南亚热带中幼龄针阔混交林生态化学计量特征

为了解南亚热带中幼龄针阔混交林植物、凋落物和土壤生态化学计量特征，本研究以10-11 a、7-9 a和3-5 a林龄人工针阔混交林为研究对象，通过对植物叶片（乔木、灌木和草本）、凋落物及土壤的碳（C）、氮（N）和磷（P）含量及计量比分析，探讨了中幼龄针阔混交林生态化学计量特征、相互关系及其N、P养分限制。结果表明，1）针阔混交林乔木、灌木和草本叶片碳含量均值分别为502.88、472.18和438.31 mg·g-1，其叶片碳含量表现为乔木〉灌木〉草本；叶片全氮含量均值分别为15.87、19.61和15.72 mg·g-1，叶片全磷含量均值为1-09、1.24和0.91 mg·g-1，其叶片氮和磷含量均表现为灌木〉乔木〉草本；凋落物碳、氮和磷含量均值分别为497-07、11-36和0.45 mg·g-1，凋落物氮和磷含量均低于植物。2）针阔混交林乔木叶片C/N、C/P和N/P均值分别为34.43、517-06和15.63，灌木和草本叶片C/N、C/P和N/P均值分别为26.60和28.55、438.77和507.59、16.52和17.95，而凋落物C/N、C/P和N/P为46.50、1193.26和26.17；不同林龄杉木叶片N/P均低于14，表明杉木生长受N限制；10-11 a林龄阔叶树生长受N的限制，7-9 a和3-5 a林龄阔叶树生长受P的限制，灌木和草本生长基本受P限制。3）植物叶片全氮和全磷含量呈极显著正相关（P〈0.01），C/N与C/P呈极显著正相关（P〈0.01），而全磷含量与C/N、C/P、N/P呈极显著和显著负相关（P〈0.01，P〈0-05）；土壤有机碳含量与土壤全氮含量、C/P、N/P呈极显著和显著正相关（P〈0.01，P〈0-05）。本研究为中幼龄人工林抚育及可持续经营提供科学参考。

Ecological Stoichiometry Characteristics of Young-and-middle Aged Conifer-broadleaved Plantation in Southern Subtropical Region

Our objective was to understand the differences of ecological stoichiometry characteristics of plants, litter and soil of conifer-broadleaved plantation in Southern subtropical region. Conifer-broadleaved plantation belonging to different forest ages （10-11 years, 7-9 years and 3-5 years） were selected, and carbon （C）, nitrogen （N） and phosphorus （P） contents and stoichiometry of plant leaves （trees, shrubs and herbs）, litter and soil were measured, aimed to investigate ecological stoichiometry characteristics, relationships and N, P nutrient limitation of young-and-middle aged conifer-broadleaved plantation. The present results showed that the mean values of leaves C content in trees, shrubs and herbs were 502.88, 472.18 and 438.31 mg＆#183;g-1, respectively, and C content of leaves showed tree〉shrub〉herb, and the mean values of leaves N content in trees, shrubs and herbs were 15.87, 19.61 and 15.72 mg/g, respectively, and the mean values of leaves P content in trees, shrubs and herbs were 1-09, 1.24 and 0.91 mg＆#183;g-1, respectively, and N and P contents of leaves showed shrub〉tree〉herb. Mean values of plant C, N and P contents in litter were 497-07, 11-36 and 0.45 mg＆#183;g-1, respectively, and N and P of litter were lower than those in plants （trees, shrubs and herbs）. The C：N, C：P and N：P of tree leaves were 34.43, 517-06 and 15.63, respectively, C：N, C：P and N：P of shrubs and herbs leaves were 26.60 and 28.55, 438.77 and 507.55, 16.52 and 17.95, respectively, while C：N, C：P and N：P of litter were 46.50, 1193.26 and 26.17. Although leaves N：P ratios indicated that Cunninghamia lanceolata with young age was N limited, and broad-leaved trees with 10-11 years ages were N limited, broad-leaved trees with 7-9 years and 3-5 years ages were P limited, shrub and herb were P limited. The total N content of plant leaves was significantly positively correlated with total P content of plant leaves （P〈0.01）, while the total P content of plant leaves was sign