PREMISE Environmental heterogeneity influences plant distributions and diversity at several spatial scales. In temperate forests, fine-scale environmental variation may promote local coexistence among herbaceous species by allowing plants to spatially partition microsites within forest stands. Here we argue that shallow soils, low soil water-holding capacity and fertility, and reduced light near tree boles should favor short, shallow-rooted, evergreen species like Anemone acutiloba with low moisture, nutrient, and light requirements. Farther from trees, richer, deeper soils should favor taller, deeper-rooted herbs with greater moisture and nutrient demands, such as Sanguinaria canadensis and Trillium flexipes. METHODS We tested these hypotheses by mapping the fine-scale distributions of Anemone, Sanguinaria, and Trillium individuals within a 50 × 50 m plot, comparing local species' distributions with respect to soil depth and proximity to neighboring trees, and characterizing intraspecific and interspecific spatial associations. RESULTS Local plant distributions were consistent with our predictions based on leaf height, physiology, and phenology. Anemone was found in microsites on shallower soils and closer to trees than either Sanguinaria or Trillium. In all three species, individual plants were spatially aggregated within 2 m, but spatially segregated from individuals of the other species beyond 2 m. CONCLUSIONS Differential plant responses to fine-scale environmental heterogeneity and observed spatial associations suggest that local species-environment associations could facilitate coexistence. These findings illustrate how fine-scale environmental heterogeneity coupled with phenological and physiological differences likely contribute to spatial niche partitioning among spring-flowering forest herbs and maintain high local plant diversity within temperate forests.

中文翻译：

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春花林草本植物精细尺度环境异质性与空间生态位划分

前提环境异质性在几个空间尺度上影响植物分布和多样性。在温带森林中，精细尺度的环境变化可以通过允许植物在林分内空间划分微型站点来促进草本物种之间的局部共存。在这里，我们认为浅层土壤、土壤保水能力和肥力低，以及树干附近的光照减少，应该有利于短根、浅根、常绿的物种，如对水分、养分和光照要求低的海葵。远离树木，更肥沃、更深的土壤应该有利于更高、根系更深、水分和营养需求更大的草本植物，例如加拿大红花和延龄草。方法 我们通过绘制海葵、血红花、和延龄草个体在 50 × 50 m 地块内，比较当地物种在土壤深度和与邻近树木的接近度方面的分布，并表征种内和种间空间关联。结果 当地植物分布与我们基于叶高、生理和物候的预测一致。海葵被发现在较浅土壤上的微型场地中，比 Sanguinaria 或 Trillium 更靠近树木。在所有三个物种中，单个植物在空间上聚集在 2 m 以内，但在空间上与 2 m 以外的其他物种的个体隔离。结论 植物对细尺度环境异质性的不同反应和观察到的空间关联表明当地物种-环境关联可以促进共存。