Soil–Arthropod Interactions Across Forest Types in a Mediterranean Mountain Landscape

Abstract

Simple Summary Arthropods living and moving on the soil surface contribute to important forest processes, including decomposition, nutrient recycling, and the regulation of other invertebrates. We studied these organisms in holm oak, Pyrenean oak, and maritime pine forests in Montesinho Natural Park, northeastern Portugal. Arthropods were collected during summer, autumn, winter, and spring, and several soil characteristics were measured at the same sampling points. Arthropod abundance was lowest in winter and highest in spring, although seasonal changes were not the same in the three forests. The taxa contributing to ecological groups such as predators and omnivores also changed among seasons and forests. Soil gradients related to texture, acidity, organic matter, roots, nitrogen, and potassium were associated with arthropod abundance and community composition. Ants showed particularly strong seasonal and soil associations, while predator taxa changed markedly among seasons and forests. Bark beetles accounted for the spring increase in plant-feeding arthropods in the pine forest, and flies and mites made a major contribution to overall abundance. These findings identify several informative groups for future monitoring and improve our understanding of how forest arthropod communities vary throughout the year and in relation to soil conditions in Mediterranean mountain landscapes.