Tree mortality during drought

Understanding the drivers and mechanisms of tree mortality during drought has significant implications for forest management, especially under the background of global climate change with increasing drought frequency and severity. Tree structures have been identified as an important factor influencing tree mortality during drought, but how it functions remained controversial.

Here, we provide the datasets and codes used to examined the influence of canopy structure on tree mortality in the southern Sierra Nevada during the 2012-2016 California drought. These datasets include maps of nearly 1.5 million individual trees, with their species information, tree health conditions during the drought, tree structure features, and environmental attributes. With these, we found that drought-induced tree mortality rate has a “negative-positive-negative” piecewise relationship with tree height, but remains a consistent negative relationship with neighborhood canopy structure. Our analyses further revealed that trees in a structurally complex forest and overshadowed by tall neighboring trees experienced lower mortality rate, likely due to reduced exposure to solar radiation and less water demand from evapotranspiration. Our finding suggests establishing complexity in canopy structure could improve forest resistance to drought.