Historic range of variability of the northern patagonian landscape

VEBLEN, T.T.; KITZBERGER, T.; RAFFAELE, E.

Ciudad del Cabo, Sudáfrica

Congreso; IV Southern Connection Congress; 2004

University of Cape Town

In recent decades, concepts of historic range of variability (HRV) have taken on an increasingly important role in resource planning and ecosystem management.  HRV concepts are now widely used in developing strategies for maintaining biological diversity and planning resource management that is consistent with the range of ecological and evolutionary conditions appropriate for particular ecosystems.  Although there has been some frustration and debate over the application of HRV concepts, resource planning strategies continue to emphasize the need to understand and integrate data on past ecosystem conditions and, in particular, on how humans and climatic variation have contributed to the spatial and temporal variability of disturbance regimes.   We briefly review the origins, applications and limitations of historic range of variability concepts.  To illustrate key research issues in the application of HRV concepts and their integration into ecosystem management, we focus on a series of recent, severe fires in northern Patagonian forests and shrublands.  We first briefly review broad-scale changes in vegetation patterns that have been driven by climatic variation and changes in land-use over the past c. 150 years.  Then, to focus on the spatial and temporal scales at which management decisions must be made we present a series of case studies to address questions of how landscape heterogeneity resulting from recent disturbance and land-use history affect the spread of fires as well as post-fire ecosystem changes.  We show that the ecological consequences of climatically-driven major fire events are sensitive to prior disturbance history and the impacts of introduced herbivores.  From a methodological perspective, we emphasize the importance of adopting a multi-scale approach  that integrates the results from local scale, short-term experiments with knowledge of regional and centennial scale patterns of climate and landscape change.