祁连山哈溪林区移植前后土壤氮对比研究

研究不同海拔梯度森林土壤氮的分布特征,对于合理利用森林资源、改善森林的生态功能都有重要意义。采用封顶埋管法,对祁连山东段哈溪林区不同海拔梯度和不同植被类型的土壤氮进行了研究。结果表明:(1)海拔2 650m青海云杉林土壤的初始TN,NH_4~+-N和NO_3~--N含量均最低,海拔2 950 m青海云杉林土壤的初始TN,NH_4~+-N和NO_3~--N含量均最高;各海拔梯度青海云杉林土壤经培养后,其TN,NH_4~+-N和NO_3~--N含量均减小。(2)就不同植被类型而言,青海云杉林土壤TN,NH_4~+-N和NO_3~--N含量均最高,草地和灌丛土壤TN,NH_4~+-N和NO_3~--N含量较低,且二者差异不大。草地和灌丛土壤培养后TN和NH_4~+-N含量显著升高,NO_3~--N含量变化不大。(3)某一海拔青海云杉林土壤移植到其他海拔青海云杉林培养后,土壤TN,NH_4~+-N和NO_3~--N含量变化不大;不同植被类型之间土壤相互移植培养后,土壤TN,NH_4~+-N和NO_3~--N含量变化明显,不同植被类型对土壤氮的含量差异显著。

Research on Soil Nitrogen After Transplant in Haxi Forest of Qilian Mountains

Study of the distribution characteristics of soil nitrogen at different elevations is a significant effect for reasonably utilizing forest resources and improving ecology function of forest.The soil nitrogen of Picea crassifolia forest at different elevations and the soil nitrogen of different vegetation types were studied by close-top incubation method.The results are summarized as follows.(1) The original contents of TN,NH4+-N and NO;-N of soil in Picea crassifolia forest at elevation of 2 650 m are the lowest;nevertheless,they are the highest at elevation of 2 950 m.The contents of TN,NH4+-N and NO3--N of soils in Picea crassifolia forests at different elevations decrease after the soils are incubated at primary position.(2) For the different vegetation types,the contents of TN,NH4+-N and NO3--N of Picea crassifolia forest are the highest,but they are lower at shrubs and grassland in which the content differences are not significant.The contents of TN and NH4+-N of soils in shrubs and grassland increase after the soils are incubated at primary position.The contents of NO3--N of soils in shrubs and grassland are stable.(3) The contents of TN,NH4+-N and NO3--N of soil Picea crassifolia forest at a certain elevation are stable when they are moved to other elevation.But these contents of nitrogen significantly vary when soils are moved to different vegetation types.It shows that vegetation type is one of the most critical factors influencing soil nitrogen.The contents of soil nitrogen in different vegetation types are significantly different.