Point-Centred Quadrangle Method: A Novel Distance Method for Density Estimation

Quantitative data are essential in characterizing vegetation. Considerable attention has been paid to vegetation sampling techniques. A series of methods have been developed for tree density estimation which utilize spacing distances instead of fixed-area quadrats. In this paper, a new plotless sampling method was proposed which we denominated a Point-centred quadrangle method. With the new method and a conventional distance method (point-centred quarter method), we investigated Larix principis-rupprechtii population in larch forests at Xiaolongmen Forest Station of Donglingshan Mountain, Beijing. Compared the two methods with quadrat method, the distance estimated by the new method needs to multiply by a coefficient for accuracy, and the precision of the new method are not better than the old one. However, this novel method is still usable for tree density estimation and is easy to use in wood engineering and forest survey work.