Beyond Co-Occurrence: Multi-Scale Evidence for Segregation-Dominated Plant Networks in the French Alps.

Abstract

Understanding how plants influence each other's spatial distribution is pivotal not only for interpreting current communities, but also for anticipating their responses to global changes. The combination of high-resolution, multi-scale sampling and novel statistical frameworks now enables us to identify species aggregations and segregations within their local co-occurrences. By applying this approach to approximately 800 plant species and their communities across the French Alps, we discovered that local species associations are dependent on soil acidity and nitrogen rather than climate. By building a regional network from these associations, we identified a centralised core comprising a few dominant, stress-tolerant graminoids and shrubs with high leaf dry matter content and no unique functional roles. Our findings demonstrate that plant community assembly is less dependent on random co-occurrence and more dependent on segregation around a few dominant, stress-tolerant species, with soil conditions modulating the outcome of local associations.