Decrease of net primary productivity in China's terrestrial ecosystems caused by severe droughts in 2009

In 2009, terrestrial ecosystems in China were hit by a series of droughts in different seasons. However, the degree at which net primary productivity (NPP) of terrestrial ecosystems was affected in China is not clear yet. In this study, the remote sensing driven process-based Boreal Ecosystem Productivity Simulator (BEPS) model was used to estimate NPP decrease in China's terrestrial ecosystems caused by the abnormal droughts in 2009. The results show that the BEPS model is able to estimate gross primary productivity (GPP) and NPP of China's terrestrial ecosystems reliably. Estimated GPP and NPP show similar spatial patterns, decreasing from east to west and from south to north. In 2009, annual NPP was lower than the averages over the period from 2000 to 2010 in most regions of China, especially in areas of southern China. The decrease of annual NPP in 2009 over southeast Tibet and southeast coastal areas was even more than 100 g C m−2 yr−1. The annual total NPP of Hunan and Yunnan provinces, Guangxi and Tibet autonomous regions in 2009 decreased by 4% to 6% of multi-year means, owing to the impact of consecutive drought from summer to winter in these areas. The national total of NPP in this year decreased about 35.5 Tg C yr−1, approximately equivalent to 1% of annual total NPP in China's terrestrial ecosystems averaged during the period from 2000 to 2010.