*Article* **Assimilation of Multi-Source Precipitation Data over Southeast China Using a Nonparametric Framework**

**Yuanyuan Zhou 1,2, Nianxiu Qin 3 , Qiuhong Tang 4,5 , Huabin Shi 1 and Liang Gao 1,2,\***

**Abstract:** The accuracy of the rain distribution could be enhanced by assimilating the remotely sensed and gauge-based precipitation data. In this study, a new nonparametric general regression (NGR) framework was proposed to assimilate satellite- and gauge-based rainfall data over southeast China (SEC). The assimilated rainfall data in Meiyu and Typhoon seasons, in different months, as well as during rainfall events with various rainfall intensities were evaluated to assess the performance of this proposed framework. In rainy season (Meiyu and Typhoon seasons), the proposed method obtained the estimates with smaller total absolute deviations than those of the other satellite products (i.e., 3B42RT and 3B42V7). In general, the NGR framework outperformed the original satellites generally on root-mean-square error (RMSE) and mean absolute error (MAE), especially on Nash-Sutcliffe coefficient of efficiency (NSE). At monthly scale, the performance of assimilated data by NGR was better than those of satellite-based products in most months, by exhibiting larger correlation coefficients (CC) in 6 months, smaller RMSE and MAE in at least 9 months and larger NSE in 9 months, respectively. Moreover, the estimates from NGR have been proven to perform better than the two satellite-based products with respect to the simulation of the gauge observations under different rainfall scenarios (i.e., light rain, moderate rain and heavy rain).

**Keywords:** precipitation; assimilation; nonparametric modeling; multi-source


**11. Final considerations**

Potassium presents many important functions in leaf and fruit vegetables, including enzymatic activation, regulation of the osmotic potential of cells, cell expansion, and opening and closing of the stomata, being the nutrient that most affects the quality of leaf and fruit vegetables. Due to potassium performance in several physiological processes, especially in the enzymatic activity, its adequate nutrition is fundamental for the development and quality of the vegetables. The horticulturist should prioritize the use of potassic fertilizers with lower salt content, if possible free of chlorine and containing magnesium and sulfur. However, it is essential to remember that the high potassium content in plants can induce deficiency of calcium and magnesium.


**3.2 Material properties**

Table 3 lists the room temperature material properties used for nickel, YSZ and LSM (Johnson & Qu, 2008; Anandakumar et al., 2010).

Table 3. Room temperature material properties used in FE analyses

Continuum Mechanics of Solid Oxide Fuel Cells

not change over the temperature range considered.

Fig. 6. Stress-plastic strain curve for nickel (Ebrahimi et al., 1999).

**4. Finite element analysis results and discussion**

**4.1 Stress analysis**

elements and 395,131 nodes.

**4.1.1 Anode microstructure**

N/m2 (i.e., Pa).

Using Three-Dimensional Reconstructed Microstructures 79

Figure 6 shows the stress-strain curve used to describe the elastic-plastic behavior of nickel (Ebrahimi et al., 1999). It was assumed in this work that the stress-strain curve of nickel does

The full 3-D FE models of the anode (50:50 NiO:YSZ weight percentage composition) and cathode (50:50 LSM:YSZ weight percentage composition) are shown in Figure 7. The FE anode model consists of 406,465 elements and 473,181 nodes. The cathode model has 244,584

The von Mises stress contour plots for the anode at ΔT = 100⁰C, 500⁰C, and 800⁰C are shown considering elastic-plastic behavior of nickel in Figure 8. The stress values are in units of

Fig. 7. Three-dimensional FE models of anode (left) and cathode (right)

Figure 4 shows the variation of the coefficients of thermal expansion of nickel and YSZ with temperature (Johnson & Qu, 2008). The CTE of LSM was assumed to be constant over the temperature range considered. The room temperature value of the CTE of LSM (as shown in Table 3) was used in the FE analyses of the cathode.

Fig. 4. Variation of CTE of nickel and YSZ with temperature (Johnson & Qu, 2008).

Figure 5 shows the variation of the Young's modulus of LSM and YSZ with temperature (Giraud & Canel, 2008). The Young's modulus of nickel was assumed to be constant over the temperature range considered. The room temperature value of the Young's modulus of nickel (as shown in Table 3) was used in the FE analyses of the anode.

Fig. 5. Variation of Young's modulus of LSM and YSZ with temperature (Giraud and Canel, 2008).

Figure 4 shows the variation of the coefficients of thermal expansion of nickel and YSZ with temperature (Johnson & Qu, 2008). The CTE of LSM was assumed to be constant over the temperature range considered. The room temperature value of the CTE of LSM (as shown in

Fig. 4. Variation of CTE of nickel and YSZ with temperature (Johnson & Qu, 2008).

nickel (as shown in Table 3) was used in the FE analyses of the anode.

2008).

Figure 5 shows the variation of the Young's modulus of LSM and YSZ with temperature (Giraud & Canel, 2008). The Young's modulus of nickel was assumed to be constant over the temperature range considered. The room temperature value of the Young's modulus of

Fig. 5. Variation of Young's modulus of LSM and YSZ with temperature (Giraud and Canel,

Table 3) was used in the FE analyses of the cathode.

Figure 6 shows the stress-strain curve used to describe the elastic-plastic behavior of nickel (Ebrahimi et al., 1999). It was assumed in this work that the stress-strain curve of nickel does not change over the temperature range considered.

Fig. 6. Stress-plastic strain curve for nickel (Ebrahimi et al., 1999).


**2. Embryonic liver development**

During embryonic development, the liver arises from the definitive endoderm (for reviews on liver development, see (7-9)). The definitive endoderm is an embryonic layer, whereas visceral endoderm is a non-embryonic derived layer, also called extra-embryonic endoderm. The definitive endoderm is one of the three germ layers, which include also ectoderm and mesoderm. The definitive endoderm is initially located beneath the ectoderm and mesoderm. In the mouse, the definitive endoderm layer forms a liver bud between E8.5 and E9.5. This layer will also form the pancreas, lung, stomach, intestine, and thyroid. The cardiac mesoderm and septum transversum mesenchyme release signals, such as fibroblast growth factors (FGF) and bone morphogenetic proteins (BMP), which are necessary to induce liver specification. The septum transversum mesenchyme has been implicated to give rise to stellate cells (also called Ito cells), which are fat and vitamin A-storing and extracellular matrix producing liver cells (10); cells positive for the Lim-homeobox gene (Lhx2) migrate from the septum transversum into the forming liver bud and become desmin and Lhx2 positive stellate cells. Cells in the developing liver bud are termed hepatoblasts and express alpha-fetoprotein (AFP). Hepatoblasts have been described as bipotential progenitors, developing into mature hepatocytes as well as bile duct epithelial cells (cholangiocytes), based on findings from *ex vivo* and *in vitro* studies (11-15). Suppression of transcription factor CCAAT-enhancer-binding protein alpha (CEBPα) has been suggested to induce their specification towards biliary differentiation (16, 17).

#### **3. Human hepatic progenitors in fetal and adult livers**

Different hepatic progenitors in human livers have been described. Based on early findings in developmental biology, hepatic stem cells were originally defined as AFP positive hepatoblasts. More recent research, however, reveals that hepatic stem cells are AFP negative and are the precursors to hepatoblasts (12, 18). Furthermore, stem cells of assumed mesendodermal origin capable of multilineage differentiation towards liver- and mesenchymal lineages have been discovered (19). An overview about human hepatic progenitors that have been isolated and characterized is given in **Table 2**.

Stem cell Cell, which is capable to differentiate into multiple lineages and is

Hepatoblast Hepatic parenchymal cell of the fetal liver. Defined by its

Oval cell Small cells with oval-shaped nuclei that emerge in livers, which have been treated with certain toxins. Table 1. Common terminology relevant to liver progenitor biology. Further details can be

During embryonic development, the liver arises from the definitive endoderm (for reviews on liver development, see (7-9)). The definitive endoderm is an embryonic layer, whereas visceral endoderm is a non-embryonic derived layer, also called extra-embryonic endoderm. The definitive endoderm is one of the three germ layers, which include also ectoderm and mesoderm. The definitive endoderm is initially located beneath the ectoderm and mesoderm. In the mouse, the definitive endoderm layer forms a liver bud between E8.5 and E9.5. This layer will also form the pancreas, lung, stomach, intestine, and thyroid. The cardiac mesoderm and septum transversum mesenchyme release signals, such as fibroblast growth factors (FGF) and bone morphogenetic proteins (BMP), which are necessary to induce liver specification. The septum transversum mesenchyme has been implicated to give rise to stellate cells (also called Ito cells), which are fat and vitamin A-storing and extracellular matrix producing liver cells (10); cells positive for the Lim-homeobox gene (Lhx2) migrate from the septum transversum into the forming liver bud and become desmin and Lhx2 positive stellate cells. Cells in the developing liver bud are termed hepatoblasts and express alpha-fetoprotein (AFP). Hepatoblasts have been described as bipotential progenitors, developing into mature hepatocytes as well as bile duct epithelial cells (cholangiocytes), based on findings from *ex vivo* and *in vitro* studies (11-15). Suppression of transcription factor CCAAT-enhancer-binding protein alpha (CEBPα) has been suggested to

Different hepatic progenitors in human livers have been described. Based on early findings in developmental biology, hepatic stem cells were originally defined as AFP positive hepatoblasts. More recent research, however, reveals that hepatic stem cells are AFP negative and are the precursors to hepatoblasts (12, 18). Furthermore, stem cells of assumed mesendodermal origin capable of multilineage differentiation towards liver- and mesenchymal lineages have been discovered (19). An overview about human hepatic

several mature hepatic functions and proteins. Hepatocyte Hepatic parenchymal cell of the adult liver. In non-pathological

expression of immature protein alpha-fetoprotein and absence of

conditions defined by its expression of mature functions and proteins, such as albumin and cytochrome P450 enzymes, and the

absence of immature proteins such as alpha-fetoprotein.

also able of self-renewal.

