1. Spatial partitioning is a classic hypothesis to explain plant species coexistence, but evidence linking local environmental variation to spatial sorting, demography and species' traits is sparse. If co‐occurring species' performance is optimized differently along environmental gradients because of trait variation, then spatial variation might facilitate coexistence.
2. We used a system of four naturally co‐occurring species of Clarkia (Onagraceae) to ask whether distribution patchiness corresponds to variation in two environmental variables that contribute to hydrological variation. We then reciprocally sowed Clarkia into each patch type and measured demographic rates in the absence of congeneric competition. Species sorted in patches along one or both gradients, and in three of the four species, germination rate in the ‘home’ patch was higher than all other patches.
3. Spatially variable germination resulted in the same three species exhibiting the highest population growth rates in their home patches.
4. Species' trait values related to plant water use, as well as indicators of water stress in home patches, differed among species and corresponded to home patch attributes. However, post‐germination survival did not vary among species or between patch types, and fecundity did not vary spatially.
5. Synthesis. Our research demonstrates the likelihood that within‐community spatial heterogeneity affects plant species coexistence, and presents novel evidence that differential performance in space is explained by what happens in the germination stage. Despite the seemingly obvious link between adult plant water‐use and variation in the environment, our results distinguish the germination stage as important for spatially variable population performance.

中文翻译：

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在四种紧密相关的一年生开花植物中，特定物种发芽率的变化比成年植物耗水对空间共存的贡献更大。

1. 空间划分是解释植物物种共存的经典假设，但是将局部环境变化与空间分类，人口统计学和物种特征联系起来的证据很少。如果由于性状变异，共生物种的性能沿环境梯度的优化不同，那么空间变异可能会促进共存。
2. 我们使用了由自然存在的克拉克属（Onagraceae）的四个自然物种共同组成的系统，来询问分布斑纹是否对应于两个导致水文变异的环境变量的变异。然后，在没有同类竞争的情况下，我们将Clarkia分别播种到每种贴片类型中，并测量人口统计率。物种沿着一个或两个梯度按斑块排序，在四个物种中的三个中，“家”斑块的发芽率高于所有其他斑块。
3. 空间变化的发芽导致相同的三个物种在其家园中表现出最高的种群增长率。
4. 与植物用水有关的物种特征值，以及家庭补丁中的水分胁迫指标，在物种之间有所不同，并与家庭补丁属性相对应。但是，发芽后的存活率在物种之间或斑块类型之间没有变化，繁殖力在空间上也没有变化。
5. 综合。我们的研究证明了社区内部空间异质性影响植物物种共存的可能性，并提供了新的证据表明，发芽阶段发生的现象可以解释空间差异性。尽管成年植物的水分利用与环境变化之间看似明显的联系，但我们的结果仍将发芽阶段区分为对空间变异种群表现至关重要。