Relationship between environmental and stand factors and root-shoot ratio in Cunninghamia lanceolata plantation

Root-shoot ratio(RSR)is the basis for biomass distribution, and plays an important roles in material circulation of forest ecosystem. By collecting 608 data from 134 published literatures on RSR measurements of Cunninghamia lanceolata plantation, we used linear function to build the relationship between RSR and mean annual temperature, mean annual precipitation, stand density and stand age, respectively. The RSR increased with mean annual temperature, mean annual precipitation and stand density, decreased with stand age. Thus, we also used structural equation model to analysis the relationship between RSR and mean annual temperature, mean annual precipitation, stand density and stand age. The results showed that mean annual temperature, mean annual precipitation, stand density and stand age effect on RSR, which direct path coefficient were 0.515 (P < 0.01), 0.548 (P < 0.01), -0.462 (P < 0.01) and 0.201 (P < 0.01), respectively. The mean annual precipitation and stand age had also indirect effect on RSR, and indirect path coefficient were -0.308 (P < 0.01) and -0.082 (P < 0.05) in our structural equation model. The structural equation model analyses also indicated that mean annual temperature, mean annual precipitation, stand density and stand age explained 69% of the variation in RSR of C. lanceolata plantation.