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Tools for Assessing and Managing
Community Forests |
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i-Tree Eco Links |
Applications |
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i-Tree Eco Performing a sample inventory
Field data inputs The data needs of Eco depend to a certain extent upon the nature of the output desired—i.e., what forest functions or values are to be quantified (see the Manual for details). For sample inventories, Eco field data is collected not only on trees and shrubs (optional) but characteristics of the plot and its landscape, including ground cover, % impervious, and land-use. Because the collection of field data is one of the most time-consuming and costly parts of the Eco analysis process, careful selection of field data attributes is critical. Sample Plots The plot size and number of plots needed for an Eco project are not fixed, although plots are usually .1 acre in size (circle with 37.2 foot radius). The number of plots needed depends on the accuracy needed. Typically 200 plots will produce about a 10% standard error for the total number of trees. Estimations are less certain with smaller samples; 30 plots is considered the minimum. Sample inventory workbooks are included with the Manual to provide methods of a sample inventory using ESRI ArcGIS. Field data collection crews typically locate field plots using street maps indicating plot location. Aerial photographs help pin down the plot center location. Plot center may fall in public land, private land, or on the border of different land ownerships and land-use types. Plot center may be permanently located by recording distance and direction from man-made features such as buildings, telephone or light poles, street corners, etc. A photo taken of plot center can help relocate the plot in the future. Permanent records of plot locations are important for assessing forest change (e.g., tree mortality). Global Positioning System (GPS) units can also be used for locating plot centers if the unique coordinates of the plot center are known. But taking GPS readings can slow data collection if satellite communications are slow or temporarily unavailable, or if there is heavy canopy cover, which can potentially block communication signals from satellites. GPS units can also be expensive to rent or buy. They are best used where no man-made features are readily available to relocate plots. Weather and pollutant concentration inputs In addition to field data inputs, location specific weather and air pollution inputs are required. These data are available for the United States for the year 2000 and used, by default, in the analysis. Hourly weather data are necessary to analyze:
Hourly pollution concentration data are required to analyze:
Boundary layer data
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Eco users interested in conducting a sample inventory are encouraged to use the integrated PDA utility for Pocket PCs. Users will be able to tailor data collection for the particular needs of their projects or use the default data collection fields for speed and full utilization of Eco’s analysis and reporting features. Using the PDA utility not only leads to faster data collection and input, but facilitates direct data transfer. Eco users can also choose to use field data collection forms for paper and pencil inventories which can then be manually entered into the application.