Intensificação ecológica: serviços ecossistêmicos e manejo da comunidade de plantas espontâneas em paisagens agrícolas

Abstract

Biodiversity present in agroecosystems can provide a complex ecological web that supports food production, in addition to curbing impacts generated by agricultural intensification. Effective management of spontaneous vegetation is a particularly important hindrance, as these can cause crop yield losses, although they can provide and amplify many ecosystem services by spillover. However, the development and adequacy of control techniques for competing species is an increasing agenda in order to reduce production costs with weeding as well as to increase environmental quality in agricultural systems. The aim of the present study was to understand, in a multiscale assessment, whether and how different parameters of the agricultural landscape and the intensity of cultivation have effects on the floristic and functional composition of the spontaneous community when associated to different types of management of weed, being: selective, conventional, living cover with Diodia saponariifolia + selective weeding and absence of weeding. For that, an experiment was carried out in 8 productive units in the São José da Boa Morte settlement, Cachoeiras de Macacu/RJ/Brazil, 4 of which were immersed in a landscape with high forest density and 4 in a simplified landscape. The spatial arrangement of the production unit includes the following scales: tillage (0.5 ha), farm (4.0 ha) and landscape (95 ha), each of which is characterized for its cultivation intensity and landscape metrics. A phytosociological survey and generation of diversity indexes were carried out to evaluate the effects of the different treatments on the community of spontaneous, as well as the influence of the living cover associated to selective weeding on the decrease of the biomass of cyperaceae and poaceae. Through a bibliographical survey, the species were grouped regarding functional aspects related to the provision of ecosystem services. Generalized linear models (GLMs) were used to select the variables with the greatest effect on the influence of the different landscape scales on the richness and abundance of the functionally grouped species. Our analyzes showed that the living cover by D. saponariifolia associated with selective weeding (LC + SW), as well as selective weeding (SW) alone, promoted the increase in diversity and equitability among the species of the spontaneous community over four months. LC + SW responded positively in reducing the biomass of cyperaceae and not enough for poaceae. Conventional weeding (CW) was detrimental in all evaluated parameters, responding positively to the increase in dominance. The richness of species providing ecosystem functions is mainly determined by the use of the soil in the scale of the productive unit, being positively influenced by the natural arboreal element in the form of forests, live fences and woods close to the agroecosystems, and negatively by the exotic arboreal element in the landscape scale; The abundance of these species is also determined by the intensity of land use on the scale of the farm and by the presence of nearby natural phytophysiognomies