Fire and Landscape Change in Northern Patagonia, Argentina: Integrating Landscape Heterogeneity, Land Use, and Climatic Variability

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In the context of global climate change and increased impacts of humans on natural landscapes, increased fire occurrence is likely to be a major cause of widespread change in forested ecosystems. Although much is known about how short-term weather conditions affect the probability of fire occurrence and its intensity, much less is known about how the history of land use and the heterogeneity of the landscape affect the ways that fires spread and ecosystem responses to fire. Through a multi-scale study in northern Patagonia, Argentina, this project will address the following key questions: (1) How does landscape heterogeneity resulting from fires and other forms of disturbance over the last two centuries affect the spread of fire and subsequent post-fire vegetation and fuel changes? (2) What are the effects of climatic conditions on post-fire vegetation recovery, especially tree regeneration? (3) What are the effects of livestock and other forms of land use on the critical, early phases of post-fire vegetation and fuels recovery? These three questions will be examined by an integrated multi-scale approach to vegetation dynamics and landscape ecology across a range of ecosystem types from dry shrublands to wet forests. The researchers will integrate broad-scale spatial analyses of vegetation and fire patterns derived from historical aerial photographs and satellite images with detailed field studies of disturbance history based on tree-ring samples. These methods will be combined with experimental manipulation of moisture availability and herbivory by livestock to simulate the effects of climatic variation and land use on vegetation recovery after fire.The proposed research will advance a long-term research program initiated in 1985 focusing on the processes through which natural disturbance, climatic variability, and human activities have and continue to alter Northern Patagonian landscapes. The expected results will quantify relationships of fire behavior and effects to landscape heterogeneity at spatial and temporal scales useful for resource managers. The results will also provide a strong empirical basis for realistic application of spatial landscape-models to predicting fire behavior and fire effects in this landscape. The patterns and causal mechanisms identified in this study will guide similar approaches to understanding and predicting the ecological effects of fire, livestock, and climatic variability in other landscapes.