Response Of Plant Community To Simulated Nitrogen Deposition In The Early State Of Restoration In Songnen Grassland

In thesis focuses on the severely degraded enclosed Songnei Grassland. We research response of the number of characteristics of grassland communities, the relationship between species diversity and productivity, dominant species and contributions of plant functional groups productivity, soil physical and chemical indicators to simulated nitrogen deposition. Provide the scientific basis for the grasslands use and management for the evaluation of nitrogen deposition on grassland ecosystems.In the early stage of succession in grassland, we completed field measurement and laboratory analysis in 2008 and 2009, studied community height, community density, species diversity, productivity and soil physical and chemical indicators of Chloris virgata Community and Miscellaneous grass Community.Experiment with five fertilizer concentration treatments: CK(0); T1(50 kg/hm2); T2(100 kg/hm2); T3(150 kg/hm2); T4(200 kg/hm2). The results show that: the early restoration of degraded grassland succession, Chloris virgata Community simulated N deposition can significantly increase the community height and community density; increase productivity while reducing the species diversity; species diversity and productivity are positively related to linear relations in 2008; the biomass contribution of Salsola collina Pall. increased with the amount of nitrogen decreased; the biomass contribution of C.virgata Swartz.; increase above-ground productivity of Annuals or biannuals (AB); increase soil available nitrogen content, reduced soil available potassium content. Miscellaneous grass Community simulated N deposition can significantly increase the community height; significant increase productivity, while enabling significantly reduced species diversity; species diversity and productivity are negatively related to linear relations in 2008; the biomass contribution of S.collina Pall. increased with the amount of nitrogen decreased; the biomass contribution of Leymus chinensis (Trin.) Tzvel. gradually increased in 2009; increase above-ground productivity of Annuals or biannuals (AB) and significantly increased above-ground productivity of Perennial rhizome grass (PR); increase soil available nitrogen content and soil available phosphorus content.In general, simulated nitrogen deposition to increase the productivity and reduced species diversity in the early stage of succession in restoration of Songnen degraded grassland, in particular, Annuals or biannuals productivity increases more significantly; due to the different community types and years, species diversity and productivity have different the correlation, increase of soil available nitrogen, while available potassium and available phosphorus have different of variation. Different community types have different response for simulated nitrogen deposition. Simulated N deposition to restore the productivity and species diversity may be beneficial for the early restoration of degraded grassland succession.