山西省油松林生态系统碳氮磷化学计量特征

Stoichiometry of Carbon,Nitrogen and Phosphorus in Pinus tabulaeformis Carr.Forest Ecosystems in Shanxi Province,China

为了评价山西省油松林生态系统的生态化学计量特征,以山西省油松人工幼龄林(AY)、人工中龄林(AM)、天然幼龄林(NY)和天然中龄林(NM)为研究对象,通过38块标准地实测数据,探讨了4种森林类型的化学计量特征。结果显示:1)AY,AM,NY和NM乔木叶片的C∶N∶P分别为276∶8∶1,283∶8∶1,458∶12∶1和362∶11∶1,灌木叶片的C∶N∶P分别为181∶11∶1,132∶8∶1,228∶9∶1和221∶15∶1,草本叶片的C∶N∶P分别为211∶8∶1,200∶9∶1,190∶8∶1和230∶11∶1,凋落物的C∶N∶P分别为347∶3∶1,246∶5∶1,507∶9∶1和327∶9∶1,土壤(0—100cm)的C∶N∶P分别为23∶6∶1,37∶7∶1,28∶6∶1和30∶5∶1;2)4种类型的C∶N和C∶P基本都表现为凋落物>叶片>土壤,凋落物和叶片的C∶N和C∶P表现为AY>AM,NY>NM,土壤的C∶N和C∶P则为AM>AY,NM>NY,而N∶P则表现为叶片>凋落物>土壤,在林龄上表现规律不明显,植物叶片N∶P<14,存在N限制;3)4种类型植物叶片C∶P均表现为乔木叶片>草本叶片>灌木叶片,表明油松林生态系统中乔木叶建成效率最高,而灌木叶建成效率最低;4)4种类型土壤层随着土层厚度的增加,C∶N表现出下降规律,C∶P和N∶P规律表现不明显。研究结果表明,4种生态系统的叶片、凋落物和土壤的化学计量特征具有一致性。

This paper reports the stoichiometry of carbon∶nitrogen∶phosphorus（C∶N∶P）in four age groups of Pinus tabulaeformis Carr.（also called Chinese pine）forest（artificial young forest,AY;artificial middle-aged forest,AM;natural young forest,NY;natural middle-aged forest,NM）in Shanxi Province,China.The results revealed the followings：（1）The mass-based average C∶N∶P ratios of tree species（shrubs,herbs,litter,soil depth of 100cm）for the four forest types were 276∶8∶1in AY,283∶8∶1in AM,458∶12∶1in NY,and 362∶11∶1in NM.（2）Regardless of forest ages,the C∶N and C∶P ratios decreased in the order,litter〉leaves〉soil.The C∶N and C∶P ratios were both greater in the litter and leaves of young forest trees than in the litter and leaves of middle-aged forest trees,and greater in the soil of middle-aged forest than in the soil of young forest.The N∶P ratio was greater in leaves than in litter,and greater in litter than in the soil,and showed variation according to stand ages.For all the species in the forests,the N∶P ratio was consistently less than 14,suggesting that there was N limitation.（3）The C∶P ratio for the leaves of plants growing in the four forest types decreased in the order,arbor leaf〉herb leaf〉shrub leaf.（4）The C∶N ratio decreased with the increase of soil depth,whereas both the C∶P and N∶P ratios did not show a consistent variation trend along soil depth.（5）The foliar C∶N∶P stoichiometry of plants in the forests did not exhibit a consistent variation trend with stand ages.