**Term Description**

**2. Embryonic liver development**

induce their specification towards biliary differentiation (16, 17).

**3. Human hepatic progenitors in fetal and adult livers**

progenitors that have been isolated and characterized is given in **Table 2**.

found also in (5, 6).

Hepatic Progenitors of the Liver and Extra-Hepatic Tissues 47

structures. Adipogenic differentiation could not be induced. As these cells were cultureselected, percentages of their *in vivo* occurrence were not established. Cells *in vitro* demonstrated exponential growth rates. When transplanted, human cells could be localized *in vivo* within the liver parenchyma of severe-combined immunodeficient (SCID) mice

Mesenchymal progenitors isolated from adult human livers were investigated for their potential to differentiate into hepatocytes (20, 21). Mesenchymal-like cells were obtained by selective culture (not sorting) of total liver cells. FACS analyses of cultured cells revealed a phenotype similar to mesenchymal stem cells with positive expression for CD90, CD73, CD29, CD44, CD13, and HLA-class I, but negative expression for CD105, CD133, CD117, CD45, CD34, and HLA-DR; cells were weakly positive for CD49e and CD49b, and only a minor fraction expressed CD49f. When cells were intrasplenically transplanted into uPA+/+- SCID mice, human albumin and AFP positive cells could be observed and human albumin secretion was detected. When transplanted into SCID mice with and without 70% hepatectomy, human albumin gene expression could be measured in mice livers that had undergone hepatectomy, and human albumin positive cells could be detected in mouse liver sections in both models. Potential fusion events were not analyzed. When cells were induced to hepatic lineages *in vitro* (21), hepatic functions were increased compared to non-

Hepatic stem cells can be isolated from fetal, neonatal, pediatric, and adult human livers with identical characteristics (12, 18), as described by Schmelzer *et al*. Cell surface and intracellular markers include CD326, CD133, CD56, E-cadherin, CD29, Patched (24), claudin 3 (18), CK19, and show weak positivity for albumin. Cells are negative for AFP, CD45, CD34, CD38, CD14, CD90, CD235a, VEGFr, vWF, CD31, CD146, desmin, ASMA, transferrin, connexins, PEPCK, DPP4, CYP450; CD117 is variably expressed. Sonic and Indian Hedgehog signaling pathway components are expressed (24). Stem cells could be selected by MACS sorting as well as under selective culture conditions, which included serum-free medium and culture on plastic. Under these culture conditions, hepatic stem cell colonies formed. These colonies (**Figure 1**) exhibit a typical epithelial morphology of densely packed, small cells with high nucleus-to-cytoplasm ratio. Stem cell colonies are positive for CD326

induced controls, but lower than those of freshly isolated adult liver cells.

(**Figure 2**), CD44h, CD56, and weakly express albumin, but are negative for AFP.

Cells were capable of self-renewal, as shown by clonogenic expansion for more than 150 population doublings. 0.5 – 2.5% of all liver cells from all ages were positive for CD326 expression. Hepatic stem cells have a small diameter of about 9 μm. *In vivo*, they are located in the ductal plates in fetal and neonatal livers and in the Canals of Hering in pediatric and adult livers. The Canal of Hering has been previously described as the reservoir of stem cells in postnatal livers (25, 26). Carpentier *et al*. recently studied lineage tracing by using a Cre recombinase Sox9 mouse model and confirmed that ductal plate cells give rise to cholangiocytes, periportal hepatocytes, and adult liver progenitor cells (27). Furuyama *et al*. (28) demonstrated that adult intestinal cells, hepatocytes and pancreatic acinar cells are physiologically supplied from Sox9-expressing progenitors using Cre-based lineage tracing in mice.

Table 2. Progenitors with hepatic potential isolated from human livers. Details are given in the respective sections.

#### **3.1 Human liver multipotent progenitors**

Dan *et al*. isolated liver stem cells co-expressing endodermal and mesenchymal phenotypes from human fetal liver by culture selection on feeder cells (19). These cells could differentiate not only into hepatocytes and bile duct cells, but also into fat, bone, cartilage, and endothelial cells. Because of their multilineage differentiation potential, these cells were termed human fetal liver multipotent progenitor cells (hFLMPC). The *in vivo* percentage of this progenitor was not given, as these cells were isolated by culture selection. Cell surface and intracellular markers included: CD34, CD90, CD117, CD326 (also called epithelial cell adhesion molecule (EpCAM)), c-met, SSEA4, CK18, CK19, CD44h, and vimentin. Cells were negative for albumin, CD133, CD45, and AFP. They could be cultured monoclonal and longterm for up to 100 population doublings. Cells had population doubling times of 46h. Early and late passages demonstrated identical morphology, differentiation potential, and telomere length. Cultured cells formed typical clusters with cells having a high nuclear to cytoplasm ratio. The morphology of these clusters resembled hepatic stem cells colonies described by Schmelzer *et al.* (12). When transplanted into immunotolerant Rag2- /- γ- /- mice (using a modified retrorsine/carbon tetra-chloride model), human-specific albumin in mouse serum and human-specific albumin in sections of the liver could be detected. Liver sections of transplanted mice demonstrated clusters of human hepatocytes. A repopulation of 0.8–1.7% was estimated. The multipotential differentiation potential and resemblance to hepatic stem cell colonies suggests that hFLMPC represent mesendodermal precursors of hepatic stem cells.

Herrera *et al*. isolated a similar population from human adult livers (22) using culture selection. These cells also expressed hepatic and mesenchymal markers. Cell surface and intracellular markers included albumin, AFP, CD29, CD73, CD44, CD90, vimentin and nestin; however, there was a negative expression of CD34, CD45, CD117, CD133, and CK19, and a weakly positive expression of CK8 and CK18. The cells were different from those described by Dan *et al*., as albumin and AFP expression could be observed and hematopoietic markers CD34 and CD117 were absent. *In vitro*, progenitors differentiated not only into hepatocytes, but also into osteogenic, endothelial, and islet-like, insulin-producing

**Isolation method**

MACS, culture **Phenotype** *In vivo*

Positive: AFP. Variable: CD326

**model for repopulation**

*In vitro*  **characteristics**

NOD/SCID Can arise from hHpSC colonies in culture

/- γ-/- mice

**Term used by authors**

Abbreviations: AFP: alpha-fetoprotein; CCl4: Carbon tetrachloride; CD: cluster of differentiation; CK: cytokeratin; GGT: γ-glutamyl transpeptidase; HLA: human leukocyte antigen; NOD: non-obese diabetic; SCID: severe-combined immunodeficient; MACS: magnetic activated cells sorting;

Table 2. Progenitors with hepatic potential isolated from human livers. Details are given in

Dan *et al*. isolated liver stem cells co-expressing endodermal and mesenchymal phenotypes from human fetal liver by culture selection on feeder cells (19). These cells could differentiate not only into hepatocytes and bile duct cells, but also into fat, bone, cartilage, and endothelial cells. Because of their multilineage differentiation potential, these cells were termed human fetal liver multipotent progenitor cells (hFLMPC). The *in vivo* percentage of this progenitor was not given, as these cells were isolated by culture selection. Cell surface and intracellular markers included: CD34, CD90, CD117, CD326 (also called epithelial cell adhesion molecule (EpCAM)), c-met, SSEA4, CK18, CK19, CD44h, and vimentin. Cells were negative for albumin, CD133, CD45, and AFP. They could be cultured monoclonal and longterm for up to 100 population doublings. Cells had population doubling times of 46h. Early and late passages demonstrated identical morphology, differentiation potential, and telomere length. Cultured cells formed typical clusters with cells having a high nuclear to cytoplasm ratio. The morphology of these clusters resembled hepatic stem cells colonies

described by Schmelzer *et al.* (12). When transplanted into immunotolerant Rag2-

(using a modified retrorsine/carbon tetra-chloride model), human-specific albumin in mouse serum and human-specific albumin in sections of the liver could be detected. Liver sections of transplanted mice demonstrated clusters of human hepatocytes. A repopulation of 0.8–1.7% was estimated. The multipotential differentiation potential and resemblance to hepatic stem cell colonies suggests that hFLMPC represent mesendodermal precursors of

Herrera *et al*. isolated a similar population from human adult livers (22) using culture selection. These cells also expressed hepatic and mesenchymal markers. Cell surface and intracellular markers included albumin, AFP, CD29, CD73, CD44, CD90, vimentin and nestin; however, there was a negative expression of CD34, CD45, CD117, CD133, and CK19, and a weakly positive expression of CK8 and CK18. The cells were different from those described by Dan *et al*., as albumin and AFP expression could be observed and hematopoietic markers CD34 and CD117 were absent. *In vitro*, progenitors differentiated not only into hepatocytes, but also into osteogenic, endothelial, and islet-like, insulin-producing

Human hepatoblasts

PDT: population doubling time; uPA: urokinase-type plasminogen activator.

**Publication Develop-**

the respective sections.

hepatic stem cells.

**3.1 Human liver multipotent progenitors**

Schmelzer *et al*. 2006, 2007 (12, 18) **mental stage of liver tissue**

Fetal (16-20 weeks of gestation)

**Presumable lineage**

structures. Adipogenic differentiation could not be induced. As these cells were cultureselected, percentages of their *in vivo* occurrence were not established. Cells *in vitro* demonstrated exponential growth rates. When transplanted, human cells could be localized *in vivo* within the liver parenchyma of severe-combined immunodeficient (SCID) mice treated with N-acetyl-p-aminophen.

