Point intercept method
The point-intercept-method (alternative names: point-square-method, point-line-intercept, line-point-intercept) is a quantitative method of ecology . It is often used by plant communities to analyze the soil cover by plants. It is one of the most common methods to describe the vegetation cover of an area.
In addition, it is also used as a non-destructive (i.e. plant-preserving) method for determining biomass (standing crop). In the applied field, the method is used to evaluate the success of biotope maintenance measures in nature conservation or to estimate the total vegetation cover, for example for purposes of erosion protection .
In practice, a series of points are laid at regular intervals through the area to be examined and for each point it is examined whether it is covered by a plant or not. The relative coverage of the area by the species under study can then be determined by dividing the covered points by the total number of measurement points. For species that are dominant in the area, 100 to 200 measuring points are considered sufficient; for rarer species, more points must be measured accordingly. If the ground is dry, a measuring frame can be used to define the measuring points. In the case of heavily structured vegetation stands, a stick is alternatively pushed through the investigation area from the edge, and then it is noted which plants it touches. This means that the coverage can also be determined separately for layers of vegetation (strata).
As a variant, a method is also used in which the measuring points are not arranged in a line, but in a regular grid (grid point intercept)
Line intercept method
The line intercept method measures along a line and determines how much of the line it covers for each species. As a result, a total coverage of over 100% can be achieved. The line intercept method is mainly used along gradients , for example a rise in the terrain, and can also document changes in the vegetation.
literature
- Ralph W. Tiner: Wetland Indicators: A Guide to Wetland Identification, Delineation, Classification, and Mapping . CRC Press, Boca Raton, Florida 1999, ISBN 978-1-4200-4861-2 , pp. 118-122 .
Individual evidence
- ^ Sven Jonasson (1988): Evaluation of the Point Intercept Method for the Estimation of Plant Biomass. Oikos Vol. 52, No. 1: 101-106.
- ↑ J. Cagney SE Cox, DT Booth (2011): Comparison of Point Intercept and Image Analysis for Monitoring Rangeland Transects. Rangeland Ecology and Management 64: 309-315 doi : 10.2111 / REM-D-10-00090.1
- ↑ H. Godınez-Alvarez, JE Herrick, M. Mattocks, D. Toledo, J. Van Zee (2009): Comparison of three vegetation monitoring methods: Their relative utility for ecological assessment and monitoring. Ecological Indicators 9: 1001-1008. doi : 10.1016 / j.ecolind.2008.11.011