Abstract: The relationship between yield and stand density is of critical importance in precision forestry. A necessary first step is how to accurately quantify the stand density. The objective of the paper aimed to find out the optimum measure from three relative stand density index based on self-thinning theory, such as Curtis’s, Reneike’s and Nilson’s stand density. These density measures were developed through the same data from experiment of Chinese Fir plantations (Cunninghamia lanceolata(Lamb.) Hook), and selected according to theoretical analysis and practical verification. Theoretically, Curtis’s relative stand density (RD) is equivalent to accepted stand density index (SDI), and SDI can be viewed as a special sample of Nilson’s stand density (SD). A case of Chinese Fir plantations showed that SD measure was superior to conventional SDI and RD for reflecting the actual dynamic change rule of stand density. Additionally, it had less correlation with site quality than SDI and RD measures. The SD measure is able to apply for modeling and predicting of planted Chinese Fir all over site index and age.

Key words: Chinese Fir plantation, stand density index, Curtis&rsquo, s relative stand density, Nilson&rsquo, s stand density