Stanik Nils, Lampei Christian, Rosenthal Gert
Department of Landscape and Vegetation Ecology Institute of Landscape Architecture and Environmental Planning University of Kassel Kassel Germany.
Institute of Landscape Ecology, Biodiversity and Ecosystem Research Group University of Münster Münster Germany.
Ecol Evol. 2020 May 8;10(11):5069-5078. doi: 10.1002/ece3.6259. eCollection 2020 Jun.
Semi-natural mountain grasslands are increasingly exposed to environmental stress under climate change. However, which are the environmental factors that limit plants in these grasslands? Also, is the present management effective against these changes? Fitness-related functional traits may offer a way to detect changes in performance and provide new insights into their vulnerability to climate change. We investigated changes in performance and variability of functional traits of the mountain grassland target species along a climate gradient in Central German low mountain ranges. This gradient represents at its lower end climate conditions that are expected at its upper end under future climate change. We measured vegetative, generative, and physiological traits to account for multiple ways of plant responses to the environment. Using mixed effects and multivariate models, we evaluated changes in trait values among individuals as well as the variability of their populations in order to assess performance under changing summer aridity and different management regimes. Fitness-related performance of most traits showed strongly positive associations with reduced summer aridity at higher elevations, while only specific leaf area and leaf dry matter content showed no association. This suggests a higher performance level at less arid montane sites and that the physiological traits are less sensitive to this climate change factor. The coefficient of variation of almost all traits declined steadily with decreasing site aridity. We suggest that this reduced variability indicates a lower environmental stress level for toward its environmental optimum at montane elevations, especially because the trait performance increased simultaneously. Surprisingly, management factors and habitat characteristics had only low influence on both trait performance and variability. In summary, summer aridity had a stronger effect to shape the trait performance and variability of under increased environmental stress than management and other habitat characteristics.
在气候变化的影响下，半天然山地草原正日益受到环境压力的影响。然而，在这些草原中限制植物生长的环境因素有哪些？此外，目前的管理措施对这些变化是否有效？与适合度相关的功能性状可能提供一种方法来检测性能变化，并为它们对气候变化的脆弱性提供新的见解。我们在德国中部低山地区沿着气候梯度调查了山地草原目标物种功能性状的性能和变异性变化。这个梯度在其下端代表当前气候条件，在其上端代表未来气候变化下预期的气候条件。我们测量了营养、生殖和生理性状，以考虑植物对环境的多种响应方式。使用混合效应和多变量模型，我们评估了个体间性状值的变化以及它们种群的变异性，以便评估在夏季干旱变化和不同管理模式下的性能。大多数性状与适合度相关的性能在海拔较高处与夏季干旱减少呈强烈正相关，而只有比叶面积和叶片干物质含量没有相关性。这表明在干旱程度较低的山地站点性能水平较高，并且生理性状对这种气候变化因素不太敏感。几乎所有性状的变异系数都随着站点干旱程度的降低而稳步下降。我们认为这种变异性降低表明在山地海拔高度朝着环境最优状态的环境压力水平较低，特别是因为性状性能同时增加。令人惊讶的是，管理因素和栖息地特征对性状性能和变异性的影响都很小。总之，在环境压力增加的情况下，夏季干旱对塑造性状性能和变异性的影响比管理和其他栖息地特征更强。
