Climate Change Has Complicated Effects on Forests

The most comprehensive review to-date of scientific papers on climate change effects on forests reveals a diverse set of consequences for forests across North America, according to researchers from Dartmouth University.

Writing in the journal Ecological Monographs, the authors say their analysis of 500 scientific papers reveals that climate change is the source of insect outbreaks in forests, plant diseases, wildfires and other problems in forests, but also that warmer temperatures are making forests grow faster and become less susceptible to pests, traits with expanded benefits such as boosting forest health and size, increased carbon storage and more timber to harvest.

Such varied consequences as a result of climate change highlight the need for adequate forest management strategies, the researchers said. 

Tree-killing insects and plant diseases, for example, are both natural elements of healthy forest ecosystems. However, climate change is quickly altering the distribution and number of forest pests, as well as altering biodiversity and the ecosystem.

For instance, more trees have been killed across more area of the US from pine bark beetles than from wildfires, even in areas with little previous experience managing pests.

"One of our prominent challenges is to adapt forest management tactics and generalize the underlying theory to cope with unprecedented changes in pest pressure," the authors said in a statement.

In the last five decades, the authors said, average global air temperature increased about 1 ̊ F, while the coldest winter night averages about 7 ̊ F warmer.

"That has permitted population explosions of tree-killing bark beetles in forests that were previously shielded by winter cold and made it easier for invasive species to become established. But tree growth rates in many regions are increasing due to atmospheric change, which may increase resilience to pest," the study authors said.