landscape conditions have been recognized as contributing to ecosystems that support sustainable wildlife populations: 1) diversity within the landscape, 2) connectivity among landscape elements, 3) appropriate habitat patch sizes, and 4) sufficient time to achieve ecological functions (Silva, 1992). The impact of the degradation of forest landscapes was succinctly summarized by Franklin (1989) as: "*In general, we have tended to forget that what is good for wood production is not necessarily good for other organisms or processes in a forest ecosystem. Fully stocked young forests,… are the most simplified stage of forest development in terms of structure and function, and the most impoverished in terms of biological*

production cycles may provide little enhancement of biodiversity if the forest structure favored by production-oriented silviculture is maintained (Carey, 2006). Furthermore, where forest reserves are small or located within inhospitable landscapes, full ecological benefits of old-growth forests may not be attainable or sustainable (Kneeshaw and Gauthier, 2003).

Fortunately, it is likely that many of the benefits conferred by old-growth forests, or at least specific species associated with old-growth forests, are positively related to the heterogeneous structure (vertical and horizontal) and other structural attributes found within these forests, not necessarily with the prolonged existence of these forests (Beggs, 2004, Carey, 2003b). As such, alternative silvicultural methods have been developed which retain or enhance structural heterogeneity within managed forests, thereby promoting structural attributes of old-growth forests and encouraging greater biodiversity (Bauhus et al., 2009, Garman et al., 2003; McClellan, 2004). Most often, increased heterogeneity and other desired attributes have been achieved via retention of living or dead trees (or other forest elements). These retained structures have been referred to as legacy elements (Franklin et al., 1997).

Based on the concept of retained legacy elements, various alternative silvicultural methods have been advocated to enhance structural complexity within managed forests (Whitman and Hagan, 2003). Some of these methods have being designated as green-tree retention harvests (Zenner, 2000), variable-retention harvests (Aubry et al., 2004. Maguire et al., 2007), dispersed retention harvests (Heithecker and Halpern, 2006), variable density thinning (Aukema and Carey, 2008), and active intentional management (Carey et al., 1999, Carey, 2006). The legacy elements retained under these different silvicultural regimes may differ markedly. Retained elements may differ in quantity (e.g., % canopy cover or % basal area retained; Fig. 2a,b) but they may also differ in their composition, as different canopy species are preferentially harvested or specific regenerating species favored for retention. In addition, the quality of retained elements may differ via selection of retained trees with differing perceived fates – from robust, canopy-emergent trees through decadent, dead or dying trees. Moreover, retained elements may differ in their dispersion (e.g., evenly dispersed or aggregated; Fig. 2c,d) and the spatial juxtaposition of retention (e.g., clumped or linear).

Wildlife forestry silviculture exploits the versatility of legacy retention by combining specific retention and removal of canopy to achieved habitat conditions that are deemed suitable for priority wildlife species. The resultant forest stand may exhibit a mixture of tree species, size classes, and decadence within a heterogeneous distribution of aggregated retention and canopy gaps (Fig. 3).

#### **2.1 Landscape considerations**

Although specific silvicultural methods have most often been developed for and are implemented within forest management units (a.k.a. forest stands), a similar ecologically based approach has evolved with regard to maintaining or restoring landscapes surrounding managed forest stands (Lindenmayer et al., 2002, Lindenmayer & Hobbs, 2007). Intact forested landscapes are conducive to maintaining floristic and wildlife diversity, but also provide tangible social and economic benefits (Poudyal et al., 2010).

production cycles may provide little enhancement of biodiversity if the forest structure favored by production-oriented silviculture is maintained (Carey, 2006). Furthermore, where forest reserves are small or located within inhospitable landscapes, full ecological benefits of old-growth forests may not be attainable or sustainable (Kneeshaw and Gauthier, 2003).

Fortunately, it is likely that many of the benefits conferred by old-growth forests, or at least specific species associated with old-growth forests, are positively related to the heterogeneous structure (vertical and horizontal) and other structural attributes found within these forests, not necessarily with the prolonged existence of these forests (Beggs, 2004, Carey, 2003b). As such, alternative silvicultural methods have been developed which retain or enhance structural heterogeneity within managed forests, thereby promoting structural attributes of old-growth forests and encouraging greater biodiversity (Bauhus et al., 2009, Garman et al., 2003; McClellan, 2004). Most often, increased heterogeneity and other desired attributes have been achieved via retention of living or dead trees (or other forest elements). These retained structures have been referred to as legacy elements

Based on the concept of retained legacy elements, various alternative silvicultural methods have been advocated to enhance structural complexity within managed forests (Whitman and Hagan, 2003). Some of these methods have being designated as green-tree retention harvests (Zenner, 2000), variable-retention harvests (Aubry et al., 2004. Maguire et al., 2007), dispersed retention harvests (Heithecker and Halpern, 2006), variable density thinning (Aukema and Carey, 2008), and active intentional management (Carey et al., 1999, Carey, 2006). The legacy elements retained under these different silvicultural regimes may differ markedly. Retained elements may differ in quantity (e.g., % canopy cover or % basal area retained; Fig. 2a,b) but they may also differ in their composition, as different canopy species are preferentially harvested or specific regenerating species favored for retention. In addition, the quality of retained elements may differ via selection of retained trees with differing perceived fates – from robust, canopy-emergent trees through decadent, dead or dying trees. Moreover, retained elements may differ in their dispersion (e.g., evenly dispersed or aggregated; Fig. 2c,d) and the spatial juxtaposition of retention (e.g., clumped

Wildlife forestry silviculture exploits the versatility of legacy retention by combining specific retention and removal of canopy to achieved habitat conditions that are deemed suitable for priority wildlife species. The resultant forest stand may exhibit a mixture of tree species, size classes, and decadence within a heterogeneous distribution of aggregated

Although specific silvicultural methods have most often been developed for and are implemented within forest management units (a.k.a. forest stands), a similar ecologically based approach has evolved with regard to maintaining or restoring landscapes surrounding managed forest stands (Lindenmayer et al., 2002, Lindenmayer & Hobbs, 2007). Intact forested landscapes are conducive to maintaining floristic and wildlife diversity, but also provide tangible social and economic benefits (Poudyal et

(Franklin et al., 1997).

or linear).

al., 2010).

retention and canopy gaps (Fig. 3).

