During a drought, rain might bring some relief, but it doesn't solve everything. Ecosystems can take years to bounce back from a water shortage, and as droughts become more frequent and severe, some trees might start to disappear.
Researchers are starting to understand just what trees have to do to survive when it gets too dry. Without sufficient water, trees can't photosynthesize, so they burn stored fuel. And it takes time for trees to recover from that stress — even when a drought ends and more water is available.
The Amazon rainforest, for example, had droughts in 2005 and 2010. Satellite images showed the forest hadn't recovered from the first before the second hit, and trees started dying.
Researchers think climate change could make severe droughts more common and that the stress might push trees to a breaking point more often. Fewer trees would mean more carbon in the atmosphere, which would lead to more warming.
It's not exactly good news, but understanding the scope of the problem is a first step. The better we understand how trees respond to drought, the more we can do to help them get through it.