腾格里沙漠东南缘生物土壤结皮对土壤理化性质的影响

Effects of Biological Soil Crusts Types on Soil Physicochemical Properties in the Southeast Fringe of the Tengger Desert

生物土壤结皮是荒漠生态系统地表景观的重要组成部分,在沙化土地恢复和流沙固定中起着重要作用。研究了腾格里沙漠东南缘固沙植被区不同类型生物土壤结皮理化性质及结皮发育对下层土壤性质的影响。结果表明:结皮层厚度、孔隙度、黏粉粒和田间持水量以及有机碳、无机碳、全氮、碱解氮、速效磷、速效钾含量和电导率均表现为藓类结皮>混生结皮>地衣结皮>藻类结皮;砂粒含量和容重表现为藻类结皮>地衣结皮>混生结皮>藓类结皮。结皮下0~2cm和2~5cm土层理化性质表现出与结皮层相同的变化规律。总体上,生物土壤结皮对下层土壤理化性质的影响表现为藓类结皮和混生结皮大于地衣结皮和藻类结皮;而结皮对下层土壤理化性质的影响随土壤深度的增加而减小。生物土壤结皮的拓殖和发育是荒漠生态系统成土过程和土壤质量的关键影响因素。

Biological Soil Crusts （BSCs） are a critical part of the surface landscape in desert ecosystem, and play a key role in the recovery of desertified land and the fixation moving-dune. The physicochemical prop- erties of BSCs and their respective subsoils in the revegetation area of the southeast margin in the Tengger desert were investigated, and the effects of BSCs on subsoil were analyzed. The results indicated that： the thickness, porosity, silt and clay content, field water holding capacity and the concentrations of organic car- bon, inorganic carbon, total nitrogen, available nitrogen, available phosphorus, available potassium and e- lectronic conductivity of crusts layer were moss crust^mixed crust^lichen crust^algae crust, while sand content and bulk density were moss crust^mixed crust^lichen crust^algae crust. The physicochemical properties of the 0--2 cm and 2--5 cm soil layers below crusts showed the same patterns. In general, the effects of moss crust and mixed crusts on their subsoil were greater than those of lichens and algae crusts; the influence of crusts on subsoils decreased with the increase of soil depth. Our results suggest that the col- onization and development of BSCs are the key factors thataffect soil formation and soil quality in desert eco- system.