Dispersal increases the resilience of tropical savanna and forest distributions

Global change may induce changes in savanna and forest distributions, but the dynamics of these changes remain unclear. Classical biome theory suggests that climate is predictive of biome distributions, such that shifts will be continuous and reversible. This view, however, cannot explain the overlap in the climatic ranges of tropical biomes, which some argue may result from fire-vegetation feedbacks, maintaining savanna and forest as bistable states. Under this view, biome shifts are argued to be discontinuous and irreversible. Mean-field bistable models, however, too, are limited as they cannot reproduce the spatial aggregation of biomes. Here, we suggest that both models ignore spatial processes, such as dispersal, which may be important when savanna and forest abut. We examine the contributions of dispersal to determining biome distributions using a 2D reaction-diffusion model, comparing results qualitatively to empirical savanna and forest distributions in sub-Saharan Africa. We fi...全球变化可能引发稀树草原（savanna）与森林的分布改变，但此类变化的动力学机制仍不明晰。经典生物群系（biome）理论指出，气候可预测生物群系的分布格局，因此分布转变是连续且可逆的。然而该观点无法解释热带生物群系气候范围的重叠现象，部分学者认为这或源于火-植被反馈，使得稀树草原与森林维持为双稳态。据此观点，生物群系的转变被认为是不连续且不可逆的。但平均场双稳态模型（mean-field bistable models）同样存在局限，无法复现生物群系的空间聚集特征。本研究指出，两类模型均忽略了扩散等空间过程——当稀树草原与森林毗邻时，该过程或起到关键调控作用。我们借助二维反应-扩散模型（2D reaction-diffusion model）探究扩散对生物群系分布的影响，并将研究结果与撒哈拉以南非洲地区的实际稀树草原与森林分布进行定性对比。我们……