Edaphic 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.

The establishment of planted trees and the natural regeneration of trees in agroecosystems is challenging. This study evaluated the establishment and natural regeneration of the following six native tree species in two agricultural systems in the Atlantic Forest in Paraguay: Cedrela fissilis Vell., Cordia trichotoma (Vell) Arráb. ex Steud., Handroanthus albus (Cham.) Mattos, Handroanthus impetiginosus (Mart. ex DC.) Mattos, Peltophorum dubium (Sprengel) Taubert, and Cordia americana (L.) Gottschling and J.S.Mill. At the study site in Caaguazú, 18 plots of 100 m2 each were established in 2 agronomic systems (conventional or agroecological) featuring 3 plantation types (pathsides, agricultural field edges, and islets). Trees were planted at this site in spring 2010 at a density of 1800 individuals ha−1, and the site was monitored for six years. At the study site in Itapúa, 30 plots of 50 m2 each were established in three agronomic systems (conventional, traditional, or agroecological). Trees were planted at this site in spring 2012 at a density of 1600 individuals ha−1, and the site was monitored for four years. Survival and relative growth rates of the planted species and natural regeneration were analyzed using generalized linear mixed models that considered species, agronomic system, and plantation type as fixed factors, and time and plot as random factors. At both sites, survival varied among species. Here, C. fissilis showed lower survival and C. trichotoma higher growth than the other species. Naturally regenerated species were C. trichotoma, H. albus, and P. dubium. The agronomic system and species affected growth and natural regeneration at both locations. Plantation type affected survival and growth in Caaguazú only. We conclude that species contributes more than agronomic system or plantation type to determining the survival, relative growth rate, and natural regeneration in agroforestry systems in the Paraguayan Atlantic Forest.

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