Drought Impact on Vegetation Productivity in the Lower Mekong Basin

The Lower Mekong Basin (LMB) has a typical monsoon climate, with high temperature and uneven distribution of precipitation throughout the year. As a result of climate change, the LMB has experienced extreme weather conditions during the past few decades. Few studies have focused on changes in net primary productivity (NPP) and the impacts of drought on NPP in the LMB. In th is study, we use MOD17 product to detect variations in NPP during the period 2000–2011 and assess the imapcts of climate and drought on NPP in the LMB. We found that: (1) NPP in the LMB has large variations during the period 2000-2011. Among the five countries, Cambodia experienced the largest NPP variations where is dominated by evergreen forest. Whereas NPP variation was the least in Thailand where is dominated by cropland. (2) Increased temperature caused reduced NPP, therefore negative correlation between temperature and NPP anomaly was identified in Lao PDR. In Cambodia and Southern Lao PDR, decreased precipitation caused reduced NPP, therefore positive correlation between precipitation and NPP was identified. (3) Severe droughts occurred in 2005 and 2010, which induced NPP reductions of 14.7% and 8.4%, respectively. Cambodia was the most severely affected country in 2005, with NPP reductions of 22%. Lao PDR was the most severely affected country in 2010, with NPP reduction of 12.6%. (4) Other factors, such as flooding and human activity, may also have impacts on NPP variations