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Home Why Transect Sampling ?

Why Transect Sampling ?

The 2015 FOA comparative study concludes the line-point transect is the "most accurate,least expensive, and most easily applied [method]."

Ken Stumpf's reasons to use the transect sampling methodology include:

  1. Data collection technique generates field data that are quantitative discrete estimates having statistical properties including variances/standard deviations. These quantitative estimates may be easily tested using Accuracy Assessment processes, such as paired T-tests or Χ2 tests.
  2. Data collection technique generates estimates that can be summarized in total or by defined layer position, or “bird’s-eye view.”
  3. Data collection technique is verifiable and repeatable.
  4. Data collection technique generates equal or more accurate vegetation descriptive data.
  5. Data collection technique is standardized and objective; it can be implemented using field personnel having less expertise.
  6. Seasonals and temps can generate the same results as permanent or more experienced staff.
  7. Volunteers can be trained and used to collect field data.
  8. Data collection efforts can be implemented using transects of different configurations and number of points selected to provide an appropriate sample of a specific area/type.
  9. Data collection technique is not likely impacted by topographic/slope influences.
  10. Data collection technique forces field crew to leave the field site location (target point) and cover the area being sampled.
  11. Data collection technique enables the field crew to provide a more comprehensive evaluation of a field site by providing a more realistic means of “covering” the field site area.
  12. Data collection efforts may be less expensive based on lower labor costs.
  13. Data collection efforts fully utilize a two-person field crew that can switch responsibilities from site to site.
  14. Data collection estimates are compatible with estimates developed using prior techniques; ocular estimates and type calls may still be observed and recorded in combination with these data collection efforts.
  15. Data estimates can provide feedback and verification of ocular estimates so the observer’s “eye” is trained.
  16. Data collection efforts characterize all canopy layers and the ground surface during one sampling effort.
  17. Other data collection protocols are easily integrated into the sampling efforts.
  18. Can be used to estimate species and layer-specific tree characteristics such as quadratic mean diameter, height, stems/unit area, volume, and biomass.

Reasons Ken hears for why someone does not use the transect sampling methodology:

  1. Believe an ocular-based technique is better.
  2. Possess sufficient expertise using another technique.
  3. Only need a type name - do not need quantitative estimates or statistics.
  4. Do not need an objective repeatable methodology.
  5. Have sufficient funding to implement current techniques.
  6. Learned a different technique.
  7. The transect methodology exceeds project standards.
  8. The transect methodology takes too long.
  9. The transect methodology is biased towards describing raster map data sets.
  10. Confident in what one is already doing.
“What we do is what I know how to do.”
“It has always worked for me.”
“This is the way we have always done this.”
If interested in more information about Line-point transect sampling methodology and how you might use it feel free to contact This e-mail address is being protected from spambots. You need JavaScript enabled to view it at GRS.

GSA# GS-10F-0451NESRI Consultant