Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland.
Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.
Glob Chang Biol. 2024 Nov;30(11):e17551. doi: 10.1111/gcb.17551.
Functional traits offer a potential avenue to generalize and forecast the impacts of changing competition on plant communities, including changing outcomes of competition among species that currently interact (current competition) or that will interact in the future following range shifts (novel competition). However, it remains unclear how well traits explain variation in the outcomes of current and novel competition as well as the underlying processes determining coexistence or competitive exclusion, under changing climate. Here, we interacted pairs of high and low-elevation species in three sites across an elevation gradient in the Swiss Alps. For each species pair, we quantified the population-level outcomes of competition (invasion growth rates), relative fitness differences, and niche overlap and related these to 15 functional traits that were measured in each site. Most traits were significantly associated with invasion growth rates at the low elevation, where species had greater relative fitness differences, but these associations were much weaker towards higher elevations. This appears to be because traits, particularly those associated with light competition, captured species' relative fitness differences at lower elevations, but not at the high elevation site, highlighting that the predictive ability of traits can depend on environmental context. The amplified relative fitness differences towards lower elevations suggest that climate warming may increase the likelihood of competitive exclusion. In addition, novel competitors tended to show greater niche overlap than current competitors, leading to stronger overall competitive effects. However, in general, trait differences predicted competitive outcomes of novel and current competitors similarly well, suggesting that traits can predict interactions between species that do not yet interact. Our study reinforces the importance of considering changing interactions for predicting species responses to climate change and provides experimental evidence supporting the usefulness of functional trait differences in forecasting the impacts of future plant interactions under changing climate.
功能性状为概括和预测变化的竞争对植物群落的影响提供了一个潜在途径，包括正在相互作用的物种（当前竞争）或在未来随着范围转移而相互作用的物种（新竞争）的竞争结果。然而，在变化的气候下，性状对于当前和新竞争的结果以及决定共存或竞争排斥的潜在过程的解释程度仍然不清楚。在这里，我们在瑞士阿尔卑斯山的一个海拔梯度上的三个地点相互作用了高海拔和低海拔物种对。对于每一对物种，我们量化了竞争的种群水平结果（入侵增长率）、相对适合度差异和生态位重叠，并将这些与在每个地点测量的 15 个功能性状相关联。大多数性状与低海拔的入侵增长率显著相关，在低海拔地区，物种的相对适合度差异更大，但这些关联在较高海拔地区要弱得多。这似乎是因为性状，特别是与光竞争相关的性状，在低海拔地区捕捉到了物种的相对适合度差异，但在高海拔地区则没有，这突出表明性状的预测能力可能取决于环境背景。较低海拔地区相对适合度差异的放大表明，气候变暖可能增加竞争排斥的可能性。此外，新的竞争者往往比当前的竞争者表现出更大的生态位重叠，从而导致更强的整体竞争效应。然而，一般来说，性状差异同样很好地预测了新的和当前竞争者的竞争结果，这表明性状可以预测尚未相互作用的物种之间的相互作用。我们的研究强调了考虑变化的相互作用对于预测物种对气候变化的反应的重要性，并提供了实验证据支持在变化的气候下使用功能性状差异预测未来植物相互作用的影响的有用性。
