Thermophilization over space but not time among communities of ground‐dwelling arthropods in a desert city

Thermophilization of communities, or shifts in composition favoring more warm-adapted species, over time and space is a common response to warming from global climate change and localized effects of land-use change. However, the interplay between community thermophilization driven by temporal warming in global climate and spatial warming in local climate is not well explored empirically. Here, we use long-term ecological monitoring of ground-dwelling arthropod communities over twenty years, sited in desert and urbanized habitats, to address the joint effects of spatiotemporal warming on community thermophilization. We found spatial convergence of high community thermophily among warm desert and highly urbanized sites, implicating temperature as a major driver of community composition. However, we found unexpected temporal declines in community thermophily, the magnitude of which depended upon space. Declines were found in urbanized sites, but not desert sites. There was evidence of both increases in occurrence of heat-intolerant taxa and decreases in heat-tolerant taxa from urban sites. Our study demonstrates the contingency of responses to recent climate change based on contemporary land-use change.