Soil microstructure as an under-explored feature of biological soil crust hydrological properties: case study from the NW Negev Desert
Soil microstructure as an under-explored feature of biological soil crust hydrological properties: case study from the NW Negev Desert
复制标题
DOI：
10.1007/s10531-014-0693-7
复制
发表时间：
2014-06-01
影响因子：
3.4
通讯作者：
Felix-Henningsen, Peter
中科院分区：
文献类型：
--
作者：
Felde, Vincent John Martin Noah Linus;Peth, Stephan;Felix-Henningsen, Peter
生物土壤结皮可在水文循环中发挥重要作用，特别是在水资源有限的旱地生态系统中。影响BSCs水文行为的因素很多，微结构是其中之一。为了描述土壤微结构的BSC水分再分配的影响，我们调查了孔隙系统的变化的三个不同的演替阶段的BSC，以及他们各自的subcrust在西北Negev沙漠，以色列，使用二维薄片，以及非侵入性的X射线三维计算机微断层扫描（XCMT）和压汞孔隙度。研究结果表明，在地壳演化过程中，孔隙系统发生了明显的变化。总孔隙度以及孔径均显著增加，从氰基到地衣到苔藓，并且孔几何形状从曲折的孔形状变为直的孔形状。我们介绍了两种新的机制，有助于在西北内盖夫，阻碍渗透的BSC的水文特性：（i）泡孔和（ii）一个不连续的孔隙系统与毛细屏障效应，由于砂埋造成的粒度的快速变化。由于这两种机制主要存在于早期阶段的蓝藻结皮和他们的丰度下降强烈的继承，很可能是他们影响BSC水文在不同程度上的各种地壳类型，他们是部分负责在西北内盖夫径流的差异。
Biological soil crusts (BSCs) can play an important role in hydrological cycles, especially in dryland ecosystems where the availability of water is limited. Many factors influence the hydrological behavior of BSCs, one of which is the microstructure. In order to describe the influence of the soil microstructure of BSCs on water redistribution, we investigated the change of the pore system of three different successional stages of BSCs, as well as their respective subcrusts in the NW Negev desert, Israel, using 2-dimensional thin sections, as well as non-invasive X-ray 3D computed microtomography (XCMT) and mercury intrusion porosimetry. Our results show that the pore system undergoes significant changes during crust succession. Both the total porosity, as well as the pore sizes significantly increased from cyano- to lichen- to mosscrust and the pore geometry changed from tortuous to straight pore shapes. We introduce two new mechanisms that contribute to the hydrological properties of the BSCs in the NW Negev that impede infiltration: (i) vesicular pores and (ii) a discontinuous pore system with capillary barrier effects, caused by a rapid change of grain sizes due to sand burial. Since both of these mechanisms are present mostly in early stage cyanobacterial crusts and their abundance decreases strongly with succession, it is very likely that they influence BSC hydrology to different extents in the various crust types and that they are partly responsible for differences in runoff in the NW Negev.