PDF(Pubmed)
Abstract：
Microorganisms participate in the soil biogeochemical cycle. Therefore, investigating variations in microbial biomass, composition, and functions can provide a reference for improving soil ecological quality due to the sensitivity of microorganisms to vegetation coverage changes. However, the differences in soil microorganisms between shrubland and meadow have not been investigated in ecologically vulnerable subalpine areas. This study aimed to investigate the biochemical composition and functions of the soil microbial community under two shrublands and a meadow at high altitudes (3,400-3,550 m). Three sites under two shrublands, Rhododendron thymifolium (RHO) and Potentilla fruticosa (POT), and one meadow dominated by Kobresia myosuroides (MEA), were selected on the southern slope of the Qilian Mountains on the northeastern edge of the Qinghai-Tibetan Plateau, China. Soil physicochemical properties, the microbial community composition expressed by the phospholipid fatty acid (PLFA) biomarker, and enzyme activities were analyzed as well as their relationships. The results showed that water holding capacity and the soil carbon, nitrogen, and potassium content in RHO and POT were higher than those in the MEA. Moreover, the soil active carbon, dissolved organic carbon, total nitrogen, and dissolved total nitrogen content in RHO were higher than those in POT. The abundance of total PLFAs, bacteria, and fungi beneath the shrublands was considerably higher than that in the MEA. The PLFA abundance in RHO was significantly higher than that in POT. The fungal-to-bacterial ratio of RHO and POT was significantly higher than that in the MEA. The activities of β-glucosidase, cellobiohydrolase, and leucine aminopeptidase were the highest in RHO among the three vegetation types, followed by POT and MEA. The redundancy analysis indicated that the biochemical composition of the soil microorganisms and enzyme activities were driven by total nitrogen, dissolved organic carbon, water holding capacity, and soil organic carbon. Therefore, shrublands, which have higher biomass, can improve soil moisture status, increase soil carbon and nitrogen content (especially active carbon and active nitrogen), and further increase the abundance of total PLFAs, bacteria, and fungi. The increase of microbial biomass indirectly enhances the activity of relevant soil enzymes. The variations in PLFA abundance and enzyme activities can be attributed to shrub species, especially evergreen shrubs, which create more favorable conditions for soil microorganisms. This study provides a theoretical basis for investigating the soil biogeochemical cycle and a scientific basis for soil management and vegetation restoration in the subalpine regions.
摘要：
微生物参与土壤生物地球化学循环。因此,调查微生物生物量的变化，composition,微生物对植被覆盖度变化的敏感性,可为改善土壤生态质量提供参考。然而,在生态脆弱的亚高山地区，尚未研究灌木丛和草甸之间土壤微生物的差异。这项研究旨在研究高海拔（3,400-3,550m）的两个灌木丛和一个草甸下土壤微生物群落的生化组成和功能。两个灌木丛下的三个地点，百叶杜鹃花(RHO)和胡桃委陵菜(POT),和一片以小麦夜蛾(MEA)为主的草地，选在青藏高原东北边缘祁连山南坡,中国。土壤理化性质,由磷脂脂肪酸（PLFA）生物标志物表达的微生物群落组成，和酶活性进行了分析以及它们之间的关系。结果表明,持水量与土壤碳,氮，RHO和POT中的钾含量高于MEA中的钾含量。此外，土壤活性炭，溶解的有机碳，总氮,RHO中溶解总氮含量高于POT。总PLFA的丰度，细菌,灌木丛下的真菌比MEA中的真菌高得多。RHO中的PLFA丰度明显高于POT。RHO和POT的真菌与细菌的比率明显高于MEA。β-葡萄糖苷酶的活性，纤维二糖水解酶，在三种植被类型中，亮氨酸氨基肽酶在RHO中最高，其次是POT和MEA。冗余分析表明，土壤微生物的生化组成和酶活性受全氮驱动，溶解的有机碳，持水能力，和土壤有机碳。因此,灌木丛,具有较高的生物量，可以改善土壤水分状况，增加土壤碳和氮含量（尤其是活性碳和活性氮），并进一步增加总PLFA的丰度，细菌,和真菌。微生物生物量的增加间接增强了土壤相关酶的活性。PLFA丰度和酶活性的变化可归因于灌木物种，尤其是常绿灌木,这为土壤微生物创造了更有利的条件。该研究为调查亚高山地区土壤生物地球化学循环提供了理论依据，为亚高山地区土壤管理和植被恢复提供了科学依据。
