| Popis: |
Effects of environmental factors on plant diversity in temperate grasslands are of interest since experiments have found plant diversity is related to ecosystem function. Although previous studies have focused on the effects of environmental factors on plant diversity, the dominant environmental factors driving diversity differences among plant community types in temperate grasslands at regional scale remains unclear. We established 38 sampling sites (45 m × 45 m) in the main distribution areas of temperate grasslands to analyze the responses of plant community along different environmental gradients and identifies the dominant environmental factors driving the floristic composition and diversity in Inner Mongolia, China. In addition, environmental variables (annual mean temperature, annual precipitation, altitude, disturbance intensity, soil pH, soil density, soil water content, soil organic carbon, soil total nitrogen, soil total phosphorus, soil calcium carbonate), species diversity indices (richness, heterogeneity, evenness), functional diversity indices (abundance, evenness, divergence, dispersion) and plant biomass were analyzed. A total of 179 vascular plant species belonging to 43 families and 113 genera were recorded and classified into six plant community types (Stipa grandis community, Leymus chinensis community, Stipa capillata community, Artemisia frigida community, Cleistogenes squarrosa community, Artemisia halodendron community) based on Ward's agglomerative hierarchical clustering. According to canonical correspondence analysis and Monte Carlo permutation test, mean annual precipitation was the dominant environmental factor driving temperate grasslands, promoting species richness, heterogeneity, evenness, functional divergence and biomass. Soil organic carbon, water content and total nitrogen played positive effects on species diversity, meanwhile, mean annual temperature, altitude, grazing intensity and soil pH inhibited species diversity, functional abundance, dispersion and biomass. Furthermore, the presence of these plant communities dominated by Cleistogenes squarrosa and Artemisia halodendron indicate that grassland degradation is imminent or has already begun. In summary, our results provide evidence on the responses of composition, functional traits and biomass among different plant community types to environmental factors and demonstrate that precipitation is the dominant factors driving the floristic composition and diversity in temperate grasslands. |
