RESUMO
The rapid and large-scale urbanization leads to drastic land-use conversion and impacts on ecosystem services. The relationship between urbanization and ecosystem services not only depends on the characteristics of the study area, but is closely related to the selected ecosystem services types and the indicators to measure urbanization level. Exploring the relationship in specific study area is necessary to support regional planning for sustainability. In this study, we analyzed the impacts of urbanization on ecosystem services from 2000 to 2010 in the Beijing-Tianjin-Hebei (BTH) urban megaregion in China. We quantified four critical ecosystem services, food production, carbon sequestration and oxygen production, water conservation, and soil retention, and identified the hotspots of ecosystem service provision. We measured the urbanization level from three aspects, namely, population growth, economic development and developed land expansion. The impacts of urbanization on the selected ecosystem services were examined at the hotspots scale and urban megaregion scale. We found both ecosystem services and urbanization level in the BTH region increased. There was an obvious spatial heterogeneity in the hotspots of ecosystem services, showing hotspots of food production aggregately distributed in the southern plain while hotspots of regulating services mainly located in the north mountainous areas with dense forest. The relationship between population growth, economic development and food production were represented by an inverse U-shaped curve, while it displayed a decreasing trend with regulating services. Both food production and regulating services decreased dramatically with urban land expansion. Additionally, the relationships between urbanization and ecosystem services were consistent across scales. Effective measures should be implemented for the hotspots of different types of ecosystem services to mitigate the loss of ecosystem services during rapid urbanization. The results can provide insights for enhancing urban sustainability in the BTH region, as well other urban megaregion with similar characteristics throughout the world.
RESUMO
This paper examines predictors of vegetative cover on private lands in Baltimore, Maryland. Using high-resolution spatial data, we generated two measures: "possible stewardship," which is the proportion of private land that does not have built structures on it and hence has the possibility of supporting vegetation, and "realized stewardship," which is the proportion of possible stewardship land upon which vegetation is growing. These measures were calculated at the parcel level and averaged by US Census block group. Realized stewardship was further defined by proportion of tree canopy and grass. Expenditures on yard supplies and services, available by block group, were used to help understand where vegetation condition appears to be the result of current activity, past legacies, or abandonment. PRIZM market segmentation data were tested as categorical predictors of possible and realized stewardship and yard expenditures. PRIZM segmentations are hierarchically clustered into 5, 15, and 62 categories, which correspond to population density, social stratification (income and education), and lifestyle clusters, respectively. We found that PRIZM 15 best predicted variation in possible stewardship and PRIZM 62 best predicted variation in realized stewardship. These results were further analyzed by regressing each dependent variable against a set of continuous variables reflective of each of the three PRIZM groupings. Housing age, vacancy, and population density were found to be critical determinants of both stewardship metrics. A number of lifestyle factors, such as average family size, marriage rates, and percentage of single-family detached homes, were strongly related to realized stewardship. The percentage of African Americans by block group was positively related to realized stewardship but negatively related to yard expenditures.