Ecology and Society (Jun 2014)
Green area loss in San Juan's inner-ring suburban neighborhoods: a multidisciplinary approach to analyzing green/gray area dynamics
Abstract
The loss of green areas and vegetation in suburban neighborhoods poses short- and long-term consequences associated with environmental changes and socioeconomic decline that can propel such developments to an unsustainable state. We summarize an interdisciplinary investigation aimed at identifying the drivers of green area loss, green cover loss, and quantifying the impact on three inner-ring suburban neighborhoods located along the Rio Piedras watershed in San Juan, Puerto Rico. An inductive approach to social-ecological research was undertaken because it provides a flexible platform for interdisciplinary collaboration on this complex and dynamic subject. The three developments selected for the study were constructed in the mid-20th century under paradigms of modernity that included providing conditions for a better and more dignified way of living, among which green areas played a central role. The green area change analysis was undertaken first, by way of using building footprint growth as a proxy, which represents a minimal estimate of change, and transferring the information from aerial photographs, original development plans, construction drawings, and GIS maps to AutoCAD to quantify building footprint change for each neighborhood. The period of analysis started from the time of the construction of each development to the year 2010. The second estimation was performed using orthorectified infrared aerial imagery to quantify green cover in year 2008 and contrast that information with the conditions at the time the developments were constructed. Green-gray area dynamics were thus analyzed together with longitudinal socioeconomic data to help in the assessment of effects. The investigation revealed long-term socioeconomic declining trends in two of the neighborhoods, weak governance of the built environment, substantial increase in automobile ownership, and distinct physical-spatial characteristics as drivers behind the changes observed. The complexity and variety of exogenous and endogenous factors that have been identified in this study as affecting private and public inner-ring suburban green areas reveals dynamic and spatially differentiated concomitant processes and suggests that these are conditioned by the socioeconomic trajectories of each neighborhood and by larger metropolitan scale socioeconomic and technological trends. Lower income neighborhoods reflect a tendency for socioeconomic decline and greater loss of green areas and vegetation cover in time, thus suggesting policies geared toward adaptive governance. In contrast, the upper income neighborhood exhibits a more stable socioeconomic trajectory and less significant green area loss as well as increase in vegetation cover. Three hypotheses are posited for future sampling increments and testing. The findings and literature on urban economics and the decline of inner-ring suburbs in the U.S. suggest the need for policy geared to sustainable urban redevelopment as a strategy for adaptive governance. The competing needs for land by higher density uses and by green areas in sustainable redevelopment initiatives requires a trade-off analysis in which a thorough account of costs and benefits is warranted. As such, sound data as that presented in this paper will aid urban ecological design in the process of achieving sustainable and environmentally sound land-use adaptations that seek to recuperate green areas' environmental services in urban and suburban contexts.
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