中亚热带4种森林土壤碳、氮、磷化学计量特征

Change characteristic of soil C, N, P stoichiometric ratios in mid-subtropical forests restoration

以湘中丘陵区杉木人工林（CL）、马尾松—石栎针阔混交林（PM）、南酸枣落叶阔叶林（CA）、石栎—青冈常绿阔叶林（LG）为对象,研究了中亚热带森林土壤有机碳（SOC）、全氮（TN）、全磷（TP）含量及其生态化学计量特征。结果表明：同一土层SOC、TN、TP含量随着森林树种增加而增加,LG、CA 0~30 cm土层SOC平均含量显著高于CL,但与PM差异不显著,CA各土壤层TN平均含量均显著高于CL、PM,但与LG差异不显著,CA各土壤层TP平均含量显著高于CL、PM、LG;4种森林土壤SOC、TN含量随土壤深度增加而下降,呈“倒金字塔”的分布模式,但TP含量随土壤深度变化不明显,呈“圆柱体”的分布模式。LG各土壤层C：N、C：P平均比值最高,其次是PM,CA、CL最低,但4种森林同一土层N∶P平均比值差异不显著,4种森林0~30 cm土层的C∶N∶P平均比值均明显高于我国土壤C∶N∶P比值的平均值（60∶5∶1）,C∶N、C∶P、N∶P比值均随土壤深度增加而下降,不同森林之间的差异也随土壤深度增加而减弱。土壤SOC、TN、TP相互之间的耦合关系显著,C∶N、C∶P比值主要受土壤SOC含量的影响,N∶P比主要受到土壤SOC、TN含量的影响,土壤C∶P比对土壤C∶N、N∶P比值影响显著。

Concentrations of SOC, total N and total P were analyzed, and the ratios of C：N, C：P, N：P were estimated in four subtropical forests： Cunninghamia lanceolata plantation forest （CL）, Pinus massoniana-Lithocarpus glaber mixed forest （PM）, Choerospondias axillaries deciduous broad leaved forest （CA）, and L. glaber-Cyclobalanopsis glauca evergreen broad-leaved forest （LG） in Dashanchong Forest Park in Changsha County, Hunan Province, China. The results showed that concentrations of soil organic C, total N, total P increased in the same soil layers with forest tree species increase, the average concentrations of soil organic C in 0-30cm soil layer of LG, CA were significantly higher than that in CL, but there were no significant differences between CL, CA, LG and PM. Average concentrations of total N in CA were significantly higher than those in CL and PM, but there were no significant differences between CA and LG. Average concentrations of total P in CA were significantly higher than those in CL, PM, and LG. Concentrations of soil organic C and total N decreased with the increase of soil depth in four forests, showed ＂inverted Pyramid＂ distribution pattern, however, total P content was no obviously change with the increase of soil depth, appeared ＂cylinder＂ distribution pattern. The average ratios of C：N, C：P of LG were the highest, followed by PM, the lowest was found in CA and CL, however the average ratio of N：P in the same soil layer of four forests had no significant difference. The average ratios of C：N：P in 0-30cm soil layer in CL, PM, CA and LG were significantly higher than that in China （60：5：1）, the ratios of C：N, C：P, N：P and their differences decreased with the increase of soil depth. The correlations between soil organic C, total N and total P was significant, the ratios of C：N, C：P were mostly influenced by the content of organic C, the N：P ratio was mostly influenced by the content of organic C, total N, and the ratios of C：N, N：P were significantly influenced by the ratio of C：P.