written by Jason Karl
Description and Uses
This method of estimating vegetation structure in a plot uses a modification of the standard line_point_intercept method. Height measurements are taken at pre-determined points along a transect. At each point, the height and species of the tallest vegetation within a fixed-radius circle (typically 6in or approximately 15cm) is recorded. The height recorded is the tallest height of the entire plant that falls within the vertical cylinder centered at the point, not just the height of the portion of the plant within the cylinder. Both living and dead vegetation are usually counted.
A number of different height/structural indices can be calculated from this method including average vegetation height with standard deviations and structural diversity.
Advantages and Limitations
Of the different vegetation height/structure methods, this on is one of the easiest and fastest to implement because it uses the transects that are already in place for estimating cover. The NRI implementation of this method uses height classes to speed up data collection.
This is a relatively new method that has not been published on extensively. Because this method is so new, there is not a lot of guidance on calculating structure/height indices from the data.
Technical and Application References
- To date, the only known application of this method is as part of the NRCS National Resource Inventory (NRI) Grazing Land On-Site Study http://www.nrisurvey.org/nrcs/range/resource/2009/Power_points.htm