摘要
以黄河三角洲翅碱蓬(重度盐渍土S1)、柽柳(中度盐渍土S2)、荻(轻度盐渍土S3)和苦楝(非盐渍土S4)四种不同生境土壤为研究对象,探究从近海到内陆土壤环境和细菌群落结构的变化以及二者之间的耦合关系,并识别各生态系统微生物网络中的关键物种及其功能。结果表明:从近海到内陆随生态系统的变化,电导率(EC)是土壤性质变化最大的参数,依次降低;随盐碱程度降低,土壤硝态氮(NO_(3)^(-)-N)和微生物生物量碳(MBC)含量明显升高,土壤有机碳(SOC)和全氮(TN)含量逐渐增加,但全钾(TK)、速效钾(AK)和有效磷(AP)含量则有降低趋势。四种生境土壤的细菌群落均以变形菌(Proteobacteria)、浮霉菌(Planctomycetes)和放线菌(Actinobacteria)为主,S1样品的细菌群落组成与其他三种土壤样品明显不同,存在更多的特异优势属(Woeseia等),而S2~S4样品则有更多的共性优势属(类诺卡氏菌属Nocardioides等)。四种土壤样品均有独特的关键物种,包括S1样品中具有解磷功能的弧菌属(Vibrio)和铁还原功能的Geothermobacter,S2样品中具有促进硝化过程的Candidatus_Entotheonella和化能异养微生物Amaricoccus,S3样品中的甲基营养型嗜盐菌Methyloceanibacter和抑病菌Luteolibacter,S4样品中具有生物固氮功能的无色杆菌属(Achromobacter)和促进有机物分解的出芽菌属(Gemmata)。对微生物群落结构变化解释率最高的土壤性质包括MBC(62.5%)、EC(11.7%)和AP(6.5%)。四种生境样品的大多数关键物种与EC和NO_(3)^(-)-N呈显著负相关,而与AK呈显著正相关。以上结果表明,微生物生物量对生态系统的变化有很高的敏感性,盐渍化并不一定引起土壤质量的全面退化,但对细菌群落结构和生态系统中的关键物种都有明显影响;在考虑生态系统功能时应关注微生物网络中的关键物种。
The relationship between soil salinization and properties and their interactions with microbial communities and functions are important for understanding the biogeochemical cycles and ecosystem function regulation in saline wetlands.However,the impacts of salinity on soil functions remain elusive.The keystone taxa and their function in various saline habitats are not fully understood.In this study,soil samples were collected from four different habitats from the coast to the inland region in the Yellow River Delta:High salinity(S1),moderate salinity(S2),low salinity(S3),and non-saline soils(S4).The four habitat soils displayed decreasing salinity from the coast moving toward the inland.In addition to electrical conductivity(EC),other soil properties,including soil nutrients and microbial biomass carbon(MBC),were determined.The bacterial diversity and structure were investigated with 16S rRNA gene sequencing to identify the keystone species in the specific habitat.Results showed that EC,representing salinity,varied most among the soil properties from the coast to the inland.As salinity decreased,the contents of NO_(3)^(-)-N and MBC considerably increased,and those of soil organic carbon(SOC)and total nitrogen(TN)gradually increased,whereas the contents of total potassium(TK),available potassium(AK),and available phosphorus(AP)were significantly decreased.The bacterial communities in the four different habitats were always dominated by Proteobacteria,Planctomycetes,and Actinobacteria,accounting for a relative abundance above 60%.The bacterial communities in S1 samples greatly differed from those in the other three habitats,with more specialist abundant genera in S1 samples and more abundant genera shared among the other three habitats.More importantly,each habitat soil featured specialist keystone taxa.For the S1 samples,the keystone species included OTU002085(phosphate-solubilizing bacteria Vibrio)and OTU000979(Geothermobacter involved in dissimilatory Fe(Ⅲ)reduction).For the S2 samples,the keystone species included OTU000585(Candidatus_Entotheonella)and OTU000199(Amaricoccus);Candidatus_Entotheonella can promote nitrification,whereas Amaricoccus can degrade complex organic matter.For the S3 samples,the keystone species included OTU000015(Methyloceanibacter)and OTU000138(Luteolibacter).Methyloceanibacter was a key player in the global carbon cycle and Luteolibacter inhibits pathogens.For the S4 samples,the keystone species included OTU001724(Achromobacter)and OTU000841(Gemmata).Achromobacter species were efficient in biological nitrogen fixation,and Gemmata elevated urease activity to increase organic matter decomposition.Most of these keystone OTUs were significantly negatively correlated with EC and NO_(3)_(-)-N content,and positively correlated with AK content.For the total bacterial community,MBC was the most influencing factor,which explained 62.5%of the variation,followed by EC(11.7%)and AP(6.5%),as revealed using multiple regression tree analysis(MRT).These results indicate that the microbial biomass is extremely sensitive to variations in habitats with different salinity.Salinization does not necessarily lead to complete land degradation but has strong influence on the composition of soil bacterial communities,especially of the keystone taxa.Therefore,the keystone taxa should be considered to assess the ecosystem function.
作者
吴桐桐
徐基胜
周云鹏
陈美淇
周谈坛
郭伟
陈金林
赵炳梓
WU Tongtong;XU Jisheng;ZHOU Yunpeng;CHEN Meiqi;ZHOU Tantan;GUO Wei;CHEN Jinlin;ZHAO Bingzi(Co-Innovation Center for Sustainable Forestry in Southern China,Nanjing Forestry University,Nanjing 210037,China;State Experimental Station of Agro-Ecosystem in Fengqiu,State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008,China)
出处
《农业环境科学学报》
CAS
CSCD
北大核心
2022年第10期2250-2261,共12页
Journal of Agro-Environment Science
基金
江苏省自然科学基金项目(BK20191105)
江苏高校优势学科建设工程项目(PAPD)
中国科学院战略性先导科技专项子课题(XDA24020104)
国家自然科学基金项目(41907090)
财政部和农业农村部“中国现代农业产业技术体系”项目(CARS-03)。
关键词
黄河三角洲
盐渍化
翅碱蓬
生态网络
关键物种
Yellow River Delta
salinization
Suaeda salsa
ecological network
keystone taxa
