Crown Asymmetry, Treefalls, and Repeat Disturbance of Broad‐Leaved Forest Gaps
Crown Asymmetry, Treefalls, and Repeat Disturbance of Broad‐Leaved Forest Gaps
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DOI：
10.2307/1941119
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发表时间：
1991-08
期刊：
影响因子：
4.8
通讯作者：
T. Young;S. Hubbell
中科院分区：
文献类型：
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作者：
T. Young;S. Hubbell
在巴拿马巴罗科罗拉多岛(BCI)的一片潮湿的热带森林中，林隙边缘的树木比其他方向更有可能陷入先前存在的林隙。不在林隙边缘的树木更有可能从近邻那里掉落，而不是朝向他们。我们表明，树冠的严重不对称是所有树木的规则，而不是例外。大多数林窗边缘树的树冠在相邻林隙内表现出强烈的不对称性，而非林窗边缘的树冠与邻近林隙之间的距离表现出较强的不对称性。树木在这些沉重的侧面有强烈而显著的倒下倾向。这样的树木下落和相关的边缘下落可能会导致林隙的重新分布和林隙再生的延迟。对BCI上绘制的50公顷样地的5年树冠高度数据的分析表明，较大林隙内的站点比最小林隙或无林隙样方的站点更有可能受到次生树木瀑布的重新干扰。这些结果表明，热带森林中的树冠空隙可能是比之前认为的更持久的干扰。
Gap—edge trees were significantly more likely to fall into pre—existing gaps than in other directions in a moist tropical forest on Barro Colorado Island (BCI), Panama. Trees not at gap edges were more likely to fall away from near neighbors than toward them. We show that gross asymmetries of tree crowns were the rule rather than the exception for all trees. The crowns of most gap—edge trees were strongly asymmetrical into their adjoining gaps, and trees not at gap edges were strongly asymmetrical way from near neighbors. Trees had a strong and significant tendency to fall on these heavy sides. Such treefalls, and related limbfalls, can result in redistribution of gaps and a retardation of gap regeneration. An analysis of 5 yr of canopy height data from a mapped 50—ha plot on BCI revealed that sites within larger gaps were significantly more likely to be redisturbed by secondary treefalls than were sites in the smallest gaps or nongap quadrats. These results suggest that treefall gaps in tropical forest may be more persistent disturbances than previously thought.