**2.1 Landscape considerations**

Fig. 2. Potential distribution of legacy elements after application of alternative silviculture, differing in quantity of retained canopy cover (a, b) or dispersion of retained elements (c, d).

Loss of diversity within landscapes is often a reflection of the increased homogeneity within forest stands. Although forest structure within a landscape ranges from regenerating stands to mature merchantable stands, these stands may be monotypic in species composition and physical structure. In addition, ensuring appropriate size of habitat patches and maintaining connectivity among these patches is critical to sustaining viable wildlife populations within landscapes (Franklin and Forman, 1987). Although the appropriate patch size is dependent upon the species under consideration, increased fragmentation tends to disrupt dispersion of fauna and flora and when habitat area is reduced without appropriate connectivity, extirpation of some species can result (MacArthur and Wilson, 1967). Finally, maintaining landscapes capable of sustaining viable wildlife populations requires that evaluation, planning, and management decisions reflect the temporal processes inherent in the ecosystem. Four landscape conditions have been recognized as contributing to ecosystems that support sustainable wildlife populations: 1) diversity within the landscape, 2) connectivity among landscape elements, 3) appropriate habitat patch sizes, and 4) sufficient time to achieve ecological functions (Silva, 1992). The impact of the degradation of forest landscapes was succinctly summarized by Franklin (1989) as: "*In general, we have tended to forget that what is good for wood production is not necessarily good for other organisms or processes in a forest ecosystem. Fully stocked young forests,… are the most simplified stage of forest development in terms of structure and function, and the most impoverished in terms of biological*

Wildlife Forestry 169

desired response, and the management context (Karau and Keane, 2007; Mayer and Cameron, 2003). As an example, the landscape appropriate for a grizzly bear is vastly

Even with knowledge of the appropriate landscape area and characteristics, manipulation of landscape conditions is usually beyond the purview of individual landowners. This is true even for large industrial or governmental landowners. Nevertheless, landscape conditions influence the ecological benefits conferred by forest stands, including the distribution, abundance, and viability of wildlife species within forest stands. In boreal forests, stand structure accounted for 54% of variability in bird and small mammal communities but landscape characteristics accounted for 29% (St Laurent et al., 2008). Similarly, bird species abundance within coniferous dominated landscapes was positively related to the proportion of broadleaf forest, with landscape thresholds for individual species ranging from 1% to 25% canopy cover. A strong negative relationship was noted between landscape broadleaf forest and avian population trends, such that the species most associated with broadleaf forests had greatest population declines. Therefore, maintaining or restoring broadleaf vegetation is

Because of landscape influences, providing desired forest conditions within forest stands may be insufficient for some priority species if these stands are located within inhospitable landscapes. Moreover, for long-term sustainable populations, most sites, even those with suitable habitat conditions, must have spatial and temporal linkages that facilitate dispersal, colonization, and interchange within metapopulations (Hanski, 1998). Towards that end, desired landscape conditions for priority wildlife species are usually composed of large forest patches as the preponderance of the landscape matrix, have a wide range of variation in patch sizes and complexities, and provide extensive

The application of wildlife forestry silviculture is in many respects the logical extension of the various alternative silviculture methods whose objectives are to maintain or increase forest biodiversity (Table 1). Although forest management targeting increased biodiversity is a laudable objective in and of itself, managers of public conservation lands (e.g., National Wildlife Refuges and State Wildlife Management Areas) or private lands under conservation easements may have legal, or self-appointed, mandates to manage and conserve priority wildlife species rather than the more general goal of improving biodiversity. On other private lands, the economic and recreational values associated with silvicolous wildlife, including fee hunting, hunt-club memberships, wildlife viewing and other eco-tourism activities, have income potential that may equal or exceed that of extractive timber harvest. Hence, ensuring sustainable populations of wildlife may be essential for maintaining

In addition, land ownership patterns of private forest lands are changing. Changing ownership demographics and associated alteration of management objectives of these forest land owners have resulted in smaller landownership holdings. For owners of small landholdings, maintaining continuous forest cover and the aesthetic considerations

associated with forests may be of paramount importance (Kaetzel et al., 2011).

different from the appropriate landscape for a shrew.

connectivity among forest patches.

financial revenues from these forest lands.

**2.2 Why wildlife forestry?**

important within coniferous dominated landscapes (Betts et al., 2010).

*diversity.. . . . Simplification--genetic, structural, landscape and temporal—reduces ecosystem resilience…[Thus] the key to retaining resilience must be in maintaining ecological complexity or diversity".*

Fig. 3. Canopy cover accounted for by individual tree crowns within bottomland hardwood forests on an untreated control stand (left) and on a stand subjected to wildlife forestry variable-retention silvicultural treatment (right), 6 years after treatment (Twedt & Wilson, 2007).

