Centre of Excellence of Plant and Vegetation Ecology, Department of Biology, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium
Climate Impacts Research Centre, Department of Ecology and Environmental Science, Umeå University, SE-981 07 Abisko, Sweden Research Institute for Nature and Forest INBO, Department of Biodiversity and Natural Environment, Kliniekstraat 25, 1070 Brussels, Belgium.
AoB Plants. 2015 Nov 10;7:plv128. doi: 10.1093/aobpla/plv128.
Recent experimental observations show that gap colonization in small-stature (e.g. grassland and dwarf shrubs) vegetation strongly depends on the abiotic conditions within them. At the same time, within-gap variation in biotic interactions such as competition and facilitation, caused by distance to the gap edge, would affect colonizer performance, but a theoretical framework to explore such patterns is missing. Here, we model how competition, facilitation and environmental conditions together determine the small-scale patterns of gap colonization along a cold gradient in mountains, by simulating colonizer survival in gaps of various sizes. Our model adds another dimension to the known effects of biotic interactions along a stress gradient by focussing on the trade-off between competition and facilitation in the within-gap environment. We show that this trade-off defines a peak in colonizer survival at a specific distance from the gap edge, which progressively shifts closer to the edge as the environment gets colder, ultimately leaving a large fraction of gaps unsuitable for colonization in facilitation-dominated systems. This is reinforced when vegetation size and temperature amelioration are manipulated simultaneously with temperature in order to simulate an elevational gradient more realistically. Interestingly, all other conditions being equal, the magnitude of the realized survival peak was always lower in large than in small gaps, making large gaps harder to colonize. The model is relevant to predict effects of non-native plant invasions and climate warming on colonization processes in mountains.
最近的实验观察表明，小体型（如草地和矮灌木）植被中的间隙殖民强烈依赖于其内部的非生物条件。同时，由于距离间隙边缘的远近而导致的生物相互作用（如竞争和促进）在间隙内的变化会影响殖民者的表现，但缺乏探索这种模式的理论框架。在这里，我们通过模拟不同大小间隙中殖民者的生存情况，来模拟在山地寒冷梯度下，竞争、促进和环境条件如何共同决定间隙殖民的小尺度模式。我们的模型通过关注间隙内环境中竞争和促进之间的权衡，为已知的沿压力梯度的生物相互作用效应增加了另一个维度。我们表明，这种权衡在离间隙边缘特定距离处定义了一个殖民者生存的峰值，随着环境变冷，这个峰值逐渐向边缘移动，最终在促进主导的系统中留下很大一部分间隙不适合殖民。当同时模拟植被大小和温度缓解与温度时，这种情况会更加强化，以便更真实地模拟海拔梯度。有趣的是，在所有其他条件相同的情况下，在大间隙中实现的生存峰值的幅度总是低于小间隙，这使得大间隙更难殖民。该模型可用于预测非本地植物入侵和气候变暖对山区殖民过程的影响。
