Laser point-quadrat sampling for estimating foliage-height profiles in broad-leaved forests

A technique for estimating the vertical distribution of foliage area in bro ad-leaved forests was developed. The technique is similar to optical point- quadrat sampling, where estimates are based on heights to the lowest leaves above numerous sample locations beneath a canopy. In optical point-quadrat sampling, heights to lowest leaves are measured with a telephoto lens. Her e, heights were measured using a commercially available laser range-finding instrument. The laser point-quadrat technique was tested in field studies conducted under broad-leaved forest canopies in western North Carolina and east-central Minnesota, U.S.A. Foliage-height profiles obtained by laser po int-quadrat sampling were consistent with two of four published foliage-hei ght profiles observed in 1995 at the North Carolina field locations. Total leaf area estimates obtained by laser point quadrats were not significantly correlated with values of leaf area index estimated by recent litter fall analyses at the North Carolina and Minnesota field locations. Although furt her evaluation and refinement of the technique is needed, laser point-quadr at sampling shows promise as a means of obtaining foliage-height profiles a t a significantly reduced effort and with greater accuracy than methods com monly in use today.