Mesenchymal progenitors isolated from adult human livers were investigated for their potential to differentiate into hepatocytes (20, 21). Mesenchymal-like cells were obtained by selective culture (not sorting) of total liver cells. FACS analyses of cultured cells revealed a phenotype similar to mesenchymal stem cells with positive expression for CD90, CD73, CD29, CD44, CD13, and HLA-class I, but negative expression for CD105, CD133, CD117, CD45, CD34, and HLA-DR; cells were weakly positive for CD49e and CD49b, and only a minor fraction expressed CD49f. When cells were intrasplenically transplanted into uPA+/+- SCID mice, human albumin and AFP positive cells could be observed and human albumin secretion was detected. When transplanted into SCID mice with and without 70% hepatectomy, human albumin gene expression could be measured in mice livers that had undergone hepatectomy, and human albumin positive cells could be detected in mouse liver sections in both models. Potential fusion events were not analyzed. When cells were induced to hepatic lineages *in vitro* (21), hepatic functions were increased compared to noninduced controls, but lower than those of freshly isolated adult liver cells.

#### **3.2 Hepatic stem cells in the human liver**

Hepatic stem cells can be isolated from fetal, neonatal, pediatric, and adult human livers with identical characteristics (12, 18), as described by Schmelzer *et al*. Cell surface and intracellular markers include CD326, CD133, CD56, E-cadherin, CD29, Patched (24), claudin 3 (18), CK19, and show weak positivity for albumin. Cells are negative for AFP, CD45, CD34, CD38, CD14, CD90, CD235a, VEGFr, vWF, CD31, CD146, desmin, ASMA, transferrin, connexins, PEPCK, DPP4, CYP450; CD117 is variably expressed. Sonic and Indian Hedgehog signaling pathway components are expressed (24). Stem cells could be selected by MACS sorting as well as under selective culture conditions, which included serum-free medium and culture on plastic. Under these culture conditions, hepatic stem cell colonies formed. These colonies (**Figure 1**) exhibit a typical epithelial morphology of densely packed, small cells with high nucleus-to-cytoplasm ratio. Stem cell colonies are positive for CD326 (**Figure 2**), CD44h, CD56, and weakly express albumin, but are negative for AFP.

Cells were capable of self-renewal, as shown by clonogenic expansion for more than 150 population doublings. 0.5 – 2.5% of all liver cells from all ages were positive for CD326 expression. Hepatic stem cells have a small diameter of about 9 μm. *In vivo*, they are located in the ductal plates in fetal and neonatal livers and in the Canals of Hering in pediatric and adult livers. The Canal of Hering has been previously described as the reservoir of stem cells in postnatal livers (25, 26). Carpentier *et al*. recently studied lineage tracing by using a Cre recombinase Sox9 mouse model and confirmed that ductal plate cells give rise to cholangiocytes, periportal hepatocytes, and adult liver progenitor cells (27). Furuyama *et al*. (28) demonstrated that adult intestinal cells, hepatocytes and pancreatic acinar cells are physiologically supplied from Sox9-expressing progenitors using Cre-based lineage tracing in mice. In CCl4 mediated liver injury, Sox9-positive progenitors contributed to liver

Hepatic Progenitors of the Liver and Extra-Hepatic Tissues 49

Human hepatoblasts do not express the mesenchymal or hematopoietic markers CD90, vimentin, and CD34 (34). In mice, hepatoblasts express the surface marker Dlk-1 (35-37), which was subsequently demonstrated to be expressed by human fetal hepatoblasts as well (34). Mouse fetal liver cells sorted for Dlk-1 can be cultured long-term; transplantation of Dlk-1 positive cells into the spleen gives rise to hepatocytes in the liver. Several signaling pathways and transcription factors contribute towards differentiation into either cell type. In mice, Notch signaling controls differentiation towards biliary epithelium by upregulation of HNF1β but downregulation of HNF1α, HNF4, and C/EBPα (38), and, in turn, suppression of C/EBPα expression in periportal hepatoblasts is suggested to induce biliary epithelial

Fig. 2. Human hepatic stem cell colonies established as described in (12) are positive for CD326 (**A**). Fluorescence microscopy for the transmembrane glycoprotein CD326 (also named epithelial cell adhesion molecule (EpCAM)) in (**A**), and corresponding nuclei stained

Various surface markers have been applied to identify hepatic stem or progenitor

Germain *et al*. described the bipotential capacity of fetal rat liver cells to differentiate into hepatic and biliary cells *in vitro* (39), as did Kubota *et al*. using clonal cultures (40). Small hepatocytes were detected in non-parenchymal fractions of adult rat liver cells (41-44). These small hepatocytes produced colonies that expressed hepatic and biliary markers. A similar type of colony could be obtained when adult liver cell clusters were placed into culture (45). Suzuki *et al*. sorted progenitor populations from fetal mice and rat livers with a

into albumin and glycogen positive cells when transplanted into retrorsine-treated adult rats that had undergone two-third partial hepatectomy. Cells negative for c-met or positive for CD45 could not repopulate recipient livers. These progenitors could be also cultured clonally. Feng *et al*. (51) demonstrated that these cells could also undergo pancreatic differentiation in culture as well as *in vivo* when transplanted into alloxan-induced diabetic

, CD45-, and TER119- (46-50). Sorted cells developed

**4. Murine and rat hepatic progenitors in the fetal and adult liver**

differentiation by increasing HNF6 and HNF1β expression (17).

with 4',6-diamidino-2-phenylindole in (**B**).

phenotype of c-met+, CD49f+, CD117-

populations in rodents.

regeneration. Hepatic stem cells have been shown to differentiate into biliary and hepatocytic lineages *in vivo* and *in vitro* (12). Freshly isolated cells or stem cells expanded in culture developed into mature liver tissue expressing human-specific proteins when transplanted into NOD/SCID mice, and lost their expression of stem cell marker CD326, CD133, and CK19. Whether those cells also possess multilineage differentiation potential beyond endodermal fates, i.e. mesodermal or ectodermal, has not yet been investigated. Khan *et al*. transplanted human fetal liver derived CD326+ sorted progenitors into patients with liver fibrosis (29). Patients demonstrated improvements in clinical and biochemical parameters and a decrease in mean MELD (model for end-stage liver disease) score at sixmonth follow-up.

Fig. 1. Human hepatic stem cell colony in culture, established from fetal liver cell suspensions as described in (12); phase contrast microscopy (**A**), and fluorescence microscopy (**B**) of proliferating cells with positive nuclei for incorporated thymidine analog bromodeoxyuridine (**B-I**) and corresponding total nuclei stained with 4',6-diamidino-2 phenylindole (**B-II**).

#### **3.3 Hepatoblasts in human liver**

Hepatoblasts are the main parenchymal cell type of the fetal liver and are defined by their expression of AFP. AFP positive cells are rare in normal adult livers, except in livers with severe injury or disease (30-32) (for review, see (33)). Hepatoblasts can give rise to hepatocytes and cholangiocytes, and are therefore also named bipotential progenitors (15). AFP-negative hepatic stem cells are the precursors to hepatoblasts that can mature into AFPpositive hepatoblasts (12). Human fetal hepatoblasts could be cultured long-term and clonally, and contributed to liver parenchyma when transplanted into SCID mice (23). Hepatoblasts express biliary and hepatocyte markers such as CK19, CK14, gamma glutamyl transpeptidase, glucose-6-phosphatase, glycogen, albumin, AFP, E-cadherin (34), α-1 microglobulin, HepPar1, glutamate dehydrogenase, and dipeptidyl peptidase IV (15, 18).

regeneration. Hepatic stem cells have been shown to differentiate into biliary and hepatocytic lineages *in vivo* and *in vitro* (12). Freshly isolated cells or stem cells expanded in culture developed into mature liver tissue expressing human-specific proteins when transplanted into NOD/SCID mice, and lost their expression of stem cell marker CD326, CD133, and CK19. Whether those cells also possess multilineage differentiation potential beyond endodermal fates, i.e. mesodermal or ectodermal, has not yet been investigated. Khan *et al*. transplanted human fetal liver derived CD326+ sorted progenitors into patients with liver fibrosis (29). Patients demonstrated improvements in clinical and biochemical parameters and a decrease in mean MELD (model for end-stage liver disease) score at six-

Fig. 1. Human hepatic stem cell colony in culture, established from fetal liver cell suspensions as described in (12); phase contrast microscopy (**A**), and fluorescence

microscopy (**B**) of proliferating cells with positive nuclei for incorporated thymidine analog bromodeoxyuridine (**B-I**) and corresponding total nuclei stained with 4',6-diamidino-2-

Hepatoblasts are the main parenchymal cell type of the fetal liver and are defined by their expression of AFP. AFP positive cells are rare in normal adult livers, except in livers with severe injury or disease (30-32) (for review, see (33)). Hepatoblasts can give rise to hepatocytes and cholangiocytes, and are therefore also named bipotential progenitors (15). AFP-negative hepatic stem cells are the precursors to hepatoblasts that can mature into AFPpositive hepatoblasts (12). Human fetal hepatoblasts could be cultured long-term and clonally, and contributed to liver parenchyma when transplanted into SCID mice (23). Hepatoblasts express biliary and hepatocyte markers such as CK19, CK14, gamma glutamyl transpeptidase, glucose-6-phosphatase, glycogen, albumin, AFP, E-cadherin (34), α-1 microglobulin, HepPar1, glutamate dehydrogenase, and dipeptidyl peptidase IV (15, 18).

month follow-up.

phenylindole (**B-II**).

