人工梭梭林对沙地土壤理化性质和微生物的影响

选取民勤生长20年的人工梭梭林沙丘和流动沙丘为对象,研究梭梭林发育过程中沙丘土壤理化性质、微生物数量的变化以及二者之间的相关性,旨在探讨人工梭梭林对沙丘土壤形成的影响,为干旱区沙化土地治理提供科学依据。结果表明,营造梭梭林使其林内土壤得到较好的改善。1)土壤粘粒、粉粒和细砂粒含量分别增加71.51%,70.64%,12.09%;有机质、全氮、全磷、全钾、水解氮、速效钾、速效磷和CaCO₃含量均增加;2)细菌、放线菌数量分别增加38.43%,32.52%,真菌数量减少75.38%,土壤碱化程度得到缓解;3)在50~100 cm土层,梭梭蒸腾消耗使土壤水分含量相对减少;4)土壤微生物和土壤理化性质均具较好的相关性,尤其是真菌和放线菌数量与pH值呈显著的负相关关系(P<0.05),有机质含量与细菌和真菌数量呈显著的正相关关系(P<0.05);土壤微生物数量与土壤粒度大小、土壤含水量之间呈线性关系且不显著(P>0.05)。可见,梭梭林的建立有利于改善土壤物理结构,提高土壤肥力,加快沙地成土进程。

Effects of Haloxylon ammodendron planting on soil physico-chemical properties and soil microorganisms in sandy dunes

In this research, the soil microbe populations, soil physical and chemical properties, and the correlation between microbe populations and soil properties of a 20-year old Haloxylon ammodendron plantation in sandy dunes and moving sandy dunes in Minqin were studied. The research aimed to explore the influence of H. ammodendron planting on soil formation on sand dunes and provide a scientific basis for desert land management in arid areas. The results showed that soil in the H. ammodendron plantation was much improved. Soil clay, silt and fine sand contents were increased 71.51%, 70.64%and 12.09%, respectively, compared to nearby unplanted areas. The contents of organic matter, total nitrogen, total phosphorus, total potassium, hydrolytic nitrogen, potassium, available phosphorus and CaCO₃ were increased as well. In addition, the quantities of bacteria and actinomycetes were increased by 38.43% and 32.52%, respectively, while presence of fungi was decreased by 75.38%. Soil alkalinity was also reduced. Soil moisture contents were reduced which can be attributed to transpiration withdrawal of water by H. ammodendron in the 50-100 cm soil depth. Soil microbe populations were highly correlated with soil physical and chemical properties, especially fungi and actinomycetes, which showed a strong negative correlation with pH value (P<0.05); and soil organic matter level displayed an obvious positive correlation with numbers of bacteria and fungi (P<0.05). Soil microbe quantities have a linear relationship with soil particle size and soil moisture content but without significance (P>0.05). In summary, H. ammodendron plantating improves soil physical structure, increases soil fertility and accelerates the process of soil formation.