Source: NORTHEASTERN RESEARCH STATION submitted to NRP
ASSESS HOW URBANIZATION IS AFFECTING THE STRUCTURE, FUNCTION, AND HEALTH OF FORESTS WITHIN AND AROUND URBAN AREAS
Sponsoring Institution
Forest Service/USDA
Project Status
COMPLETE
Funding Source
USDA INHOUSE
Reporting Frequency
Annual
Accession No.
0197445
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Jan 20, 2000
Project End Date
Jan 20, 2005
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
NORTHEASTERN RESEARCH STATION
11 CAMPUS DRIVE
NEWTOWN SQUARE,PA 19073
Performing Department
URBAN FORESTRY LAB - SYRACUSE, NY
Non Technical Summary
(N/A)
Animal Health Component
30%
Research Effort Categories
Basic
70%
Applied
30%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1240699106030%
1240699107070%
Knowledge Area
124 - Urban Forestry;

Subject Of Investigation
0699 - Trees, forests, and forest products, general;

Field Of Science
1060 - Biology (whole systems); 1070 - Ecology;
Goals / Objectives
The process of urbanization alters the physical landscape (e.g., altering of soils and vegetation structure, changes in micro and meso-climates, introduction of exotic vegetation and pest species, etc.) and creates many byproducts that alter the chemical landscape (e.g., air pollution, excess nitrogen deposition, water pollution). The byproducts of human activity affect the health and structure of urban trees, natural forest stands, and urban streams. By understanding what type of alterations occur due to urbanization and the impact of these alterations on forest structure and health, management plans can be developed to minimize adverse impacts of urbanization. Objectives of this research include: quantify the short and long-term effects of human activity on soil properties and processes located in urban and urbanizing landscapes; determine the human-induced multiple stress effects on the dynamics of carbon (C), nitrogen (N), and vegetation in forest patches embedded within urban and urbanizing landscapes; assess the effects of social patterns and processes on ecological patterns and processes within urban and urbanizing landscapes; quantify the impact of various degrees of urbanization on stream organism productivity and health and water quantity/quality.
Project Methods
The basic approach to solving this problem involves the establishment of field studies. There are unique aspects to this research due to the complexities of conducting research in urban areas. Elements of this approach include: evaluate the relationships between soil characteristics and social indices, vegetation structure, and management practices; develop an urban soil classification system that includes a classification for disturbed soil types; develop a new conceptual model of soil genesis that incorporates human modifications of soil; determine new soil hydrologic and soils runoff parameters for urban watershed modes that include hydrophobic soil surfaces; compare forest soil chemical and physical properties, organisms, and carbon and nitrogen dynamics between urban-to-rural gradients in New York City and Baltimore; investigate the mechanisms responsible for increased rates of nitrification in urban forest soils (the approach will use a series of microcosm and field experiments that control suspected casual factors including earthworms, high N deposition, input of poor quality organic matter, relatively high soil N:P ratios, and reduced immobilization of ammonium due to heavy metals); analyze how landscape patterns of tree-covered patches, riparian habitat and upland forests vary spatially and temporally along an urban-to-rural gradient; analyze how patterns of physical structure and species composition within tree-covered patches, riparian habitat and upland forests vary along an urban-to-rural gradient; develop methodologies to analyze the patterns of spatial heterogeneity (i.e., the mix of different land uses and cover) across urban and urbanizing landscapes; measure the impact of storm water runoff and varying degrees of urban land cover in Baltimore on stream macro invertebrates and plant organisms (this work will focus on monitoring stream plant and animal populations along with stream conditions such as water temperature, stream flow and volume, sediment loads, toxins, dissolved oxygen, and community production to respiration ratios as they differ along an urban-to-rural stream gradient); and quantify the impact of urban tree cover on stream flow, surface runoff, and contaminants reaching the stream.

Progress 01/20/00 to 01/20/05

Outputs
Research has provided a better understanding of how urban ecosystems affect water quality, particularly in terms of bacterial infestation and salinization of streams. Surveys of the presence of E. coli, a diarrheal disease among infants and children, in stream water in the Baltimore area indicate that E. coli are continually deposited into a variety of stream habitats and suggest that this organism may be a permanent member of the gastrointestinal microflora of humans and animals in the Baltimore metropolitan area. Other fresh water stream analyses reveal chloride concentration of up to 25% of the concentration of seawater during the winter months with chloride concentrations increasing as a function of impervious surface cover (deicing salts). If salinization were to continue at its present rate due to changes in impervious surface cover, many waters in the Northeastern United States would not be potable for human consumption and would be come toxic to freshwater life within the next century.

