Oak canopy arthropod communities: which factors shape its structure?
Canopy of forest ecosystems has been recognized as a habitat that supports a wide variety of plants, vertebrates, invertebrates, and microbes. Within the invertebrate group, arthropods are characterized by their great abundance, diversity, and functional importance. Particularly in temperate forests, species of the genus Quercus (oaks) are one of the most important tree canopy groups, for its diversity and dominance. Different studies have shown that the oak canopy contains a high diversity of arthropods suggesting their importance as habitat for this group of organisms. In this review, we investigated the factors that determine the establishment, organization, and maintenance of arthropod communities in the oak canopy. In general, it was found that there is a lack of literature that addresses the study of oak canopy arthropod communities. Also, the following patterns were found: (a) the research has covered a wide variety of topics; however, there are differences in the depth to which each topic has been analyzed, (b) there are ambiguous criteria to define the structure of the canopy, (c) groups with different habitat preferences belonging to different guilds and uneven development stages have been studied, avoiding generalizations about patterns found, (d) the standardization in sampling techniques and collection has been difficult, (e) bias exists towards the study of phytophagous insects belonging to the Coleoptera, Hymenoptera, and Lepidoptera orders, and (f) there are few studies in other groups of arthropods, for example, acorn borers, whose activity has an impact on the fitness and dispersion of the host plants. Finally, we propose that the detection and study of patterns in oak canopy communities can be of great value to propose management and conservation strategies in these forests.