黄土高原洞子沟流域植被自然恢复年限对土壤氮素的影响

Effects on Soil Nitrogen of Natural Recovery Period in Dongzigou Basin of Loess Plateau

[目的]为了探究自然植被恢复对黄土高原土壤退化修复的影响,分析自然植被恢复年限、土壤土层等因素对土壤氮素的影响。[方法]以黄土高原洞子沟流域土壤氮素为研究对象,测定流域内南北坡不同植被恢复年限土壤不同层次（0~10、10~20 cm）的3种氮素形态（有机氮、铵态氮和硝态氮）含量,并且探讨各氮素间相互关系。[结果]随着恢复年限的增加,3种土壤氮素整体上持续增长,其中南坡表现为自然恢复60年〉自然恢复30年〉自然恢复10年,且有机氮含量的增加最明显,增长了3.07倍,北坡土壤氮素含量表现为自然恢复100年〉自然恢复60年〉自然恢复10年〉退耕2年,同时硝态氮的增加最明显,增加了13.19倍;氮素的各形态之间均存在极显著的相关关系,相关系数均介于0.50~0.94之间;随着植被恢复年限的增加,不同形态氮素的含量在总氮中所占比例呈现小幅度的波动,但总体上基本保持稳定。[结论]该研究可以为黄土高原地区植被恢复与生态保护提供科学理论依据。

[ Objective] The research aimed to explore the effects of natural vegetation restoration on remediation of soil degradation in Loess Plateau, and analyze the effects of factors such as years of natural vegetation restoration and soil horizon on soil nitrogen. [ Method] Taken the soil nitrogen in Loess Plateau of Dongzigou Basin as the research object, soil samples from 0 - 10 cm and 10 -20 cm depths were collected in Dongzigou basin and analyzed to determine soil N content （soil organic-N, ammonium-N, nitrate-N）. [ Result] Along with natural recovery, three kinds of soil nitrogen increased gradually in general, which manifested in the south slope was that natural recovery of 60 years 〉 natural recovery of 30 years 〉 natural recovery of 10 years, and organic nitrogen increased the most significantly by 3.07 times. North slope showed that natural recovery to 100 years 〉 natural＇recovery to 60 years 〉 natural recovery to 10 years 〉 abandoned 2 years, and nitrate nitrogen in- creased the most significantly by 13.19 times. A significant positive correlation was found among the three kinds of soil nitrogen, and the correlation coefficient ranged from 0.50 to 0.94. The proportion of content of different nitrogen forms in the total nitrogen showed a small amplitude fluctuations ,but remained stable overall. [ ConclusionI The research could provide the scientific basis for vegetation restoration in Loess Plateau Area and ecological protection.