Impacts
Findings from the research have significant implications for human health and water quality in and around urban areas. The research on salinity could significantly impact future management practices and is of concern to a large portion of the U.S.

Publications

  • Taylorson, A.; Belt, K.T.; Pouyat, R.V.; Stack, W.P.; Cherigo, M.; Schindler, D.; Zhou, J. 2005. Monitoring the subterranean urban realm: watershed 263 storm water sampling and flow measurement. In: Proceedings 2005 Mid-Atlantic Ecological Society of America conference; 2005 March 12-13; Baltimore, MD. Washington, DC: Ecological Society of America. Abstract.
  • Yesilonis, I.; Pouyat, R.; Szlavecz, K.; Russell-Anelli, J. 2005. A comparison of soil chemical characteristics: urban and rural gradients of Baltimore and New York and cities of Baltimore and Budapest. In: Proceedings 2005 Mid-Atlantic Ecological Society of America Conference; 2005 March 12-13; Baltimore, MD. Washington, DC: Ecological Society of America. Abstract.
  • Kaushal, S.S.; Groffman, P.M.; Likens, G.E.; Belt, K.T.; Stack, W.P.; Kelly, V.R.; Band L.E.; Fisher, G.T. 2005. Increased salinization of fresh water in the northeastern United States. Proceedings of the National Academy of Sciences. 102(38): 13517-13520.
  • Szlavecz, K.; Pouyat, R.P.; Yesilonis, I.; Groffman, P.; Holifield, Q. 2005. The suburban landscape: patterns and processes in the soil. In: Proceedings 2005 Mid-Atlantic Ecological Society of America conference; 2005 March 12-13; Baltimore, MD. Washington, DC: Ecological Society of America. Abstract.
  • Higgins, J. A.; Belt, K. T.; Karns, J. S.; Russell-Anelli, J.; Shelton, D.R. 2005. Tir- and Stx-positive Escherichia coli in stream waters in a metropolitan area. Applied and Environmental Microbiology. 71(5): 2511-2519.
  • Holifield, Q.; Hom J. L.; Patterson, M. 2005. Soil respiration contribution to urban carbon dynamics at Cub Hill in response to global change. In: Proceedings 2005 Mid-Atlantic Ecological Society of America conference; 2005 March 12-13; Baltimore, MD. Washington, DC : Ecological Society of America. Abstract.
  • Hom, J. L.; Patterson M.; Grimmond, S.; Crawford, B.; Holifield, Q.; Yesilonis, I.; Golub, D.; Offerle, B.; Nowak, D.; Heisler, G.; Pouyat, R.; Zipperer, W. 2005. Studies on carbon dioxide concentration and carbon flux in a forested region in suburban Baltimore. In: Proceedings, 3rd USDA Symposium on greenhouse gases and carbon sequestration in agriculture and forestry; 2005 March 21-24; Baltimore, MD: Manhattan, KS: Soil Carbon Center, Kansas State University. 120. Abstract.
  • Belt, K.T.; Readel, K.; Higgins, J.; Groffman, P. 2004. E. coli in urban streams: season, landuse, and hydrologic drivers. In: Maryland Water Monitoring Council 10th annual conference; 2004 November 18; Linthicum, MD. [Place of publication unknown]: Maryland Department of Natural Resources, Maryland Coastal Zone Management Program: 18. Abstract.
  • Belt, K.T.; Pouyat, R.V.; Heisler, G.; Taylorson, A.; Stubbs, J.; Smith, B.. 2004. Thermal fluxes and impacts in small urban headwater catchments: a question of special and temporal scales. In: 2004 Baltimore Ecosystem Study (BES) annual meeting; 2004 October 23; Baltimore, MD. Millbrook, NY: Institute of Ecosystem Studies. Abstract. http://www.beslter.org/frame7-page_10.html
  • Belt, K.T.; Pouyat, R.V.; Stack, W.P.; Heisler, G.; Groffman, P.M.; Ghosh, U.; Taylorson, A.; Zhou, J. 2004. Watershed 263 small headwater storm drain catchment hydrology: preliminary water quality results. In: 2004 Baltimore Ecosystem Study (BES) annual meeting; 2004 October 23; Baltimore, MD. Millbrook, NY: Institute of Ecosystem Studies. Abstract. http://www.beslter.org/frame7-page_10.html
  • Belt, K.T.; Pouyat, R.V.; Stack, W.P.; Groffman, P.M.; Taylorson-Collins, A. 2005. The watershed 263 small headwater storm drains: restoration of an urban catchment's hydrology. In: Proceedings 2005 Mid-Atlantic Ecological Society of America conference; 2005 March 12-13; Baltimore, MD. [Place of publication unknown]: Ecological Society of America. Abstract.
  • Belt, K. T.; Pouyat, R. V.; Heisler, G.; Taylorson, A.; Stubbs, J.; Smith, B. 2005. Thermal fluxes and impacts in small urban headwater catchments: a question of spatial and temporal scales In: 2nd Maryland streams symposium; 2005 August 10-13; Westminister, MD. [Place of publication unknown]: Maryland Department of Natural Resources and Carroll Community College. Abstract. [CD-ROM].
  • Belt, K.T.; Pouyat, R. V.; Stack, W. P.; Heisler, G.; Groffman, P.M.; Ghosh, U.; Taylorson, A.; Zhou, J. 2005. Watershed 263 small headwater storm drain catchment hydrology: preliminary water quality results. In: 2nd Maryland streams symposium; 2005 August 10-13. Westminister, MD. [Place of publication unknown]: Maryland Department of Natural Resources and Carroll Community College. Abstract. [CD-ROM].
  • Chumble, P.; Zhao, J.; Pouyat, R.; Belt, K.; Ghosh, U. 2004. Use of caffeine to identify and quantify wastewater contamination in urban streams. In: Maryland Water Monitoring Council 10th annual conference; 2004 November 18; Linthicum, MD. [Place of publication unknown]: Maryland Department of Natural Resources, Maryland Coastal Zone Management Program: 20. Abstract.
  • Groffman, P.; Band, L. E.; Belt, K. T.; Fisher, G.T. 2004. Long-term stream data in BES. In: 2004 Baltimore Ecosystem Study (BES) annual meeting; 2004 October 23; Baltimore, MD. Millbrook, NY: Institute of Ecosystem Studies. Abstract. http://www.beslter.org/frame7-page_10.html
  • Heisler, G.; Walsh, J.; Fisher, G. 2005. Accessing long term ecological research program climate and hydrology data. In: Proceedings 2005 Mid-Atlantic Ecological Society of America conference; 2005 March 12-13; Baltimore, MD Washington, DC: Ecological Society of America. Abstract.
  • Higgins, J., Hohn, C., and K. Belt. 2004. Profiling bacterial populations in BES streams with DNA sequencing. In: 2004 Baltimore Ecosystem Study (BES) annual meeting; 2004 October 23; Baltimore, MD. Millbrook, NY: Institute of Ecosystem Studies. Abstract. http://www.beslter.org/frame7-page_10.html.


