Recognition of urban green space ecosystem services for adaptation to extreme climate events. Methodological Validation

Abstract

Objective: This study evaluated the ecosystem services of water regulation (EvapoTranspiration, ET) and Forest Carbon Stock (ECF) in the urban area of Campo Grande based on mapping and random sampling stratification of diameters at breast height (DBH or simply d) per unit area in five types of Urban Green Spaces (EVU). Methodology: The evaluation of ecosystem services for water regulation ET and ECF in the urban area of Campo Grande was based on mapping and random sampling stratification of diameters at breast height (DBH or simply d) per unit area in five EVU typologies. By integrating d data - its distribution follows a Power Law - with the ecohydrological concepts and the Ecological Metabolic Theory (EMT), the medians and interquartile ranges for ET and ECF of the identified EVU typologies were then calculated. Originality/Relevance: Despite the importance of ecosystem services in cities, few studies show methodologies to evaluate and quantify them. The present study brings an unprecedented approach to estimate ECF and ET in EVU with typical cerrado tree vegetation. The methodology is used to prospect the impact of the increase in EVU area and its ecosystem services (ECF and ET) on Carbon (C) capture and the water and thermal regulation. Therefore, the methodology aims on the security of urban citizens from tropical regions against future scenarios of extreme (episodic) flood and wave events or (persistent) heat islands. Results: The mapping of EVU and their respective ecosystem services in Campo Grande showed the deficiency of these environments in certain parts of the city. Currently, the EVU areas in Campo Grande sum up to 898 hectares (2.5% of the urban area in 2010), which store between 33,368.5 and 456,801.7 tons of C in the form of forest biomass and they are responsible for daily atmospheric humidification on a scale of 31,458.0 to 105,277.3 m3 of water. The study also reveals that ecosystem regulation services such as ecohydrological concepts like Forest Carbon Stock (ECF) and Evapotranspiration (ET) in the urban area can be estimated by integrating DBH data (d). The results suggest that the scaling of EVU from 2.5 to 10% of the urban area in Campo Grande may have important consequences for the adaptation of future urban generations and for the mitigation of climate change. Theoretical/methodological contributions: Statistical analyzes show that the values obtained with the field survey can be modeled by the distributions of power law through the Ecological Metabolic Theory (TME). It was found that the TME has great application potential, but also limitations, as it allows evaluating flows and stocks in a system only for intervals (interquartiles) that contain the average of the distribution. The use of the interquartile to evaluate natural processes with a power law distribution guarantees a reliable margin of uncertainty, which can be scaled independently of the woody species and its successional stage, seasonality and environment. Social / management contributions: The results show the importance of increasing these spaces to maximize the realization of ecosystem services for atmospheric C capture, as well as for adapting urban areas to face extreme floods, heat waves and for the prevention of urban heat islands (IUC). In addition, future studies should be conducted for the geolocation of new EVU that maximize ecosystem services, which also incorporate sociocultural aspects.