As when considering disturbance within the context of forest stand development, landscape conditions have often been influenced by large-scale disturbance events, particularly fires (Kaufmann et al., 2003, Van Willgenburg and Hobson, 2008). Forest landscapes that result from management based on historical fire regimes, when compared with landscapes with extensive reserves and traditional silvicultural management, had increased area of late-successional habitat, more overstory structure in young forests, and larger forest patches (Cissel et al., 1999). Similarly, when compared with human altered landscapes, natural landscapes were composed of larger habitat patches which formed the landscape matrix, had greater connectivity among patches, the range of variation in patch size and complexity was greater, as was the likelihood of encountering 'rare' habitat types (Mladenoff et al., 1993).

Despite some understanding of desirable characteristics of forested landscapes, the appropriate landscape area remains nebulous. In part this is because an appropriate landscape area is dependent upon the species being considered, landscape characteristics,

*diversity.. . . . Simplification--genetic, structural, landscape and temporal—reduces ecosystem resilience…[Thus] the key to retaining resilience must be in maintaining ecological complexity or*

Fig. 3. Canopy cover accounted for by individual tree crowns within bottomland

hardwood forests on an untreated control stand (left) and on a stand subjected to wildlife forestry variable-retention silvicultural treatment (right), 6 years after treatment (Twedt &

As when considering disturbance within the context of forest stand development, landscape conditions have often been influenced by large-scale disturbance events, particularly fires (Kaufmann et al., 2003, Van Willgenburg and Hobson, 2008). Forest landscapes that result from management based on historical fire regimes, when compared with landscapes with extensive reserves and traditional silvicultural management, had increased area of late-successional habitat, more overstory structure in young forests, and larger forest patches (Cissel et al., 1999). Similarly, when compared with human altered landscapes, natural landscapes were composed of larger habitat patches which formed the landscape matrix, had greater connectivity among patches, the range of variation in patch size and complexity was greater, as was the likelihood of encountering 'rare' habitat types

Despite some understanding of desirable characteristics of forested landscapes, the appropriate landscape area remains nebulous. In part this is because an appropriate landscape area is dependent upon the species being considered, landscape characteristics,

*diversity".*

Wilson, 2007).

(Mladenoff et al., 1993).

desired response, and the management context (Karau and Keane, 2007; Mayer and Cameron, 2003). As an example, the landscape appropriate for a grizzly bear is vastly different from the appropriate landscape for a shrew.

Even with knowledge of the appropriate landscape area and characteristics, manipulation of landscape conditions is usually beyond the purview of individual landowners. This is true even for large industrial or governmental landowners. Nevertheless, landscape conditions influence the ecological benefits conferred by forest stands, including the distribution, abundance, and viability of wildlife species within forest stands. In boreal forests, stand structure accounted for 54% of variability in bird and small mammal communities but landscape characteristics accounted for 29% (St Laurent et al., 2008). Similarly, bird species abundance within coniferous dominated landscapes was positively related to the proportion of broadleaf forest, with landscape thresholds for individual species ranging from 1% to 25% canopy cover. A strong negative relationship was noted between landscape broadleaf forest and avian population trends, such that the species most associated with broadleaf forests had greatest population declines. Therefore, maintaining or restoring broadleaf vegetation is important within coniferous dominated landscapes (Betts et al., 2010).

Because of landscape influences, providing desired forest conditions within forest stands may be insufficient for some priority species if these stands are located within inhospitable landscapes. Moreover, for long-term sustainable populations, most sites, even those with suitable habitat conditions, must have spatial and temporal linkages that facilitate dispersal, colonization, and interchange within metapopulations (Hanski, 1998). Towards that end, desired landscape conditions for priority wildlife species are usually composed of large forest patches as the preponderance of the landscape matrix, have a wide range of variation in patch sizes and complexities, and provide extensive connectivity among forest patches.

#### **2.2 Why wildlife forestry?**

The application of wildlife forestry silviculture is in many respects the logical extension of the various alternative silviculture methods whose objectives are to maintain or increase forest biodiversity (Table 1). Although forest management targeting increased biodiversity is a laudable objective in and of itself, managers of public conservation lands (e.g., National Wildlife Refuges and State Wildlife Management Areas) or private lands under conservation easements may have legal, or self-appointed, mandates to manage and conserve priority wildlife species rather than the more general goal of improving biodiversity. On other private lands, the economic and recreational values associated with silvicolous wildlife, including fee hunting, hunt-club memberships, wildlife viewing and other eco-tourism activities, have income potential that may equal or exceed that of extractive timber harvest. Hence, ensuring sustainable populations of wildlife may be essential for maintaining financial revenues from these forest lands.

In addition, land ownership patterns of private forest lands are changing. Changing ownership demographics and associated alteration of management objectives of these forest land owners have resulted in smaller landownership holdings. For owners of small landholdings, maintaining continuous forest cover and the aesthetic considerations associated with forests may be of paramount importance (Kaetzel et al., 2011).

Wildlife Forestry 171

empirical evaluations of wildlife species responses to different silvicultural treatments provide insight into the general habitat conditions that benefit different species groups.

