Multi-scale drivers of community diversity and composition across tidal heights: an example on temperate seaweed communities

1. Despite recent advances in understanding community assembly processes, appreciating how these processes vary across multiple spatial scales and environmental gradients remains a crucial issue in ecology.
2. This study aimed to disentangle the drivers of diversity and composition of seaweed communities through a gradient of spatial scales based on a hierarchical sampling design consisting of 19 sites distributed in four sectors along the Brittany coastline. Using randomised community matrices and Moran’s eigenvector maps (MEMs), we compared i) the relative importance of deterministic and stochastic processes, ii) the environmental correlates of community composition and iii) the scale of variation in community composition for seaweed communities located at two different tidal heights.
3. Processes shaping community patterns are expected to vary along a gradient of tidal heights. Therefore, we specifically examined the following hypotheses: the contribution of deterministic over stoc...