**3.3 Hepatoblasts in human liver**

Human hepatoblasts do not express the mesenchymal or hematopoietic markers CD90, vimentin, and CD34 (34). In mice, hepatoblasts express the surface marker Dlk-1 (35-37), which was subsequently demonstrated to be expressed by human fetal hepatoblasts as well (34). Mouse fetal liver cells sorted for Dlk-1 can be cultured long-term; transplantation of Dlk-1 positive cells into the spleen gives rise to hepatocytes in the liver. Several signaling pathways and transcription factors contribute towards differentiation into either cell type. In mice, Notch signaling controls differentiation towards biliary epithelium by upregulation of HNF1β but downregulation of HNF1α, HNF4, and C/EBPα (38), and, in turn, suppression of C/EBPα expression in periportal hepatoblasts is suggested to induce biliary epithelial differentiation by increasing HNF6 and HNF1β expression (17).

Fig. 2. Human hepatic stem cell colonies established as described in (12) are positive for CD326 (**A**). Fluorescence microscopy for the transmembrane glycoprotein CD326 (also named epithelial cell adhesion molecule (EpCAM)) in (**A**), and corresponding nuclei stained with 4',6-diamidino-2-phenylindole in (**B**).


**1. Introduction**

The modern society needs specialists that can undertake non-standard decisions and actions in solving technical and economic problems. Above strict and rather narrow qualification stands the social need for persons to be able to enrol high-tech solution for accomplishment of human needs, under various social, cultural and feasibility constraints.

An assessment presented in 2007 by the Institute of Directors [1] grouped the skills and qualities that employers seek as items in four sets: employability, people, social and personal qualities.

In the employability set, creative and innovative thinking was considered quite important by 51% and very important by 40% of employer respondents, after advanced oral communication

skills, appreciated as quite important by 46% and very important by 42% of the employers. Decision-making skills received, correspondingly 51 and 38%, while problem-solving skills were considered quite important by 37% and very important by 59% of the employers, positioned on the third place after ability to meet deadlines (29 and 60%, correspondingly) and attention to detail (34 and 61%). As it appears, half of the employers appreciate creativity, in strong liason with problem solving.

A recent survey conducted by the Millennial Branding [2] reveals that, in the engineering fields, effective communication skills are crucial to success. The second soft skill found crucial in an engineer's career is creativity, defined as the driving force behind innovation and increasingly gaining recognition as the new capital in the actual economic conditions. As a consequence, creativity should be treated like a skill that needs to be identified, cultivated and trained. One effective way to do that is to foster a creative culture during the educational process and many authors propose some turning keys to develop a culture for innovation and creativity [3].

In conclusion, extended experience and knowledge need creativity as a third component to create a base for any innovative endeavour or advancement.


4.5 Involvement of households' in waste minimization

On the residents' readiness to separate and recyclable their waste at the house (source) for collection, the result indicates that majority (50 and 49%) of the respondents in Berekum and Dormaa respectively were ready to separate their waste at the source given the necessary incentives. They pointed the increase in collection rate to two times a week, the free provision of plastic bags with variety of colors, and to be provided with free bins by the companies or the assembly for separate collection as the incentives needed for effective waste separation. Over 40% accepted to purchase their own receptacles for storing organic waste. Whereas 33% called the enforcement of by-laws to ensure everybody separate their waste. The respondents acknowledged their awareness on waste reuse, recycling, as well as composting. Majority indicated that they use food waste to feed livestock, salvage used plastics and cans, and sachet rubbers for the informal buyers or scavengers. Moreover some continue to engage in burning waste. Small number of them uses organic waste as manure for vegetable garden. Notwithstanding, the residents' awareness on reuse and recycling of waste in the municipalities are very low as more reusable and recyclable materials continue to be seen in the streets, drains and streams. This implies that the existing collection system does not ensure recycling as varied wastes are sent to the dumping grounds with very little or no recycling by scavengers.

#### 4.6 Service quality of waste management in Berekum and Dormaa

The quality of SWM was assessed by asking the respondents to indicate service satisfaction by responding either satisfied or not satisfied with the quality of service on a five-point scale from very poor to very good in terms of two service quality attributes (reliability of collection and sanitary conditions at bin/container location). To rate the quality SWM of the service providers effectively, all the communities served by the waste management company were selected for the survey. The study shows considerable disparities in terms of quality in the existing SWM system as practiced in the municipalities. In the Berekum Municipality, a total of 65% of the respondents who patronize house-to-house collection service rated there liability of service and sanitary condition and waste overflow as fair and good. Areas such as Estate, Nyamebekyere and Osofokyere which have larger number of high and medium income households' fall in this category of the respondents rated the quality of service of the company in their vicinity as good. The level of service quality could be attributed to the perceived quality of service by the people. This is because they pay for waste services that recover full cost and therefore they expect the service to be devoid of waste overflow from bins located in front of their house. The service reliability and sanitary conditions of communal collection in the low income areas of Atonotia, Kyirikwede and Amangoase were largely rated as poor by residents. Surprisingly, a total 76% of the respondents for communal collection rated the service as poor. This is because the waste overflow from communal containers unto the ground was widespread. The people in these areas confirmed that collection is irregular and the containers 'sites are not desirably maintained by the company and the Assembly.

In the Dormaa Municipality, the survey revealed similar results. There were also considerable disparities in terms of quality in the existing SWM system as practiced in the municipality. About 71% of the respondents who patronize house-to-house collection service rated the sanitary condition and waste spill over as good. In addition 59% said the reliability of waste collection was also good. Areas such as Kumidaa Street and Asikafo Amantem which have larger number of high and

Decentralization and Solid Waste Management in Urbanizing Ghana… DOI: http://dx.doi.org/10.5772/intechopen.81894

medium income households' fall in this category of the respondents rated the quality of service of the company in their vicinity as good. The service reliability and sanitary conditions of communal collection in the low income areas of Atoase, Ahantrase and Ahenbrono were generally rated as poor by residents. Interestingly, about 67 and 74% in these areas rated the sanitary condition and Reliability of waste collection respectively as poor. To them, the rate of waste overflow, from communal containers unto the ground at the container sites were high. The households confirm that collection is irregular and the containers 'sites are not cleaned by the company. Comparatively, more of the residents in Dormaa Municipality rated the service quality for the house to house as good than those from Berekum Municipality. Approximately 71 and 59% of the residents from Dormaa Municipality rated the sanitary condition at the container site and the reliability of waste collection respectively as good whereas 65 and 54% also rated the sanitary condition at the container site and the reliability of waste collection respectively in Berekum Municipality. Similar, results came out regarding communal collection. A total of 43 and 36% rated the sanitary condition at the container site and the reliability of waste collection respectively as good from the Dormaa Municipality whereas 27 and 24% also rated the sanitary condition at the container site and the reliability of waste collection respectively in Berekum Municipality.

#### 4.7 Mechanisms for solid waste management regulation

To monitor the quality of service effectively, the companies are mandated to furnish the Local Assembly with information on monthly basis. This comprises of performance targets, vehicle tour schedule, proceeds and expenditure from houseto-house collection and tonnage of waste disposed of. The key informants revealed that the performance targets as well as the formal rules and regulation for private waste companies were obviously elucidated in the contract signed. In addition, they affirmed that, the company cooperate with the Municipalities and provide information on tonnage on waste collected. This information is kept and used as the basis for paying the companies. With reference to house-to-house service, the companies further admitted that they (companies) provide the municipalities with information on revenues from the house-to-house services. In contrast, the staffs of the WMD were of the view that actual revenue from house to house collection is not properly accounted for in the reported to the Assemblies. Further result from them pointed out that detailed document on claims and revenue collected always lag behind time and the revenue figures usually were far below expectation. There was a clear evident of information asymmetry with the reports on cost and revenue in all the two municipalities. The information asymmetry in the report of the companies did not arguer well for the Assemblies to have a firm grip on cost and revenue to make any meaningful plan for effective cost recovery mechanism.

The results further revealed that the Assembly alone set up the service charge for the communal as well as house-to-house service. They further pointed out that the tariff for house-to-house services devoid of any central government support are fixed by the individual companies and submitted to the Municipal Assemblies for approval. The Assemblies specify an indicative levy for house-to-house collection to be collected monthly and a unit price per emptying the skips for communal collection service as specified in the contract document. The final levies and the unit prices at are susceptible to changes using the price escalation formula in the contract after the award of contract. Concerning waste collection charges and fee (unit price) and cost recovery, the companies providing the house-to-house collection takes approved service fees from their client on monthly basis in both Berekum and Dormaa. The house-to-house collection fees for waste management were GH¢12

(US\$2.50) Berekum and GH¢10 (US\$2) for Dormaa but those who patronize the communal services do not pay for user charges. However the cost for lifting a tonne of waste keep increasing with time and over time, this has become a burden on the assemblies. It was further revealed that the user charges were not regularly reviewed. This has resulted in big cash flow problems for the companies due to the continuous increase in exchange rate of the cedi, inflation and fuel prices. The user charges need to be reviewed by the Assembly and published the new fees in national gazette as by-law for it to be legally binding on residents. This according to Assemblies is cumbersome and requires political will on the part of the central government and municipalities. This indicates clearly that there is a look warm attitude from the Municipal Authorities to implement full cost recovery through charging of all households in the two municipalities.

Also, the key informants revealed that the Assemblies hardly conduct public education. There was only two and four count for Berekum and Dormaa Municipalities respectively. This has adversely affected the residents' attitude toward waste management. The residents continue to litter indiscriminately. In relation to the Assembly's commitment to bye-laws it revealed that the two assemblies had bye-laws fully gazetted to keep the companies and the residents within the confines of SWM best practices. However, the bye-laws were not strictly enforced. Subsequent result shows that the Assembly finds it difficult to fulfill the terms of payment as stated in SWM contractual arrangements with private companies. More so, there had not been any occasion where interest had been paid on delayed payments beyond the 3 months as stated in most contracts. The difficulties and holdups identified in the Assemblies commitment to its contractual obligations are basically lack of financial resources. The key informant from the waste management department said they keep on changing their schedule for educating the masses on waste management year in year out all because of the lack of funds. Conversely, according to the companies, the cost recovery mechanism is inadequate. With this the assemblies find it difficult to generate enough revenue to pay the companies. There was also weak mechanism in place to deal with residents who refuse to pay for the waste collection services rendered. The Assembly delays so much with the payment of monies and this in effect affects service quality. It can be concluded that Assemblies' non-adherence to contract obligations have a major influence on service quality and productivity of companies.