*Amphibians* – Within landscapes, amphibians benefit from protection of existing forest, avoiding further forest fragmentation, and disturbances that mimic natural processes (Kingsburg & Gibson, 2002). Within stands, seasonally available water, especially vernal pools, should be protected from disturbance (e.g., siltation) by retaining forest canopy (≥75%) immediately surrounding pools and maintaining >50% canopy for up to 120 m from seasonal waters (Calhoun & deMaynadier, 2004). Amphibians tend to benefit from retention of sufficient canopy throughout the forest stand to provide a partially shaded forest floor. Their abundance also tends to be positively associated with a deep litter layer and abundant woody debris on the forest floor (Maguire et al., 2005). Within southern pine forests (e.g., longleaf pine [*Pinus palustris*]), thinning and burning are positively related to increased

*Reptiles* - The effects of silvicultural treatments on reptiles have been mixed, often exhibiting no discernable effect. Despite inconclusive studies, development of heterogeneous canopies, with numerous gaps enabling light to reach the forest floor, enhances thermoregulation opportunities for reptiles. Herpetofauna (reptiles and amphibians) may exhibit different regional responses to silviculture. Similarly, species-specific response to silviculture may result in species responding positively, negatively, or not at all (Russell et al., 2004). Thus, more research is needed on the effects of thinning and retained structural elements on

*Birds*: The intensity of harvest, otherwise stated as the magnitude of retention, influences species composition of bird communities. More canopy retention favors retention of matureforest species, whereas more intense harvest tends to favor early-successional species and forest generalist species (Schieck et al., 2000). In northern hardwood forests, retention of, 20 m2 ha-1 basal area maintained habitat for mature-forest birds yet afforded habitat for birds using early-successional habitat (Homes and Pitt, 2007). Similarly, in South American hardwood forests, combined dispersed and aggregated retention permitted colonization by early successional birds yet retained species characteristic of old-growth forests within retained aggregates (Lencinas et al., 2009). In Tasmanian eucalypt forest, long-term, aggregated retention harvests better sustained mature forest bird communities, post-harvest, compared with clearcut or dispersed retention harvests (Lefort and Grove, 2009). In young, coniferdominated stands, thinning promotes diversity of breeding birds ― a variety of thinning intensities and patterns, ranging from no thinning to widely spaced residual trees, will maximize avian diversity at the landscape scale and provide structural diversity within and among stands (Hagar et al., 2004). In southern pine forests, bird abundance and richness were positively related to volume of coarse woody debris and density of snags (Jones et al., 2009). In Midwestern oak-hickory forests, thinning harvest and prescribed fire increased avian nest survival (Streby and Miles, 2010). However, responses to variable retention harvests are species specific and temporally dynamic: Response of some species is immediate but shortlived, whereas other species exhibit a deferred (maybe several years post-treatment) but long-

abundance of priority (open-pine adapted) amphibian species (Steen et al., 2010).

reptiles and amphibians (Jones et al., 2009; Verschuyl et al., 2011).

lasting response (Hagar and Friesen, 2009, Twedt and Somershoe, 2009).

*Bats* – Many bat species avoid spatial clutter: Thus bats tend to be more abundant in forests with open structure (harvested or old-growth) compared to closed-structured midsuccessional forest (Loeb and O'keefe, 2006; Patriquin and Barclay, 2003; Menzel et al., 2005).

Table 1. State of habitat features following different distubances and prescribed wildife forsetry silviculture (expanded from Swanson et al., 2011).

Even on large land ownerships, such as industrial forest lands or lands managed by timber consortiums, there are increased public expectations to provide sustainable, 'green' forest products (Barneycastle, 2001). Concurrently, corporate efforts to maintain positive environmental images have prompted greater reliance on alternative silviculture, such as wildlife forestry. Finally, even on lands where implementation of traditional silviculture may be the preferred management option, exurban encroachment may constrain traditional forest management practices (Egan and Luloff, 2000).

#### **2.3 Priority species**

What are 'priority' species? For some groups of wildlife species, conservation planners have established priority rankings based on objective criteria such as current population abundance, distributions, availability of suitable habitats, perceived threats to habitat, etc. (Mehlman et al., 2004). For example, for North American landbirds, Partners in Flight has established ecoregional priority rankings (Panjabi et al., 2005). For other wildlife groups, priority status may be conferred based on species being listed as threatened or endangered by national or regional governmental agencies (Greenwald et al., 2006) or listed as a species of concern by private conservation organizations (Butcher, 2007). Regardless of the underlying rationale for their selection, priority wildlife species within managed forests differ among regions and forest types. Moreover, the priority species targeted for habitat improvement via prescribed management actions ultimately are determined by the landowner's objectives.

Why favor these species over others? All forest management, including no active management (a.k.a., passive management or benign neglect), influences the abundance and composition of wildlife species. For many priority species, insufficient habitat, or an overabundance of habitat with unsuitable conditions, likely contributed to their designation as a priority species. Therefore, where modification of forest habitat will promote habitat conditions conducive to supporting sustainable populations of these species, it behooves managers to prescribe silvicultural actions that will result in increased habitat for these species.

#### **3. Desired habitat conditions for priority species**

Because priority species differ among regions and among forest types, quantification of specific habitat characteristics suitable for all forests and all species is not practical. Even so,

Live trees Sparse Variable Variable Sparse Sparse Variable Snags Abundant Variable Abundant Abundant Sparse Variable

debris Variable Abundant Variable Variable Sparse Variable

development Abundant Abundant Variable Variable Abundant Variable

state Variable Variable Variable Variable Long Variable

Even on large land ownerships, such as industrial forest lands or lands managed by timber consortiums, there are increased public expectations to provide sustainable, 'green' forest products (Barneycastle, 2001). Concurrently, corporate efforts to maintain positive environmental images have prompted greater reliance on alternative silviculture, such as wildlife forestry. Finally, even on lands where implementation of traditional silviculture may be the preferred management option, exurban encroachment may constrain traditional

