Effects of resource patch quality and connectivity on fungal colonization and metacommunity dynamics

Habitat connectivity and quality are fundamental drivers of species colonization and, consequently, metacommunity dynamics. However, their respective roles in the dispersal and establishment phases of colonization remain poorly resolved in empirical studies. To address this, we conducted an extensive field experiment in a mainland–island system using 480 experimental deadwood habitat patches. Fungal communities were screened using DNA metabarcoding across multiple sample types, capturing three key colonization phases: dispersal (air), deposition (bark), and establishment (wood). Bark and wood samples were collected twice, once prior to the placement of deadwood habitat patches and again one year later. We found that both habitat connectivity and habitat quality influence colonization, but their relative importance differed across the different phases. At the dispersal stage, fungal occurrences were mainly influenced by habitat connectivity, whereas at the deposition and establishment phases were mainly influenced by habitat quality. These results provide empirical evidence for a core principle of metacommunity theory: that spatial processes dominate early colonization stages, while local environmental filtering becomes increasingly important during later stages. This study provides a unifying view of how habitat connectivity shapes colonization, a crucial process for understanding community dynamics at the metacommunity scale.