Relatively little is known about how disturbance regimes vary along major environmental gradients and how that variation contributes to coarse-scale vegetation patterns. The proposed research will focus on variation i disturbance regimes along a west-to-east trans-Andean transect from Andean montane rainforests to the ecotone with the Patagonian steppe at c. 40 S latitude. The major disturbance are fie windthrow mass movements, logging, and the effects of introduced browsing animals. The research is multi-scale in approach and includes the qualification of vegetation and disturbance patterns at a landscape scale as well as the analysis of mechanisms responsible for those patterns at stand scales. The will map vegetation and disturbances from a series of aerial photographs of different ages, date disturbance events with tree-ring techniques, and quantitatively analyze tree population structure to examine responses to disturbances. The expected results will be significant contributions to both the theory of landscape ecology and to the methodology for quantification of the spatial and temporal characteristics of disturbances along an extensive environmental gradient. It will also provide an understanding of how spatial heterogeneity in the vegetation results from both the variation in the physical environment and variation in disturbance regimes as modified by human activities. //
