Agroforestry improves soil fauna abundance and composition in the Atlantic Forest of Paraguay

Abstract

AbstractEdaphic fauna is a major determinant of agricultural soil quality, but few studies have investigated soil fauna in different agroforestry systems. The objective of this study was to evaluate the effect of agroforestry plantations of Ilex paraguariensis on the abundance and composition of ants, earthworms, and nematodes in two agronomic systems, conventional and agroecological, and three plantation types (pathsides, agricultural field edges, and islets) in the Atlantic Forest in Paraguay. The study was conducted on 26 plots distributed in the different agronomic systems and plantation types (three plots per combination of agronomic system and plantation type, with a total of 18 plots, plus eight control plots). We compared agroforestry plots with non-agroforestry plots and with natural forests. Eighteen individuals of different native species (Cordia americana, Cedrela fissilis, Handroanthus impetiginosus, Handroanthus albus, Peltophorum dubium, and Cordia trichotoma) were planted in each plot, together with five individuals of I. paraguariensis (total of 2300 individuals ha−1). The agroforestry scheme increased the abundance and improved the composition of beneficial soil fauna in the two agricultural systems. The agroecological system showed 238% higher abundance of ants and 90% higher abundance of earthworms than the conventional one. In both systems, the agroforestry scheme led to lower abundance of deleterious Atta sexden and Acromyrmex spp. leafcutter ants and higher abundance of beneficial species. The three plantation types increased the abundance of beneficial species. Agroforestry plots, particularly those in an agroecological system, were more similar to reference forest than to non-agroforestry plots. Our results suggest that the composition of soil fauna at the study site was significantly affected by the agroforestry scheme and, agronomic system, but not by plantation type. These results support the advantages of agroforestry and agroecological systems for favoring the diversity of soil fauna and related ecosystem services, which may help guide the design of successful agroforestry interventions.