Progress 10/01/03 to 09/30/04

Outputs
Progress in the element has been in the areas related to water quality and urban soils. With regards to water quality, investigations involving numerous field measurements have revealed that urban and suburban watersheds have much higher nitrogen losses than forested watersheds, but less than agricultural watersheds. The retention of nitrogen in suburban watersheds is surprisingly high. These watersheds retain 75% of the nitrogen inputs, which mainly come from home lawn fertilization and atmospheric deposition. Understanding how the urban and suburban landscape affects nitrogen losses and retention can have a significant impact on local and regional water quality through the development of management plans to reduce nitrogen losses to streams. Other studies have been investigating means to detect and measure E. coli in streams. Initial E. coli populations were calculated for 33 Baltimore watershed and results indicate that E. coli are present in surface water samples but at very low concentrations. The development and testing of E. coli measurement procedures will lead to means of protecting public health. Understanding how carbon cycles through ecosystems is important for developing management strategies to reduce the greenhouse gas effect. Relatively little is known on vegetation impacts on carbon cycles in urban areas, and even less is known on the role of urban soils in storing carbon. Measurements of carbon storage in urban soils were conducted to understand the role of urban soils in carbon storage and cycling. The results review the variability of carbon storage by soils among various land use types and results suggest that urban environmental changes can affect soil carbon pools in forest that area not directly or physically disturbed by urban development.

