Wednesday, August 4, 2010

PS 64-166: A spatially explicit analysis of net primary production in urban ecosystems

Kevin Bigsby, North Carolina State University, J. Morgan Grove, U.S. Forest Service, and Melissa R. McHale, North Carolina State University.

Background/Question/Methods

Urban areas are distinct ecosystems that include interactions among biophysical processes and the actions of individuals and institutions, typically altering ecosystem structure and function. Development patters can have a large influence on carbon storage capacity, as well as, the ability of urban systems to offset some of their CO2 emissions through carbon sequestration. We explore the spatial patterns of carbon storage and net primary productivity in Raleigh, North Carolina. Specifically, we evaluate the relationships between carbon dynamics, socio-economic status, lifestyle indicators, and land cover patterns across the region. We scaled plot level vegetation data, analyzed with the Urban Forest Effects model, to a land cover classification to create a spatially explicit representation of net primary production and carbon storage in vegetation. The net primary production and carbon storage values were then aggregated to the census tract to correspond with the resolution of the independent variables. MANOVA was used to examine how the pattern of net primary production is related to socio-economic variables (e.g., household income, house age, ethnicity, education, etc.), lifestyle indicators (PRIZM market segments), and biophysical variables (e.g., elevation, aspect, rainfall, etc.) and determine the drivers of net primary production in the region.

Results/Conclusions

Consistent with studies in other cities, like Baltimore and Phoenix, our results suggest higher socio-economic status is associated with higher tree cover. We successfully created a spatially explicit representation of carbon storage for the entire study area by relating plot level data on carbon storage and net primary production to our land cover analysis. The relationship between carbon storage and net primary production was also positively related with higher socio-economic status. Future work should be dedicated to evaluating the method linking the Urban Forests Effects model with land cover, as well as alternative methods like INVEST, in cities of various sizes and in different biomes. Also in other biomes, additional test must be done to examine the relationship between net primary production and carbon storage and socio-economic variables. The results of these studies can be used to influence planning dedicated to sustainable development patterns and targeting education and awareness in existing developments. Furthermore, our results are important for understanding the effects of cities on the carbon cycle and will allow us to begin comparing urban areas as ecosystems.