USFS: Effects of Drought on Forests and Rangelands in the U.S.

From the U.S. Forest Service (USFS), “Effects of Drought on Forests and Rangelands in the United States,” is a 200+ page report focusing on drought characterization; drought impacts on forest processes and disturbances such as insect outbreaks and wildfire; and consequences for forest and rangeland values.

The report depicts how hotter, drier and more extreme weather will initiate massive insect outbreaks, tree and plant die-offs, bigger and more costly wildfires, and economic impacts to timber and rangeland habitat. The study summarizes years of peer-reviewed research and provides the best science available to forest and rangeland managers on the effects of climate change on the 193 million acres of national forest.

The topics addressed in this assessment are:

    • Characterizing Drought for Forested Landscapes and Streams
    • Physiological Responses of Forests to Future Drought
    • Impacts of Drought on Forest Dynamics, Structure, Diversity, and Management
    • Forest Biogeochemistry in Response to Drought
    • Insect and Pathogen Responses to Drought
    • Fire and Drought
    • Rangeland Drought: Effects, Restoration, and Adaptation
    • Detecting and Monitoring Large-Scale Drought Effects on Forests: Toward an Integrated Approach
    • Ecohydrological Implications of Drought
    • Economics and Societal Considerations of Drought in Forests and Rangelands

As described in much greater detail in the report, some examples of the impacts of climate change and drought discussed include:

Drought in rangelands reduces forage and water available for livestock grazing. Reduced vegetative cover can lead to wind and water erosion. Drought-related disturbance, such as wildfire, can have protracted effects that include significant timber market losses.

Combined field evidence and models suggest that climate change is causing relocation of habitats at rates much faster than populations of trees can migrate. Reorganizations of stand structure and species composition are expected to lag behind shifts in habitat caused by increasing drought and temperature change.

As a consequence of long-term drought and warming in the Western U.S., bark beetles are currently the most important biotic agent of tree mortality. Multiple large outbreaks have killed hundreds of millions of trees in recent decades. Host trees weakened by drought allow beetle populations to build, while warming facilitates northward range expansion.

 

The Forest Service suggests options to mitigate drought, including detailed strategies around altering structural or functional components of vegetation, minimizing drought-mediated disturbance such as wildfire or insect outbreaks, and managing for reliable flow of water.

 

Developed by 77 scientists from the Forest Service, universities, non-governmental organizations and national labs, this research establishes a scientific foundation necessary to manage for drought resilience and adaptation. In addition, this assessment provides input to the National Integrated Drought Information System (NIDIS) and the National Climate Assessment.

 

 

Publication Date: January 2016

Authors or Affiliated Users:

  • James M. Vose
  • James S. Clark
  • Charlie H. Luce
  • Toral Patel-Weynand

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  • Assessment

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