The Ecological Response Of Carex Lasiocarpa To Water Depth In The Sangjiang Plain, Northeast China

In order to investigate the relationship between the wetland vegetations andwater depth in the Nongjiang River in Honghe National Nature Reserve (HNNR),Northeast China，From river center to island,28and47sampling spots were set alongthe line perpendicular to Nongjiang River from river way to island, from June toSeptember in2011and2012, respectively.（1）The wetland vegetations was classified into6associations by theTWINSPAN, a polythetic and divisive classification tool. The associations are asfollows: Assoc. Carex pseudo-curaica+Glyceria spiculosa, Assoc. Carexpseudo-curaica+Carex lasiocarpa+Glyceria spiculosa, Assoc. Carexpseudo-curaica+Carex lasiocarpa+Glyceria spiculosa+Comarum palustre, Assoc.Carex lasiocarpa+Carexpseudo-curaica+Glyceria spiculosa, Assoc. Carexlasiocarpa and Assoc. Calamagrostis angustifolia+Carex humida. The CCAordination demined soil organic matter, total nitrogen and soil moisture were the mainfactors affecting the wetland vegetations.（2）The optimum water depth, which determined by Gaussian Model, of Carexlasiocarpa to was [13.45cm,29.78cm] based on biomass,[2.31cm,40.11cm] onaverage height, respectively. The optimum ecological amplitude of Carex lasiocarpato water depth is [13.45cm,29.78cm] and the optimist growing point of Carexlasiocarpa to water depth was21.4cm.（3）The TWINSPAN and biodiversity indices were combined to analyze therelationship between Carex lasiocarpa community biodiversity and water depth bythe index of diversity. Our results showed Carex lasiocarpa maintains high coveracross most water depths, but requires high variability with plenty water. The waterdepth in the freshwater marsh was in sequence of Carex pseudocuraica, Carexlasiocarpa, Glyceria spiculosa, and Calamagrostis angustifolia in order from thehighest to the lowest.（4）the optimum ecological water requirement of Carex lasiocarpa communitywas8.79×10~7m~3and the optimum ecological water requirement of Carex lasiocarpa community was [8.00×10~7m~3,9.74×10~7m~3], determined according to wetland floodanalysis of research area based on DEM with Carex lasiocarpa ecological amplitudeby the platform of GIS.