祁连山大野口流域典型灌丛植物与土壤中氮磷的 化学计量特征

通过野外取样与室内分析相结合的方法,对祁连山西水林区的鬼箭锦鸡儿(Caragana jubata)、吉拉柳(Salix gilashanica)、金露梅(Potentilla fruticosa)、鲜黄小檗(Berberis diaphana)和甘青锦鸡儿(Caragana tangutica)等5种典型灌丛植物和土壤氮(N)和磷(P)含量进行了测定和分析,旨在阐明植物与土壤中N、P的化学计量特征。结果表明:(1)5种灌丛植物叶片的N、P含量均显著高于其他器官的N、P含量,N含量的变化范围为15.72~29.08 g/kg,P含量的变化范围为1.58~3.47 g/kg;细根和粗根的N含量的变化范围分别为5.11~12.20 g/kg和4.46~11.84 g/kg,P含量的变化范围分别为0.87~1.58 g/kg和0.63~2.02 g/kg;叶片N∶P值范围为7.00~9.95,细根和粗根中的N∶P值分别为5.60~8.97和5.09~8.84,叶片和根系对N、P元素有着相似的利用格局。(2)5种灌丛土壤N含量均随土层深度增加逐渐减小,不同土层N含量的变化范围为1.40~6.80 g/kg,P含量均随土层深度增加较为稳定,不同土层P含量的变化范围为0.45~0.96 g/kg;N∶P值随土层深度增加其值不断减小,主要取决于土壤N含量。0~10 cm土层中,吉拉柳、鬼箭锦鸡儿、金露梅、鲜黄小檗和甘青锦鸡儿N∶P值分别为11.02、7.30、7.41、7.40和2.69。(3)5种灌丛叶片N含量与土壤N含量呈显著或极显著正相关,与土壤P含量无显著相关(甘青锦鸡儿除外);叶片N∶P值与土壤N含量呈显著负相关,而与土壤P含量呈显著正相关;灌丛叶片和土壤N、P含量及化学计量比与其他变量之间均无显著相关。同时研究还发现,祁连山5种典型灌丛生长可能主要受N素限制。

Nitrogen and Phosphorus Stoichiometry of Plants and Soils of Typical Shrubs in Dayekou Basin of Qilian Mountains

The N and P contents of plants and soils of five typical shrub communities (Caragana jubata,Salix gilashanica, Potentilla fruticosa,Berberis diaphanaandCaragana tangutica) in the Xishui forest zone of the Qilian Mountains were measured and analyzed by field investigation and laboratory analysis, and the stoichiometry of N and P in the plants and soils of five shrubs were also clarified. The results showed that: 1) N and P contents in the leaves were significantly higher than those in the other organs of five shrubs, N and P contents of the leaves ranged from 15.72 to 29.08 g/kg and 1.58 to 3.47 g/kg, respectively. N contents in fine roots and thick roots ranged from 5.11 to 12.20 g/kg and 4.46 to 11.84 g/kg, respectively, P contents in fine roots and thick roots ranged from 0.87 to 1.58 g/kg and 0.63 to 2.02 g/kg, respectively. N:P ratio of leaves ranged from 7.00 to 9.95, N:P ratios of fine roots and thick roots ranged from 5.60 to 8.97 and 5.09 to 8.84, respectively. N and P in leaves and roots had similar use pattern. 2) N content in soil increased with the decrease of soil depth in five shrubs, N and P contents in soils at different layers ranged from 1.40 to 6.80 g/kg and 0.45 to 0.96 g/kg, respectively. N:P ratio, mainly dependent on N content, decreased with the increase of soil depth. N:P ratios ofSalix gilashanica, Caragana jubata,Potentilla fruticosa,Berberis diaphanaandCaragana tanguticawere 11.02, 7.30, 7.41, 7.40 and 2.69, respectively at 0-10 cm soil layers. 3) Significant or extremely significant positive correlations appeared between N contents in the leaves and in the soils, while no significant correlations occurred between P contents in the leaves and in the soils (exceptCaragana tangutica). N:P ratio of the leaves was significantly negatively correlated with soil N content while was significantly positively correlated with soil P content. N and P contents and stoichiometric ratios had no significant correlations with other variables of leaves and soils. Furthermore, the study also found that nitrogen may be a limiting factor for the growth and development of five shrubs in the Qilian Mountains.