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How much drought can a forest take ? Aerial tree mortality surveys show patterns of tree death during extreme drought

ScienceDaily (January 19, 2017)

Titre : How much drought can a forest take ? Aerial tree mortality surveys show patterns of tree death during extreme drought

ScienceDaily (January 19, 2017) 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 ?

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. _ Tree mortality in the Sierra Nevada in 2015 was the worst in recorded history. The U.S. Forest Service aerial tree mortality surveys in 2015 estimated 29 million trees in California had died after four years of extreme drought. Though the drought began in 2012, major effects on trees did not appear immediately. While some trees died every year, mortality spiked only in the fourth year of extreme drought.

Story Source  : University of California - Davis.

Annonce (ScienceDaily)

Page publiée le 5 mai 2017