Tree height explains mortality risk during an intense drought

Abstract

Forest mortality is accelerating due to climate change and the largest trees may be at the greatest risk, threatening critical ecological, economic, and social benefits. Here, we combine high-resolution airborne LiDAR and optical data to track tree-level mortality rates for ~2 million trees in California over 8 years, showing that tree height is the strongest predictor of mortality during extreme drought. Large trees die at twice the rate of small trees and environmental gradients of temperature, water, and competition control the intensity of the height-mortality relationship. These findings suggest that future persistent drought may cause widespread mortality of the largest trees on Earth.

Abstract

Drought is intensifying due to climate change, impacting forests globally. Here, the authors track nearly 2 million trees through severe drought and show that tree height is the greatest predictor of mortality risk, suggesting that the tallest trees may be the most vulnerable.