不同退化程度对高寒草甸土壤无机氮及脲酶活性的影响

doi:10.11686/cyxb2018098

摘要/Abstract

摘要： 以东祁连山围封草地(FG)、轻度退化草地(LD)、中度退化草地(MD)、重度退化草地(HD)4种类型高寒草甸为研究对象,分别在春季、夏季和冬季采集各类型高寒草地0~10 cm、10~20 cm和20~30 cm土层的土壤样品,研究了土壤的无机氮总量、铵态氮(NH4+-N)、硝态氮(NO3--N)含量及土壤脲酶活性,以明确不同退化程度对高寒草甸土壤无机氮和脲酶活性特征及其季节动态的影响。结果表明,草地退化对表层土壤的无机氮总量影响较大,春季和夏季3种不同退化程度高寒草地土壤无机氮总量均显著升高,春季LD、MD和HD分别比FG升高了39.9%、28.9%和68.4%,夏季分别升高了19.1%、28.7%和33.6%,但冬季却显著降低,LD、MD和HD分别比FG降低了20.4%、27.2%和47.4%。土壤无机氮形态的研究结果表明草地退化对土壤无机氮形态的效应存在季节差异,草地退化导致春季表层土壤铵态氮含量升高,而对硝态氮含量影响不大,从而导致土壤无机氮总量升高,而夏季情况正好相反,草地退化对夏季表层土壤的铵态氮含量影响不大,而硝态氮含量升高,同样导致土壤无机氮总量升高。草地退化对脲酶活性的影响同样存在季节差异,相比FG,春季LD 和MD的表层土壤脲酶活性显著提高, HD下降,而夏季和冬季随着退化程度的加剧,脲酶活性均表现出逐渐升高的趋势,表明轻度和中度退化加快了春季高寒草甸土壤氮素的转化,增加了土壤无机氮的供应能力。

关键词: 草地退化, 土壤无机氮, 土壤铵态氮, 土壤硝态氮, 土壤脲酶

Abstract: Four types alpine meadow, fenced grassland (FG), lightly degraded grassland (LD), moderately degraded grassland (MD) and heavily degraded grassland (HD), were selected to study the effects of grassland degradation on soil inorganic nitrogen characteristics and their seasonal dynamics in the eastern Qilian Mountain area. Samples of the 0-10 cm, 10-20 cm and 20-30 cm soil layers were collected from the four grassland types in spring, summer and winter. Soil total inorganic nitrogen, ammonium nitrogen (NH4+-N), nitrate nitrogen (NO3--N) contents and urease activities were measured. The results showed that grassland degradation has more influence on total inorganic nitrogen contents in the surface soils than deeper layers, but these effects varied by season. Compared with FG, the total inorganic nitrogen content of LD, MD and HD soils increased by 39.9%, 28.9% and 68.4% in spring and increased by 19.1%, 28.7% and 33.6% in summer. In winter, the total inorganic nitrogen content of these three kinds of grassland decreased by 20.4%, 27.2% and 47.4% respectively. The results also showed that grassland degradation has varying effects on the forms of soil inorganic nitrogen. In spring, grassland degradation significantly increased NH4+-N content in surface soils and there was little effect on NO3--N. In summer, NO3--N content increased significantly in surface soils while there was little effect on NH4+-N content. Degradation levels were also associated with seasonal differences in soil urease activity. Compared with FG, in spring the urease activities of LD and MD soils increased while HD decreased significantly. Soil urease activity increased gradually with increased degradation levels in summer and winter, which indicates that degradation increased soil inorganic nitrogen supplication and improved the soil nitrogen conversion process.

Key words: grassland degradation, soil inorganic nitrogen, soil ammonium nitrogen (NH4+-N), soil nitrate nitrogen (NO3--N), soil urease activity

李亚娟, 刘静, 徐长林, 曹文侠. 不同退化程度对高寒草甸土壤无机氮及脲酶活性的影响[J]. 草业学报, 2018, 27(10): 45-53.

LI Ya-juan, LIU Jing, XU Chang-lin, CAO Wen-xia. Effects of different grassland degradation levels on inorganic nitrogen and urease activity in alpine meadow soils[J]. Acta Prataculturae Sinica, 2018, 27(10): 45-53.

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