For the first time in human history, more than 50 percent of the world's population resides in urban centers. By the year 2015, this fraction is expected to rise by more than 10 percent. The increasing expansion of urban centers is significantly impacting ecosystem services and the human communities dependent on these services, not least because the biogeophysical environments of urban regions and their surrounds are substantially different from those of rural areas. The effects of this difference can be seen in modified water cycles and climates within urban centers and exurban areas, amended urban soil properties and ecosystem species, and polluted urban airways and waterways. In many cases, degraded urban biogeophysical environments also are contributing to severe health problems among urban populations. Concern about the major ecological impact of urbanization has prompted the development of numerous strategies for improving ecological services within cities, many of which are focused on the preservation and/or recreation of natural landscape features. One strategy that is gaining rapid attention in the U.S. is the concept of an urban Green Area Factor (GAF) program. The goal of a GAF program is to provide a cost-effective, decentralized approach to the restoration or expansion of ecosystem services in urban environments, by setting targets for the percentage of "greening" to occur in the development of different parcels of urban land. The use of the GAF as an urban planning tool has multiple potential benefits from the perspectives of improving urban ecology and health, improving the aesthetics and habitability of urban environments, and engaging urban stakeholders in strategies for sustainable development. But despite its potential, scientific linkages between GAF guidelines and ecological outcomes remain nascent. Furthermore, information about U.S. public willingness to provide support and stewardship for various GAF strategies is limited. The goal of this research project is to conduct interdisciplinary research on the dynamic interactions between people, natural ecosystems, and green technologies in the dense urban environment of New York City. The investigators will build on their own prior research as well as partnerships with diverse local community groups and practitioners to monitor and quantify the ecological and public health benefits of natural ecosystems and evolving green technology interventions in three New York City neighborhoods; to establish the acceptance and value of such systems and interventions to stakeholders; and to develop a GAF-based tool that might work as a common planning platform for urban stakeholders interested in optimizing the ecological and public benefits associated with different urban greening strategies.
This project will help provide the underlying scientific basis to advance and refine the GAF concept in order to more effectively take account of human interactions with urban greening strategies, including environmental justice communities. Optimally, it could be applied to dense and diverse urban environments such as the mega-city of New York. As well as advancing scientific knowledge, the project will deliver a new planning tool that can provide a common platform for different New York City stakeholders to explore various greening strategies in the context of their different missions and goals. The project also will build a team of scientists, community organizations, and practitioners who can work together to create new knowledge on urban ecosystem sustainability and functionality. Research training will be provided to post-doctoral scholars, graduate students, and undergraduate students, and educational, outreach, and teaching activities will form major components of the project. This award was funded as an Urban Long-Term Research Area Exploratory (ULTRA-Ex) award as the result of a special competition jointly supported by the National Science Foundation and the U.S. Department of Agriculture Forest Service.
The major goals of this UltraEx project were to: 1) gain a better understand of the ecosystem services in a dense urban environment, with a focus on New York City (NYC), 2) gain a better understanding of the links between the urban environment and these ecosystem services, 3) establish the acceptance and value of urban greening efforts/ interventions to NYC stakeholders, 4) examine how different urban stakeholders perceive, value and interact with the local urban ecosystems within their neighborhoods and the greater city and 5) compare perceptions to calculated environmental benefits of urban greening interventions. To meet goals 1) and 2) we completed a study of foliar Nitrogen characteristics of several common northeastern deciduous tree species planted in four New York City afforestation sites as well as at the Black Rock Forest a rural oak-dominated forest in the Hudson Highlands of New York. To meet goals 3), 4) and 5) we focused on studying 35 urban gardens in East Harlem (a predominately low income community of color) because they are an example of an urban greening effort with a large stakeholder component, which create significant opportunities for understanding the intersection of social and environmental benefits. For our tree study we found that foliage sampled at Black Rock Forest (BRF) was consistently depleted in 15N compared to urban foliage, and Amelanchier canadensis, Nyssa sylvatica, Prunus serotina, and Quercus rubra showed significant variation in foliar nitrogen isotope signatures (δ15N) among the four urban sites. Our isotopic and %N data suggest greater N availability but less available nitrate at the newly planted urban sites compared to BRF, possibly due to different anthropogenic inputs or higher rates of nitrification and nitrate leaching at the recently planted urban sites compared to likely lower rates of N cycling in the intact rural forest. In addition, the tree species varied in their response to N availability at the urban sites, with potential implications for growth and survival. For our urban garden student we found that the gardens provide a wide variety of benefits to the residents of East Harlem including 5,007 square meters of permeable surface, 2,774 meters of planting surface, 18 structures, 759 places to sit, and 15 pieces of art. Some gardens are primarily the domain of one or two individuals, while others boast memberships of 20-60 people. Additionally, some gardens are heavily focused on planting and interactions with nature while others are primarily social spaces. For our analysis of the stormwater benefits of the gardens we used the rational method to find that approximately 72 meters cubed (1/5 the size of a standard swimming pool) of runoff is avoided during a standard storm due to the existence of the gardens. For the temperature analysis, we have found that pairs of gardens display a 1-2 degree difference in temperature, which we are currently correlating to garden shade. The analysis of our social survey results for the gardens indicate that food growing opportunities and access to nature in the community gardens provide meaningful benefits to garden members, but that the unique social and organizational opportunities in the gardens may be among their most valued components, especially when garden members are included in internal and external decision making processes. These findings support, and will add to, existing literature on community gardens, place attachment, and urban green infrastructure. Overall, the project highlighted differences between urban and non-urban ecosystem services, as well as the complex value systems urban stakeholders place on such services. As more U.S. cities adopt greening strategies to combat the negative impacts of stormwater runoff and urban islands, among other pressing problems, there is increasing necessity to understand the environmental and social value of such strategies in order to develop sustainable pathways forward. This work has laid the foundation for such understanding, as well as advanced environmental measurement and social analysis methods that could be used in the development of a wider urban ecological observatory system. In addition the work has provided information to residents of East Harlem on the ecological benefits of urban green spaces as well as interdisciplinary training at the intersection of social and environmental sciences, with a focus on the emerging field of sustainability science, to all project participants.
