This project looks at how representative tree species in forests of South Carolina and Georgia were affected by the major ice storm that occurred on February 11-13, 2014. While ice storms periodically strike southern forests, their role in affecting ecosystem composition, structure and function is poorly understood, because they are currently rare (10-15 years apart), are hard to predict, and because their frequency decreases across the region towards the coast. As a result, previous studies are largely anecdotal and limited to ad-hoc assessments of losses in commercial timber. In the case of this storm, there was a major economic impact, with an estimated direct timber loss of $360 million from about 1.5 million affected forested acres in South Carolina alone. The frequency and magnitude of weather extremes is predicted to increase in many regions and such changes may pose a greater threat to ecosystems than simple changes in average conditions. By studying ice storms in southern forests, this project will help scientists better predict the effects of such storms. This in turn could be very useful to forest managers, municipalities and other property owners for adapting to and mitigating damage. For example, knowledge and understanding of how different tree species respond could improve predictions of how tree species may adjust their future ranges in response, while also leading to better forestry practices to mitigate the impacts on southern forests.
In this project, scientists will document levels of local ice accumulation, measure the damage caused by ice accumulation on individual trees, record other characteristics of the trees themselves, and record other important variables that may affect ice accumulation and damage patterns across the landscape. This particular storm was unique in that its impact area extended much farther into southern and coastal locations than previous ice storms, which provides a rare opportunity for studying differential species responses to ice damage, including many species that have never been studied before. The specific objectives of the project are: (1) to characterize tree responses to different levels of ice accumulation so that the potential role of periodic ice storms on their distributions and overall forest composition can be better understood, and (2) to study mechanisms underlying differential species responses so that new computer models can be developed to predict tree damage and mortality in response to different levels of ice accumulation in the future. There are no standardized methods for assessing the ecological impacts of ice storms and no models for predicting damage and mortality. This limits tests of relevant hypotheses and comparisons across regions. This project will fill several important knowledge gaps and, by testing specific hypotheses that relate current distributions to species-level responses, should enable better understanding of ice storms as an ecological factor limiting tree species distribution and diversity.
