Restoration Of Alpine Meadow Community Respond To The Cessation Of Fertilization

Many studies have found that fertilization can cause decrease in diversity and change in species composition. However, there are fewer studies focusing on the restoration of fertilized community. The restorational dynamics of community structure and function are unknown, and whether community is able to recovery to pristine state is a controversy topic. Our study focuses on the common respond of community succession in order to deeply understand community assembly and find the general mode of restorational succession in alpine meadow. The experimental site lies in Maqu county, Gansu province, China, and the coenotype is alpine meadow. Fertilization began in 2000, and cessation of fertilization had lasted for four years form 2011 to 2014. We had investigated five aspects of the community:productivity (biomass), biodiversity, productivity-diversity relation, temporal synchrony, and species composition. We had surveyed the vegetation for five continuous years (2010-2014) and found that:(1) The restoration of productivity was faster than diversity, the restoration of evenness was faster than richness; (2) In the period of four-year restoration, the productivity-diversity relation changed form negative linear relation (2011) to non-relation (2012) to positive linear relation (2013) to non-relation (2014); (3) Restorational succession can be divided into three stages, different processes control the community, in first stage residual fertilization effect and hysteresis behavior of dominant species control the restorational succession, in second stage dominant process is that species in local species pools randomly colonize the gap, in third stage the slow transition of species composition controls the restorational succession; (4) There exist an threshold of fertilization, and the community will lose its reversibility above the threshold.