Impacts
Urbanization has significant impacts on water quality and carbon cycling related to global warming. Research is revealing how various landscape structures affect nitrogen levels in streams and carbon that is stored in urban soils. By understanding the magnitude of the effect of urbanization on water quality and greenhouse gases, management plans can be developed to help improve environmental quality at the local and global scales.

Publications

  • Shelton, Daniel R.; Van Kessel, Jo Ann S.; Wachtel, Marian R.; Belt, Kenneth; Karns, Jeffrey S. 2003. Evaluation of parameters affecting quantitative detection of Escherichia coli 0157 in enriched water samples using immunomagnetic electrochemiluminescence. Journal of Microbiological Methods. 55: 717-725.
  • Zipperer, Wayne C. 2002. Species composition and structure of regenerated and remnant forest patches within an urban landscape. Urban Ecosytems. 6: 271-290.
  • Pouyat, Rich. 2002. Earthworm effects on forest soils: the good, the bad, and the ugly. In: Proceedings of the state of the forest symposium: ecological issues regarding highlands forest degradation and restoration; 2002 October 3; Morristown, NJ. Bernardsville, NJ: New Jersey Audubon Society: 6-7.
  • Pouyat, Richard V. 2004. Anthro-soils: urban effects on soil carbon pools and fluxes. In: In: Lessons of Lewis & Clark: ecological exploration of inhabited landscapes. Proceedings, Ecological Society of America 89th annual meeting; 2004 August 1-6; Portland, OR. Washington, DC: Ecological Society of America: 406. Abstract. [CD-ROM].
  • Shelton, Daniel R.; Higgins, James A.; Van Kessel, Jo Ann S.; Pachepsky, Yakov A.; Belt, Kenneth; Karns, Jeffrey S. 2004. Estimation of viable Escherichia coli 0157 in surface waters using enrichment in conjunction with immunological detection. Journal of Microbiological Methods. 58: 223-231.
  • Hager, Guy; Belt, Ken; Grove, J. Morgan. 2003. Techniques for monitoring and assessing social and ecological dynamics in Watershed 263. In: Program and abstracts, Maryland Water Monitoring Council 9th annual conference; 2003 November 13; Linthicum, MD. Baltimore, MD: Maryland Department of Natural Resources. Abstract.
  • Heisler, Gordon M. 2004. Review of Climate variability and ecosystem response at long-term ecological research sites. Bulletin of the American Meteorological Society. 85(8): 1157-1159.
  • Holifield, Q. 2003. Forest floor exchange chemistry and microbial biomass in red spruce stands along a Ca/Al gradient in the northeastern United States. Syracuse, NY: State University of New York, College of Environmental Science and Forestry. 178 p. Ph.D. dissertation.
  • Belt, Kenneth T.; Readel, Karen; Zoller, Katherine. 2004. E. coli in urban streams: season, land use, and hydrologic drivers. In: Lessons of Lewis & Clark: ecological exploration of inhabited landscapes. Proceedings, Ecological Society of America 89th annual meeting; 2004 August 1-6; Portland, OR. Washington, DC: Ecological Society of America: 40. Abstract. [CD-ROM].
  • Groffman, Peter M.; Law, Neely L.; Belt, Kenneth T.; Band, Lawrence E.; Fisher, Gary T. 2004. Nitrogen fluxes and retention in urban watershed ecosystems. Ecosystems. 7: 393-403.


Progress 10/01/02 to 09/30/03

Outputs
Research has advanced on investigating soil nitrogen cycle processes in urban riparian zones, and leaf loss and nitrogen / carbon dynamic differences between urban and rural areas. In the first study, urban and suburban streams tended to have deeper incisions and lower water tables than more forested riparian areas. The results of this study suggest that urban hydrologic factors can increase the production and reduce the consumption of NO3 in riparian zones, reducing their ability to functions as sinks for NO3 in the landscape. Another study investigating differences in leaf litter between urban and rural forest stands found that land use had no effect on decomposition and nitrogen dynamics of native leaf litter. However, the environment and litter types strongly affected decomposition. Urban environments tend to have greater decomposition rates but urban leaves tend to be of poorer quality and decompose more slowly than rural leaves. In urban stands, exotic earthworms and warmer temperatures may be compensating for what otherwise would be slowly decaying leaf litter because of its lower quality. These differences are important factors affecting leaf decay and could alter the response of these forests to disturbance and variations in climate. A similar study investigating nitrogen transformation rates concluded that urban and suburban forest stands have the potential for higher losses of nitrogen than rural stands. An investigation of urban soils data revealed that soil organic carbon can be directly and indirectly affected by urbanization. Carbon in urban soils is highly variable, though urban landscapes store relatively small amounts of carbon. Changes in carbon content in soils due to urbanization can be significant with these changes likely to be persistent. An understanding of carbon levels and dynamics in urban soils is essential for understanding and quantifying ecosystem effects on the global carbon cycle and global warming.

