Girdler E Binney, Knight Tiffany M, Evers Sanne M, Compagnoni Aldo, Leberger Roxanne, Marik Julie E, Hamzé Samara I, Jolls Claudia L
Department of Biology Kalamazoo College Kalamazoo Michigan USA.
University of Michigan Biological Station Pellston Michigan USA.
Ecol Evol. 2025 Aug 31;15(9):e72080. doi: 10.1002/ece3.72080. eCollection 2025 Sep.
Changes in population responses to climate are usually studied at broad spatial grains, such as across species ranges. Only a handful of studies have investigated how small-scale variation, for example driven by soil conditions and microtopography, can mediate the responses of population vital rates to climate. Here, we examine responses of vital rates to climate across five subpopulations occurring in coastal dune locations that range from the foredune to the backdune. We consider five vital rates: seedling survival, adult survival, growth, flowering probability, and the size of new adults. We use generalized linear mixed models to quantify vital rate variation across the dune gradient. Then, we analyze the estimates to quantify the so-called "portfolio effect": the stabilizing effect of spatial asynchrony among the five subpopulations on the population as a whole. Finally, we use a sliding window approach to test whether climate drivers contribute to the portfolio effect. We found evidence of substantial portfolio effects across the dune gradient. These effects arise in part from the opposite responses of vital rates to climatic drivers in our five subpopulations. Strikingly, seedling survival, adult survival, and growth were negatively correlated with precipitation in the subpopulation closer to shore and positively correlated with precipitation in the subpopulation farthest from the shore. We explain this pattern by noting that storms that bring precipitation to the dune system may also cause disturbance and sand burial that negatively affect plants close to the water's edge. Such climate-mediated portfolio effects should have a stabilizing effect on the population abundance over time, with implications for population projections and for assessments of range-wide vulnerability of rare plant species. We call for further scrutiny of variation in small-scale responses to climate and for further empirical tests, especially in coastal dune environments.
通常在较大的空间尺度上研究种群对气候的响应变化，比如跨物种分布范围。只有少数研究调查了小规模变异（例如由土壤条件和微地形驱动的变异）如何调节种群生命率对气候的响应。在此，我们研究了沿海沙丘地区从沙丘前沿到沙丘后沿的五个亚种群的生命率对气候的响应。我们考虑了五个生命率：幼苗存活率、成体存活率、生长、开花概率以及新成体的大小。我们使用广义线性混合模型来量化沙丘梯度上的生命率变化。然后，我们分析这些估计值以量化所谓的“投资组合效应”：五个亚种群之间空间异步性对整个种群的稳定作用。最后，我们使用滑动窗口方法来测试气候驱动因素是否对投资组合效应有贡献。我们发现沙丘梯度上存在显著的投资组合效应证据。这些效应部分源于我们五个亚种群中生命率对气候驱动因素的相反响应。引人注目的是，在靠近海岸的亚种群中，幼苗存活率、成体存活率和生长与降水量呈负相关，而在离海岸最远的亚种群中则与降水量呈正相关。我们通过指出给沙丘系统带来降水的风暴也可能导致干扰和沙埋，从而对靠近水边的植物产生负面影响来解释这种模式。这种气候介导的投资组合效应应该会随着时间对种群数量产生稳定作用，这对种群预测以及对稀有植物物种全范围脆弱性评估都有影响。我们呼吁进一步审视对气候的小规模响应变化，并进行更多实证检验，特别是在沿海沙丘环境中。
