Development of stand density management diagrams for Chinese fir plantations

Abstract

Stand density management diagrams (SDMDs) are powerful tools for the design, display and evaluation of different density management regimes derived without long-term thinning trials in the field. The SDMDs can be used to predict future stand development based on specific thinning schedules and to optimize forest management. Even though Chinese fir (Cunninghamia lanceolata [Lamb.] Hook) covers the largest area in China’s plantations with an area of 8.54 million ha, there is no management tool for optimization of different management regimes. In this study, SDMDs, generated from common one-time inventory data, provided information about the evolution of quadratic mean diameter, stand volume, stem and above ground biomass with stand development for the widely planted Chinese fir plantations in southern China. A system of four equations was fitted simultaneously to data collected from 74 inventory plots. Relative spacing index was used to characterize the growing stock. These SDMDs can be easy tools for local forest managers to estimate the stand volume, stem and above ground biomass and could be the reference to determine optimum thinning schedules.