Replacement patterns and species coexistence in an Andean Araucaria-Nothofagus forest
Replacement patterns and species coexistence in an Andean Araucaria-Nothofagus forest
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DOI：
10.1111/j.1654-1103.2009.01117.x
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发表时间：
2009-12-01
影响因子：
2.8
通讯作者：
Gonzalez, Mauro E.
中科院分区：
文献类型：
--
作者：
Fajardo, Alex;Gonzalez, Mauro E.
在智利中南部的安第斯地区，火灾似乎影响了Araucaria araucana-Nothofagus pumilio森林的替换模式和共存。然而，在最近没有火灾的情况下，缺乏对共存的定量评估。在本研究中，我们考虑了两种树种的生活史属性，招募时间和空间格局，以解决以下问题。这两个物种的招募有多频繁？是否存在时间上的生态位分化？这两个物种在空间上是正相关还是负相关，如果是，在多大的尺度上，在多大的年龄和大小类别上？是否存在空间生态位分化？地理位置智利安第斯山脉地区维拉里卡国家公园（39度35分，71度31分，西经1300米）。方法利用1 ha样地的1073棵树进行茎图绘制和核取，研究林分的时空分布规律。我们使用半变异函数模型和对相关函数来区分再生模式和描述物种间的相互作用。结果两种植物的更新模式存在差异，在时间和空间上，砂棘猴的更新更具连续性，而矮毛猴的更新以偶发脉冲为主。在小尺度上，小年龄层茎随机分布，大年龄层茎聚集。这与温带树种（包括矮矮木）的常见模式形成对比，后者遵循自疏过程。在相似树冠直径的尺度上，小林龄级与老同种木的分布呈负相关，而小林龄级与老同种木的分布呈负相关。结论在没有近期火灾的情况下，由于其更强的耐荫性、更长的寿命和不断的补充，araucana可能会单独占据主导地位。然而，在冠层关闭尚未完成的情况下，不耐阴的矮毛蕨能够在种子掌握后在这些开放区域内繁殖，并与沙蚕共存。
QuestionsFire appears to affect both replacement patterns and coexistence of Araucaria araucana-Nothofagus pumilio forests in the Andean Araucarian region of south-central Chile. A quantitative assessment of coexistence in the absence of recent fires, however, is lacking. In this study, we considered the life-history attributes, time of recruitment and spatial pattern of individuals of both tree species to address the following questions. How regular has recruitment of both species been in time? Is there any temporal niche differentiation? Are the two species positively or negatively associated in space and, if so, at what scale and for what age and size classes? Is there any spatial niche differentiation?LocationAndean Araucarian region of Chile, Villarrica National Park (39 degrees 35'S, 71 degrees 31'W; 1300 m a.s.l.).MethodsWe stem-mapped and cored a total of 1073 trees in a 1-ha plot in a late-successional post-fire stand to examine spatiotemporal patterns of establishment. We used semivariogram modelling and the pair-correlation function to distinguish between regeneration modes and describe species interactions.ResultsThe two species differ in their regeneration mode: whereas A. araucana appeared to recruit more continuously in time and space, episodic pulses of establishment were dominant for N. pumilio. At small scales, younger age-class stems of A. araucana were randomly distributed, while older age-class stems were aggregated. This was in contrast to common patterns for temperate tree species, including N. pumilio, following processes of self-thinning. Younger age classes of A. araucana were distributed independently of older trees of both species, but younger age classes of N. pumilio had a negative association with older conspecifics at scales similar to crown diameter.ConclusionsIn the absence of recent fires, it is likely that A. araucana would dominate the stand alone, given its greater shade tolerance, greater longevity and continuous recruitment. However, while canopy closure is still incomplete, the shade-intolerant N. pumilio will be able to recruit in those open areas after seed masting and will coexist with A. araucana.