Use of a no prism total station for field measurements in Pinus tabulaeformis Carr. stands in China

A Pentax R-422N no prism total station was used to improve data quality, survey efficiency and contributed to crown volume study in field measurements of forestry resources. The study was conducted through field measurements in Chinese Pine, Pinus tabulaeformis Carr. (Pinaceae) stands in Beijing, Miyun County of China. The data included independent tree variables, such as three-dimensional coordinate, tree height, diameter at breast height (DBH), and crown width. Compared with control values which were approximate to values obtained by a research team composed of skilled surveyors, the results indicated that three-dimensional coordinate, tree height, DBH, and the crown width of each tree can be measured to a high precision using a no prism total station in less than 1 min. The relative error of tree height was <3% and for DBH <2%, the accuracy of crown width was >90%, which means measurement quality objectives (MQOs) adopted in the Forest Inventory and Analysis Programme (FIA) of the USDA Forest Service were achieved. Crown volume calculation and three-dimensional modelling by using 3D-MAX were practiced out with reliable data acquired by the no prism total station. The results can be used in different tree growth studies and for the assessment of forest volume and biomass in China.