What are 'priority' species? For some groups of wildlife species, conservation planners have established priority rankings based on objective criteria such as current population abundance, distributions, availability of suitable habitats, perceived threats to habitat, etc. (Mehlman et al., 2004). For example, for North American landbirds, Partners in Flight has established ecoregional priority rankings (Panjabi et al., 2005). For other wildlife groups, priority status may be conferred based on species being listed as threatened or endangered by national or regional governmental agencies (Greenwald et al., 2006) or listed as a species of concern by private conservation organizations (Butcher, 2007). Regardless of the underlying rationale for their selection, priority wildlife species within managed forests differ among regions and forest types. Moreover, the priority species targeted for habitat improvement via prescribed

Why favor these species over others? All forest management, including no active management (a.k.a., passive management or benign neglect), influences the abundance and composition of wildlife species. For many priority species, insufficient habitat, or an overabundance of habitat with unsuitable conditions, likely contributed to their designation as a priority species. Therefore, where modification of forest habitat will promote habitat conditions conducive to supporting sustainable populations of these species, it behooves managers to prescribe

Because priority species differ among regions and among forest types, quantification of specific habitat characteristics suitable for all forests and all species is not practical. Even so,

management actions ultimately are determined by the landowner's objectives.

silvicultural actions that will result in increased habitat for these species.

**3. Desired habitat conditions for priority species**

Table 1. State of habitat features following different distubances and prescribed wildife

Variable Variable High Variable Low High

disease Flood Clearcut Wildlife

forestry

characteristic Wildfire Wind Insect /

forsetry silviculture (expanded from Swanson et al., 2011).

forest management practices (Egan and Luloff, 2000).

Legacy

Downed woody

Duration of alterted

**2.3 Priority species**

Understory

Spatial heterogeneity empirical evaluations of wildlife species responses to different silvicultural treatments provide insight into the general habitat conditions that benefit different species groups.

*Amphibians* – Within landscapes, amphibians benefit from protection of existing forest, avoiding further forest fragmentation, and disturbances that mimic natural processes (Kingsburg & Gibson, 2002). Within stands, seasonally available water, especially vernal pools, should be protected from disturbance (e.g., siltation) by retaining forest canopy (≥75%) immediately surrounding pools and maintaining >50% canopy for up to 120 m from seasonal waters (Calhoun & deMaynadier, 2004). Amphibians tend to benefit from retention of sufficient canopy throughout the forest stand to provide a partially shaded forest floor. Their abundance also tends to be positively associated with a deep litter layer and abundant woody debris on the forest floor (Maguire et al., 2005). Within southern pine forests (e.g., longleaf pine [*Pinus palustris*]), thinning and burning are positively related to increased abundance of priority (open-pine adapted) amphibian species (Steen et al., 2010).

*Reptiles* - The effects of silvicultural treatments on reptiles have been mixed, often exhibiting no discernable effect. Despite inconclusive studies, development of heterogeneous canopies, with numerous gaps enabling light to reach the forest floor, enhances thermoregulation opportunities for reptiles. Herpetofauna (reptiles and amphibians) may exhibit different regional responses to silviculture. Similarly, species-specific response to silviculture may result in species responding positively, negatively, or not at all (Russell et al., 2004). Thus, more research is needed on the effects of thinning and retained structural elements on reptiles and amphibians (Jones et al., 2009; Verschuyl et al., 2011).

*Birds*: The intensity of harvest, otherwise stated as the magnitude of retention, influences species composition of bird communities. More canopy retention favors retention of matureforest species, whereas more intense harvest tends to favor early-successional species and forest generalist species (Schieck et al., 2000). In northern hardwood forests, retention of, 20 m2 ha-1 basal area maintained habitat for mature-forest birds yet afforded habitat for birds using early-successional habitat (Homes and Pitt, 2007). Similarly, in South American hardwood forests, combined dispersed and aggregated retention permitted colonization by early successional birds yet retained species characteristic of old-growth forests within retained aggregates (Lencinas et al., 2009). In Tasmanian eucalypt forest, long-term, aggregated retention harvests better sustained mature forest bird communities, post-harvest, compared with clearcut or dispersed retention harvests (Lefort and Grove, 2009). In young, coniferdominated stands, thinning promotes diversity of breeding birds ― a variety of thinning intensities and patterns, ranging from no thinning to widely spaced residual trees, will maximize avian diversity at the landscape scale and provide structural diversity within and among stands (Hagar et al., 2004). In southern pine forests, bird abundance and richness were positively related to volume of coarse woody debris and density of snags (Jones et al., 2009). In Midwestern oak-hickory forests, thinning harvest and prescribed fire increased avian nest survival (Streby and Miles, 2010). However, responses to variable retention harvests are species specific and temporally dynamic: Response of some species is immediate but shortlived, whereas other species exhibit a deferred (maybe several years post-treatment) but longlasting response (Hagar and Friesen, 2009, Twedt and Somershoe, 2009).

*Bats* – Many bat species avoid spatial clutter: Thus bats tend to be more abundant in forests with open structure (harvested or old-growth) compared to closed-structured midsuccessional forest (Loeb and O'keefe, 2006; Patriquin and Barclay, 2003; Menzel et al., 2005).