Also, concerning the companies' commitment to contractual obligations, indicators used includes company achieves daily collection target in the contract, company's cover waste containers during transporting, company collection crew use protective clothing, company keeps container site free of litters and clean. The directors of both the private companies and the WMD interviewed said the companies were able to achieve their daily targets of about 80%. It was confirmed together with other key informant and the resident in the household survey that the collection crew have protective clothing and use them their activities, however very few about 10% refuse to wear theirs in most cases. The few workers who do not in most cases use the protective clothing started with the informal sector and believed they are responsive to the waste collection without protective clothing. Regarding the companies obligation to keeping the container sites clean especially with the communal collection. Twenty-five out of over 100 container sites were kept clean and tidy whiles the others had litters all over. Large heaps of waste remains at these container sites after solid waste has been move to the disposal sites. In relation to this is the companies' obligation to repair and maintain communal waste skips. The key informant said the company barely does this function it is only the assemblies that squeeze some funds out of pressure from the residents for few repairs works on these containers.

### Decentralization and Solid Waste Management in Urbanizing Ghana… DOI: http://dx.doi.org/10.5772/intechopen.81894

Regarding the enforcement of legislation and sanctions, the municipal assemblies have the sole responsibility to enforce legislations and sanctions on the provision of public services. The Assembly uses bye-laws as well as terms and condition in the contract as the basic mechanism to managing solid waste collection services in their area of jurisdiction. It was realized from the companies' point of view that the bye-laws were enforced. In addition they were also of the view that the monitoring of compliance was done effectively. In addition, they opined that the sanctions for noncompliance to the bye-laws were punitive enough. They also revealed that the environmental health standards and sanitation were strictly observed and enforced. However, the household survey shows a different picture. It indicated that very little have been done to enforce bye-laws. It was realized that, the Assemblies find it very difficult to sanction offenders due to the frequency at which these bye-laws are flouted. The residents show lax attitude toward effective waste management. It was also observed that there were inadequate waste containers and low frequency of waste collection especially with the communal collection. Relating to this is the lack of environmental sanitation courts in these areas. This hinders the enforcement of solid waste and sanitation regulation.

The fines for non-compliance are the same in the two municipalities and are subject to review. They may be changed by the Assemblies after the service provider has been informed of such changes. The fine ranges from GH¢100 (US\$20)- GH¢200 (US\$40). The study revealed that the municipal assemblies have so far not been able to apply any sanction to the companies though evidence from the household survey shows the companies fail enormously in waste pick up as well as the cleaning up of the container sites. This study is therefore consistent with the finding of Oduro-Kwarteng that there is lack of sanctions in the waste management sector. In a similar study involving five cities, Oduro-Kwarteng [39] discovered that many of the contracts had credible threats of sanctions that required sanction, but noncomplying companies were not penalized.


*3.1.2 Thermal degradation*

Plastic waste litters on the coastal shorelines are exposed to elevated temperatures, leading to a thermo-oxidative breakdown of the plastic. Thermal degradation of plastics involves absorption of heat and breaking of polymeric chains thus releasing radicals that react with atmospheric oxygen to produce hydroperoxide, which eventually cleaves into hydroxyl and alkoxy free radicals. These radicals result in the formation of aldehydes, ketones, esters, or alcohols, causing plastic degradation [69]. Chain scission and cross-linking of the polymers are responsible for the thermal degradation process [70, 71]. In the environmental matrix related to beaches and coastal shorelines, slow thermal degradation of plastics may occur concurrently with photodegradation (due to the presence of sunlight), resulting in enhanced plastic degradation [72].


**A New Livelihood Sustainability Index for Rural Revitalization Assessment—A Modelling Study on Smart Tourism Specialization in China**

#### **Huiqin Li 1, Peter Nijkamp 2,\*, Xuelian Xie 1 and Jingjing Liu 1,\***

Received: 20 March 2020; Accepted: 13 April 2020; Published: 14 April 2020

**Abstract:** In our rapidly urbanizing world, the problem of rurality versus urbanization is becoming a source of concern. Rural tourism development may become a new important stimulus for promoting a sustainable transformation of the farmers' livelihood. This calls for a smart specialization in rural tourism where the focus is on a balanced rural revitalization strategy. As part of the empirical research, this paper introduces a livelihood sustainability index. This index helps to construct a balanced system for the evaluation of livelihood sustainability achievements in rural tourism destinations. It is based on livelihood capital, livelihood strategy, and the interlinkage between livelihood and environment, in order to dynamically assess the livelihood sustainability of rural households. Taking Huangpi District of the Wuhan area in China as our applied case study, the livelihood sustainability index appears to show over the past years a significant rise, based on a comprehensive index method, an entropy method, and a coupling coordination model. Our findings show that the development of rural tourism has clearly promoted livelihood sustainability. This has inter alia resulted in the accumulation of livelihood capital, an asset of which both social and cultural capital have benefitted greatly; livelihood strategies have also improved, and therefore so have livelihood diversity and stability; and finally, the interlinkage and coordination degree between livelihood and the environment has also changed positively from a primary to intermediate balanced development. However, the livelihood sustainability index in the area concerned is still relatively low, and has not yet reached its possible optimal level. Hence, there is still much room for improvement. Various approaches can be proposed to achieve a more sustainable livelihood, such as enhancing livelihood capital; narrowing the economic gap between farmers by participating in professional tourism activity; establishing the mechanism of industrial integration and the development of rural eco-tourism; and coordinating a balanced development of livelihood and environmental quality.

**Keywords:** sustainable livelihoods; rural ecological environment; rural tourism; smart specialization; livelihood sustainability index; rural revitalization strategy

#### **1. Rural Revitalization and Smart Specialization: New Opportunities for Rural Tourism**

The rapid urbanization of our world has started already more than half a century ago. Nowadays, cities—and in a more general sense, urban agglomerations—accommodate already more than half of the world's population. From this perspective, the UN is even speaking of the "urban century" as a new epoch in human history. This rising urbanization is not only a simple geographic and demographic phenomenon of spatial movements of people. The new map of our planet, called the "New Urban World" by Kourtit, mirrors also a change in economic–political power positions of modern cities [1]. In the "urban century" we observe a fundamental transformation in the roles of urban

agglomerations and mega-cities (cities with more than 10 million inhabitants), which may be generally described as "urban empires" [2]: cities and urban areas tend to become economic–political magnets, which attract a significant part of global socio-economic activity (e.g., business, visitors, culture, science and technology) and become the smart leaders of world economic forces.

The above sketch of global megatrends prompts two broad categories of policy challenges, viz. (i) an effective management of the multi-faceted constellation of large-scale urban areas (e.g., housing, mobility, poverty, environmental quality, human health); and (ii) sufficient care for a balanced socio-economic position of the rural population, which is nowadays gradually turning into a minority, at least from a geographic–demographic perspective. In the present study we will focus our attention on the development of new opportunities for the rural population in the urban world. In particular, we will address here novel perspectives offered by rural tourism to the agricultural sector where we will use China as a case study.

Rural development strategies have been advocated worldwide as a policy intervention aiming at supporting a healthy livelihood for the rural population, often oriented towards agriculture, handicraft, small-scale informal activities, wellness, nature, and ecology [3]. In recent decades, eco-tourism—inspired by an environmentally benign orientation of less urbanized areas—has become a new focal point of rural development opportunities. There is a growing set of studies on rural transitions in the context of regional resilience. An interesting case study on the attractiveness of rural landscapes and nature in small-scale tourism can be found in a Japanese case study on rural wellness by Romao et al. [4].

It is clear that a re-orientation of a local economy towards rural tourism is a major challenge, from both an economic and sustainability point of view. This calls for a long-range strategic policy, which will ensure economic livelihood, entrepreneurial vitality, and environmental awareness of all stakeholders involved. The framing of the present research on a smart, sound, and sustainable development of rural areas in China will be based on a so-called "smart specialization" policy [5]. Smart specialization has in recent years become a popular policy strategy for supporting less privileged areas. Given the territory-specific assets in a given area that is in need of public assistance, new public stimuli aiming at innovative behavior by all actors have to be provided in a tailor-made way that support specific and novel development opportunities of the area concerned. Generic policies (e.g., general infrastructure, education) do not adequately address the weaknesses of a given area; a "one size fits all" strategy is not sufficient for a significant upgrading of a certain less developed region [6]. Smart specialization calls for a case-specific approach that exploits all forms of local or regional capital and balances emerging discrepancies or disparities by a carefully harmonized supply of public resources aiming at strengthening local opportunities and eliminating local bottlenecks. Various scientific studies on smart specialization as promising forms of new regional development policy can be found inter alia in Boschma [7], Capello and Kroll [8], Foray [9], and Romao and Nijkamp [10].

In addition to research and policy interest in the impact of tourism strategies, it should be noted that sustainable development of rural tourism has a far-reaching impact on village residents. In villages located in mountainous areas, the contribution of sustainable development of agricultural tourism activities to economic improvement and demographic trends cannot be ignored either [11]. In post-socialist rural areas, sustainable development of tourism has diversified the rural economy towards ecological, economic, and social sustainable development, especially in terms of improving the quality of life of the local people, reducing poverty, as well as mitigating social and environmental degradation [12]. It is noteworthy that the sustainability of rural tourism is based on the idea of combining the social and economic interests of rural areas and the interests of the natural environment. Combining rural and local resources and traditional products that are unique to rural areas with tourism activities can facilitate the current trend of sustainable development [13].

