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Abstract
Forest disturbances from wind damage and fire are ubiquitous and have important ecological effects. Recent research in disturbance ecology emphasizes the potential for compounded disturbances to interact in unpredictable ways. Much of this research has focused on the possibility of wind damage to increase flammable fuel loads and lead to severe wildfires. However, there are many possible mechanisms by which wind damage and fire interact, including many where wind damage can lessen, or buffer, fire intensity or severity. This dissertation explores several themes surrounding windfire interaction mechanisms. In Chapter 1, I review available literature on theories and studies of forest disturbance by wind damage and fire and classify interaction mechanisms based on whether they act in synergy (amplifying) or whether they are antagonistic (buffering). The review emphasizes the importance of buffering effects especially during low-intensity fire and that both amplifying and buffering effects play a role in windfire interactions in a heterogeneous spatial mosaic. In chapter 2, I describe a field experiment simulating wind damage gaps from tornados and compare fuel characteristics and fire behavior in gaps and intact forest. The study shows that wind damage influences fuel loading, but also fuel arrangementan important component of fuel continuity in prescribed fires. The study emphasizes that wind damage has the potential to increase fire intensity, but much of this effect is limited to areas directly within down tree crowns. In chapter 3, I examine the ecological effects of the combined disturbances from Chapter 2 on several vegetation parameters. The major results of this study show that interaction mechanisms vary by individual species leading to a heterogeneous mixture of amplifying and buffering effects following compounded disturbances. Despite the importance of landscape pattern on ecological processes, few studies address the landscape-scale distribution of tornado damage. In chapter 4, I describe a remote sensing methodology to measure tornado severity and landscape-scale characteristics of tornado damage. I also apply the methodology to test hypotheses about how tornados behave in rugged terrain. The remote sensing method presented could be used on multiple tornado tracks to generalize patterns of tornado damage at the landscape-scale.