Análise e valoração da disponibilidade de bens e serviços ecossistêmicos em uma microbacia hidrográfica predominantemente urbanizada, Paraiba, Brasil.

Abstract

Urbanisation has been a main cause of land use land cover (LULC) change worldwide, often with irreparable consequences to the provision of goods and ecosystem services that are fundamental to human physical, mental and spiritual well-being, as well as to the maintenance of life on the planet. This research analyzes the goods and ecosystem services availability change as a function of LULC, in the period of 1989, 2007 and 2014; and the social valuation of ecosystem benefits provided by a predominantly urbanised microwatershed, located in the Agreste ecotone (transition area between Atlantic Forest and Caatinga biomes), in Northeast Brazil. Remote sensing techniques and geographic information system were used to quantify LULC changes in Riacho das Piabas microwatershed, Paraíba. The benefit transfer method was applied to quantify changes in the ecosystem goods and services supply between the years analyzed. The stakeholders perception (community, technical and expert) about the environments that offer ecosystem goods and services in the study area and their respective importance levels were obtained through participatory mapping. Replacement of tree vegetation area (46% of the study area in 1989 and 5% in 2014) by the built environment was the key factor driving the 73% decline in the ecosystem goods and services availability between 1989 and 2014. Urban sprawl resulted losses of 89% in the eight ecosystem services supply, including climate regulation, water flow regulation, moderation of disturbance, nutrient cycling and biological control, which are critical locally when considering the regional trend towards aridification and the existing pressures on water resources. There was a significant difference between the stakeholders perception about the mapped areas number per ecosystem goods and services section available by the study area to the population (Factorial Anova, F = 21.62, p <0.001). The community perception about the benefits offered by the studied microwatershed distinguished from technicians and experts. The environments that most offered ecosystem goods and services were transitional areas between the between freshwater and terrestrial environments; and green spaces. The service maintenance of hydrological cycle and water flux presented very high average importance level. Management that wishes to reduce the urbanisation impacts on the provision of ecosystem goods and services should consider implementation of ecosystem-based spatial planning, focusing on urban green infrastructure and natural habitats restoration and their connectivity. In addition, it is fundamental to approach the stakeholders perception in the planning process and decision making to minimize and manage potential social conflicts.