*Background/Question/Methods* Understanding how interactions amongst species contribute to their distribution is central to community ecology. However, it is not understood how these processes may change under different environmental conditions. In this study, we present evidence that suggests interactions amongst canopy arthropods contribute to assemblage structure, depending on both the sampling time and location. We sampled canopy arthropod species abundances on individual trees in three adjacent, monospecific stands of Populus fremontii (Fremont cottonwood), which differ in planting year (2000, 2002, 2005). We then conducted null-model based co-occurrence analysis using the freely available software EcoSim (Kesey-Bear and Acquired Intelligence, Inc.)... |