Limited salvage logging effects on forest regeneration after moderate-severity windthrow.
Limited salvage logging effects on forest regeneration after moderate-severity windthrow.
复制标题
中度风灾后，抢救性伐木对森林再生的影响有限。
作者：
C. Peterson;A. Leach
最近的概念进展解决森林在很短的时间内对多种干扰的反应，提供了一个理想的框架，审查自然干扰的后果，其次是人为的管理活动。短期内两种或两种以上干扰的组合可能产生“生态意外”，模型预测累积干扰严重程度的阈值，超过该阈值，森林组成将急剧改变，再生可能受到损害。抢救性采伐（在自然干扰后采伐木材;也称为“抢救”或“卫生采伐”）是常见的，但没有测试自然风干扰后抢救对木本植物再生的影响。在这里，我们提出了三年后，在美国田纳西州中西部的中度严重的风扰动的研究结果。我们比较了两个未打捞的网站和两个网站，有中等强度打捞。我们的方法演示了累积的严重程度的措施，结合联合收割机自然风抛严重性和人为树木砍伐和清除，在一个地块的基础上计算。幼苗/幼树密度和物种丰富度的累积干扰强度的影响不大，但物种多样性表现出边际增加，增加累积严重性。的组成变化量（从干扰前的树木干扰后的幼苗/树苗）的累积严重程度的干扰显着增加，但没有证据表明在严重程度范围内的阈值检查。总的来说，在这些网站上很少有害的变化是明显的。中等强度的自然干扰，其次是中等强度的打捞可能对森林再生和多样性在这些系统中的不利影响不大;生态惊喜和阈值成分变化更有可能在自然和人为干扰的组合，有更大的累积严重程度。
Recent conceptual advances address forest response to multiple disturbances within a brief time period, providing an ideal framework for examining the consequences of natural disturbances followed by anthropogenic management activities. The combination of two or more disturbances in a short period may produce "ecological surprises," and models predict a threshold of cumulative disturbance severity above which forest composition will be drastically altered and regeneration may be impaired. Salvage logging (the harvesting of timber after natural disturbances; also called "salvaging" or "sanitary logging") is common, but there have been no tests of the manner in which salvaging after natural wind disturbance affects woody plant regeneration. Here we present findings from three years after a moderate-severity wind disturbance in west-central Tennessee, USA. We compare two unsalvaged sites and two sites that had intermediate-intensity salvaging. Our approach demonstrates the calculation of cumulative severity measures, which combine natural windthrow severity and anthropogenic tree cutting and removal, on a plot-by-plot basis. Seedling/sapling density and species richness were not influenced by cumulative disturbance severity, but species diversity showed a marginal increase with increasing cumulative severity. The amount of compositional change (from predisturbance trees to post-disturbance seedlings/saplings) increased significantly with cumulative severity of disturbance but showed no evidence of thresholds within the severity range examined. Overall, few deleterious changes were evident in these sites. Moderate-severity natural disturbances followed by moderate-intensity salvaging may have little detrimental effect on forest regeneration and diversity in these systems; the ecological surprises and threshold compositional change are more likely after combinations of natural and anthropogenic disturbances that have a much greater cumulative severity.