Network topology differentially shapes ecological processes across scales in experimental metacommunities

The spatial configuration of habitat patches is a key driver of metacommunity dynamics, yet the role of network topology remains poorly understood. In this study, I experimentally tested how different aspects of network structure influence metacommunity processes operating at different spatial scales. Using protist microcosms, I assembled metacommunities with patches connected as random or scale-free networks, and quantified occupancy, biomass, and extinction dynamics in relation to local (patch degree) and global (closeness centrality) metrics of connectivity. Scale-free metacommunities supported higher occupancy and biomass than random networks. At local scales, biomass declined with increasing patch degree, suggesting that reduced connectivity may enhance productivity, likely by limiting negative interactions. In contrast, extinction dynamics were not related to degree but strongly associated with patch centrality, with network topology modulating the relationship. These results reveal a decoupling between ecological processes, showing that different components of network structure can regulate dynamics at different spatial scales.