What, Exactly, Causes Trees To Die During Drought?

How trees respond to drought is important for models used to predict climate change. Plants take up a large portion of the carbon dioxide (CO2) in the atmosphere — fewer trees means more CO2. Sudden large-scale changes in plant populations, such as the tree die-offs observed worldwide in recent decades, could affect the rate at which climate changes. Current global vegetation models have faced challenges in producing consistent estimates of plant CO2 uptake, scientists say. The predictions vary widely depending on assumptions about how plants respond to climate. One idea for improving the models is to base forest responses to climate change on how trees die in response to heat, drought and other stresses. (CLick on title for full story.)