米槠次生林和天然林细根养分及化学计量特征

探讨人为干扰对森林养分利用和生物地球化学循环特征的影响，对亚热带米槠(Castanopsis carlesii)次生林和天然林细根化学计量特征及其随土壤深度(0～80cm)的变化趋势进行了研究。结果表明，混合线性模型表明林分和土层深度对细根化学计量特征影响的主效应显著，但是交互作用不显著；米槠次生林细根N和P含量均显著低于天然林，而细根C浓度、C:N、C:P显著高于天然林，天然林1～2mm细根C浓度显著低于次生林;天然林和次生林细根N、P含量均随土层深度增加而呈显著下降趋势，C:N、C:P、N:P均随土层深度增加而呈显著上升趋势，且两林分下降趋势无显著差异；天然林和次生林细根N、P含量及N:P分别与土壤全N、全P含量和N:P存在线性关系，而细根N、P含量和N:P随土层深度变化均与直径显著相关，与细根比根长(SRL)无关。天然林经过人为干扰后，细根化学计量特征随土层深度变化规律虽未发生改变，但细根N和P浓度显著降低。

Difference of Fine Root Nutrients and Stoichiometric Characteristics Between Castanopsis carlesii Secondary Forest and Natural Forest in Subtropical China

In order to understand the effects of human disturbance on forest nutrient utilization and biogeo-chemical cycling, the stoichiometric characteristics of fine roots in Castanopsis carlesii secondary forest and natural forest and their variation trend with soil depth (0-80 cm) were studied. The results showed that the main effect of stand and soil depth on fine root stoichiometry was significant by mixed linear model, but the interaction effect was not significant. The contents of N and P in fine roots of secondary forest were significantly lower than those in natural forest, while the C content, C:N and C:P in fine roots were significantly higher than those in natural forest. The C content of fine root at 1-2 mm diameter in secondary forest was significantly higher than that of natural forest. Fine root The N and P contents of fine root in natural and secondary forest decreased significantly with the increase of soil depth, while C:N, C:P, N:P increased with the increase of soil depth, and the change trend of root stoichiometric characteristics with soil layer were similar between secondary forest and natural forest. The contents of N, P and N:P in fine roots of natural and secondary forests were linear with the contents of total N, total P and N:P in soil, respectively. The contents of N, P and N:P in fine roots were significantly correlated with the soil depth, but not with the specific root length (SRL). Therefore, the stoichio-metric characteristics of fine roots did not change with soil depth in the natural forest after human disturbance, but the concentrations of N and P in fine roots decreased significantly.