Damage patterns after Hurricane Dean in the southern Yucatán: Has human activity resulted in more resilient forests?

We investigated how patterns of hurricane damage were related to windspeed, stand characteristics, and land use in a region where forest composition and structure have been strongly influenced by human activities. In 2007 Hurricane Dean hit the biological corridor between the two largest biosphere reserves on the Yucatán Peninsula as a category 5 hurricane. Land use in the corridor has altered both landscape and forest stand structure. Compared to the upland protected areas, forests in the study area were significantly shorter and characterized by smaller stems. Nine months after the hurricane we assessed the damage in a set of 91 plots to test the effect of local stand structure on hurricane resistance. For each 5 × 100 m plot, we calculated the proportion of both stems and basal area damaged using 7 classes (no damage, small branch, major branch, stem bent, stem snapped, tree uprooted and tree death). Interviews with land- owners provided recent land use histories for the past 30 years for most study plots. For the two dominant forest types analysis of variance found that canopy height, median dbh and basal area all varied significantly with land use history and forest type. We tested the effect of median stem diameter, canopy height, stem density, basal area and tree species density on damage. Despite the strength of the storm, on average 27% of stems at the stand level showed no signs of damage and only 5% across the study were killed by the hurricane. In step-wise linear regression models, 13-52% of the variation in damage frequency was accounted for by windspeed and stand structure. Canopy height, basal area and median dbh were significant predictors. For moderate to severe damage classes, measures of stand size were generally positively correlated with damage frequency suggesting that stands with higher canopies and/or greater basal area or median dbh suffered the most during this storm event.