Effects of Drought on Forests and Rangelands in the United States: A Comprehensive Science Synthesis

This assessment provides input to the reauthorized National Integrated Drought
Information System (NIDIS) and the National Climate Assessment (NCA), and
it establishes the scientific foundation needed to manage for drought resilience
and adaptation. Focal areas include drought characterization; drought impacts
on forest processes and disturbances such as insect outbreaks and wildfire; and
consequences for forest and rangeland values. Drought can be a severe natural
disaster with substantial social and economic consequences. Drought becomes
most obvious when large-scale changes are observed; however, even moderate
drought can have long-lasting impacts on the structure and function of forests and
rangelands without these obvious large-scale changes. Large, stand-level impacts
of drought are already underway in the West, but all U.S. forests are vulnerable
to drought. Drought-associated forest disturbances are expected to increase with
climatic change. Management actions can either mitigate or exacerbate the effects
of drought. A first principal for increasing resilience and adaptation is to avoid
management actions that exacerbate the effects of current or future drought.
Options to mitigate drought include altering structural or functional components
of vegetation, minimizing drought-mediated disturbance such as wildfire or insect
outbreaks, and managing for reliable flow of water.