Ayres, M.P., and M.J. Lombardero. 2000. Assessing the consequences of climate change for forest herbivore and pathogens. The Science of the Total Environment 262:263-286. Full text in pdf |
Herbivores and pathogens impact the species composition, ecosystem function, and socioeconomic value of forests. Herbivores and pathogens
are an integral part of forests, but sometimes produce undesirable effects and a degradation of forest resources. In the United States, a few
species of forest pests routinely have significant impacts on up to 20 million ha of forest with economic costs that probably exceed $1 billion /
year. Climatic change could alter patterns of disturbance from herbivores and pathogens through: (1) direct effects on the development and
survival of herbivores and pathogens; (2) physiological changes in tree defenses; and (3) indirect effects from changes in the abundance of
natural enemies (e.g., parasitoids of insect herbivores), mutualists (e.g., insect vectors of tree pathogens), and competitors. Because of their
short life cycles, mobility, reproductive potential, and physiological sensitivity to temperature, even modest climate change will have rapid
impacts on the distribution and abundance of many forest insects and pathogens. We identify 32 syndromes of biotic disturbance in North
American forests that should be carefully evaluated for their responses to climate change: 15 insect herbivores, browsing mammals, 12
pathogens, 1 plant parasite, and 3 undiagnosed patterns of forest decline. It is probable that climatic effects on some herbivores and pathogens
will impact biodiversity, recreation, property value, forest industry, and even water quality. Some scenarios are beneficial (e.g., decreased snow
cover may increase winter mortality of some insect pests), but many are detrimental (e.g., warming tends to accelerate insect development rate
and facilitate range expansions of pests and climate change tends to produce a mismatch between mature trees and their environment, which
can increase vulnerability to herbivores and pathogens). Changes in forest disturbance can produce feedback to climate through affects on water
and carbon flux in forest ecosystems; one alarming scenario is that climate warming may increase insect outbreaks in boreal forests, which
would tend to increase forest fires and exacerbate further climate warming by releasing carbon stores from boreal ecosystems. We suggest a list
of research priorities that will allow us to refine these risk assessments and adopt forest management strategies that anticipate changes in biotic
disturbance regimes and mitigate the ecological, social, and economic risks.
Bioscience Review of this and related papers. National Assessment of Climate Change Impacts on the United States |
Climate change; herbivory; pathogens; forest epidemiology; risk assessment; disturbance; forest ecology; population dynamics; plant defense; ecological economics |