Disturbance Ecology Research

Fire, insect, and disease disturbances can profoundly affect the health and productivity of ecosystems. In some regions, O₃ and acidic deposition interact with other factors to change how ecosystems behave. Large-scale disturbances may even become natural disasters, as did the Yellowstone fires of 1988 and the northeastern gypsy moth epidemic. Global climate projections suggest that drought cycles, precipitation patterns, temperature extremes, strong winds, and intense storms may change in the future. These climatic factors drive both the occurrence and severity of fire, insects, and disease episodes. To assess the potential impact of disturbance changes on forest ecosystems, the FSGCRP addresses three categories of disturbance: fire, insects and diseases, and air pollution.

Fire research focuses on changes in frequency and severity of fire weather resulting from global atmospheric changes, the processes by which fire affects the current equilibrium between climate and ecosystems, and the net result of new fire regimes on production of trace gases and particulate matter in the atmosphere. Research has been initiated to analyze changes in fuel buildup and fire hazard as well as to predict wildland fire activity and emissions with global change. Historical fire occurrence, determined from fire scars on both live and dead trees, provides a record of fire frequency and severity over a long period of time. Coupling these data with dendroclimatological and other paleoecological pollen data gives a history of fire in transitional ecosystems and its associated climate relations, which are used to project future conditions. Understanding the role of both human-caused and natural fire in ecosystems provides information on how ecosystems recover from major disturbances. Interactions between humans and fire (such as suppression activities, planned use of fire and the urban/wildland interface) are sensitive to climate and are also assessed.

Insect and disease research focuses on how climate change influences the frequency and severity of insect and disease outbreaks. Their importance as a disturbance influence on ecosystems and how those disturbances accelerate ecosystem change are emphasized. In addition, insect and disease epidemics are studied because they may serve as early warnings of changes in ecosystems. Research also addresses the direct effects of climate change on pest organisms as well as how insect and disease organisms function to influence host species stressed by climate and air pollution.

Air pollution, particularly O₃ and acid deposition, affects ecosystems across the Eastern United States and parts of the West. The FSGCRP participates in monitoring networks and modeling activities to estimate and predict O₃ and acidic deposition at many locations. In addition, there is a need to understand how these disturbances interact with other atmospheric changes such as increased CO₂, and with insects and diseases, to influence ecosystem dynamics.