小叶锦鸡儿灌丛对草地土壤固氮微生物群落的影响  

Effects of Caragana microphylla shrubs on the soil nitrogen-fixing microbial communities in steppe land

作　　者：王春雯 赵芳 张晨 解李娜 马成仓 WANG Chun-wen;ZHAO Fang;ZHANG Chen;XIE Li-na;MA Cheng-cang(Tianjin Key Laboratory of Animal and Plant Resistance,College of Life Sciences,Tianjin Normal University,Tianjin 300387,China)

机构地区：[1]天津师范大学生命科学学院,天津市动植物抗性重点实验室,天津300387

出　　处：《草业学报》2022年第10期28-40,共13页Acta Prataculturae Sinica

基　　金：国家自然科学基金(31901140,31570453)资助。

摘　　要：草原灌丛化已成为全球干旱和半干旱地区的普遍现象,关于灌木扩张对草地土壤固氮微生物群落的影响及其机制尚不清楚。小叶锦鸡儿是广泛生长于内蒙古草原的豆科灌木,研究其对土壤固氮微生物群落的影响具有重要意义。本研究采用传统培养法结合分子生物学技术,比较了荒漠草原(干旱地区)和典型草原(半干旱地区)小叶锦鸡儿灌丛内外不同土壤深度固氮微生物群落的差异,并从灌丛对群落物种的选择性、灌丛沃岛效应、灌丛效应和干旱效应的相互关系等方面探讨引起这些差异的机制。结果表明:小叶锦鸡儿灌丛不仅增加了固氮微生物群落的物种丰富度和多度,而且改变了群落组成。群落组成的改变表现在37.50%~58.33%种属的多度发生显著变化、优势属及其优势地位改变、灌丛内外Jaccard相异性指数较大(0.40~0.76)和灌丛内外NMDS(非度量多维度尺度分析)群落组成排序图的分异;ANOSIM检验表明灌丛内外群落组成差异显著。灌丛对固氮微生物群落的效应随着土层深度增加而衰减,随着干旱增加而加强。灌丛对固氮微生物群落的影响大于气候干旱对其的影响。灌木小叶锦鸡儿对固氮微生物群落影响机理是:1)灌丛对固氮微生物物种具有选择性;2)灌丛通过改变土壤理化性质而影响了固氮微生物群落;3)气候干旱增强了灌丛对固氮微生物群落的影响;4)灌丛还通过缓解干旱的作用而影响固氮微生物群落。Encroachment of woody species has become a common phenomenon in arid and semi-arid grassland worldwide. However, the effects of shrubs on soil nitrogen-fixing microbial(NFM) communities and the mechanisms underlying them are poorly known. Caragana microphylla(Fabaceae)is widely distributed in the Inner Mongolian Steppe. It is important to explore the effects on NFM communities. In this paper,we compared the differences of soil NFM communities outside and within the canopy areas of shrubs in different soil horizons of desert steppe(arid zone) and typical steppe(semi-arid zone) by traditional culture methods and molecular biology techniques. Furthermore,our study explored the mechanisms underlying the shrub effects in terms of the species selectivity,fertile-island effect,and the interaction of the shrub and aridity effects. It was found that C. microphylla significantly increased the abundance and richness of NFM communities, and also affected their community composition. The change in community composition was manifested as significant variation in abundance of37. 50%-58. 33% of genera,as change in the dominant genera and their dominance position,as a large Jaccard dissimilarity index(0. 40-0. 76)for samples from outside and samples from within shrub canopies,and differences in the ordination of NMDS(non-metric multidimensional scaling)results inside and outside shrub canopies. Based on these data an‘analysis of similarity’test showed significant differences in NFM community composition outside and within shrubs. The effect of shrubs on NFM communities decreased with increasing soil depth,and increased with increasing aridity. Shrubs exerted a greater effect on NFM communities than aridity. The mechanisms underlying the C. microphylla effects on NFM communities were:1)Shrubs had a selective effect on NFM species presence;2) Shrubs affected NFM communities through soil physical and chemical characteristics;3) Climate aridity enhanced the impact of shrubs on NFM communities;4) Shrubs affected NFM communities th

关 键 词：气候干旱 固氮微生物 群落组成 沃岛效应 灌丛化 

分 类 号：S812.2[农业科学—草业科学]