尺度
灾难性的风损和随后的森林恢复空间和尺度现象时间尺度是重要的理解的影响灾难性的风。莱文(1992)指出,“没有一个机制解释说在所有尺度模式。“Consequently, it is essential to clarify both the spatial and temporal scale over which wind damage and recovery patterns occur and are examined.
暴风通常是分布在一个广泛的空间尺度上,和某些伤害法术和恢复模式只能观察到在一个特定的空间尺度在特定进程的上下文中(福斯特&矿石内的脉石,1992,1994,1995,2000)。例如,地理和气象因素控制飓风的形成和运动只能被理解在大陆范围内(约5000公里),而风速网站曝光,当地地形(差异),和个人属性的控制因素飓风灾害在景观尺度(~ 10公里)。在小尺度上生物因素变得越来越重要。例如,彼得森(2004)发现within-stand损伤的变化在很大程度上可以解释的背景下,树的大小和种类。我们的研究在美国东南部的山麓森林还显示,在站规模,树的大小(即。,它的垂直层)和抗风是最重要的死亡概率指标和损伤类型在一个主要飓风(Xi, 2005;习et al ., 2008)。重要的是要明确研究的时间尺度在和生态模式进行比较。恢复时间从灾难性的暴风森林之间参差不齐几年预测几百年,取决于风力强度和破坏森林的再生能力。森林生态学家常常把风暴影响,post-disturbance反应分为三个时间分类:直接(几个月到一年,例如,沃克et al ., 1992)、短期(几个月到几年,例如,范德米尔et al ., 2000;Pascarella et al ., 2004)和长期(几十年几百年,例如,海布斯,1983; Foster, 1988; Burslem et al., 2000). Moreover, forest recovery processes also vary with time. For example, during and immediately after a hurricane, mortality processes dominate, whereas the recruitment process becomes important in the years immediately after the wind damage. Consequently, the timing of surveys of wind-disturbed forests is critical for understanding the damage, mortality and recovery. The predictability of forest damage from catastrophic winds and the subsequent recovery pattern generally is scale-dependant. Although wind conditions are highly variable in all aspects during a windstorm, wind gusts are more random at smaller scales. The predictability of forest damage at the stand scale (~1 km) is, therefore, relatively low due to the random effects of wind gusts and the complex interactions among their neighbour individuals. The larger-scale forest damage patterns and recovery processes (e.g., at landscape and regional scale) can be predicted reasonably well (Fig. 1). For example, forest damage patterns across post-hurricane landscapes are predictable based on风速、地形(站点曝光),站结构,干扰和土地利用历史(例如,福斯特,1998;福斯特&矿石内的脉石,1992;DeCoster, 1996;习,2005;习et al ., 2008)。
继续阅读:再生的幸存的树木发芽
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