Influence of edaphic factors along an altitudinal gradient on a litter arthropod community in an Abies-Quercus forest in Mexico

Elevational gradients can serve as natural experiments to study how species are restricted spatially according to environmental conditions. The variation in resources and conditions that habitats experience in relation to the seasons can be useful for understanding why the abundance and distribution of the species change temporarily. In this study, we evaluated the influence of an altitudinal gradient and seasonality on the composition, richness (S'), diversity (H'), and density of arthropod community associated with litter in a conserved Abies-Quercus forest in Central Mexico. We defined five altitudinal ranges in an altitudinal gradient that oscillated between 2570 and 2770 m, in which edaphic factors [pH, organic matter (OM), carbon (C), total nitrogen (N), total phosphorous (P), C/N, C/P, N/P ratios] and environmental temperature were characterized. Litter arthropods were collected through this vertical gradient in dry and rainy season. We identified 163 species belonging to 22 orders. Arthropods composition on each elevation zone is significantly different from one another in both seasons. The highest abundance and S values through altitudinal gradient were registered in the rainy season; in contrast, H' values were higher during the dry season. We detected a significant negative effect related to the altitude on S', H' and abundance of litter arthropods during the dry season and total data. An exception was the rainy season in which we did not detect any pattern. The community similarity reduces as altitude increases. Surprisingly, the intermediate altitudinal range showed the higher density values in the rainy season. On the other hand, OM, C/N and C/P ratios had a negative influence on litter community parameters analyzed in the rainy season and total data. In contrast, P shows a positive influence on S of litter arthropods in the same period. Edaphic characteristics recorded along the altitudinal gradient can explain differences in litter arthropod communities.