Avaliação das infraestruturas verdes buscando a valoração dos serviços ecossistêmicos na Bacia Hidrográfica Urbana do Arroio Preto, município de Santa Cruz do Sul, RS, Brasil.

Abstract

Urban centers have become the most familiar environment for human population, which affected the way we understand, we connect, and we use natural resources. The cities, unlike natural ecosystems, have a strong relationship between built-up and green areas, where the proportion and quality of each part of the matrix will determine the functions and the total environment quality. Continuous monitoring of green areas in cities can provide accurate information on urban forest structure and ecosystem services, which are changing over time, and indicates priority conservation actions, management and implementation of new areas for promoting quality of the urban environment. In this way, this research aimed at evaluating the magnitude and quality of urban green infrastructures in the Preto Stream Urban Watershed, Santa Cruz do Sul County, RS, Brazil. For data collection, we used combined analysis with field survey and computational resources. The urban afforestation inventory demonstrated the predominance of exotic species such as Lagerstroemia indica L., in addition to the strong presence of invasive exotic species such as Hovenia dulcis Thunberg and Ligustro lucidum W.T.Ait., representing a great risk to natural forest remnants. Still, it was possible to identify several vegetation conflicts with other urban structures, important factors to be consider that may affect the green areas sustainability, reducing canopy coverage rates as well as the future provision of ecosystem services, increasingly needed in urban centers. The aerial survey demonstrated the remarkable presence of vegetation in the Preto Stream Basin, allowing an estimation of the ecosystem services provided by the basin. However, in the urban perimeter the canopy cover values were significantly reduced. We developed a low-cost methodology, with significant potential to describe the current state of urban forest, as well as to monitor future changes in canopy cover in urban watersheds, and small and medium-sized developing cities.