In our analysis of the potential of—and bottlenecks for—a sound rural tourist development, we will take the region of Wuhan in China as an example. The rapid urbanization of China has exerted a deep impact on China's rural areas, with lagging public facilities, a declining population, and less

prosperous local economic perspectives. A clear orientation of rural areas towards small-scale rural tourism may be an interesting form of smart specialization for agriculture in these areas. However, before such a smart rural tourism policy can be implemented more generally, it is necessary to profoundly analyze the strengths and weaknesses of rural tourism in the appropriate, dedicated target areas to be tested. In our approach, we will put the emerging Chinese Rural Revitalization Strategy in the context of a more general Smart Specialization Policy by zooming in on rural tourism development opportunities in the Wuhan region. We aim to identify the critical success factors of such a strategy, based on a wealth of statistical data. Using a quantitative analysis of evidence-based facts, we also will distil useful policy lessons.

This paper is organized as follows. After this introductory section, we will offer a sketch of China's Rural Revitalization Strategy (Section 2), followed by a presentation of the empirical data base (Section 3). The research methodology is outlined in Section 4, while the research results are presented in Section 5. Conclusions and policy lessons are given in Section 6.

#### **2. Sustainable Livelihoods for China's Farmers**

In recent years, China's economic development policy has increasingly focused on the improvement of the growth potential of rural areas. The report of the 19th National Congress of the Communist Party of China put forward the implementation of the new Rural Revitalization Strategy. The livelihood of farmers is an important factor affecting the prosperity of both industry and human life in general. Before analyzing the concept of sustainable livelihoods, we pay attention to the meaning of sustainable tourism development, which usually refers to meeting the needs of local residents and foreign tourists, while protecting the resources they rely on so as to ensure future opportunities and possibilities for tourism development (World Tourism Organization, 1993) [14]. In analyzing sustainable tourism, in addition to the study of the impact of tourism development, researchers will also focus on the excessive development of tourism and on the sustainable development of tourism companies. Over-exploitation of tourist destinations will increase interference with local lifestyles and cause residents to develop a feeling of exclusion, thereby affecting their sustainable tourism development [15]. For tourism enterprises, tourism SMEs and tourism clusters can foster new sustainable development narratives and maintain sustainable ecotourism through absorption, innovation, and adaptability [16].

We know that residents 'attitudes towards tourism are the key to ensuring the success and long-term sustainable development of tourism destinations, and are also important factors in favoring tourism products and protecting the sustainable development of local communities [17]. Compared with urban tourism destinations, the seasonality of tourism will have a greater impact on the sustainable development of rural tourism destinations. The seasonality of the tourism industry will further affect the attitude of the residents towards the tourism industry by affecting the composition of the residents' livelihood capital [18]. At the same time, it is pertinent to consider the typical conflicts of interest in rural areas. In the planning process, one should prioritize the sustainability of protection and the development goals [16]. Therefore, it is without doubt necessary to study the sustainability of rural households' livelihoods in rural areas.

A sustainable livelihood is an important goal of the Rural Revitalization Strategy. "Livelihood" refers to the way people can make a living, which affects the ecological environment depending on their capabilities and assets. Livelihoods are sustainable when people can cope with changes in fragile environments and can recover from external shocks, as well as maintain or strengthen capacities and assets for the benefit of future generations without damaging natural resources [19]. Sustainable livelihoods also include livelihoods that are independent of external support and do not destroy others [20]. In this context, the Sustainable Livelihoods Framework (SLF) proposed by the UK's Department for International Development (DfID) provides a systematic approach to conduct research on poverty governance and rural development [21]. The SLF reveals the nature of livelihoods, demonstrates the relationship between development and poverty, helps people identify their own livelihood capital and adaptations to the external environment, and leverages their strengths and

external environmental support in order to achieve sustainable livelihoods. Being a holistic and people-centered approach to sustainability, SLF has proved to be a useful analytical tool for the examination of tourism and community relations, particularly in a rural context [22,23].

As a balanced tourism development causes less damage to natural resources than other types of development, China has regarded tourism as one of the most effective approaches for rural area development. Rural tourism has become more popular since the 1990s in China [24]. The development of rural tourism is an important driving force for the transformation of the livelihood of rural households [25]. The livelihood value of tourism is mainly reflected in livelihood capital, livelihood strategy, and livelihood outcomes, and should be sustainable from generation to generation [26]. Tourism development affects the reserves, quality, and allocation of livelihood capital, while the combination, flow, and transformation of capital may become more flexible, which may increase the ability of farmers to reduce risks to a considerable extent [27–29]. The development of rural tourism has promoted the reconstruction and change of the farmers' livelihoods. The traditional single livelihood approaches tend to be diversified, which helps to spread risks and reduce livelihood vulnerability [25]. Livelihood outcomes include increased household income, greater welfare, lower livelihood vulnerability, improved food security, and a sustainable use of natural resources. In addition, factors such as household income and expenditure, mental health, physical health, and the social and natural environment are usually included in the evaluation of sustainable livelihood outcomes [30–32]. The development of rural tourism has an important impact on the farmers' livelihood. The tourism-oriented specialized livelihood model is of great significance for achieving the sustainability of farmers' livelihood [29]. However, insufficient accumulation of livelihood capital, lack of professional organizational guidance, and residents' own myopic perspectives have sometimes prevented farmers from benefiting from tourism development [33,34].

In general, farmer poverty is closely related to the vulnerability of their livelihood. Consequently, important questions are: Does the development of rural tourism improve the sustainability of farmers' livelihood? What are its limiting factors? Clearly, how farmers can be helped to build a sustainable livelihood is related to the realization of the general goal of poverty alleviation in China. At present, tourism and livelihood have gradually become an attractive topic of academic research, and most of this is horizontal or comparative, based on static or multiple livelihood methods [35], with only a few dynamic and longitudinal research studies. Taking the Huangpi District of Wuhan as an example, this paper aims to (i) construct a sustainable evaluation index system for assessing rural households' livelihood; (ii) dynamically assess the sustainable livelihood of farmers before and after they participate in tourism; (iii) uncover its constraints; and (iv) explore novel ways to improve the farmers' sustainable livelihood. Finally, this paper provides a guide for the implementation of the strategy for Rural Revitalization in China and the alleviation of rural poverty through tourism.

#### **3. Overview of Research Area and Data Sources**

#### *3.1. Overview of the Study Area*

Our study area, Huangpi District, is located in the northern part of the province of Wuhan, with a land area of 2261 km2 and a population of 1.13 million. Huangpi District was selected as the site of the case study in this paper, mainly because of the following considerations: 1) Rural tourism in Huangpi District has a promising socio-economic foundation and the farmers' driving effect is clearly visible. In recent years, Huangpi District, relying on landscape resources, has created the Mulan eco-cultural tourism brand and is vigorously developing rural tourism. At present, there is 1 AAAAA (5A)-level tourist scenic spot; five AAAA (4A)-level tourist scenic spots; and more than 600 star-rated farmhouses. In 2018, the number of tourists in the region reached 24.043 million, and the total tourism income reached 14.31 billion yuan, assisting about 100,000 farmers in the region to benefit from tourism development. 2) The rural tourism development model in Huangpi District is typical. In 2016, Huangpi District was included in China's first batch of global tourism demonstration zones, and

implemented a project that involves "citizens going to the countryside, capable people returning to the countryside, and enterprises revitalizing the countryside", according to the official local government. This initiative gradually generated a favorable development trend in driving the promotion of scenic areas, helping enterprises and the participating farmers. In view of this, our study takes the Huangpi Mulan eco-cultural tourist area as the main research area; the scenic spots at different development stages and with high popularity were selected as the empirical research case. According to the ranking of strength of the surrounding villages, the bottom eight villages were selected as the research sites. The basic situation, location, and participation mode of the surveyed villages are shown in Appendix A (Table A1 and Figure 1). Farmers in Huangpi District appear to participate in various forms of tourism, mainly tourism business activities, including catering, accommodation, tourist shops, and fruit picking on farms. Some farmers also obtain tourism income through land transfer, vacant farmhouse rentals or investment, scenic spots or hotel activity, and ticket bonus sharing. Some tourist enterprises at scenic spots got a great deal of revenue from selling entrance tickets, and gave a proportion of this revenue (e.g., 10%–30%) to the local people, who supply land, forests, and other resources used by tourists.

**Figure 1.** Locations of the investigated villages in Huangpi District.

#### *3.2. Data Sources*

Many data in our research stem from field investigations and surveys. Using the participatory rural assessment method, the authors conducted field research in Huangpi District in July 2018. First, the authors conducted in-depth interviews with village authorities and scenic area managers to acquire data on the development of rural tourism, the livelihood of the farmers, and the changes in the rural ecological environment. Secondly, using random sampling, 103 farmers who participated in the tourism were selected from eight villages; the investigation was conducted in the form of one-on-one in-depth interviews. The survey time for each household was about 60 minutes. The survey included: 1) basic information of family members (gender, age, education level, health status, etc.); 2) the status of household livelihood capital before and after participating in tourism (natural capital, physical capital, financial capital, social capital, and cultural capital) and livelihood strategies (means of livelihood and

livelihood stability); and 3) farmers' evaluation of the rural ecological environment before and after tourism development. The basic situation of the surveyed farmers is shown in Appendix A (Table A2). The gender, age, and participation time of the survey participants appear to be quite evenly distributed. Most of the interviewees were educated up to the junior high school level, while their overall education level is low. The family size is mostly 3–5 members. After the presentation of our database, we will sketch out in Section 4 the research methodology applied for our study.