Wildlife Forestry 173

the extent and location of extant habitat, 5) set site-specific habitat goals, and 6) establish metapopulations goals (Mueller et al., 2000). A variation of this method was used to characterize priority of lands for forest restoration within the Mississippi Alluvial Valley and thereby delineate 107 discrete landscape units that were deemed capable of supporting viable populations (assumed to be ≥500 pairs) of priority silvicolous birds (Twedt et al.,

Building upon this model, the Lower Mississippi Valley Joint Venture Forest Resource Conservation Working Group (Wilson et al., 2007) quantified desired forest conditions

2. 70-95% of forest area actively managed via silviculture intended to encourage desired

3. 35-50% of forest should meet desired forest conditions at any point in time, (Recognizing that habitat conditions are dynamic, silvicultural treatments should target

5. ~5% of area should be in shrub-scrub (thamnic woody vegetation) habitat, but this may

6. 5-30% of forest area should be passively managed as wilderness, natural areas, or set-

A further refinement of this method has been used within the West Gulf Coastal Plain and Ouachita Mountains Ecoregion to characterize landscape requirements of birds reliant on open-canopy, mature pine forests (Keister et al., 2011). The first steps were again to identify priority species and define suitable habitats for priority species. However, area requirements for each of these priority species were determined by assessing the minimum territory size or home range of breeding pairs. Connectivity among territories of appropriate size was assumed to be related to the likely dispersal distance of each priority species. The minimum viable population size was estimated for each species (Hanski et al., 1996). These species-specific characteristics were used to evaluate existing landscape suitability for priority species. The sum of the total area of all habitats that were capable of supporting a breeding pair (assuming silvicultural management would yield suitable stand conditions) and that were joined by virtue of being within dispersal distance of other suitable habitat was used to evaluate landscapes. Landscapes were deemed suitable when their total areas were sufficient to support a minimum viable population of the species: Non-suitable landscapes were characterized with regard to their suitability based on the proportion of a minimum viable population that could be supported (Fig. 4b-d). Desired landscape conditions for multiple species were then jointly

Desired site conditions are dependent upon which species have been designated as priority species. Even so, as identified above, there are commonalities among stand characteristics that have been found to benefit many species and species groups. Prescribed wildlife

conditions that yield extended temporal duration of desired stand conditions); 4. ≤10% of forest should be in regeneration harvests (where >80% of overstory is removed)

1. >70% forest habitat, with large contiguous forest areas preferred;

aside areas that are not subjected to silvicultural manipulation.

2006; Fig. 4a).

within these landscapes as:

stand conditions;

that are >3 ha in area;

considered (Fig. 4, right).

**3.2 Desired site conditions**

including early seral forest stages; and

Forest structure appears more important than forest composition for foraging bats (Loeb and O'Keefe, 2006). Increased species and structural diversity of woody species, including providing broadleaf trees and shrubs in corridors and surrounding water features, tend to enhance foraging opportunities for bats. Conversely, forest type (or tree species) may be an important determinant of roosting location or behavior (Barclay and Kurta, 2007; Perry et al., 2007). Specifically, roost trees of bats are generally tall with large diameters and are located in stands with open canopies and high snag densities (Kalcounis-Rüppell et al., 2005). Compared to trees used by foliage-roosting bats, cavity-roosting bats use trees within stands that have more open canopies and trees that are closer to water than are random trees (Kalcounis-Rüppell et al., 2005).

*Deer* – Within landscapes, decreased road density and lessening of associated traffic reduces the negative impacts of disturbance. Silviculture should promote structurally complex, uneven-aged stands, that include forest openings (1 – 20 ha), and provide structural heterogeneity within and among stands (Nelson et al., 2008). Resulting habitat should provide understory forage and cover while retaining species diversity of trees.

*Bear* – Habitat selection is largely influenced by food abundance (Costello and Sage, 1994). A diversity of tree and shrub species producing hard mast (acorns and nuts) as well as soft mast (berries and fruits) is beneficial. Thinning, group selection, or patch cuts should be used to promote regeneration and recruitment of mast producing species, as well to increase understory food production, escape cover, and bedding areas. Care should be exercised to retain some large trees within each stand and to protect potential den trees during harvest.

*Small Mammals* – Silviculture that retains legacy structures, variable-density thinning, and management for increased forest decadence combined to support 3 species of squirrel in Douglas-fir forests (Carey, 2000). In southwestern conifer forests, thinning and burning treatments had positive effects on most small mammals. Even so, effects of silviculture on small mammals are species-specific, such that a positive response in abundance of one species may be offset by negative response in abundance of another species.

Effective strategies to achieve habitat for different species across spatial and temporal scales should include developing: 1) measurable objectives, 2) integrated conservation goals and silvicultural prescriptions, 3) clear and practical guidelines, effective training, and communication programs, and 4) a monitoring and an adaptive management process to evaluate and improve results (Munks et al., 2009).

#### **3.1 Desired landscape conditions**

Landscape conditions deemed suitable for priority species are highly dependent upon which species have been designated as priority species within the landscape under consideration. Furthermore, even after priority species have been designated, determining the nature and extent of desired landscape conditions have relatively little empirical justification (Moilanen, 1999). Even so, various methods have been employed to evaluate the appropriate landscape area and context for priority species.

