不同林龄米槠更新林叶和枝碳氮磷含量及其化学计量特征

Carbon,Nitrogen and Phosphorus Concentrations in Leaves and Branches and their Stoichiometry Characteristics in Naturally Regenerated Castanopsis carlesii Forests at Different Stand Ages

在福建顺昌选择21年生、31年生和49年生米槠人工促进天然更新林,测定各个林分叶片和枝条C、N和P的含量,分析其化学生态计量特征。结果表明:1)不同林龄的林分枝和叶C含量的时空变异较小,变化范围在473.0~485.6 mg·g^(-1)之间;N含量随着林龄的增加而呈升高的趋势;而叶片和枝条P含量随林龄变化的趋势不明显;2)不同林龄人工促进天然更新林C∶P平均值为809.5,是中国东部南北样带森林(313.9)和全球森林(300.9)的2.6和2.7倍;N∶P均值为30.1,是中国东部南北样带(11.5)、中国平均(18.0)和全球平均(13.8)的2.6倍、1.7倍和2.2倍。较高的N∶P表明研究区域受P限制,同时人工促进天然更新林较高的C∶P表明该森林能够在低P条件下提高P的利用率,以维持林木的生长。

A chronosequence of 21-, 31- and 49-year-old assisted naturally regenerated forests were selected to measure carbon （ C） , nitrogen （ N） and phosphorus （ P） concentrations in leaves and bran-ches and to analyze their stoichiometry characteristics. Results indicated that： （ 1 ） the C concentra-tions varied slightly among three forests, ranging from 473. 0 mg · g-1 to 485. 6 mg · g-1 , while N concentrations increased with stand age. No clear tendency were found for P concentrations among three forests;（2） C∶P in leaves in assisted naturally regenerated forests were 2. 6 and 2. 7 times of the average value of forests in Eastern China and global value, and N∶P in leaved were 2. 6, 1. 7 and 2. 2 times of the average value of the forests in Eastern China, the whole nation and global value, indicating that the productivity of the research area is limited by P and a higher P utilization could be presumed in assisted naturally regenerated forests to maintain tree growth.