The Evolution of Poyang Lake Wetland Hydroecology

This study used remote sensing technology, employing Landsat-TM image covering the Poyang Lake wetland during fall and winter of 1991-2009, to investigate the water level variation characteristics of the Poyang Lake before and after the Three Gorges Reservoir water storage. And then the CoupModel was used to simulate the respiration amount of the wetland typical vegetation during 1990-2009. The results indicate that the water body area of Poyang Lake wetland shows a downward trend, while the grass lands the tendency of expansion. The average value of the percentage share of water body area before and after the Three Gorges Reservoir water storage are 56.62% and 29.35%, respectively, the percentage share of the thick grass land are 22.98% and 34.6%, respectively. The typical wetland vegetation respiration amount also shows a downward trend during September to November of 1990-2009, namely the typical vegetation biomass is reduced, thereby destroying the habitat and food chain of migratory birds. It is concluded that the Three Gorges Reservoir operation makes the decline of the Poyang Lake water level which reduces the typical vegetation biomass.