A relatively simple, 6-step approach was put forward to identify the appropriate landscapes for forest bird conservation in the Mississippi Alluvial Valley: 1) establish priority species, 2) establish habitat priorities, 3) identify habitat requirements for priority species, 4) determine

Forest structure appears more important than forest composition for foraging bats (Loeb and O'Keefe, 2006). Increased species and structural diversity of woody species, including providing broadleaf trees and shrubs in corridors and surrounding water features, tend to enhance foraging opportunities for bats. Conversely, forest type (or tree species) may be an important determinant of roosting location or behavior (Barclay and Kurta, 2007; Perry et al., 2007). Specifically, roost trees of bats are generally tall with large diameters and are located in stands with open canopies and high snag densities (Kalcounis-Rüppell et al., 2005). Compared to trees used by foliage-roosting bats, cavity-roosting bats use trees within stands that have more open canopies and trees that are closer to water than are random

*Deer* – Within landscapes, decreased road density and lessening of associated traffic reduces the negative impacts of disturbance. Silviculture should promote structurally complex, uneven-aged stands, that include forest openings (1 – 20 ha), and provide structural heterogeneity within and among stands (Nelson et al., 2008). Resulting habitat should

*Bear* – Habitat selection is largely influenced by food abundance (Costello and Sage, 1994). A diversity of tree and shrub species producing hard mast (acorns and nuts) as well as soft mast (berries and fruits) is beneficial. Thinning, group selection, or patch cuts should be used to promote regeneration and recruitment of mast producing species, as well to increase understory food production, escape cover, and bedding areas. Care should be exercised to retain some large trees within each stand and to protect potential den trees during harvest. *Small Mammals* – Silviculture that retains legacy structures, variable-density thinning, and management for increased forest decadence combined to support 3 species of squirrel in Douglas-fir forests (Carey, 2000). In southwestern conifer forests, thinning and burning treatments had positive effects on most small mammals. Even so, effects of silviculture on small mammals are species-specific, such that a positive response in abundance of one

Effective strategies to achieve habitat for different species across spatial and temporal scales should include developing: 1) measurable objectives, 2) integrated conservation goals and silvicultural prescriptions, 3) clear and practical guidelines, effective training, and communication programs, and 4) a monitoring and an adaptive management process to

Landscape conditions deemed suitable for priority species are highly dependent upon which species have been designated as priority species within the landscape under consideration. Furthermore, even after priority species have been designated, determining the nature and extent of desired landscape conditions have relatively little empirical justification (Moilanen, 1999). Even so, various methods have been employed to evaluate the

A relatively simple, 6-step approach was put forward to identify the appropriate landscapes for forest bird conservation in the Mississippi Alluvial Valley: 1) establish priority species, 2) establish habitat priorities, 3) identify habitat requirements for priority species, 4) determine

provide understory forage and cover while retaining species diversity of trees.

species may be offset by negative response in abundance of another species.

evaluate and improve results (Munks et al., 2009).

appropriate landscape area and context for priority species.

**3.1 Desired landscape conditions**

trees (Kalcounis-Rüppell et al., 2005).

the extent and location of extant habitat, 5) set site-specific habitat goals, and 6) establish metapopulations goals (Mueller et al., 2000). A variation of this method was used to characterize priority of lands for forest restoration within the Mississippi Alluvial Valley and thereby delineate 107 discrete landscape units that were deemed capable of supporting viable populations (assumed to be ≥500 pairs) of priority silvicolous birds (Twedt et al., 2006; Fig. 4a).

Building upon this model, the Lower Mississippi Valley Joint Venture Forest Resource Conservation Working Group (Wilson et al., 2007) quantified desired forest conditions within these landscapes as:

A further refinement of this method has been used within the West Gulf Coastal Plain and Ouachita Mountains Ecoregion to characterize landscape requirements of birds reliant on open-canopy, mature pine forests (Keister et al., 2011). The first steps were again to identify priority species and define suitable habitats for priority species. However, area requirements for each of these priority species were determined by assessing the minimum territory size or home range of breeding pairs. Connectivity among territories of appropriate size was assumed to be related to the likely dispersal distance of each priority species. The minimum viable population size was estimated for each species (Hanski et al., 1996). These species-specific characteristics were used to evaluate existing landscape suitability for priority species. The sum of the total area of all habitats that were capable of supporting a breeding pair (assuming silvicultural management would yield suitable stand conditions) and that were joined by virtue of being within dispersal distance of other suitable habitat was used to evaluate landscapes. Landscapes were deemed suitable when their total areas were sufficient to support a minimum viable population of the species: Non-suitable landscapes were characterized with regard to their suitability based on the proportion of a minimum viable population that could be supported (Fig. 4b-d). Desired landscape conditions for multiple species were then jointly considered (Fig. 4, right).

#### **3.2 Desired site conditions**

Desired site conditions are dependent upon which species have been designated as priority species. Even so, as identified above, there are commonalities among stand characteristics that have been found to benefit many species and species groups. Prescribed wildlife

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butterfly and moth larvae are consumed by many wildlife species, especially birds, maintaining a diversity of trees and other flora within forest stands extends the temporal availability and increases the diversity of these insects (Hagar, 2004, Twedt and Best, 2004). In addition, forests with diverse species compositions are less vulnerable to catastrophic effects of disease and insects. Indeed, recent detrimental oak mortality in the Ozark Mountains Ecoregion has been attributed, in part, to the preponderance of oaks within these forests (Riggins et al. 2009). Similarly, species-specificity of many diseases and insects (e.g. chestnut blight [*Cryphonectria parasitica*] impact on American chestnut [*Castanea dentate*] or emerald ash borer [*Agrilus planipennis*] infestation of ash species [*Fraxinus* spp.]) provides argument for the maintenance of forest diversity to ameliorate the potentially catastrophic effects of regional

Fig. 5. Forest structure observed during summer (left) and winter (right) within bottomland hardwood forests circa 4 years after variable-retention, wildlife-forestry based silvicultural

Finally, our naïve perception of the value of "undesirable species" is likely insufficient to comprehend the value of these species within the ecosystem. Therefore, preferential retention or diminution of native species may have unintended detrimental consequences (Lockhart 2004). For example, although the presence of piñon pine (*Pinus edulis*) is among the most important habitat features for many birds in piñon–juniper forests, the favored (86%) location of nests in juniper (*Juniperus osteosperma*) suggests that managers should