Impacts
As urban areas continue to expand, understanding the influences of urbanization on nutrient cycling and carbon in soils is essential for protecting forest health and productivity. Research results show that urbanization influences nitrogen sinks and cycling in urban areas, as well as carbon storage in urban soils. Improved management to mitigate or enhance these effects could improve tree health in urban and urbanizing areas.

Publications

  • Zipperer, Wayne C. 2003. Vegetation patterns of upland and riparian forest patches along urban-rural gradients. In: Franks, Andrew; Pearson, Diane; Waqar, Kamil, comps. Crossing frontiers: landscape ecology down under. International Association for Landscape Ecology world congress, book of abstracts; 2003 July 13-17; Darwin, Northern Territory, Australia. [Place of publication unknown.]: [Publisher name unknown]: 138. Abstract.
  • Groffman, Peter M.; Boulware, Natalie J.; Zipperer, Wayne C.; Pouyat, Richard V.; Band, Lawrence E.; Colosimo, Mark F. 2002. Soil nitrogen cycle processes in urban riparian zones. Environmental Science and Technology. 36(21): 4547-4552.
  • Groffman, Peter M.; Bain, Daniel J.; Band, Lawrence E.; Belt, Kenneth T.; Brush, Grace S.; Grove, J. Morgan; Pouyat, Richard V.; Yesilonis, Ian C.; Zipperer, Wayne C. 2003. Down by the riverside: urban riparian ecology. Frontiers in Ecology and the Environment. 1(6): 315-321.
  • Phelps, Marcus G.; Hoppe, Martina C., comps. 2002. New York - New Jersey Highlands regional study: 2002 update. Tech. Pap. NA-TP-02-03. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northeastern Area, State and Private Forestry. 209 p.
  • Pouyat, Richard V.; Turechek, William W. 2001. Short- and long-term effects of site factors on net N-mineralization and nitrification rates along an urban-rural gradient. Urban Ecosystems. 5: 159-178.
  • Pouyat, Richard V. 2003. The ecology-policy interface. Frontiers in Ecology and the Environment. 1(1): 48-49.
  • Pouyat, Richard V.; Carreiro, Margaret M. 2003. Controls on mass loss and nitrogen dynamics of oak leaf litter along an urban-rural land-use gradient. Oecologia. 135: 288-298.
  • Pouyat, Richard V; Russell-Anelli, Jonathan; Yesilonis, Ian D.; Groffman, Peter M. 2003. Chapter 21. Soil carbon in urban forest ecosystems. In: Kimble, J.M.; Heath, Linda S.; Birdsey, Richard A.; Lal, R., eds. The potential of U.S. forest soils to sequester carbon and mitigate the greenhouse effect. Boca Raton, FL: CRC Press: 347-362.
  • Zipperer, Wayne C. 2002. Urban influences on forests. In: Macie, Edward A.; Hermansen, L. Annie, eds. Human influences on forest ecosystems. The southern wildland-urban interface assessment. Gen. Tech. Rep. SRS-55. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station: 73-91.
  • Zipperer, Wayne C. 2003. Exotic species patterns and functions in urban landscapes. In: Fosbroke, Sandra L.C.; Gottschalk, Kurt W., eds. Proceedings U.S. Department of Agriculture interagency research forum on gypsy moth and other invasive species; 2002 January 15-18; Annapolis, MD. Gen. Tech. Rep. NE-300. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northeastern Research Station: 108-109. Abstract.


Progress 10/01/01 to 09/30/02

Outputs
Research on carbon in urban soils has revealed that soil organic carbon pools are directly and indirectly affected by urban land-use conversions and these changes can be observed in adjacent undisturbed soils. The results show how urbanization is affecting the carbon pools in both urban and exurban areas. Urban forests stands have significantly higher organic carbon densities than suburban and rural stands. Soil carbon densities also varied by land use type within cities. Physical disturbances and inputs of various materials (e.g., fertilizers) can greatly affect the amount of carbon stored in soils. Even in the absence of physical disturbances, carbon in soils is affected by urbanization (e.g., changes in air temperatures). These changes in soil carbon due to urbanization can have significant impacts on carbon cycles and global climate change.

