【目的】运用菌根技术改良石漠化土壤性状,已成为石漠化地区植被与土壤恢复的重要生物学途径。揭示丛枝菌根(AM)真菌与植物共生驱动下石漠化土壤碳库及养分状况的变化,探明石漠化土壤易氧化碳(ROC)对土壤碳库及养分变化的响应过程及机制,为石漠化土壤的微生物修复及提高石漠化治理效率提供参考。【方法】采集云南昆明寻甸石漠化土壤,以尼泊尔桤木(Alnus nepalensis)为寄主植物,分别接种摩西斗管囊霉(Funneliformis mosseae, FM)、幼套近明球囊霉(Claroideoglomus etunicatum, CE)、根内根孢囊霉(Rhizophagus intraradices, RI),并设置对照处理(无寄主植物及无AM接种),采用高锰酸钾氧化法测定不同试验处理下土壤ROC含量,探究土壤ROC与碳库组成、养分状况及植物生长之间的相互关系。【结果】不同AM真菌均具有显著的侵染与促生效应,其中RI的侵染率与菌丝侵染密度最大,相较于对照分别提高155%和100%,并显著促进桤木树高(60%)与基径(46%)生长;不同AM真菌均显著提高ROC含量,3菌种对ROC含量的提升率大小顺序为:RI(122%)> CE(78%)> FM(61%)。ROC在土壤总有机碳库中所占比例(52%)远高于微生物生物量碳(3%~6%);3种菌种对土壤养分含量的提升效应表现为:RI > CE > FM。相较于对照,RI 菌种对植物可利用性氮、微生物生物量碳、总有机碳及植物可利用性磷的提升率分别为161%、127%、110%及97%;对ROC变化具有较大贡献的土壤环境因子分别为AM真菌侵染率(96%)、植物可利用性氮(94%)、微生物生物量碳(85%)、总有机碳(78%)及植物可利用性磷(72%)。【结论】AM真菌与尼泊尔桤木共生,显著驱动石漠化土壤碳库与养分含量变化并促进植物生长,进而增加石漠化土壤易氧化碳的积累。研究结果有助于理解石漠化地区植物生长、土壤恢复及活性有机碳沉积的微生物学调控机制。

【Objective】Mycorrhizal technology may play a critical role in improving soil nutrient conditions, becoming an important biological approach to restore vegetation and soils in rocky desert areas. Readily oxidized carbon (ROC) is sensitive in its response to altered soil variables. This study aimed to reveal changes in the organic carbon pool and soil nutrient properties driven by the symbiosis between arbuscular mycorrhizal fungi (AM) and host plants in rocky desert habitats. We also attempted to elucidate the response of ROC accumulation to these changes.【Method】We inoculated Alnus nepalensis seedlings with three AM species in rocky desert soils sampled in Xundian, Yunnan Province, China. Four treatments were established to explore the association of altered ROC concentration with changes in the carbon pool, soil nutrients, and plant growth for rocky desert habitats: (1) Funneliformis mosseae (FM); (2) Claroideoglomus etunicatum (CE); (3) Rhizophagus intraradices (RI); (4) without AM and plant (CK). The ROC concentrations in the four treatments were determined by potassium permanganate oxidation.【Result】 The symbiosis and growth of host plants were significantly enhanced in the three AM species. The RI fungi had the highest infection effectiveness; the infection rate and density of RI fungi increased by 155% and 100%, respectively, compared with the control. The RI fungi also significantly enhanced the tree height (by 60%) and base diameter (by 46%) of seedlings. Three AM fungal species increased the soil ROC concentration; this increased rate was ranked in descending order as: RI (122%) > CE (78%) > FM (61%). The ROC concentration accounted for the largest proportion in the total organic carbon (TOC) pool. The greatest proportion of ROC was 52%, which was much higher than the microbial biomass carbon (3%-6%). The improvement rate of soil nutrients by the three AM fungi was ranked in descending order as: RI > CE > FM. The RI fungi strongly increased plant available nitrogen (161%), microbial biomass carbon (127%), TOC (110%), and plant available phosphorus (97%). The infection rate of AM fungi (96%), plant available nitrogen (94%), microbial biomass carbon (85%), TOC (78%), and plant available phosphorus (72%) obviously contributed to ROC changes. 【Conclusion】 The data indicate that the symbiosis of AM fungi with A. nepalensis can induce alterations in the soil carbon pool and nutrient properties alongside improving plant growth; this drives the accumulation of oxidized organic carbon in rocky desert soil. The results also help to elucidate the microbiological mechanisms regulating plant growth, soil restoration, and active organic carbon deposition in rocky desert habitats.