Competition for water and species coexistence in phenologically structured annual plant communities
Competition for water and species coexistence in phenologically structured annual plant communities
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DOI：
10.1111/ele.13990
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发表时间：
2022-03-17
期刊：
影响因子：
8.8
通讯作者：
Pacala, Stephen W.
中科院分区：
文献类型：
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作者：
Levine, Jacob, I;Levine, Jonathan M.;Pacala, Stephen W.
对水分的竞争和物候变化都是植物群落结构的重要决定因素，但生态学家缺乏关于它们如何影响共存结果的综合理论。我们为地中海一年生群落开发了一个易于分析处理的水分竞争模型，并证明了仅凭物候变化就可以在空间上同质的限水植物组合中保持高度的多样性。我们模拟了一个系统，在这个系统中，所有的水都在季节的早期到达，物种在干燥条件下生长的能力有所不同。因此，物种在生长季长度上存在差异，并通过缩短竞争对手的生长季来竞争。这个模型复制了在物候如何影响地中海一年生植物共存的经验研究中观察到的模式，并提供了机械论解释。此外，我们发现，在简单但现实的假设下，增长率和水资源获取之间的递减、凹陷的权衡可以保持高度的多样性。高多样性是可能的，因为：(1)较晚的植物在较早的季节竞争对手结实后逃避竞争，(2)较早的季节物种通过生长速度优势对其缩短的生长季节进行了充分的补偿。总而言之，这些机制为物候可变的一年生植物物种在仅争夺水分时如何共存提供了解释。
Both competition for water and phenological variation are important determinants of plant community structure, but ecologists lack a synthetic theory for how they affect coexistence outcomes. We developed an analytically tractable model of water competition for Mediterranean annual communities and demonstrated that variation in phenology alone can maintain high diversity in spatially homogenous assemblages of water-limited plants. We modelled a system where all water arrives early in the season and species vary in their ability to grow under drying conditions. As a consequence, species differ in growing season length and compete by shortening the growing season of their competitors. This model replicates and offers mechanistic explanations for patterns observed in empirical studies of how phenology influences coexistence among Mediterranean annuals. Additionally, we found that a decreasing, concave-up trade-off between growth rate and access to water can maintain high diversity under simple but realistic assumptions. High diversity is possible because: (1) later plants escape competition after their earlier season competitors have gone to seed and (2) early-season species are more than compensated for their shortened growing season by a growth rate advantage. Together, these mechanisms provide an explanation for how phenologically variable annual plant species might coexist when competing only for water.