Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, USA.
Ecol Lett. 2024 Mar;27(3):e14422. doi: 10.1111/ele.14422.
Understanding how diversity is maintained in plant communities requires that we first understand the mechanisms of competition for limiting resources. In ecology, there is an underappreciated but fundamental distinction between systems in which the depletion of limiting resources reduces the growth rates of competitors and systems in which resource depletion reduces the time available for competitors to grow, a mechanism we call 'competition for time'. Importantly, modern community ecology and our framing of the coexistence problem are built on the implicit assumption that competition reduces the growth rate. However, recent theoretical work suggests competition for time may be the predominant competitive mechanism in a broad array of natural communities, a significant advance given that when species compete for time, diversity-maintaining trade-offs emerge organically. In this study, we first introduce competition for time conceptually using a simple model of interacting species. Then, we perform an experiment in a Mediterranean annual grassland to determine whether competition for time is an important competitive mechanism in a field system. Indeed, we find that species respond to increased competition through reductions in their lifespan rather than their rate of growth. In total, our study suggests competition for time may be overlooked as a mechanism of biodiversity maintenance.
要理解植物群落中的多样性是如何维持的，我们首先需要了解竞争有限资源的机制。在生态学中，有一种被低估但很基本的区分，即资源耗尽会降低竞争者生长速度的系统，和资源耗尽会减少竞争者生长时间的系统，我们将后者称为“竞争时间”。重要的是，现代群落生态学和我们对共存问题的框架是建立在竞争降低生长速度的隐含假设之上的。然而，最近的理论工作表明，竞争时间可能是广泛的自然群落中的主要竞争机制，这是一个重大进展，因为当物种竞争时间时，多样性维持的权衡就会自然出现。在这项研究中，我们首先使用一个简单的相互作用物种模型从概念上介绍竞争时间。然后，我们在一个地中海一年生草原进行了一项实验，以确定竞争时间是否是一个野外系统中的重要竞争机制。事实上，我们发现物种通过减少寿命而不是生长速度来应对竞争的增加。总的来说，我们的研究表明，竞争时间可能是一个被忽视的维持生物多样性的机制。
