Patterns of tree death during extreme drought

 

Photo credit: Science Daily

Dead trees in the Sierra National Forest in April 2016.

Credit: USFS Region 5

How much drought can a forest take?

Aerial tree mortality surveys show patterns of tree death during extreme drought

Date:

January 19, 2017

Source:

University of California – Davis

Summary:

Why do some trees die in a drought and others don’t? And how can we predict where trees are most likely to die in future droughts? Scientists have examined those questions in a new study.

Scientists from the University of California, Davis, and colleagues examined those questions in a study published in the journal Ecology Letters.

Using climate data and aerial tree mortality surveys conducted by the U.S. Forest Service during four years (2012-2015) of extreme drought in California, they found that when a drought hits the region, trees growing in areas that are already dry are most susceptible.

The research also showed that the effects of drought on forests can take years to surface, suggesting that such effects may linger even after the drought has ended.

Southern Sierra Nevada trees are most vulnerable

The study said that trees in the driest and densest forests are the most at risk of dying in an extreme drought. In California, that makes crowded stands of trees in the Southern Sierra Nevada the most vulnerable in the state.

The concept is simple: Trees in dense forests are like multiple straws competing for the same glass of water. In wet climate conditions, that competition goes largely unnoticed. But when it’s dry, few are able to quench their thirst, setting the stage for mass mortality.

‘How much drought a tree can take’

Read the full story: Science Daily