【摘要】 在马尾松纯林及其与阔叶树混交林生态系统中,对乔木层、林下植被层和森林地被物层的主要养分元素含量进行了系统的分析 结果表明:①N在乔木层中的含量最小,而在林下植被层中则普遍较高;P、K的含量大小在各植被层中表现为:林下植被层>乔木层>地被物层;Ca、Mg则在地被物层中的含量最高 ②在乔木层中,Ca含量最高,Mg的含量最低,而N、P、K的含量则随器官不同而异,但表现出一致的趋势,即叶>枝>根>皮>干 ③马尾松与阔叶树的养分含量存在一定差异,N在阔叶树叶片中的含量普遍高于马尾松,P、K在阔叶树叶片和根系中的含量大于马尾松,而在树皮中的含量则相反 ④不论是马尾松还是阔叶树,N的含量随林木根系径级增大而下降(细根>中根>粗根) ⑤森林地被物层中各养分元素的含量在群落和组分之间存在明显差异,但总的趋势表现为Ca>N>Mg或K>P.更多还原

【Abstract】 Chemical analyses of five nutrient elements (N,P,K,Ca,and Mg) for the arbor,undergrowth,and forest floor were conducted in the pure Pinus massoniana stand and its mixed forests with hardwood species. The major results are as follows:① For N,the lowest concentration occurred in the arbor,the highest in the undergrowth;for P and K,the concentrations decreased in the order:undergrowth>arbor>forest floor and;for Ca and Mg,the forest floor had the highest. ② In the arbor layer,the concentration of Ca was the highest and Mg the lowest;for N,P,and K,the concentrations differed with the organs,but showing the consistent trends:leaf>branch>root>bark>stem. ③ Nutrient concentrations exhibited some difference between Pinus massoniana and the hardwoods,with hardwoods having the higher N in the leaves,and higher P and K in the leaves and roots. ④ For both of Pinus massoniana and hardwood species,the N concentrations decreased with the increased diameter classes of the roots. ⑤ Significant differences in nutrient concentrations existed between forest communities and litter components,but the elements consistently revealed the same trend,decreasing in the order:Ca>N>Mg or K>P.更多还原