Widespread Increase of Tree Mortality Rates in the Western United States

  title={Widespread Increase of Tree Mortality Rates in the Western United States},
  author={Phillip J. van Mantgem and Nathan L. Stephenson and John C Byrne and Lori D. Daniels and Jerry F. Franklin and P. Ful{\'e} and Mark E. Harmon and Andrew J Larson and Jeremy Smith and Alan H. Taylor and Thomas T. Veblen},
  pages={521 - 524}
Persistent changes in tree mortality rates can alter forest structure, composition, and ecosystem services such as carbon sequestration. Our analyses of longitudinal data from unmanaged old forests in the western United States showed that background (noncatastrophic) mortality rates have increased rapidly in recent decades, with doubling periods ranging from 17 to 29 years among regions. Increases were also pervasive across elevations, tree sizes, dominant genera, and past fire histories… 

Increasing rates of subalpine tree mortality linked to warmer and drier summers

Warming temperatures and rising moisture deficits are expected to increase the rates of background tree mortality–low amounts of tree mortality (~0.5%–2% year−1), characterizing the forest

Over half of western United States' most abundant tree species in decline

A standardized forest demographic index is developed and used to quantify trends in tree population dynamics over the last two decades in the western United States, and it is suggested that sustained anthropogenic and natural stress will likely result in broad-scale transformation of temperate forests globally.

Climate change-associated tree mortality increases without decreasing water availability.

The effects of conspecific tree-to-tree competition have intensified temporally as a mechanism for the increased mortality of shade-intolerant tree species, suggesting the consequences of climate change on tree mortality are more profound than previously thought.

Tree mortality in response to climate change induced drought across Beijing, China

Tree mortality in response to climate change induced drought has emerged as a global concern. Small changes of tree mortality rates can profoundly affect forest structure, composition, dynamics and

Mortality predispositions of conifers across western USA.

Intrinsic water-use efficiency increased over time in both dying and surviving trees, with a weaker increase in dying trees at five of the eight sites, but this approach does not capture processes that occur in the final months of survival.

Long-term trends in tree mortality rates in the Alberta foothills are driven by stand development

The results indicate that warming-related changes did not affect background tree mortality rates in mature forests in the Alberta foothills over the study period, indicating that the trend of increasing tree mortality over time found in raw data is primarily a result of stand development.

Long-term demographic trends in a fire-suppressed mixed-conifer forest

In the western United States, forests are experiencing novel environmental conditions related to a changing climate and a suppression of the historical fire regime. Mixed-conifer forests, considered

Apparent climatically induced increase of tree mortality rates in a temperate forest.

The findings suggest that these forests (and by implication, other water-limited forests) may be sensitive to temperature-driven drought stress, and may be poised for die-back if future climates continue to feature rising temperatures without compensating increases in precipitation.


Although suppression was the dominant demographic process, mechanical damage yielded greater loss of biomass and greater structural heterogeneity through creation of windthrow gaps, suggesting gap-forming processes that operate late in succession and contribute to structural complexity in old-growth forests can also occur early in stand development.

Concerted changes in tropical forest structure and dynamics: evidence from 50 South American long-term plots.

  • S. LewisO. Phillips B. Vinceti
  • Environmental Science
    Philosophical transactions of the Royal Society of London. Series B, Biological sciences
  • 2004
Large long-term increases inStand-level BA growth and simultaneous increases in stand BA and stem density imply a continent-wide increase in resource availability which is increasing net primary productivity and altering forest dynamics.

Forest turnover rates follow global and regional patterns of productivity.

Using a global database, it is found that forest turnover rates parallel broad-scale patterns of net primary productivity and are broadly similar to the patterns of turnover in populations of plant organs (leaves and roots) found in other studies.

Decelerating growth in tropical forest trees.

While the underlying cause(s) of decelerating growth is still unresolved, these patterns strongly contradict the hypothesized pantropical increase in tree growth rates caused by carbon fertilization.

Has fire suppression increased the amount of carbon stored in western U.S. forests?

Active 20th century fire suppression in western US forests, and a resulting increase in stem density, is thought to account for a significant fraction of the North American carbon sink. We compared

Pattern and process in Amazon tree turnover, 1976-2001.

  • O. PhillipsT. Baker B. Vinceti
  • Environmental Science
    Philosophical transactions of the Royal Society of London. Series B, Biological sciences
  • 2004
Previous work has shown that tree turnover, tree biomass and large liana densities have increased in mature tropical forest plots in the late twentieth century. These results point to a concerted

Drought induces lagged tree mortality in a subalpine forest in the Rocky Mountains

Large interspecific differences in drought-related mortality are found with fir showing the strongest effect followed by spruce and pine, with the potential for driving large-scale changes in subalpine forests of the Rocky Mountains.

Spatial patterns of forest characteristics in the western United States derived from inventories.

Spatial patterns of characteristics of forest ecosystems in the western United States, including area, stand age, forest type, and carbon stocks are reported, and comparisons of these patterns with those from satellite imagery and simulation models are compared.

Intraspecific Variation in Sapling Mortality and Growth Predicts Geographic Variation in Forest Composition

Intraspecific variation in growth models among sites was characterized by significantly different estimates of growth at low light, suggesting that light and other resources can be simultaneously limiting, and challenges Liebig's law of the min- imum to tree sapling growth.