Fire, climate change, and forest processes during the past 2000 years

Lake sediment records of vegetation, climate, and fire history indicate dynamic responses to climate changes of the past 2000 years. Studies of nitrogen (N) mineralization and forest structure within catchments of the same lakes suggest that responses may represent complex direct and indirect effects of climate on vegetation. Existing patterns in plant composition, mineralization rates, and topography indicate that spatial variability is influenced by microclimate and drainage. Xeric southwest aspects have low mineralization rates, high fire frequency, and support species that tightly cycle N. During the past 2000 years, vegetation, fire, and sediment indicators of drought have changed several times. High fire frequencies during more xeric intervals before A.D. 1200 prevailed during periods dominated by fire-tolerant hardwoods and then white pine. Decade and century scale climate fluctuations since A.D. 1200 resulted in altered fire frequencies may in turn explain the recent expansion of red pine in the region. Taken together with patterns of N cycling in the existing catchments, these changes in climate, fire, and vegetation may have had important consequences for terrestrial nutrient budgets. Such terrestrial effects may not have influenced nutrient loading to lakes.

Duke Scholars

Author James S. Clark Environmental Sciences and Policy