Seed dispersal and recruitment limitation across spatial scales in temperate forest fragments
Seed dispersal and recruitment limitation across spatial scales in temperate forest fragments
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DOI：
10.1890/03-4006
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发表时间：
2004-02-01
期刊：
影响因子：
4.8
通讯作者：
Curran, LM
中科院分区：
文献类型：
--
作者：
McEuen, AB;Curran, LM
尽管越来越多的证据表明森林生态系统中的种子受到限制，但有关大空间尺度（> 1 公顷）种子雨空间模式的数据仍然很少。我们在两年内监测了密歇根州东南部五个北部硬木森林碎片（在 14 公里（2）面积内采样了 27 公顷）的种子雨（28.5 m(2)）。四个碎片是最近的邻居（300-700 m），但物种组成不同，提供了检测景观规模种子交换的机会。在种子雨中存在的 37 种木本植物（98 032 颗成熟种子）中，只有 3 种（白桦、维吉尼亚州榆树和美洲榆）在所有包含常驻源的碎片中具有广泛的种子分散（种子存在于每个碎片中 > 70% 的诱捕器中）。种子传播（以接收种子的碎片内诱捕器的百分比来衡量）在使用不同传播载体的物种之间存在差异，其中动物传播的物种到达的种子诱捕器的百分比低于风传播的种子。在给定的源密度下，种子分散度随着种子质量的减少而增加。与重种子物种（槭树、白蜡树、椴树）相比，轻种子、多产的物种（如桦树或铁杉）需要较低的源密度来使碎片充满种子。大量种子的风散和动物散布物种也显示出种子限制的最有力证据，幼苗的存在与 Carpinus caroliniana、Fagus grandifolia、Prunus avium 和 Tilia americana 的种子存在显着相关。在 17 个物种中，只有 4 个与干扰相关的物种（Acer negundo、Betula papyrifera、Celastrus scandens、Eleaganus umbellata）检测到景观规模的种子交换。尽管在具有常驻来源的碎片中种子广泛分散（> 50％），但没有检测到红枫、阿勒加尼桦或加拿大铁杉的交换，这表明这些物种在更大的空间尺度上可能存在种子限制。种子遭遇概率表明，潜在的种子竞争者通常无法同时殖民微型站点。我们认为，北方硬木森林中的所有优势物种都可以在一定的空间尺度上进行种子限制，并且结果与森林生态系统多样性维护的“以失而胜”的情景一致。
Despite increasing evidence of seed limitation in forest ecosystems, data remain sparse on Spatial patterns of seed rain at large (>1 ha) spatial scales. We monitored seed rain (28.5 m(2)) throughout five northern hardwood forest fragments (27 ha sampled across 14-km(2) area) in southeastern Michigan over two years. Four fragments were nearest neighbors (300-700 m), yet varied in species composition, providing,the opportunity to detect landscape-scale seed exchange. Of the 37 species of woody plants present in the seed rain (98 032 mature seeds), only three (Betula papyrifera, Ostrya virginiana, and Ulmus americana) had widespread seed dispersions within all fragments containing resident sources (seed in >70% of traps in each fragment). Seed dispersions, measured as the percentage of traps within a fragment receiving seed, differed among species using different dispersal vectors with animal-dispersed species arriving in a lower percentage of seed traps than wind-dispersed seeds. At a given source density, seed dispersions increased with decreasing seed mass. Light-seeded, fecund species such as Betula or Tsuga required lower source densities to saturate fragments with seed compared to heavy-seeded species (Acer, Fraxinus, Tilia). Heavy-seeded wind- and animal - dispersed species also displayed the strongest evidence of seed limitation, with seedling presence significantly associated with presence of seed for Carpinus caroliniana, Fagus grandifolia, Prunus avium, and Tilia americana. Of 17 species, landscape-scale seed exchange was detected for only four disturbance-associated species (Acer negundo, Betula papyrifera, Celastrus scandens, Eleaganus umbellata). No exchange was detected for Acer rubrum, Betula alleghaniensis, or Tsuga canadensis, despite broad seed dispersions (>50%) in fragments with resident sources, suggesting the potential for seed limitation for these species at larger spatial scales. Seed encounter probabilities suggest that potential seed competitors often fail to simultaneously colonize microsites. We suggest that all dominant species in northern hardwood forests can be seed limited at some spatial scale and that results are consistent with "winning by forfeit" scenarios of diversity maintenance in forest ecosystems.