section_path: Degradation/Causes/Climate change
section_name: Climate change
paragraph_text: Climate change
  
  Grasslands often occur in areas with annual precipitation is between 600 mm (24 in) and 1,500 mm (59 in) and average mean annual temperatures ranges from −5 and 20 °C. However, some grasslands occur in colder (−20 °C) and hotter (30 °C) climatic conditions. Grassland can exist in habitats that are frequently disturbed by grazing or fire, as such disturbance prevents the encroachment of woody species. Species richness is particularly high in grasslands of low soil fertility such as serpentine barrens and calcareous grasslands, where woody encroachment is prevented as low nutrient levels in the soil may inhibit the growth of forest and shrub species. Another common predicament often experienced by the ill-fated grassland creatures is the constant burning of plants, fueled by oxygen and many expired photosynthesizing organisms, with the lack of rain pushing this problem to further heights. When not limited by other factors, increasing CO concentration in the air increases plant growth, similarly as water use efficiency, which is very important in drier regions. However, the advantages of elevated CO are limited by factors including water availability and available nutrients, particularly nitrogen. Thus effects of elevated CO on plant growth will vary with local climate patterns, species adaptations to water limitations, and nitrogen availability. Studies indicate that nutrient depletion may happen faster in drier regions, and with factors like plant community composition and grazing. Nitrogen deposition from air pollutants and increased mineralization from higher temperatures can increase plant productivity, but increases are often among a discount in biodiversity as faster-growing plants outcompete others. A study of a California grassland found that global change may speed reductions in diversity and forb species are most prone to this process.