M. Ajami, F. Khormali,
Volume 15, Issue 57 (10-2011)
Abstract
Biological soil covers such as lichens have critical roles in soil stability and prevention of erosion. In order to study the effect of lichen biological covers on aggregate stability and soil conservation, loess hills covered with lichen and uncovered ones were selected in Northern Golestan Province. Five samples were taken from the depth 0 to 5 cm of both two areas for physico-chemical analyses. The undisturbed soil samples were taken for micromorphological studies, too. Analyses of soils revealed that soil organic carbon content increased markedly, compared to uncovered soils. Mean weight diameter also increased about three folds in soils covered with lichen. Fungal hyphae and polysaccharides excretions bind soil particles together and increase size of aggregates. Micromorphological study of thin sections showed that uncovered soils had a weak and massive structure, but soils covered with lichen had a crumb granular and also well -separated angular block and higher proportion of voids. Due to the effect of lichen on upward movement of calcium carbonate, crystallitic b-fabric appeared in the surface layer of covered soils and speckled b-fabric underneath. Excremental pedofeatures are the most common pedofeatures in the covered soils.
D. Khosraviani, A. R. Davoudian Dehkordi, J. Givi, M. Sheibi,
Volume 19, Issue 74 (1-2016)
Abstract
The concentrations of rare-earth elements (REEs) were determined with the aim of investigating the behavior of these elements in granitic rock, granitic soils and soils between rock and lichen in Shir-kuh of Yazd province. Rare earth element patterns of the P-rich granite were determined by the mixture of Eu-enriched feldspars, middle REEs to heavy REEs-enriched apatite and Light REEs-enriched monazite. Granite-normalized REEs patterns for soils and soil lichen-granite interface represented the same signatures and similar to parent rocks. The REEs levels of the soils lichen-granite interface were similar to the concentrations of the elements in the natural compositions (Upper Continental Crust and Post-Archean Australian Shale). PAAS-normalized Rare earth element patterns for three soils’ lichen-granite interface were identical to each other and PAAS and close to the reference axis (PAAS). The same signatures of REEs in granitic rock, granitic soils and soils lichen-granite interface in arid and semi-arid mountainous areas indicate that the elements are immobile and therefore, they can be used as a suitable tracer in soil provenance studies.
