Species' responses to environmental conditions and competitive interactions are critical components of community dynamics and responses to climate change. The impacts of these processes integrate over an uneven, changing landscape. While 'patches' are a handy theoretical construct, and empirical work often focuses on the most favourable areas for study organisms (for good reason), communities dynamically inhabit a range of locations of varying quality and containing a mix of competitors.
Here, we conducted an exhaustive survey of oviposition habitat for a well-studied community of caddisflies in the family Hydrobiosidae. We surveyed emergent rocks (oviposition substrate) in 5-m units totalling more than 36 km across three streams and three years, within which we sampled 883 randomly selected units (totalling 4.5 km) for oviposition. Taken together, these data comprise a previously unavailable characterisation of the distribution of environmental conditions as they vary over time and space. We also identify correlations between species-specific abundances and habitat, yielding new information about how the environment structures oviposition patterns across scales, community composition, and potential competitive interactions.
While observational, these data suggest that species are distributed across the landscape in a way that concentrates their experienced interactions within species, potentially supporting coexistence and maintaining diversity. Moreover, we accentuate the importance of characterising the full distribution of landscape conditions for studying community responses to climate change. Considering only 'best' habitats misses important information determining the ability of species to maintain stable experienced environmental conditions in the face of shifting conditions. In the spirit of this session, we also accentuate the importance of follow-on detailed ecological fieldwork; do the changes in competitive interactions implied by these results actually occur? How strong are they, and how do they manifest in terms of species' fitness and distributions?