三江源地区高寒湿地土壤微生物生物量碳氮磷及其化学计量特征

Soil microbial biomass carbon,nitrogen,phosphorus and their stoichiometric characteristics in alpine wetlands in the Three Rivers Sources Region

微生物生物量及其化学计量特征是土壤养分循环的重要参数,对预测气候变化和提高模型准确性及理解陆地生态系统养分循环都起到重要作用。为了明晰高寒生态系统土壤微生物生物量碳(MBC)、微生物生物量氮(MBN)、微生物生物量磷(MBP)浓度及其化学计量特征,该研究通过在三江源区高寒湿地连续两年的野外调查和室内培养,分析了50个样点的数据,探究三江源高寒湿地MBC、MBN、MBP浓度及其化学计量特征,明确了土壤理化特性和微生物群落特征对其影响。结果表明:(1)三江源高寒湿地MBC、MBN和MBP浓度分别为105.11、3.79和0.78mmol·kg^(-1),MBC:MBN、MBC:MBP、MBN:MBP和MBC:MBN:MBP分别为50.56、184.89、5.42和275:5:1。高寒湿地土壤的MBC浓度显著高于高寒草甸土壤,而MBN和MBP浓度在高寒湿地和高寒草甸土壤之间没有显著差异;高寒湿地土壤的MBC:MBN和MBC:MBP显著高于高寒草甸土壤,而MBN:MBP在高寒湿地和高寒草甸土壤之间差异不显著。(2)土壤理化特性与MBC、MBN和MBP浓度具有显著相关性。土壤含水率与MBC:MBN和MBC:MBP存在显著负相关关系,而土壤密度与MBC:MBN和MBC:MBP浓度存在显著正相关关系,土壤全氮含量和MBC:MBP存在显著负相关关系,而与MBC:MBN的相关关系不显著。土壤理化特性对MBN:MBP的影响不显著。(3)整体而言,微生物群落结构与MBC、MBN和MBP浓度之间存在显著的相关性。微生物群落结构和MBC:MBN、MBC:MBP的关系是相似的,总磷脂脂肪酸(PLFA)含量、革兰氏阳性菌、革兰氏阴性菌、细菌、放线菌、丛枝菌根真菌浓度和其他PLFA含量与MBC:MBN和MBC:MBP存在显著负相关关系,而真菌:细菌与MBC:MBN和MBC:MBP之间存在显著正相关关系,真菌浓度与MBC:MBN和MBC:MBP之间的相关关系不显著。除丛枝菌根真菌外,MBN:MBP与微生物群落结构均无显著相关关系。

Aims Microbial biomass and their stoichiometric characteristics not only are important parameters of soil nutrient cycling,but also can contribute to prediction of climate changes,improvement of model accuracy,and understanding of terrestrial nutrient cycling.Our objective was to investigate microbial biomass carbon(MBC),microbial biomass nitrogen(MBN),and microbial biomass phosphorus(MBP)concentrations and their stoichiometric characteristics in alpine wetlands in the Three Rivers Sources Region.Methods Using data from 50 sites,we explored MBC,MBN,MBP,their stoichiometry and their relationships with the controlling factors of alpine wetlands in the Three Rivers Source Region.Important findings Our results showed that 1)MBC,MBN,MBP concentrations were 105.11,3.79,0.78 mmol·kg^(-1),respectively,and MBC:MBN,MBC:MBP,MBN:MBP,MBC:MBN:MBP were 50.56,184.89,5.42,275:5:1,respectively.2)Soil physical and chemical properties could significantly affect MBC,MBN and MBP concentration.Soil moisture had significantly negative effects on both MBC:MBN and MBC:MBP,while soil density had positive effects on both MBC:MBN and MBC:MBP.Soil total nitrogen content had negative relationship with MBC:MBP,while having weak effects on MBC:MBN.Soil physical and chemical properties also had weak effects on MBN:MBP.3)Generally,soil microbial community composition had significant effects on MBC,MBN and MBP concentration.Soil microbial community composition had similar effects on MBC:MBN and MBC:MBP.Total phospholipid fatty acid(PLFA)content,gram-positive bacteria,gram-negative bacteria,bacteria,actinomycete,arbuscular mycorrhizal fungi concentration,and other PLFA content had negative effects on MBC:MBN and MBC:MBP,while fungi:bacteria had positive effects on both MBC:MBN and MBC:MBP,but fungi had weak relationships with both MBC:MBN and MBC:MBP.Except for arbuscular mycorrhizal fungi,MBN:MBP had weak relationships with soil microbial community composition.Soil physical and chemical properties,and soil microbial community composition had significant effects on soil microbial biomass and their stoichiometric characteristics in Three Rivers Sources Regions in the alpine wetlands,which are greatly helpful for deeply understanding of terrestrial high altitude nutrient cycling.