توزیع نابرابر فضاهای سبز شهری
Abstract
Introduction
Methods
Results
Discussion
References
Abstract
Extent and distribution of urban green spaces (UGS) in Mazatlan (Mexico) are analysed using remote sensing and GIS techniques. Vegetated areas (2,270 ha), a third of the urban area in 2015, were reclassified into green spaces (GS), urban tree (UT) and open spaces (OS), based in the normalised difference vegetation index, relating them with demographic and socioeconomic data. UGS allocation per capita amount 55 m2, mainly represented by the UT class, with the largest patches associated with low developed and very high marginalised areas, and also with very low marginalised sectors, while the lowest allocation correspond to medium and low marginalisation, highly populated sector, without significant correlations. Despite the USG allocation, it is required a better urban planning to maintain public UGS and to protect the local flora, threatened by the introduction of exotic, ornamental species (64% of UT), to guarantee the provision of ecosystem services to the population.
Introduction
Current trends in human population suggest that more than a half of the world’s population is living in urban areas, and probably this figure will rise up to two thirds of the population to the year 2050 (United Nations 2014). The American continent and Europe are clearly the most urbanised regions, with >70% of the population living in cities smaller than 500,000, but also in megacities with more than 10 million people (United Nations 2014). On the other hand, Africa and Asia, remain basically as rural regions, but at the same time embracing the most populated cities in the world, displaying some of the highest urban growing rates in the recent years (Seto et al. 2011). Cities and their regions are hubs for people, infrastructure and commerce, requiring extensive resources and putting intense pressure on the environment. The environmental impacts include the loss of biodiversity, air and water pollution, noise increasing, higher greenhouse gases (GHG) emissions and increasing runoff and flood potential (Wilson et al. 2003; Grimm et al. 2008; Poelmans and Van Rompaey 2009; Atu, Ayama, and Eja 2013; Derkzen, Teeffelen, and Verburg 2015). As the urban demographic growth demands resources and services, alterations in the availability and quality of natural resources occur, invading fertile soils, reducing biodiversity, modifying biogeochemical processes and the local climate, sometimes permanently (Ruiz-Luna and Berlanga-Robles 2003; Grimm et al. 2008).