#### **4. Research Methods**

#### *4.1. Composition of the Indicators System*

This paper combines the sustainable livelihood framework of the abovementioned DfID with the current research information [35], in order to construct the sustainable livelihood evaluation index of farmers in rural tourism destinations. The indicators system includes livelihood capital, livelihood strategy, and the linkage (coupling) and coordination degree between farmers' livelihood and ecology. All indicators are given in Appendix A (Table A3).

Livelihood capital is at the core of the sustainable livelihood framework, including natural capital, material capital, human capital, financial capital, and social capital (for a broader overview of the different forms of capital for regional development, see Capello 2019 [36]). Rural culture is an important attraction for rural tourism [37], while scholars such as Gale introduce cultural capital [38]. Livelihood capital is an important basis for farmers to carry out livelihood activities and is also an important barrier against livelihood risk [35]. A lack of livelihood capital is an important factor in restricting the benefit people obtain from tourism development. Therefore, livelihood capital is an important part of evaluating the sustainability of farmers' livelihood [39]. Livelihood strategies are the ways in which farmers can combine and use their own livelihood assets in order to pursue positive livelihood outputs or achieve their livelihood goals [40].

Livelihood diversification is an important indicator of livelihood strategies, which can diversify livelihood, facilitate risk spreading, and reduce vulnerability [25]. The stability of livelihood is an important goal of sustainable livelihoods, and is mainly expressed by the annual change in household income [40,41].

The transformation and upgrading of the farmers' livelihood and the improvement of the ecological environment are important elements of rural revitalization; they are an important guarantee for the sustainable development of rural tourism. The relationship between livelihood and the ecological environment is complex, since they mutually promote and restrict each other. The rural ecological environment is the basis for maintaining the livelihood of farmers, while ecological governance also offers the possibility of improving livelihood [42]. It should be noted here that farmers are often both the destroyers of the ecological environment and its defenders. The improvement of the farmers' sustainable livelihood is an important force in promoting environmental protection [43]. Tourism development clearly plays a vital role in realizing the improvement of the farmers' livelihood and ecological protection [44]. The sustainable and balanced development of livelihoods and the ecological environment is an important condition for farmers to achieve a sustainable livelihood. Therefore, the coupling and coordination degree between the farmers' livelihood and the rural ecological environment is an important indicator for evaluating the sustainable development of the farmers' livelihood. Referring to the coupling coordination model [45], the coupling degree between livelihood and the ecological environment includes the two systems of livelihood and the ecological environment. The standard PSR (Pressure–State–Response) model is then constructed according to the way in which the rural-tourism–ecological-environmental index system is constructed [46,47].

#### *4.2. Data Processing*

The study mainly compares the livelihood sustainability index of farmers before and after participating in tourism through the calculation of comprehensive values, the degree of coordination of livelihood and ecosystem coupling, and the livelihood sustainability index, so as to evaluate the impact of rural tourism development on the sustainable livelihoods of farmers.

During the calculation, livelihood capital, livelihood strategy, livelihood system, and the ecosystem lead to a comprehensive value of livelihood by using a weighted summation. The data is processed dimensionless by the method of extreme difference normalization. In order to avoid a bias caused by subjective factors, the weight of the index is calculated by the entropy method of objective weighting [45].

In order to calculate the comprehensive value of each system, the following formula was used:

$$\mathbf{f} = \sum\_{\mathbf{j}=1}^{n} w\_{\mathbf{j}} \mathbb{X}\_{\mathbf{j}} \tag{1}$$

where: f represents the comprehensive value (0 ≤ f ≤ 1); n represents the nth indicator of criteria on j (j = 1, 2, 3, ... n); ωj represents the weight of each indicator; Xj represents the mean value of each indicator.

Next, we may calculate the degree of coupling between the livelihood system and the ecosystem by

$$\mathbf{C} = \begin{cases} \frac{\mathbf{f}(\mathbf{L}) \cdot \mathbf{f}(\mathbf{E})}{\left[\frac{\mathbf{f}(\mathbf{L}) + \mathbf{f}(\mathbf{E})}{2}\right]^2} \\\\ \frac{\mathbf{f}(\mathbf{L}) + \mathbf{f}(\mathbf{E})}{2} \end{cases} \tag{2}$$

where: C is the degree of coupling (the larger the value, the better the coupling); f (L) and f(E) are the comprehensive value of the livelihood system and the ecosystem (its value is calculated by Formula (1)); k (*n* ≥ 2) is the regulation coefficient, and k is set as 2.

Now, to increase the discrimination capacity of the coupling degree, we may calculate the coupling coordination degree of the two systems by

$$\mathbf{T} = \mathbf{a}\mathbf{f}(\mathbf{L}) + \mathbf{\mathfrak{f}}\mathbf{f}(\mathbf{E}) \tag{3}$$

$$\mathbf{D} = \sqrt{\mathbf{C} \cdot \mathbf{T}} \tag{4}$$

where: α and β represent the weights of the livelihood system and the ecosystem (in this study, both are equally important, so both are set to 0.5); D represents the degree of coupling coordination.

Subsequently, the livelihood sustainability index was derived as follows:

$$S = \omega\_1 \chi\_{\rm L\overline{C}} + \omega\_2 \chi\_{\rm LS} + \omega\_3 \chi\_{\rm L\overline{C}} \tag{5}$$

where: S represents the livelihood sustainability index; ω represents the weight including ω1, ω2, ω3; XLC, XLS and XLEC represent the combined value of livelihood capital, livelihood strategy, and the coupling degree between livelihood and the ecological environment. The above equations will now be used in our empirical analysis.

#### **5. Empirical Research Results**

Our empirical results are presented in Figure 2 and Table 1, respectively. They will now concisely be described.

**Figure 2.** The change in sustainable livelihoods in 2018.

(Note: Since the decimal value is retained to the fourth digit, the value of the skill training indicator before participation is 0).

#### *5.1. Livelihood Capital*

The development of rural tourism has clearly promoted the improvement of the farmers' livelihood capital, the changes in livelihood capital reserves, and its portfolio allocation, among which social capital and cultural capital show the greatest increase. The changes in livelihood capital before and after farmers participate in tourism are shown in Table 1. The development of rural tourism has prompted some farmers to move closer to the scenic spot, which is conducive to tourism management, while the livelihood value of the family location has increased in several aspects: 1) the drinking water

conditions have improved. The quality of the drinking water of a few farmers has changed from the previous pond and well water to tap water, benefiting from the improvement of rural infrastructure construction; 2) material capital has also significantly increased. After participating in rural tourism, some farmers have independently renovated their old houses, built new houses, and even purchased other houses in order to provide tourist accommodations and catering facilities, so their housing capital value has risen. The capital value of the households' durable goods has also increased substantially, and so has the number of TVs and air conditioners. Some farmers have even bought small cars; 3) financial capital has been effectively upgraded. After participating in tourism, the farmers' income and savings have increased. As a result of the large investment required at an early stage and the increase in the amount of loans and borrowing, the government has decided to give appropriate subsidies to the farmers who manage accommodation and catering. Consequently, the enthusiasm of farmers to participate in tourism has grown, the government support has increased, and farmers believe that borrowing finance is easier; 4) the human capital of farmers has increased. Mainly after participating in tourism, their degree of cognitive ability and the extent of skill training has increased significantly, especially for employees at scenic spots and in hotels. The amount of training carried out by enterprises has increased, which has improved the professional skills and knowledge base of the farmers; 5) the relationship between people has intensified, and their expenditure on personal expenses and telephone calls has increased significantly. The value of social network support has increased. Whether a relative or friend is in the public village domain or is a scenic spot manager is very important for farmers in their decision to participate in tourism. Farmers are increasingly welcoming tourists, and it is generally believed that more tourists will generate more benefits; and 6) the value of cultural capital has increased. Rural culture is an important part of rural tourism resources. Folk customs in rural areas are the basis of rural authenticity. In order to attract more tourists, farmers pay more attention to rural culture and are willing to actively understand and inherit traditional culture.

Notwithstanding the overall success, the accumulation of the farmers' livelihood capital is still not at its maximum, while the difference in livelihood capital among farmers is large. After participating in tourism, the family livelihood mode has often changed from farming to tourism management; thus, the dependence on land becomes lower, so that land capital was greatly reduced. Most farmers who are willing to participate lack opportunities to conduct tourism operations because of a poor family situation. Housing capital and household durable goods are the basis for the farmers' production and life, but material capital is still at a low level. Financial capital is still low, especially for farmers who run farmhouses. Due to the large investment required for tourism development, household savings are small or even zero. The existence of human capital is generally characterized by a low level of education, and the number of farmers receiving skills training is also low. Such training mainly happens on the job. Most farmers lack social network support and social capital. Although farmers have an understanding of local folk customs and are willing to inherit them, the cultural characteristics of rural tourism products are still insufficient, and the cultural capital is relatively low.

#### *5.2. Livelihood Strategy*

The development of rural tourism has promoted the reconstruction and change of farmers' livelihoods; nowadays their livelihoods tend to be more diversified. After the completion of the construction of new tourist attractions, the number of non-tourist livelihood farmers has decreased significantly. Before farmers participated in tourism, there were more farmers who had a single way of livelihood, and they were mainly migrant workers. The proportion of farmers who participated in two or more livelihoods after tourism has increased, but only slightly. More farmers are participating in catering and accommodation, followed by working in tourism enterprises. More than 50% of the farmers participate in one type of tourism, mostly accommodation and catering, and family members are almost all involved in tourism management, while tourist shops, tourism enterprises, and rentals require less labor, and are usually performed by other members of the family. Clearly, other livelihood options can be chosen as well.

