Topographical and biophysical modeling of vegetation patterns at alpine treeline

Brown, Daniel

Dissertation highlights research that models the spatial patterns of vegetation communities along the treeline ecotone relative to topo-climatic and disturbance processes. Alpine treeline represents the transition from environments that sustain dense stands of subalpine forest to sites that are unable to support any trees. The purpose of this research was to model the spatial patterns of vegetation communities along the treeline ecotone relative to topo-climatic and disturbance processes. Surrogates of several topographically controlled climatic elements (solar radiation potential, soil moisture potential, and wind/snow potential) were constructed from digital elevation models (DEMs) for a study area in east-central Glacier National Park, Montana. Vegetation communities in the study area were characterized through statistical classification of Landsat Thematic Mapper digital data, field calibration, and validation. Topographical Empirical Models of Treeline (TEMTREEs) were constructed to examine the relative importance of factors which affected the treeline transition. TEMTREEs were also evaluated as predictive tools for extending the analysis through additional variables representing multi-scale processes. Spatial autocorrelation in the model residuals suggested that additional variables should be used to account for the patterns of treeline. Analysis of the residuals indicated that basin-scale variables accounted for some of the unexplained variation between the observed and expected pattern of alpine treeline characterized through closed-canopy forest, open-canopy forest, tundra, and bare surfaces.

Topographical and biophysical modeling of vegetation patterns at alpine treeline

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