COS 88-8
A venerable range management field data collection technique used to develop plant community cover and frequency characteristics provides unexpected new levels of detailed species-specific information
The line-point transect is an old, tested, and proven field data collection methodology used in range management and ecology studies in the U.S. for nearly
one-hundred years. This technique may be used to develop species-specific cover estimates necessary to characterize ecosystems and generate expected values of cover equal to those developed using ocular-based methods, such as the relevé approach. Such accurate and detailed information is invaluable while undertaking a Vegetation Classification effort. This sampling technique was used to collect field data between 2006-2010 during both the Lassen Volcanic National Park Comparative Mapping Project and the Redwood National and State Parks Vegetation Classification and Mapping Project resulting in data sets that sampled nearly 2,000 field sites that represent over 100,000 individual point observations.
Results/Conclusions
While this venerable methodology generates cover estimates comparable to other methods, it can also lead to the development of new levels of information that far exceed the information developed based upon ocular methods. Secondary levels of information include species-specific cover estimates by canopy position, tree size, and height class that are nearly impossible to accurately estimate otherwise. In addition, statistical measures of the variance of total and species-specific cover estimates may be developed enabling statistical comparison and testing of the field data estimates. Accuracy assessments may be based on cover estimates that have confidence limits rather than "fuzzy" boundaries. Tertiary levels of information may be developed that represent individual plant species relationships to other plants and landscape features based on the relative frequency of occurrence at a common point or within known distances of a specified species of interest, thereby providing species occurrence information that may change relative to the scale of the species interactions being evaluated.
Examples of these different levels of ecosystem cover and occurence information, including vegetation description information, will be presented based upon field data collection efforts undertaken during the aforementioned field data collection efforts that demonstrate the wealth of information that may be developed when implementing this methodology.
The use of such a comprehensive, standardized, objective, and repeatable approach as the line-point methodology also provides a means of developing information having greater reliability and accuracy using staff of varying levels of expertise and training; seasonal staff can, at a minimum, generate the same results as experienced staff, ultimately resulting in the development of plant community data and information at a lower cost per sample site.