Spatial patterns and competition of tree species in a Douglas-fir chronosequence on Vancouver Island
Spatial patterns and competition of tree species in a Douglas-fir chronosequence on Vancouver Island
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DOI：
10.1111/j.2006.0906-7590.04675.x
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发表时间：
2006-10-01
期刊：
影响因子：
5.9
通讯作者：
Wiegand, Thorsten
中科院分区：
文献类型：
--
作者：
Getzin, Stephan;Dean, Charmaine;Wiegand, Thorsten
西北太平洋地区道格拉斯-冷杉林的演替动态和大尺度结构已得到了较好的研究，但林分水平上的细尺度空间特征仍鲜为人知。在这里，我们调查了温哥华岛森林的精细空间结构，以了解三个优势物种，道格拉斯冷杉，西部铁杉和西部红柏是如何共存并沿着由未成熟、成熟和老生长的林分组成的时间序列划分空间的。我们利用尺度依赖点模式分析、成对相关函数g(R)和Ripley的L函数对物种沿时间序列的空间分布和关联度的变化进行了量化。种内和种间竞争的证据也从最近邻距离和树大小之间的相关性中推断出来。结果表明：1)老树阶段道格拉斯冷杉种群的聚集主要是由于当地立地条件的差异所致；2)只有存活的铁杉比死亡前的格局更规整，这与种内竞争较强一致；3)由于空间资源的分割，种间竞争随着林分年龄的增长而迅速下降；(4)树木死亡在较大的盖层乔木之间呈随机分布。这项研究强调了空间异质性对于耐荫先锋道格拉斯冷杉和耐荫西部铁杉和西部红柏长期共存的重要性。
While the successional dynamics and large-scale structure of Douglas-fir forest in the Pacific Northwest region is well studied, the fine-scale spatial characteristics at the stand level are still poorly understood. Here we investigated the fine-scale spatial structure of forest on Vancouver Island, in order to understand how the three dominant species, Douglas-fir, western hemlock, and western redcedar, coexist and partition space along a chronosequence comprised of immature, mature, and old-growth stands. We quantified the changes in spatial distribution and association of the species along the chronosequence using the scale-dependent point pattern analyses pair-correlation function g(r) and Ripley's L-function. Evidence on intra- and inter-specific competition was also inferred from correlations between nearest-neighbor distances and tree size. Our results show that 1) the aggregation of Douglas-fir in old-growth was primarily caused by variation in local site characteristics, 2) only surviving hemlock were more regular than their pre-mortality patterns, a result consistent with strong intra-specific competition, 3) inter-specific competition declined rapidly with stand age due to spatial resource partitioning, and (4) tree death was spatially randomly distributed among larger overstory trees. The study highlights the importance of spatial heterogeneity for the long-term coexistence of shade-intolerant pioneer Douglas-fir and shade-tolerant western hemlock and western redcedar.