干旱区生态环境知识资源中心

Fine (<= 2 mm) and coarse roots (>= 5 mm) play important roles in water and nutrient cycling in forested ecosystems and are the major organs that trees use to absorb water and nutrients. However, few studies have investigated the distributions of these root types in rocky mountain regions. An understanding of the distribution of root systems would facilitate the study of how available resources are used belowground in rocky mountain regions. We measured the distribution of the root biomass (RB), specific root length (SRL), and root length density (RLD) for both fine and coarse roots of two tree species: Platy-cladus orientalis and Prunus davidiana. The results showed that the fine-root RB and RLD of P. orientalis were higher than those of P. davidiana, but that the fine-root SRL of P. orientalis was lower than that of P. davidiana. In contrast, the coarse-root RB, SRL, and RLD of P. orientalis were lower than those of P. davidiana. From the 2D contour distribution, we found that most fine and coarse roots of P. orientalis and P. davidiana were concentrated near tree stems. The horizontal distribution of P. davidiana root showed less horizontal extension ability than that of P. orientalis root. The RB, SRL, and RLD of both fine and coarse roots of P. orientalis declined with increasing soil depth, and the roots of P. davidiana exhibited different distribution patterns. We found that P. orientalis has a more dominant and explorative fine-root system, whereas P. davidiana has an explorative coarse-root system. The fine-and coarse-root traits of P. orientalis were susceptible to soil nutrients, but these nutrients had only a slight effect on the coarse-root traits of P. davidiana.