Linking microenvironment modification to species interactions and demography in an alpine plant community

Individual plants can modify the microenvironment within their spatial neighborhood. However, the consequences of microenvironment modification for demography and species interactions remain unclear at the community scale. In a study of co-occurring alpine plants, we (1) determined the extent of species-specific microclimate modification by comparing temperature and soil moisture between vegetated and non-vegetated microsites for several focal species. We (2) determined how vital rates (survival, growth, fecundity) of all species varied in response to aboveground and belowground vegetative overlap with inter- and intraspecific neighbors as proxies for microenvironment modification. For (1), surface temperatures were buffered (lower maximums and higher minimums) and soil moisture was higher below the canopies of most species compared to non-vegetated areas. For (2), vegetative overlap predicted most vital rates, although the effect varied depending on whether aboveground or belowground overlap was considered. Vital rate response to microenvironment-modification proxies (vegetative overlap) was also frequently context dependent with respect to plant size and macroclimate. Microenvironment modification and spatial overlapping of individuals are key drivers of demography and species interactions in this alpine community.