Grassland ecology in China: perspectives and challenges

During the last few decades, there have been an increasing number of studies on grassland ecology in China, involving the classic ecology concepts or theories and the applicable ecological principles of grassland conservation or management. This paper reviews the main progress in the following aspects.(1) Research on grassland species adaptation and resistance, population dynamics and foraging behavior, and biodiversity and community stability.(2) Research on managed grassland ecosystems(grassland grazing ecology) including grazing effects on grassland ecosystem function and foraging behavior by large herbivores.(3) Global climate change and grassland processes and functioning.(4) Applied research on grassland restoration and ecosystem health assessments such as vegetation restoration, restoration of ecosystem functioning, and assessment methods. There have been significant advances in grassland ecology,including the functions of ecosystem biodiversity, the ecological stoichiometry mechanisms affecting grassland community stability, grazing regulation of plant diversity and nutrient cycling. Grassland ecologists have succeeded in making these advances through observational, experimental and theoretical studies. Nevertheless, there are still significant challenges for the grassland ecology research,including understanding of grassland spatial processes,grassland grazing and multi-functionality, integrated effects of global climate change across grassland areas,as well as the ecological methodology and experimental techniques in grassland ecology.

The relative and combined effects of herbivore assemblage and soil nitrogen on plant diversity

Plant diversity can be affected by both herbivore grazing and soil resources. However, it is unclear if the joint effects of herbivores and soil resources might vary with components of plant diversity. Here, we evaluated the relative and combined effects of herbivore assemblage and soil nitrogen(N) quantity and heterogeneity on the α and β components of plant diversity in a grassland that was subjected to four years of grazing under differing herbivore assemblages(no grazing, cattle grazing, sheep grazing, and mixed grazing). We found that herbivore assemblage combined with soil N quantity explained 41% of the variation in plant α-diversity, while herbivore assemblage combined with soil N heterogeneity explained 15% of the variation in plant β-diversity. The independent effects of herbivore assemblage explained more than those of soil N for both α-and β-diversity(α-diversity: 12% vs. 4%;β-diversity: 18% vs. 16%). We concluded that the effects of herbivores are stronger than those of soil N,and that grazing-induced changes in soil resources are important drivers of plant diversity change, especially α-diversity.Therefore, we suggest that managing herbivore species by accounting for the effects that their grazing can have on soil resources may be significant for plant diversity maintenance.