石漠化土壤碳矿速率对丛枝菌根真菌接种的响应

Response of Soil Carbon Mineral Rate in Rocky Desertification to Arbuscular Mycorrhizal Fungi Inoculation

为探明丛枝菌根(Arbuscular mycorrhiza,AM)真菌接种对石漠化土壤碳矿化影响的过程及机制,选择圆柏(Sabina chinensis)为供试寄主植物,分别接种幼套近明球囊霉(Claroideoglomus etunicatum,CE)、摩西斗管囊霉(Funneliformis mosseae,FM)、根内根孢囊霉(Rhizophagus intraradices,RI),设对照处理(无AM真菌,CK),采用室内需氧培养法测定不同处理土壤碳矿化速率的时空变化,分析其与根系侵染状况、微生物生物量碳氮和土壤性质的关系。结果表明,1)3种AM真菌接种对土壤碳矿化速率的影响存在差异。CE处理下的碳矿化速率(13.1 mg·kg^(-1)·d^(-1))高于RI(11.7 mg·kg^(-1)·d^(-1))和FM(9.7 mg·kg^(-1)·d^(-1));3种AM真菌处理下碳矿化速率均表现为湿季大于干季,沿土层加深而减小,随季节和土层的变幅均呈现CE>RI>FM的特征。2)AM真菌接种显著提高根系侵染率、菌丝侵染密度、土壤碳氮磷组分和水分含量,其提升率变幅范围为16.4%-81.6%。3)AM真菌接种引起土壤微生物量碳和氮含量变化显著影响碳矿化,其对碳矿化速率的解释量大小为:CE(93.3%､87.6%)>RI(86.4%､80.7%)>FM(81.1%､75.1%)>CK(65.2%、67.6%)。4)AM真菌处理下碳矿化速率与根系侵染率、菌丝侵染密度、易氧化碳、有机碳、全磷、全氮和含水率呈显著正相关,与容重和pH呈显著负相关;主成分结果表明,易氧化有机碳、微生物量碳氮、容重是土壤碳矿化速率的主要影响因子。因此,AM真菌共生主要通过改变碳组分、微生物量氮及土壤紧密度,进而促进云南石漠化土壤碳矿化速率。

This study aimed to explore the process and mechanism of arbuscular mycorrhizal(AM)fungal inoculation affecting soil carbon mineralization.Sabina chinensis was selected as host plant to inoculate separately with Claroideoglomus etunicatum,Funneliformes mosseae,and Rhizophagus intraradices,using no AM fungal inoculation as a control(CK).The indoor aerobic cultivation method was used to determine the spatiotemporal changes of carbon mineralization rate in different treatments.We also determine the linkage of soil carbon mineralization with root infection,microbial carbon and nitrogen,and physicochemical properties.This results were as follows:1)Three AM fungal inoculation had different effects on soil carbon mineralization.The mineralization rates were higher in the CE treatment(13.1 mg·kg^(-1)·d^(-1))than in the treatments of RI(11.7 mg·kg^(-1)·d^(-1))and FM(9.7 mg·kg^(-1)·d^(-1)).Soil carbon mineralization rates in the AM fungi treatments were higher in the wet season than in the dry season and decreased along with soil profile.They were ranked as CE>RI>FM across different seasons and soil layers.2)AM fungal inoculation significantly increased the values of root colonization,hyphal length density,soil carbon,nitrogen,phosphorus pools and water content,the magnitude order of its improvement rate was 16.4%–81.6%.3)Soil carbon mineralization was significantly affected by changes in soil microbial carbon and nitrogen induced by AM fungi inoculation.The order of the extent of soil microbial carbon and nitrogen in explaining carbon mineralization change was CE(93.3%,87.6%)>RI(86.4%,80.7%)>FM(81.1%,75.1%)>CK(65.2%,67.6%).4)The carbon mineralization rates in three AM fungal treatments were positively correlated with root colonization,hyphal length density,easily oxidizable carbon,total organic carbon,total phosphorus,total nitrogen and soil water content,while they were negatively correlated with bulk density and pH.The principal component analysis showed that soil readily oxidizable carbon,microbial biomass carbon and nitrogen and bulk density were the main factors influencing carbon mineralization rate.Therefore,AM fungal symbiosis promoted soil carbon mineralization primarily through altering carbon components,microbial biomass nitrogen,and soil compactness in Yunnan rocky desertification area.