The stability of livelihood in this area has certainly improved, and rural tourism has a definite role in promoting the stability of the farmers' livelihoods. In addition to being affected by the macroeconomic environment, livelihood stability is also related to the level of education, work skills, and engaging in specific livelihood strategies. Before participating in tourism, the farmers' livelihood stability was poor, the frequency of their work changes was large, and their annual income was unstable. After participating in tourism, however, the overall livelihood stability of farmers has slightly improved, and the work situation became relatively fixed. In particular, the annual income of employees who rent out houses, land, and tourism enterprises is relatively stable now.

Consequently, after participating in tourism, the number of farmers with only one source of income has not fallen sharply. The single way of farming and working has now changed into a single way of tourism livelihood. Most farmers have a higher dependence on tourism. Although the tourism livelihood is more stable than the livelihoods based on farming and labor, the farmers involved in tourism management are highly dependent on the level of development at scenic spots, especially those farmers participating in catering, accommodation, and tourist shops, whose income depends on the tourists who visit the scenic spot. Quantity, and thus overall stability, is not high. At the same time, as more and more farmers participate in the operation of catering, accommodation, and tourist shops, the need for product homogeneity is serious and competition is fierce, resulting in low tourism income for some farmers. Here, a single way of tourism livelihood and low livelihood stability are both factors that restrict the sustainability of farmers' livelihood.

#### *5.3. Coupling Degree between Livelihood and Ecology*

Farmers appear to believe that rural tourism has improved the rural ecological environment, including the water environment, the atmospheric environment, the soil environment, and animal and plant resources. Compared with the natural environment, the improvement of the rural human environment has been greatly improved, especially in terms of physical and mental health. Tourism companies help to upgrade the villages' infrastructure and enhance the rural environment. Governments, scenic spots, and communities have also improved their policies, funds, and facilities for the improvement of the rural ecological environment. As a direct beneficiary of tourism development, farmers are paying more attention to the protection of the rural ecological environment and can actively participate in village governance and ecological protection. Tourism has had a definite positive effect on the improvement of the rural environment, and its ecological function is remarkable, as is shown in Table 2.

The coupling degree reflects the interaction between the livelihood and the ecosystem. Before and after the introduction of tourism, the coupling in terms of correlation between livelihood and the ecosystem is very high, 0.95 and 0.96, respectively, which is close to 1, indicating that the coupling of the two systems is significant. The two are mutually restrained and have strong synergies. Achieving a win–win situation between the two systems plays an important role in promoting the harmonious development of human–land relations. The coordination degree of coupling measures the level of overall coordinated development of these relations. According to the type of coordination and the development of coupling and coordination, before and after tourism, the coupling degree of farmers' livelihood and the ecosystem is 0.69 and 0.74, respectively, from primary to intermediate. However, although rural tourism has a definite role in promoting the coupling and coordination of livelihood and the ecosystem, the improvement appears to be relatively small, and the livelihood and the ecosystem are not coordinated very successfully, which restricts the sustainability of the farmers' livelihood.

Tourism development has resulted in the improvement of the rural tourism ecological environment, but nevertheless, the ecological pressure has increased significantly. Most of the farmers who are involved in catering and accommodation have significantly increased their use of water and electricity, but also the volume of garbage, while the ecological pressure has increased. Some farmers believe that rural noise pollution will increase, which will have a definite adverse impact on daily life. Even after the development of rural tourism, the level of coupling and coordination of livelihood and the ecosystem is still low, and the relationship between humans and the land has not yet reached its optimal state. It is, therefore, necessary to further adjust the smart specialization development model of rural tourism, to improve the ecological environment of rural tourism, and to achieve a win–win situation between livelihood and the ecosystem.

#### *5.4. Livelihood Sustainability Index*

According to the entropy method and Formula (1), the values of ω1, ω2, and ω3 before the residents participated in tourism are respectively, 0.3268, 0.2923, and 0.3809, while after participation the values are 0.3429, 0.3150, and 0.3421. The index weights have not changed greatly. XLC, XLS, and XLEC have contributed, respectively, to the tourism values with 0.4636, 0.3613, and 0.3421, while the participation values were 0.5980, 0.4141, and 0.6867. After the farmers participated in the tourism, the coupling of livelihood capital, livelihood strategy, and livelihood and the ecosystem were improved.

According to Formula (5), the farmer's livelihood sustainability index increased from 0.4143 to 0.5704. Tourism thus has a definite role in promoting the sustainability of farmers' livelihoods, but there is insufficient accumulation of livelihood capital, and a poor livelihood diversity, stability, and ecology. As a result of the impact of the poor level of coordinated development and other constraints, the tourism livelihood sustainability index is still at a relatively low level. Figure 3 clearly shows the difference in the livelihood sustainability index between farmers before and after participating in tourism.

To examine the effects of the independent variables, such as family characteristics and livelihood characteristics, on the livelihood sustainability index, a one-way variance analysis was used in our research (see Table 3). The number of those engaged in household labor, the highest level of education, and the number of livelihoods all have a significant impact on the livelihood sustainability index. The livelihood sustainability index does not increase with the number of family members and the number of family laborers. The households with a household labor force of four family members have the highest index of livelihood sustainability, while families with fewer or many family members might require more help and support. The level of education and the number of livelihoods are positively correlated with the livelihood sustainability index. From the perspective of the increase in that index, it appears that Guantian Village has the largest increase (0.2198) and Qunyi Village (0.1359) has the smallest, mainly because the development cycle of the scenic spots is different. The Mulan Tianchi Scenic Area appears to be relatively mature and attracts more tourists. The farmers' livelihood in this village is relatively sustainable.

**Figure 3.** The change in the livelihood sustainability index.

#### **6. Conclusions and Recommendations**

#### *6.1. Conclusions*

This study has positioned rural tourism strategies in the broader context of smart specialization as a vehicle for effective regional development. The Chinese case study has highlighted the importance of sustainability objectives in regional smart specialization policy.

According to the sustainable livelihood concept, the present paper has developed a livelihood sustainability index. Next, this index was applied and tested in order to dynamically assess the sustainability of farmers' livelihood before and after tourism. The study found that, after farmers participate in tourism, the livelihood sustainability index improves, and so does the coupling of livelihood capital, livelihood strategies, and the linkage of livelihoods and ecology. The number of those engaged in household labor, the highest level of education of family members, and the number of different livelihoods all have a significant impact on the livelihood sustainability index. Nevertheless, the farmers' livelihood strategies are still relatively simple, and they are still vulnerable. The livelihood of farmers has not yet reached its optimal state (in comparison to opportunities elsewhere), and there is still much room for improvement. The factors that restrict the sustainability of farmers' livelihood include insufficient accumulation of livelihood capital, a single livelihood, poor stability, and high ecological pressure, while the coupling of livelihoods and the ecological environment are of a relatively poor quality and lack a coordinated development.

#### *6.2. Recommendations*

The transition from traditional farming to more modern rural tourism activities calls for effective resilience of all actors involved. Farmers are in a favorable position in the development of rural tourism, which guarantees benefits to farmers. In fact, a sustainable development of farmers' livelihoods

may be the end-result of a sustainable development of rural tourism and of the underlying Rural Revitalization Strategy, as a specific case of smart specialization. In order to continuously increase the value of tourism for livelihood, the following implementation path seems plausible and realistic: 1) enhancing the degree of specialization of tourism livelihood capital, strengthening education and skills training, encouraging skilled workers to go to the countryside, establishing interest in protection and benefit-sharing mechanisms, and ensuring that farmers have equal opportunities for development; 2) guiding farmers to participate professionally in tourism according to their own conditions, choosing appropriate tourism livelihood methods, exploring industrial integration mechanisms, implementing an integration of the agriculture, tourism and culture industry, and promoting the integration of tourism livelihoods and other livelihood methods in order to achieve livelihood diversification; 3) innovating the development model of eco-tourism, avoiding ecologically destructive development, maintaining ecological balance, rationally arranging regional environmental capacity, and guiding farmers to adopt green development in order to save resources and reduce ecological pressure. Clearly, sustainable tourism development—as part of a smart specialization strategy—needs a balanced and well-orchestrated regional development policy.

Rural tourism destinations have a wide range of perspectives for sustainable development policy and research. This study has focused on a quantitative livelihood indicators evaluation for farmers in transition. Smart specialization appears to be a good strategy for successful resilience. Clearly, the article also has certain shortcomings. Due to the different roles of managers in rural tourism destinations and the differences in farmers' perceptions of tourism in different livelihood strategies, the tourism sustainability assessment system based on farmers' livelihoods needs to be further improved. At the same time, there is a lack of long-term, dynamic follow-up research on farmer livelihood long-run perspectives. Therefore, building a dynamic evaluation database for sustainable tourism livelihoods and dynamically revealing the long-term evolution of sustainable tourism livelihoods and their driving mechanisms will be one of the key points for future research.

**Author Contributions:** Conceptualization and methodology, H.L.; guidance instruction and comments on research design and approaches, P.N.; investigation, H.L. and X.X.; analysis of the data, H.L., X.X. and J.L.; paper writing, H.L., P.N. and X.X. All authors have read and agreed to the published version of the manuscript.

**Funding:** The National Social Science Foundation of China (Grant No. 19BJY202); The National Natural Science Foundation of China (Grant No.41801138); Ministry of Research and Innovation, CNCS-UEFISCDI, project number PN-III-P4-ID-PCCF-2016-0166, within the PNCDI III project ReGrowEU—Advancing ground-breaking research in regional growth and development theories, through a resilience approach: towards a convergent, balanced and sustainable European Union.

**Conflicts of Interest:** The authors declare no conflict of interest.

**Appendix**

 **A Database and**

**Descriptors**

## **Table A4.** Coupling and Coordination Development Type Classification and Evaluation Criteria.

#### **References**

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