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Information on tree density and characteristics are valuable for a variety of purposes, including:
Timber Volume, Growth, and Valuation relative to eventual sale of the wood
Ecological Characterizations such as habitat assessments for specific wildlife species (especially listed species), or evaluation of species diversity post enrichment planting
Site Review for Specific Trees including estimations of mitigation relative to clearing of protected trees, or infestations of invasive/exotic species
While a 100% review of a site is often possible, sufficient data is typically available
using a statistically-sound arrangement of plots. These plots are typically either fixedarea
plots or variable-point sampling. Fixed-area plots are typically round with a
specified radius from point center, and either 1/10th acre (radius of 37.24’) or 1/20th
acre (radius of 26.33’). They are most effective in areas with variable tree densities,
and when information not related to timber value is required. Variable-point sampling
uses a prism which designates tally trees based on a distance from point-center relative
to tree diameter. Typically these use either a 10 basal-area factor (BAF) or 20 BAF
prism, with basal area factor being a measurement of the cross-sectional squarefootage
of wood in an area, and are most appropriate when valuing timber since larger-diameter (more valuable) trees are more frequently sampled.
Plots are located in a systematic arrangement, typically a grid system. If stand characteristics
are known, and sufficiently variable, plots may be stratified so that sampling
intensity is highest in areas with greater variability. A sampling intensity of 10% (the proportion of the area sampled
compared to the entire area) is generally sufficient.
ESI Capabilities
ESI staff have significant educational background and experience in collecting this information, including the arrangement
of a sampling system (plot type, grid), data collection, and data analysis. Previous projects have used
plots to estimate timber values for private landowners and industrial timber management firms, to assess ecological
condition relative to habitat requirements and permit conditions, and to determine mitigation for clearing of protected
trees. These assessments are typically budgeted on a per-plot basis, with costs ranging from $11-17 per plot.
 Depending on field conditions, plot type, and data to be collected, approximately 25-40 plots can be completed in a
day. Small projects may be budgeted on a flat fee basis, to cover fixed costs.
Value to Clients
Assessments are especially appropriate to clients in the following circumstances: in preparation for a timber sale, to
assess compliance with permitted wetland/upland enhancement, including supplemental planting or thinning and to
provide pre-planning information on protected tree mitigation.
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