Ecological indexes of arthropods on Sapindus saponaria (Sapindaceae) plants fertilized with urban dehydrated sewage sludge

The agricultural sector causes negative impacts, such as soil degradation and land abandonment, which must be addressed and recovered. Conservation programs typically focus on vulnerable animal species, neglecting arthropods such as insects and spiders, and their roles in the ecosystems. The objective was to evaluate the number of leaves per branch, branches per plant, ground cover, and the ecological indices of arthropods of Sapindus saponaria plants, a native plant of the Americas, with or without application of dehydrated sewage sludge. The hypothesis is that sewage sludge increases leaf production and ground cover by this plant, as well as the abundance, richness, and diversity of arthropods. The trial was carried out in a degraded area in Montes Claros, Minas Gerais state, Brazil. Sapindus saponaria plants were grown fertilized (T1) or not fertilized (T2) with urban dehydrated sewage sludge. The numbers of leaves and branches, ground cover, and arthropod population were assessed over 24 months. The numbers of leaves per branch, branches per plant, ground cover, and abundance and diversity of arthropods, including predators and chewing insects, were higher on plants fertilized with sewage sludge. The development of S. saponaria and the abundance and diversity of arthropods were greater with the application of dehydrated sewage sludge. The use of this compost material can enhance the benefits for this plant and its ecological interactions in ecosystems during the recovery of degraded areas. This increases the importance of using urban wastes in the restoration of degraded areas with biodiversity conservation and ecosystem restoration.