Fuel Loading in Simulated Hurricane Experiment at Harvard Forest since 1993

Wind disturbance profoundly shapes temperate forests but few studies have evaluated patterns and mechanisms of long-term forest dynamics following major windthrows. In 1990, we initiated a large hurricane simulation experiment in a 0.8 ha manipulation (pulldown) and 0.6 ha control area of a maturing Quercus rubra-Acer rubrum forest in New England. We toppled 276 trees in the pulldown, using a winch and cable, in the northwesterly direction of natural treefall from major hurricanes. Eighty percent of canopy trees and two-thirds of all trees greater than 5 cm dbh suffered direct and indirect damage. An enormous input of dead wood was one result of the manipulation. Many perceive an increased risk of wildfire after trees are blown down, but this depends on the amount, size, and persistence of the dead wood inputs.

风扰深刻塑造温带森林的结构与动态，但针对大规模风倒事件后森林长期动态的格局与机制，相关研究仍较为匮乏。1990年，我们于美国新英格兰地区一片处于成熟阶段的红栎（Quercus rubra）-红枫（Acer rubrum）林内，设置了0.8公顷的伐倒处理样地与0.6公顷的对照样地，开展大型飓风模拟实验。实验中，我们借助绞车与钢索，按照大规模飓风引发自然倒树的西北向方位，在处理样地内伐倒了276株树木。样地内80%的冠层树木，以及胸径（dbh）大于5厘米的所有树木中的三分之二，均遭受了直接或间接损伤。此次人为干预的直接后果之一，是产生了大量枯木输入。不少人认为树木倒伏后野火风险会升高，但该风险实际取决于枯木输入的总量、径级与留存持久性。