Factors affecting plant primary productivity of grasslands: a review

Grassland is the largest distribution area of terrestrial ecosystems on the earth. The plant net primary production (NPP) is an important indicator to reflect the function of the grassland ecosystems. Some research results are reviewed about the effects of plant species diversity, resource availability, grazing, restoration of degraded grassland and climate change on NPP of grassland ecosystems in the paper. The researches show that there are inconsistent conclusions about the relationship between plant diversity and NPP which depends on experimental site, starting status and indicators measured. Most of experimental warming studies show that there are inconsistent effects of warming on NPP and plant diversity which varies with the different locations and grassland ecosystems due to differences of resource availability and grazing/clipping. Therefore, understanding how grazing with future climate change affects plant primary productivity and recovery of degraded grassland ecosystems is a key knowledge to realize the ecological security and sustainable development of economy and society.