Recent Vegetation Change at Voyageurs National Park
Investigators:
Katherine Crowley, Dept. of Ecology, Evolution and Behavior, University of MN, St. Paul,
MN.
Kenneth L. Cole, USGS Colorado Plateau Research Station, 928-523-7767
Summary:
Patterns of compositional change in the vegetation of Voyageurs National Park, northern Minnesota, were studied through an analysis of permanent-plot data collected in 1977-78 and 1992-93. This study examined significant compositional changes and rates of change in the vegetation, in the context of successional processes, fire and land-use history, spatial scale, and predictability of future change. Changes during the study period included slow, expected aging of currently undisturbed vegetation types (upland black spruce, lowland black spruce, red pine, white pine, white cedar); maturation and extensive senescence of trees in disturbance-dependent types (aspen, birch, jack pine); and rapid, inconsistent change in recently disturbed or recovering types (spruce-fir, upland hardwood, black ash, muskeg, upland shrub/rock outcrop). Rapidly changing vegetation types, either regenerating after fire or affected by other disturbance factors (e.g. disease and insect outbreak), were least likely to fit into a successional model, to change consistently over time at any spatial resolution, or to change directionally or predictably into the future. Predictability of succession in the southern boreal forest has historically been limited by the frequency of fire; under fire suppression, general trends in canopy species may be most predictable when they are averaged over a large area, in order to minimize the noise of haphazard disturbance in local areas.
Gif Image (122k): Sampling in a mature white pine forest.
Gif Image (190k): Two photos showing fifteen years of tree growth in a shrub association. Rapidly growing trees in background are white spruce.
Gif Image (207k): Two photos showing fifteen years of thinning in an upland black spruce stand. Tree density declined while basal area remained steady.
Publications:
Crowley, K. F., 1995. Patterns of Temporal and Spatial Change in the vegetation of
Voyageurs National Park. University of Minnesota, MS Thesis.
Crowley, Katherine F., and Kenneth L. Cole. 1995. Patterns of temporal and spatial change in the vegetation of Voyageurs National Park. Bull. Ecol. Soc. Amer. 77: 57. (Abstract)
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