Comparative seed shadows of bird-, monkey-, and wind-dispersed trees
Comparative seed shadows of bird-, monkey-, and wind-dispersed trees
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DOI：
10.1890/04-1325
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发表时间：
2005-10-01
期刊：
影响因子：
4.8
通讯作者：
Parker, VT
中科院分区：
文献类型：
--
作者：
Clark, CJ;Poulsen, JR;Parker, VT
虽然种子分布的空间格局被认为是由不同的载体传播的植物物种之间的差异很大，很少有研究直接检验这一假设。我们比较了在喀麦隆的一个封闭的树冠森林中，由大型鸟类、猴子和风传播的9种树木的种子雨模式。我们使用最大似然方法来拟合种子雨数据的四个扩散函数：逆幂，负指数，高斯和学生t。然后，我们测试了扩散特性的差异（1）物种内的个体之间，（2）由同一载体传播的物种之间。一般来说，反幂函数最好地描述了动物分散的物种，高斯和学生t函数最好地描述了风分散的物种。动物传播种的平均传播距离比风传播种长，但繁殖力较低。除了这些明显的差异，平均传播距离和功能形式的种子阴影之间的动物和风分散的物种，种子阴影内的物种和矢量变化显着，同种和物种内的矢量不同的传播规模，繁殖力，和丛生参数。传播媒介决定了种子分布的大量变异，但仍有许多变异有待解释。最后，我们证明，大多数种子，无论矢量，直接落在父树冠下。远距离传播事件（>60米）占种子作物的一小部分，但在传播种子的绝对数量和对种群和群落动态的影响方面可能仍然很重要。
Although spatial patterns of seed distribution are thought to vary greatly among plant species dispersed by different vectors, few studies have directly examined this assumption. We compared patterns of seed rain of nine species of trees disseminated by large birds, monkeys, and wind in a closed canopy forest in Cameroon. We used maximum-likelihood methods to fit seed rain data to four dispersal functions: inverse power, negative exponential, Gaussian, and Student t. We then tested for differences in dispersal characteristics (1) among individuals within species, and (2) among species dispersed by the same vector. In general, an inverse power function best described animal-dispersed species and the Gaussian and Student t functions best described wind-dispersed species. Animal-dispersed species had longer mean dispersal distances than wind-dispersed species, but lower fecundities. In addition to these distinct differences in average dispersal distance and functional form of the seed shadow between animal- and wind-dispersed species, seed shadows varied markedly within species and vector, with conspecifics and species within vector varying in their dispersal scale, fecundity, and clumping parameters. Dispersal vectors determine a significant amount of variation in seed distribution, but much variation remains to be explained. Finally, we demonstrate that most seeds, regardless of vector, fall directly under the parent canopy. Long-distance dispersal events (>60 m) account for a small proportion of the seed crop but may still be important in terms of the absolute numbers of dispersed seeds and effects on population and community dynamics.