Disturbance after Disturbance: Combined Effects of Two Successive Hurricanes on Forest Community Structure

Abstract

Our attempts to gain knowledge from studying the effects of a single windstorm might be complicated by one or more other events that pass through the same system before it recovers from prior damage. In this article, we had the opportunity to examine permanent plots affected by two consecutive catastrophic storms of comparable intensity within a short time frame (less than a decade). We compared tree damage patterns resulting from Hurricane Rita in 2005 and Hurricane Ike in 2008, which struck the same five forest plots (40 m x 50 m each; 1 ha total) established in the Big Thicket National Preserve of southeast Texas. The results showed that the post-Rita forest structure was characterized by intense damage to short, shade-tolerant stems and increased canopy openness. Hence, trees damaged by Ike were, in general, taller, more shade intolerant, and more spatially distant from their undamaged counterparts than trees damaged by Rita. These contrasting damage patterns indicate that Ike affected the plots differently to a normal windstorm occurring in isolation (after a long absence of prior windstorms). We anticipate that the cumulative, compounded effects of these two storms will potentially have long-lasting footprints on the structure and function of the study forest. The need to account for compounding disturbance interactions in forest research and management will grow, because many atmospheric scientists predict increases in both the intensity and frequency of hurricanes in conjunction with future climate change scenarios. Key Words: Big Thicket, disturbance interaction, forest structure, hurricane, spatial point pattern analysis.