Vegetation Changes in T H e Poyang Lake Wetland Linked to the Three Gorges Dam: an Assessment Based on Moderate Resolution Imaging Spectroradiometer (MODIS) Observations from 2000 to 2012

Vegetation changes in the Poyang Lake wetland related to the construction of the Three Gorges Dam (TGD) and climate change have received increasing attention in recent decades. However, due to the high spatial heterogeneity, the changes in wetland vegetation have not been well quantified at a large spatial scale. We addressed this challenge by using Moderate Resolution Imaging Spectroradiometer (MODIS) data from 2000 to 2012. Using a Mann-Kendall (MK) test, statistically significant decreasing trends were found in the Enhanced Vegetation Index (EVI) at the upper edge of the Poyang Lake wetland. In contrast, the vegetation distributed at lower elevations experienced a significant increasing trend during the study period. Downward boundaries of wetland vegetation in response to declining water levels could partially explain the increases in vegetation coverage. Vegetation colonized the non-vegetation area more quickly after the implementation of the TGD due to the earlier recession of the lake level during the recession period. Our findings suggested that hydrological changes caused by the lake decline might be the main factors driving the vegetation area changes. The information provided in this study is critical for future conservation and restoration efforts in the Poyang Lake wetland ecosystem.