Tropical forests accounts for 25% of the terrestrial carbon pool and one-third of the net primary production; thus, they form crucial component of the global carbon cycle. If protected from clearance, logging, and fires, uptake by tropical forests could offset a significant proportion of the emissions from fossil fuels during the transition to a low-carbon future. However, this carbon pool is vulnerable to droughts (periods of ‘abnormally dry weather long enough to cause a serious hydrological imbalance’) and drought-associated fires.
By consulting a large amount of literature, a professor of Xishuangbanna Tropical Botanical Garden (XTBG) reviewed the impacts of droughts in tropical forests.
Forecasts from climate models suggest an increased risk of droughts in tropical forests over the next few decades, potentially threatening the large existing carbon sink. Natural droughts and rainfall exclusion experiments showed that droughts decreased tree growth and increased mortality, with large trees most affected in both cases.
 According to the review, mechanisms at the tree level were still incompletely understood. Hydraulic failure seemed to be robustly associated with tree death; however, other failure modes including carbon starvation and phloem failure may also be significant. Experiment transfers of genes from model plants have increased drought tolerance of economic trees, suggesting that at least some components of the molecular mechanisms are universal.
 Some elements of drought responses at the cellular and molecular level have been identified in model plants, but a full mechanistic understanding is still far away. It is still unclear about drought responses at community level above, which includes changes in species composition and interactions between droughts, forest fragmentation, and fire.
The researcher regarded that the current challenge is to understand the mechanistic links between drought stress and hydraulic failure and then to incorporate the understanding into improved models, although understanding of the mechanisms is incomplete. 
The study entitled “The Impacts of Droughts in Tropical Forests” has been published online in Trends in Plant Science.