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Title: A LASER POINT FRAME TO MEASURE COVER

Author
item VANAMBURG, L - USDA-FS
item Booth, D
item Weltz, Mark
item TRLICA, M - COLORADO STATE UNIVERSITY

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2006
Publication Date: 9/5/2006
Citation: Vanamburg, L.K., Booth, D.T., Weltz, M.A., Trlica, M.J. 2005. A laser point frame to measure cover. Rangeland Ecology and Management 58:557-560.

Interpretive Summary: A "point frame" is an instrument used to establish an array of points from which ground cover (plant material for example) is measured by counting the number of points making contact with different types of ground cover. This paper describes a frame utilizing lasers in place of conventional metal pins. The new frame allows data to be collected more quickly and correlations between cover data collected using a conventional frame and the laser point frame (LPF) were acceptably high (r=0.67 to 0.81). We conclude that the use of the LPF has the potential to reduce the cost of collecting ground cover data; however, we recommend further testing to confirm the apparent LPF advantage and to assess the relative accuracy of the LPF.

Technical Abstract: The point sample method has been a standard plotless method for measurement of ground cover on rangelands since it was introduced by Levy in 1927. The instrument most commonly used to collect point-samples is the point frame. Since its introduction, the point frameha undergone numerous modifications to improve efficiency and ease of use. This paper introduces a laser point frame (LPF) that was designed by the Agricultural Research Service for measurement of ground cover and utitilizes lasers in place of conventional metal pins. A comparative pilot study was conducted on a shortgrass prairie in northern Colorado, to compare data collected using a magnetic point frame (MPF) with data collected using the LPF. Cover by species was measured from identical plots using 100 points per plot for each point frame, and sampling times were recorded for each plot. Correlations between cover data collected using the MPF and the LPF were relatively high (r=0.67 to 0.81). Total average vegetative cover measured with the MPF was 35% compared to 40% using the LPF. Cover of total grasses, C4 grasses, C3 grasses, and litter were significantly greater using the LPF method. Total sampling time per 100 points was almost half using the LPF, compared to the MPF. The LPF was easy to use, was efficient for measurement of cover, and is a potential replacement for conventional point frames.