A Point Frame for Circular Plots in Southern Forest-Ranges

A point frame has been modified to allow for plant cover estimates to a 152 cm height. Construction ofa third crossmember that can be added to a 76.cm tall point frame allows sampling pins to be projected both upward and downward. Spacings between pins were changed to produce equal sampling areas while sampling circular plots. This design was tested with a miniature point frame on artificial plant populations and was shown to measure within 3~5% of actual cover values. The point frame, widely used in range ecological work, is normally placed at selected field points or moved along a transect. Point frames have been used to measure plant height (Heady 1957) insect damage (Nerney 1960) leaf area (Warren-Wilson 1963) basal cover (Fisser and Van Dyne 1966), foliar cover, frequency, herbage production and species composition (Hughes 1962), and to determine plant density in rectangular quadrats (Ellison 1942). The basic point frame with its sampling precision (Schultz et al. 1961, Hutchings and Pase 1963, Fisser and Van Dyne 1966) is easily modified and retains its accuracy and usefulness with design modifications. Point frames have been constructed of wood, steel, and aluminum. Modifications are normally made for specific purposes such as the sampling of a vegetation type, the increase of accuracy, or the ease of sampling (Nerney 1960, Long et al. 1972, Sharrow and Tober 1979). Foliar cover of herbaceous and woody vegetation is important in determining understory vegetation production and composition in southern forests (Pearson and Sternitzke 1974). The point frame can be used to determine foliar cover and botanical composition accurately; therefore, it was selected for use in training and checking ocular estimates of plant cover on I-m* circular plots by Forest Service Renewable Resource Evaluation field personnel during extensive forest resource surveys in midsouth forests. (Foliar cover of herbage can be used to estimate herbage production from established foliar cover-herbage production relationships). We will discuss how modifications in frame height and pin spacing can allow the point frame to be used in small, circular plot sampling.