沙坡头固定沙丘结皮层的微生物区系动态

对中科院沙坡头沙漠研究试验站的人工植被固定沙丘、红卫自然植被固定沙丘的结皮层和流动沙丘表层(0~ 05cm)中的微生物类群数量的研究结果表明:①好气性细菌数量影响着微生物总数量的变化趋势;②微生物总数量分布依次排列为:自然植被固定沙丘>1956年栽植区>1964年栽植区>自然半固定沙丘>1982年栽植区>流动沙丘;③土壤微生物类群数量与结皮层的形成、植物覆盖度和土壤含水率等因子有密切的关系;④结皮层中的微生物类群数量与流动沙丘的固定程度呈正向关系。

Microflora Dynamic in Microbiotic Crust Layer of Fixed Sand Dunes in Shapotou Region, Tengger Desert

Microflora in different soil crusts such as crust of sand dunes fixed by natural and artificial vegetation and that of flowing sand, are various. Bacteria's number is the most in all groups of microorganism, and the variation trend of the total microorganism's number rest with the amount of aerophilic bacteria. Distribution order of microbial number in different soil crusts showed that fixed sand dune with natural vegetation > sand dune with artificial vegetation of 1956 > sand dune with artificial vegetation of 1964 > semi-fixed sand dune with natural vegetation > sand dune with artificial vegetation of 1982 > sand-flowing dune without vegetation. The amount of microorganisms in soil crust of fixed sand dunes with natural vegetation was most, it is 4.46 times of sand dune with artificial vegetation in 1956, 7.44 times of sand dune with artificial vegetation in 1964, 18.52 times of semi-fixed sand dune with natural vegetation, 43.51 times of sand dune with artificial vegetation in 1982, and 90.21 times of sand-flowing dune without vegetation. Microbial number in soil crust was various with the years of sand fixed, the longer years of sand fixed, the more number of microorganism; the shorter years of sand fixed, the less number of microorganism in sand dune. Microbial number of flowing sand dunes was the least in sand dunes. Number of microbial groups in crust of artificial vegetation type are various in different seasons. It is less in summer than in autumn, the ratios of amount between in summer and in autumn was 1:4.91 in sand dune with artificial vegetation of 1956, 1:1.11 in sand dune with artificial plantation of 1964, 1:7.38 in sand dune with artificial vegetation of 1982, and 1:2.9 in sand-flowing dune without vegetation. Soil microbial number is related to ecological factors such as formation of the crust, condition of vegetation and water content of sand dunes, the longer ages of fixed sand dunes with artificial vegetation, the thicker layer of the crust, the more amount of soil microorganism, the more coverage with herbage, the less coverage with shrub. The number of soil microorganism in soil crusts are positive related to fixed degree of sand dunes.