• CCSI Home
• Initiatives
• Application
• Contact
• More sustainability@claremont

2008 Initiatives

• Claremont Colleges Tree Canopy
• Solar Technologies for the Claremont Colleges
• Scripps College Food and Sustainability Community Project

2007 Initiatives

• Greening the Office Supply Stream
• Urban Ecosystem Analysis Using GIS:
  • Introduction
  • Major Findings
  • Tree Inventory
  • Web Maps
  • Recommendations
  • GIS Data
  • Final Report
  • Presentation slides
  • Resources
  • Team Members
• 5-College Environmental Audit

Campus Trees

Major Findings

Urban Ecosystem Analysis Using GIS

Value of CGU’s Trees

• Claremont Graduate University’s campus contains 319 trees of 44 different species (see Tree Inventory). The tree canopy covers 2.7 acres (23.4%) of the 11.6-acre campus. The trees are displayed on several web maps.
• Trees absorb and filter out nitrogen dioxide (NO₂), sulfur dioxide (SO₂), ozone (O₃), carbon monoxide (CO), and particulate matter less than 10 microns (PM10) in their leaves. CGU trees remove 556 lbs of pollutants per year. The value of the pollution removal is estimated to be approximately $1,400 per year based on “externality” costs borne by society, such as rising health care expenditures and reduced tourism revenue.
• Trees remove carbon dioxide from the air through their leaves and store carbon in their biomass. Approximately half of a tree’s dry weight, in fact, is carbon. Thus trees reduce the amount of greenhouse gas in the atmosphere. CGU’s trees store over 100 tons of carbon and sequester nearly a ton of carbon annually.
• Trees decrease total stormwater volume and slow peak flow. If CGU’s trees were removed, over 40,000 cu ft of additional stormwater storage would be need to contain the water from the largest 24-hr rainfall that occurs on the average every two years. This additional storage would cost nearly $90,000, and if financed over 20 years at 6% interest would cost over $7,500 per year.
• Trees improve water quality by preventing erosion and filtering contaminants from surface water, both of which maintain or improve water quality. If CGU’s trees were removed, the concentration of the cadmium, chromium, and chemical oxygen demand (COD) in runoff would increase 60%–80% during a typical storm event, and the concentration of nitrogen, phosphorus, biological oxygen demand (BOD), and suspended solids would increase 20–60%.
• Planting 16 more trees on the CGU campus (a 5% increase) would initially increase air pollutant removal and carbon sequestration by only about 1-2% and have a negligible effect on stormwater retention and cleaning. However, once growth of new and existing trees has increased the tree canopy by 10%, air pollutant removal and carbon sequestration would increase by 15-20%, stormwater retentions by about 9%, and removal of most stormwater pollutants by 15-30%.
• The CITYgreen software used for this project could not calculate the energy savings due to CGU’s trees. This deficiency is due to insufficient research on modeling energy savings in dense urban settings, rather than a problem in the software itself.

Lessons Learned for Applying UEA at the Claremont Colleges

• The Claremont Colleges Campuses CAD drawing are somewhat problematic for GIS work. The variety of sources (CUC, college facilities, etc.) undoubtedly impacts the accuracy, unity, etc. of the resultant GIS datasets. In addition, the CAD drawings were not georeferenced, and georeferencing is neither straightforward nor precise.
• Surveying and delineating surface areas (turf, ground cover, impervious surfaces, etc) in AutoCAD and transferring them into GIS for coefficient assignment for analysis in CITYgreen requires many hours in the field.
• Although satellite imagery is available from the library, more recent imagery is available online with minimal investment.
• Existing GIS and satellite datasets are generally lacking in metadata.
• Surveying CGU’s 319 trees required 20 hours = 16 trees/hour.
• Because sub-meter GPS devices are very expensive and tree canopy interferes with signal, paper maps and paper forms proved to be the best method for performing the tree inventory. However, much time could be saved during and after the survey is completed, if the Tree Inventory Data Sheets were in a digital format; e.g., if the data were entered into a PDA or laptop during the survey in the field.
• While a detailed tree inventory, such as this, is useful for performing a CITYgreen analysis, it is not absolutely essential.
• Before a CITYgreen analysis may begin, many detailed parameters (including Air Pollution, Carbon, Soils, Landcover Types, Rainfall, and Elevation) must be reset to customize the analysis — both for initial conditions and each subsequent analysis. The analytic parameters used in this study could and should form the basis of future CITYgreen analyses at the Claremont Colleges — there is no need to “reinvent the wheel”.

More detailed description of the findings is included in the final report .