Impacts
Balancing the global carbon budget is critical for developing policies related to global climate change. Even though urban areas continue to expand, very little is known about carbon cycling in these areas. Research on soil carbon pools and fluxes in urban areas is filling in a critical void of information that is important for balancing the global carbon budget and helping reduce the impacts of global climate change.

Publications

  • Pouyat, Richard V.; Zipperer, Wayne C. 2001. Managing forests in urbanizing landscapes. In: Program and abstracts: the wildland-urban interface: sustaining forests in a changing landscape; 2001 November 5-8; Gainesville, FL. Gainesville, FL: University of Florida: 68. Presentation abstract.
  • Pouyat, Richard V. 2002. Soil carbon pools and fluxes in urban ecosystems. In: Advances in terrestrial ecosystem carbon inventory, measurements, and monitoring; 2000 October 3-5; Raleigh, NC. [Place of publication unknown]:[Publisher name unknown]: 79. Presentation abstract.
  • Pouyat, R.; Groffman, P.; Yesilonis, I.; Hernandez, L. 2002. Soil carbon pools and fluxes in urban ecosystems. Environmental Pollution. 116: S107-S118.
  • Stander, Emilie K; Groffman, Peter M; Pouyat, Richard V. 2002. Soil nitrogen cycling in urban forests and grasslands. In: A convocation; understanding and restoring ecosystems: Ecological Society of America 87th annual meeting; 2002 August 4-9; Tucson, AZ. Washington, DC: Ecological Society of America: 273. Presentation abstract.
  • Szlavecz, Katalin; Pouyat, Richard V. 2002. Earthworm diversity and abundance in the urban landscape. In: A convocation; understanding and restoring ecosystems: Ecological Society of America 87th annual meeting; 2002 August 4-9; Tucson, AZ. Washington, DC: Ecological Society of America: 438-439. Poster abstract.
  • Zipperer, Wayne C. 2001. An ecosystem based management approach to land-use decisions in the urban-wildland intermix. In: Program and abstracts: the wildland-urban interface: sustaining forests in a changing landscape; 2001 November 5-8; Gainesville, FL. Gainesville, FL: University of Florida: 76. Presentation abstract.
  • Zipperer, Wayne C. 2001. Urban influences on forest ecosystems. In: Program and abstracts: the wildland-urban interface:sustaining forests in a changing landscape; 2001 November 5-8; Gainesville, FL. Gainesville, FL: University of Florida: 18. Presentation abstract.
  • Band, Lawrence E.; Belt, Ken; Groffman, Peter; Fisher, Gary; Law, Neely; Tenenbaum, David; Doheny, Ed. 2001. Watersheds, ecosystems and us: the Baltimore Ecosystem Study. In: Program and abstracts: Maryland Water Monitoring Council 7th annual meeting; 2001 November 16; Linthicum, MD. Baltimore, MD: Maryland Department of Natural Resources. Presentation abstract.
  • Belt, Kenneth T.; Groffman, Peter M.; Band, Lawrence E.; Neely, Law; Fisher, Gary T. 2002. Nitrogen and phosphorus fluxes in urban ecosystem watersheds. In: Abstracts of American Geophysical Union spring 2002 meeting: 2002 May 28-31; Washington, DC. Washington, DC: American Geophysical Union. EOS Suppl. 83(19): S113. Presentation abstract.
  • Escobedo, Francisco J.; Ffolliott, Peter F.; Gottfried, Gerald J.; Garza, Florentino. 2001. Fire frequency effects on fuel loadings in pine-oak forests of the Madrean Province. Res. Note RMRS-RN-10. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 6 p.
  • Groffman, P.M.; Belt, K.T.; Band, L.W.; Fisher, G.T. 2001. Nitrogen fluxes in urban watersheds. In: Program and abstracts: N2001 the second international nitrogen conference; 2001 October 14-18; Potomac, MD. Washington, DC: Ecological Society of America: 84. Presentation abstract.
  • Pickett, S.T.A.; Cadenasso, M.L.; Grove, J.M.; Nilon, C.H.; Pouyat, R.V.; Zipperer, W.C.; Costanza, R. 2001. Urban ecological systems: linking terrestrial ecological, physical, and socioeconomic components of metropolitan areas. Annual Review of Ecology and Systematics. 32: 127-157.