*Increased structural heterogeneity (horizontal and vertical)* – More structure generally provides a greater number of habitat niches for occupancy by different wildlife species, thereby increasing species richness, which may include priority species. Managers must, however,

avoid preferential thinning of juniper within these forests (Francis et al., 2011).

treatments (bottom) and on untreated control stands (top).

outbreaks of disease or insect pests.

forestry silvicultural practices can induce disturbance within forests and thereby stimulate development of desired structural conditions. Specific needs to be addressed when prescribing management actions include: 1) development and maintenance of structural (vertical and horizontal) heterogeneity, 2) achieving and retaining site appropriate tree species diversity, 3) maintaining an appropriate [sufficient yet acceptable] level of decadence, and 4) providing adequate reproduction to ensure sustainable habitat conditions and maintain future management options (Fig. 5).

Fig. 4. Landscapes identified for priority birds based on forest restoration (a) in the Mississippi Alluvial Valley (Twedt et al. 2006) and on proportion of minimum viable population supported for Bachman's sparrow (b), brown-headed nuthatch (c), and redcockaded woodpecker (d) within the West Gulf Coastal Plain (Keister et al. 2011).

*Maintaining or enhancing diversity of species – A* diversity of flora, in the canopy, mid-story, and understory, buffers fluctuations (annual, seasonal, and temporal) in phenology, productivity, susceptibility, and merchantability of forests, although this is not universally applicable to canopy species (e.g., longleaf pine stand canopies may be predominately one species). Because diversity of fruiting species affords temporal and spatial availability of fruits, and because fruit use by wildlife in temperate forests is substantial, with fruits being consumed primarily during winter (McCarty et al., 2002), maintaining and enhancing diversity of fruit bearing species should be encouraged. Moreover, a variety of fruits provide alternative foods in the event of mast crop failure of other species. Similarly, different plants host different caterpillar (larval Lepidoptera) species, some of which have species-specific relationships. Because

forestry silvicultural practices can induce disturbance within forests and thereby stimulate development of desired structural conditions. Specific needs to be addressed when prescribing management actions include: 1) development and maintenance of structural (vertical and horizontal) heterogeneity, 2) achieving and retaining site appropriate tree species diversity, 3) maintaining an appropriate [sufficient yet acceptable] level of decadence, and 4) providing adequate reproduction to ensure sustainable habitat conditions

Fig. 4. Landscapes identified for priority birds based on forest restoration (a) in the Mississippi Alluvial Valley (Twedt et al. 2006) and on proportion of minimum viable population supported for Bachman's sparrow (b), brown-headed nuthatch (c), and redcockaded woodpecker (d) within the West Gulf Coastal Plain (Keister et al. 2011).

*Maintaining or enhancing diversity of species – A* diversity of flora, in the canopy, mid-story, and understory, buffers fluctuations (annual, seasonal, and temporal) in phenology, productivity, susceptibility, and merchantability of forests, although this is not universally applicable to canopy species (e.g., longleaf pine stand canopies may be predominately one species). Because diversity of fruiting species affords temporal and spatial availability of fruits, and because fruit use by wildlife in temperate forests is substantial, with fruits being consumed primarily during winter (McCarty et al., 2002), maintaining and enhancing diversity of fruit bearing species should be encouraged. Moreover, a variety of fruits provide alternative foods in the event of mast crop failure of other species. Similarly, different plants host different caterpillar (larval Lepidoptera) species, some of which have species-specific relationships. Because

and maintain future management options (Fig. 5).

butterfly and moth larvae are consumed by many wildlife species, especially birds, maintaining a diversity of trees and other flora within forest stands extends the temporal availability and increases the diversity of these insects (Hagar, 2004, Twedt and Best, 2004). In addition, forests with diverse species compositions are less vulnerable to catastrophic effects of disease and insects. Indeed, recent detrimental oak mortality in the Ozark Mountains Ecoregion has been attributed, in part, to the preponderance of oaks within these forests (Riggins et al. 2009). Similarly, species-specificity of many diseases and insects (e.g. chestnut blight [*Cryphonectria parasitica*] impact on American chestnut [*Castanea dentate*] or emerald ash borer [*Agrilus planipennis*] infestation of ash species [*Fraxinus* spp.]) provides argument for the maintenance of forest diversity to ameliorate the potentially catastrophic effects of regional outbreaks of disease or insect pests.

Fig. 5. Forest structure observed during summer (left) and winter (right) within bottomland hardwood forests circa 4 years after variable-retention, wildlife-forestry based silvicultural treatments (bottom) and on untreated control stands (top).

Finally, our naïve perception of the value of "undesirable species" is likely insufficient to comprehend the value of these species within the ecosystem. Therefore, preferential retention or diminution of native species may have unintended detrimental consequences (Lockhart 2004). For example, although the presence of piñon pine (*Pinus edulis*) is among the most important habitat features for many birds in piñon–juniper forests, the favored (86%) location of nests in juniper (*Juniperus osteosperma*) suggests that managers should avoid preferential thinning of juniper within these forests (Francis et al., 2011).

*Increased structural heterogeneity (horizontal and vertical)* – More structure generally provides a greater number of habitat niches for occupancy by different wildlife species, thereby increasing species richness, which may include priority species. Managers must, however,

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dispersed or aggregated

Monoculture with supplemental natural reproduction

Partial removal of competitors

Table 2. Effects of wildlife forestry and other silviculture on stand structure (expanded from