翻埋与覆盖林木枝条对干旱区沙化土壤及紫花苜蓿根系丛枝菌根真菌的影响

沙化是全球干旱半干旱地区土壤退化的主要类型之一，而该地区的生态防护林、农田防护林及城市森林的林木修剪物为沙化土壤的改良提供了丰富的资源。本研究以宁夏易得的杨树枝条为材料，设置了覆盖（M）、翻埋（W）、翻埋+覆盖（WB）及无任何枝条添加的对照（CK）4种处理，测定了土壤理化性质、土壤酶活性、紫花苜蓿地上生物量及菌根侵染率等指标，并利用Illumina Miseq高通量测序技术研究了土壤与根系丛枝菌根（AM）真菌群落结构，分析了影响AM真菌侵染率及群落结构的主要驱动因子。研究结果表明，翻埋与覆盖处理均不同程度改善了土壤性质，提高了紫花苜蓿地上生物量，但总体以WB处理效果较佳；相比CK，处理WB还显著提高了紫花苜蓿根系总侵染率、丛枝侵染率、菌丝侵染率、泡囊侵染率及土壤孢子数（P<0.05），同时亦显著提高了根系AM真菌Chao1和ACE指数，但所有林木枝条施用方式对土壤α多样性影响均不显著（P>0.05）。此外，NMDS和PERMANOVA分析结果显示，处理WB对土壤与根系AM真菌群落结构存在显著响应（P<0.05）。相关分析和dbRDA分析结果进一步表明，AM真菌的侵染状...

Effects of incorporated and mulched tree branches on arbuscular mycorrhizal fungi in the desertified soil and root of alfalfa in arid areas

Desertification is one of the main land degradation processes in arid and semiarid areas globally. However， there is an abundant supply of woody organic materials， from ecological shelterbelts， farmland shelterbelts， and urban forests which can provide raw materials for amendments for soil restoration in these areas. Trimmed poplar （Populus alba） branches available in Ningxia were used for amendment materials in this study. Four amendment treatments （with five replicates） were set up： Wood chip mulch （M）， wood chip incorporation （W）， wood chip incorporation with branch cover （WB） and zero addition （CK）. Then， soil physio-chemical properties， enzyme activities， aboveground biomass of Medicago sativa， and arbuscular mycorrhizal （AM） fungi colonization rate were determined. Meanwhile， the Illumina Miseq high-throughput sequencing technology was used to measure AM fungal community structure both in soil and roots. Finally， data were analyzed to identify the key driving factors which affect AM fungi colonization and community structure. It was found that all branch amendments improved soil properties and increased the aboveground biomass of alfalfa. Compared with CK， the WB treatment generated the best enhancement effect. Moreover， the WB treatment also significantly increased the colonization of roots by arbuscular mycorrhizal fungi （AMF）， and increased clump abundance， hyphal abundance， vesicle abundance， and soil spore number （P<0.05）. Also， compared with CK， the WB treatment significantly increased the Chao1 and ACE indexes of AM fungi in the root （P<0.05）， although there were no differences among treatments for α-diversity of AM fungi in soil （P>0.05）. In addition， non-metric multidimensional scaling （NMDS） and permutational MANOVA （PERMANOVA） analyses indicated that the WB treatment induced a significant soil and root AM fungal community structure response （P<0.05）. Additionally， correlation analysis and distance-based redundancy analysis （dbRDA） indicated that colonization and community structure of AM fungi were closely correlated with soil properties and alfalfa above-ground biomass. Furthermore， above-ground biomass of alfalfa and inorganic nitrogen were identified as the mutual and key factors affecting AM fungal community both in soil and root. In all， WB substantially improved soil properties and accelerating colonization and activity of AM fungi， so these results provide a scientific basis for promoting the use of forest residues for the improvement and restoration of desertified soil in arid and semi-arid areas.