文献类型：期刊文献

中文题名：大兴安岭南缘林草过渡区放牧对土壤氮素含量的影响

英文题名：Effects of Grazing on Soil Nitrogen Content in the Forest-steppe Ecotone on the Southern Edge of the Greater Khingan Mountains

作者：乌日娜[1] 马帅[1] 兰岚[2] 田佳鹏[3] 丁伟[4] 周志军[4] 王明达[5] 毕连才[5] 王陇[3]

第一作者：乌日娜

机构：[1]中国林业科学研究院,北京10091;[2]中国林业科学研究院生态保护与修复研究所,北京10091;[3]中国林业科学研究院林业研究所,北京10091;[4]内蒙古克什克腾旗白音敖包林场,赤峰025350;[5]内蒙古克什克腾旗林业和草原局,赤峰025350

年份：2023

卷号：3

期号：5

起止页码：48-55

中文期刊名：陆地生态系统与保护学报

外文期刊名：Terrestrial Ecosystem and Conservation

基金：国家林业和草原局林草科技创新发展与研究(2021133007);中国林业科学研究院林业研究所专项资金(1LYSZX202003)。

语种：中文

中文关键词：林草过渡区;放牧;氮素含量;阔叶混交林;针阔混交林;典型草原

外文关键词：forest-steppe ecotone;grazing;soil nitrogen content;broadleaved mixed forestry;coniferous and broadleaved mixed forestry;typical steppe

分类号：S714

摘要：【目的】明确大兴安岭南缘林草过渡区不同植被类型土壤氮素分布特征及对放牧的响应,为该地区放牧管理提供理论依据。【方法】2021年7月,在林草过渡区阔叶混交林、针阔混交林和典型草原植被类型区域分别设立采样点,每个采样点设置放牧处理和未放牧对照。放牧处理从2002年开始至今,放牧强度中等,为6~9羊单位/hm2。在每个植被类型区随机选取3个50 m×50 m的大样方,间距15 m以上。在每个大样方内沿对角线设置3个5 m×5 m的小样方,在每个小样方内用五点法采集0~10 cm土层的土样,带回实验室测定全氮、铵态氮、硝态氮和微生物生物量氮含量。【结果】1)植被类型、放牧以及交互作用(植被类型×放牧)对土壤全氮、铵态氮、硝态氮以及微生物生物量氮含量均有显著(P<0.01)或极显著(P<0.001)影响。2)研究区土壤全氮含量变化范围在0.96~6.39 g·kg^(?1),在未放牧条件下为针阔混交林>阔叶混交林>典型草原,放牧条件下为针阔混交林显著高于其他2种植被类型(P<0.05),放牧后3种植被土壤全氮含量均显著降低(P<0.05)。3)土壤铵态氮含量变化范围在0.41~4.44 mg·kg^(?1),在未放牧条件下为阔叶混交林>典型草原>针阔混交林,放牧条件下为阔叶混交林显著高于其他2种植被类型(P<0.05),放牧后3种植被均显著降低(P<0.05)。4)土壤硝态氮含量变化范围在21.47~112.13 mg·kg^(?1),在放牧条件下,其含量为针阔混交林>典型草原>阔叶混交林,放牧后在阔叶混交林和针阔混交林显著降低(P<0.05),但在典型草原显著增加(P<0.05)。5)土壤微生物生物量氮含量变化在35.08~69.57 mg·kg^(?1),未放牧条件下在植被类型之间无显著差异(P>0.05),放牧条件下为典型草原显著低于其他2种植被(P<0.05),放牧处理后的土壤微生物生物量氮含量在典型草原显著降低(P<0.05),而阔叶混交林与针阔混交林无显著变化(P>0.05)。【结论】阔叶混交林和针阔混交林的土壤全氮、铵态氮和硝态氮含量均在放牧后显著降低,而微生物生物量氮含量无显著变化;典型草原的土壤全氮、铵态氮和微生物生物量氮含量也均在放牧后显著降低,但硝态氮含量放牧后显著增加。为减少林草过渡区因放牧导致的土壤氮素损失,应当在放牧阶段合理规划放牧活动,并加强林区的科学管护。
【Objective】The purpose of this study is to clarify the distribution characteristics of soil nitrogen in different vegetation types of the forest-steppe ecotone on the southern edge of the Greater Khingan Mountains and its response to grazing.This information aims to provide a theoretical basis for grazing management in the region.【Methods】In July 2021,sampling points were established in areas representing broadleaved mixed forest,coniferous and broadleaved mixed forest,and typical steppe vegetation types within the forest-steppe ecotone.Each sampling point had both a grazing treatment and a non-grazing control.Grazing has been ongoing since 2002 at a moderate intensity of 6~9 sheep units per hectare.Three large quadrats of 50 m×50 m were randomly selected in each vegetation type area,with a spacing of more than 15 m.Within each large quadrat,three small quadrats of 5 m×5 m were set along the diagonal,and soil samples from the 0~10 cm layer were collected using a five-point method for laboratory analysis of total nitrogen,ammonium nitrogen,nitrate nitrogen,and microbial biomass nitrogen content.【Results】1)Vegetation type,grazing,and their interaction(vegetation type×grazing)significantly(P<0.01)or extremely significantly(P<0.001)affected soil total nitrogen,ammonium nitrogen,nitrate nitrogen,and microbial biomass nitrogen content.2)The range of soil total nitrogen content in the study area was 0.96~6.39 g·kg^(?1),with coniferous and broadleaved mixed forest>broadleaved mixed forest>typical steppe under non-grazing conditions,and coniferous and broadleaved mixed forest significantly higher than the other two vegetation types under grazing conditions(P<0.05);soil total nitrogen content in all three vegetation types significantly decreased after grazing(P<0.05).3)The range of soil ammonium nitrogen content was 0.41~4.44 mg·kg^(?1),with broadleaved mixed forest>typical steppe>coniferous and broadleaved mixed forest under non-grazing conditions,and broadleaved mixed forest significantly higher than the other two vegetation types under grazing conditions(P<0.05);soil ammonium nitrogen content in all three vegetation types significantly decreased after grazing(P<0.05).4)The range of soil nitrate nitrogen content was 21.47~112.13 mg·kg^(?1),with coniferous and broadleaved mixed forest>typical steppe>broadleaved mixed forest under grazing conditions;after grazing,nitrate nitrogen content significantly decreased in broadleaved mixed forest and coniferous and broadleaved mixed forest(P<0.05),but significantly increased in typical steppe(P<0.05).5)The variation in soil microbial biomass nitrogen content ranged from 35.08 to 69.57 mg·kg^(?1).Under non-grazing conditions,there was no significant difference between vegetation types(P>0.05),but under grazing conditions,typical steppe was significantly lower than the other two vegetation types(P<0.05);After grazing,soil microbial biomass nitrogen content significantly decreased in typical steppe(P<0.05),while no significant change was observed in broadleaved mixed forest and coniferous and broadleaved mixed forest(P>0.05).【Conclusion】Soil total nitrogen,ammonium nitrogen,and nitrate nitrogen content in broadleaved mixed forest and coniferous and broadleaved mixed forest significantly decreased after grazing,while microbial biomass nitrogen content showed no significant change.In typical steppe,soil total nitrogen,ammonium nitrogen,and microbial biomass nitrogen content also significantly decreased after grazing,but nitrate nitrogen content increased significantly.To reduce soil nitrogen loss in the forest-steppe ecotone due to grazing,grazing activities should be planned rationally during the grazing stage,and scientific management should be strengthened in forest areas.