Relationship of Climatic and Forest Factors to Drought- and Heat-Induced Tree Mortality

PLoS One. 2017 Jan 17;12(1):e0169770. doi: 10.1371/journal.pone.0169770. eCollection 2017.

Abstract

Tree mortality due to warming and drought is a critical aspect of forest ecosystem in responding to climate change. Spatial patterns of tree mortality induced by drought and its influencing factors, however, have yet to be documented at the global scale. We collected observations from 248 sites globally where trees have died due to drought and then assessed the effects of climatic and forest factors on the rate of tree mortality. The global mean annual mortality rate was 5.5%. The rate of tree mortality was significantly and negatively correlated with mean annual precipitation (P < 0.01). Tree mortality was lowest in tropical rainforests with mean annual precipitation >2000 mm and was severe in regions with mean annual precipitation <1000 mm. Mortality rates varied amongst species. The global annual rate of mortality was much higher for gymnosperms (7.1%) than angiosperms (4.8%) but did not differ significantly between evergreen (6.2%) and deciduous (6.1%) species. Stand age and wood density affected the mortality rate. Saplings (4.6%) had a higher mortality rate than mature trees (3.2%), and mortality rates significantly decreased with increasing wood density for all species (P < 0.01). We therefore concluded that the tree mortality around the globe varied with climatic and forest factors. The differences between tree species, wood density, stand density, and stand age should be considered when evaluating tree mortality at a large spatial scale during future climatic extremes.

MeSH terms

  • Climate Change*
  • Droughts*
  • Ecosystem
  • Forests
  • Hot Temperature*
  • Models, Biological
  • Population Density
  • Trees / growth & development*

Grants and funding

This work was supported by the National Natural Science Foundation of China (41390461, 41501233) to Xiaoxu Jia (http://www.nsfc.gov.cn/); the National Natural Science Foundation of China (41530854) (http://www.nsfc.gov.cn/); the National Key Project for Research and Development (2016YFC0501605) to Mingan Shao (http://www.most.gov.cn/); the Program for Bingwei Excellent Talents from Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences (2015RC204) to Xiaoxu Jia (http://www.cas.cn/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.