毛乌素沙地沙打旺根围AM真菌的空间分布

Spatial distribution of arbuscular mycorrhizal fungi in Astragalus adsurgens root-zone soil in Mu Us sand land

对毛乌素沙地5个不同生态条件下沙打旺(Astragalus adsurgens)根围土壤0～50cm土层AM真菌空间分布进行研究.结果表明:不同样地和采样深度下AM真菌孢子密度和定殖率存在显著差异,最高定殖率和最大孢子密度均出现在10～30cm土层;定边样地孢子密度最高,并显著高于其他样地;塔湾样地菌丝和总定殖率最高,宁条梁和塔湾样地泡囊定殖率高于其他样地.总球囊霉素(TG)和易提取球囊霉素(EEG)含量均在塔湾样地最高,分别为1.18mg.g-1和0.65mg.g-1.土壤pH对孢子密度、泡囊和丛枝定殖率、TG和EEG均有极显著正效应,TG和EEG分别与孢子密度、土壤有机C、碱解N和速效P呈极显著正相关.沙漠土壤球囊霉素占有机C的比例高于农田土壤,可能是沙漠土壤有机C的主要来源之一.球囊霉素可作为评估沙漠土壤AM真菌活动和土壤生态状况的有效指标.

This paper studied the spatial distribution of arbuscular mycorrhizal （AM） fungi in Astragalus adsurgens root-zone soil in Mu Us sand land under five different ecological conditions. The results showed that the colonization and spore density of AM fungi differed significantly with sampiing sites and soil depths. The highest colonization rate and spore density of AM fungi were found in 10-30 cm soil layer, and the highest spore density was at Dingbian site. Ningtiaoliang and Tawan sites had the highest vesicular colonization, and Tawan site had the highest total and hyphal colonization. The contents of total glomalin （TG） and easily extractable glomain （EEG） were the highest at Tawan site, being 1.18 mg · g^-1 and 0. 65 mg · g^-1, respectively. Soil oH had significant positive effects on the vesicular and arbuscular colonization, spore density, TG, and EEG, and the TG and EEG had significant positive correlations with spore density, soil organic carbon （SOC）, and soil available N and P. The proportion of glomalin to SOC was higher in desert soils than in agricultural soils, which implied that glomalin could be one of the main origins of SOC in desert ecosystem. Therefore, glomalin could be a useful index for the evaluation of soil AM fungal activity and soil ecology.