RAPID: Topographic variation in tornado blowdown severity, and consequences for forest regeneration

RAPID：龙卷风吹袭严重程度的地形变化以及对森林再生的影响

• 批准号: 1143511
• 负责人: Chris Peterson
• 金额: $ 15万
• 依托单位: University of Georgia Research Foundation Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1143511&HistoricalAwards=false
• 关键词: RAPID; Topographic; variation; tornado; blowdown

Ecologists have recently come to recognize that natural disturbances are an inherent part of the ebb and flow of forests, yet understanding of forest response to natural disturbances is patchy at best. There exists a good understanding of forest responses to fire, insect outbreaks, and hurricanes, but a poor grasp of forest response to ice storms, floods, and tornadoes. This project will examine forest damage caused by three long-track tornadoes that were part of the record-setting April 27-28, 2011 tornado outbreak. One tornado passed through the western section of Great Smoky Mountains National Park in southern Tennessee, and the other two through Chattahoochee National Forest in northern Georgia. The core goals of the project are to develop detailed inventories of the forest damage severity along these tornado tracks, and use that severity information to test three ecological models that hypothesize about how forests respond to different severity of disturbance. The study needs to begin promptly in order to accurately measure the severity of the disturbance and to identify the tree species that were blown down before they are salvage-logged or decompose. Once forest damage severity has been characterized along the tornado tracks, the recovery of the forests will be monitored, to see which model most accurately predicted the recovery of the forest. The model whose predictions are most accurate will be confirmed as the best understanding of how forests respond to wind disturbance. Knowledge of how forests respond to disturbance is important to society for a number of reasons: 1) guide management decisions, such as whether or not to log downed timber after disturbance; 2) project the likely future species composition after disturbance, i.e. will the tornado blowdown areas in 50 years be mostly cherry and maple, or mostly birch and hemlock?; 3) improve projections of carbon fixation in regrowing forests, a vitally important service provided by forests in a high-CO2 atmosphere; and, if future climate change brings increases in extreme weather events, 4) allow forecasts of how forests will change under the altered disturbance regime.

生态学家最近开始认识到，自然干扰是森林潮起潮落的固有部分，但对森林对自然干扰的反应的了解充其量也是支离破碎的。人们对森林对火灾、虫害暴发和飓风的反应有很好的了解，但对森林对冰暴、洪水和龙卷风的反应了解很少。该项目将研究2011年4月27日至28日创纪录的龙卷风暴发期间发生的三场长轨迹龙卷风对森林造成的破坏。一场龙卷风穿过田纳西州南部大烟山国家公园的西段，另外两场龙卷风穿过佐治亚州北部的查塔胡奇国家森林。该项目的核心目标是制定这些龙卷风路径沿线森林破坏严重程度的详细清单，并使用这些严重程度信息来测试三个生态模型，这些模型假设森林如何应对不同严重程度的干扰。这项研究需要迅速开始，以便准确衡量干扰的严重程度，并在打捞记录或分解之前确定被吹倒的树种。一旦确定了龙卷风路径上森林破坏的严重程度，就将监测森林的恢复情况，看看哪个模型最准确地预测了森林的恢复。预测最准确的模型将被证实是对森林如何应对风扰的最好理解。关于森林如何应对干扰的知识对社会很重要，原因如下：1)指导管理决策，例如在干扰后是否砍伐木材；2)预测干扰后未来可能的物种组成，即50年后龙卷风的衰退区将主要是樱桃和枫树，还是主要是桦树和铁杉？3)改进对再生林的固碳预测，这是森林在高二氧化碳大气中提供的至关重要的服务；如果未来的气候变化带来极端天气事件的增加，4)使能够预测森林在改变的干扰制度下将如何变化。