Urban agriculture as a biodiversity conservation environment for edaphic fauna in the West Zone of the municipality of Rio de Janeiro, Brazil

Abstract

Agroecological urban agriculture areas are remnants of biodiversity and provide ecosystem services for urbanized areas, as well as being important alternatives for food security and income generation. The aim of this work was to assess the capacity of these areas to shelter soil fauna, contributing to their conservation in the urban environment. It also aimed to assess which soil attributes and landscape features most interfere with the occurrence and abundance of these soil invertebrates. Fifteen areas were selected in the neighborhoods of Campo Grande and Vargem Grande, in the West Zone of the municipality of Rio de Janeiro, making up a gradient of different plantations and forest areas. In each area, a transect was established with three sampling points 5 m apart, where the soil mesofauna was sampled with a specific auger, collecting litter and soil up to 10 cm. Earthworms were sampled using the TSBF method at a depth of 0–10 cm. Soil samples were collected at each fauna sampling point, at the same depth, for routine analysis of soil fertility and texture. The data was analyzed using multivariate techniques, first using principal component analysis (PCA) to select soil attributes representing the local scale of influence and percentages of landscape features. The percentages of landscape features were measured using two buffers around the sampling area, 500 m and 250 m. A multidimensional scaling (NMDS) analysis was carried out to select the fauna groups with the greatest representativeness and degree of response to environmental factors. Environmental factors at the local scale and at the 500 m and 250 m scales were determined using generalized linear model (GLM) analysis, through which it was possible to select models composed of variables that determine the occurrence and density of the different groups of fauna selected. The most abundant groups were Acari, Collembola Entomobryomorpha, and Formicidae. In the crop areas, Acari was dominant, while in the forest area used as a reference Entomobryomorpha was more abundant. On a local scale, pH was the most common factor in the models, often with a negative sign, showing an inverse relationship between the pH value and the density of the fauna group. This result suggests that pH is a good indicator for correlations with soil mesofauna and earthworms. The 250 m models were able to select groups with a greater affinity for crops and highly anthropized areas. In conclusion, it was observed that these areas are capable of maintaining an abundant and diverse community of soil fauna.