The C:N:P Stoichiometry Of Root, Foliar And Soil Of Different Aged Koelreuteria Paniculata Forests In Xiangtan Manganese Mine Wasteland

To reveal the C:N:P stoichiometry of root, foliar and soil in Koelreuteria paniculata forests, the C、N and P concentrations and their stoichiometry features were investigated in3-,5-and9-year-old stands in Xiangtan Manganese Mine wasteland, a typical degraded ecosystem in southern China. The results suggested the limiting factor of controlling the process of plant growth, and revealed the synergistic trend of the "soil-root-foliar" system. The results sgowed that as follows:(1). The C concentrations of soil increased with the soil depth, but there was no great changes of the N and P concentrations in soil; The soil C:N and C:P ratio decreased with the soil depth, while N:P ratio had no changes. The C and N concentrations increased with the aged stands, but P concentrations showed the opposite trend; The C:P and N:P ratio increased with the aged stands, while the C:N ratio increased in5-year old stand and decreased in9-year old stand; As a whole, the soil N concentrations had significant positive correlation with N:P ratio, while P concentrations was opposite.(2).The root C, N and P concentrations among aged stands were significantly different, N and P concentrations decreased with the aged stands; Both coarse root and fine root rised greatly with the aged stands; Root N concentrations and C:N ratio,N concentrations and N:P ratio, P concentrations and C:P ratio all showed obvious linear relationship.(3). The leaf C concentrations first rised with the ages till steady state. Both N and P concentrations decreased with the ages; C:N and C:P ratios greatly dropped with the increasing ages, while N:P ratio increased; There was positively linear relationship between N concentrations and C:N ratio, P concentrations and C:P ratio, while negative to N concentrations and N:P ratio.(4). Different ages of root C:N, C:P and N:P ratios is not affected by soil C, N, P concentrations greatly. Soil N concentrations was positively correlated with fine root C:N ratio and coarse root C:P ratio in3-year old stand; Soil C, N concentrations was positively correlated with fine root C:P ratio in5-year old stand; Soil C concentrations was positively correlated with fine root C:N ratio in9-year old stand.(5). Analysing the nutrient elements of soil and leaves of aged stands, Soil C concentrations was positively correlated with leaf C:N ratio in5-year old stand; Soil P concentrations was positively correlated with leaf C:P ratio in9-year old stand; As a whole, soil N concentrations was positively correlated with leaf N:P ratio.(6). The root was correlated with leaf among different aged stands to some extent: Fine root C concentrations was positively correlated with leaf N, N:P ratio in3-year old stand, P concentrations between fine root and leaf were also positively correlated; Fine root and leaf C concentrations were positively correlated in5-year old stand, fine root P concentrations and leaf N, P concentrations, leaf C concentrations, C:N ratio and coarse root C:N ratio were positively correlated with, while leaf C concentrations and fine root C:P, N:P ratio were negatively correlated; Coarse root and leaf N concentrations, coarse root C concentrations and leaf C concentrations, C:N ratio were positively correlated, while coarse root N concentrations and leaf C concentrations, C:N ratio, leaf N concentrations and coarse root C:N ratio, coarse root N:P and leaf C:N were negatively correlated.(7). Our results indicated that P was probably the limiting factor controlling the process of plant growth in Xiangtan Manganese Mine wasteland. The results provided scientific references for vegetation restoration, management and sustainable development in the abandoned mine lands.