Importance of abiotic factors in shaping canopy arthropod assemblages: the case of Quercus castanea Nee (Fagales:Fagaceae) a Mexican endemic oak

The understanding of ecological mechanisms shaping canopy arthropods community assembly, remains as one of the main targets of ecology. It is necessary to elucidate how abiotic factors such as precipitation shape arthropod communities in oak canopy. We evaluated the changes of canopy arthropod diversity assemblages associated to Quercus castanea along a precipitation gradient in four study sites, where Q. castanea occurs. Five mature Q. castanea trees were selected per site to collect canopy arthropods using fogging techniques. We collected 7,447 arthropods representing 754 morphospecies grouped into 16 different orders associated to Q. castanea along the precipitation gradient. We found differences in arthropod richness and abundance as well as in guild composition along the precipitation gradient. The general pattern showed higher canopy arthropod diversity in dry sites compared to wet sites. Also, arthropod guild composition differed along the precipitation gradient; dry sites harbored higher abundance of phytophages and detritivores, while wet sites had higher richness of phytophages and predators. Local climatic variables such as temperature were related to the canopy of Q. castanea arthropod community in dry sites. Our findings confirm that at a local scale, water availability is an important abiotic factor that generates changes in the assemblies of canopy arthropod community of Q. castanea, harboring more arthropod diversity in dry sites. We highlight the importance of conserving oak species because Mexico is the main center of richness, diversification and endemism of oaks in the northern hemisphere, and they represent key species in temperate forest harboring a great diversity of unique canopy arthropods.