Soil chemical characteristics influenced by selected lichen and moss species, a case study from an arid region of Iran

The effects of various biological soil crusts (BSCs) on soil properties have been extensively studied. However, the impacts of specific species such as Placidium squamulosum, Peccania terricola, and Grimmia ovalis on soil properties in arid regions have not been documented. Besides, the effects of soil parent rock on the extent of changes in soil properties caused by BSCs have not been thoroughly investigated. The objective of this study was to examine how BSCs including two different terricolous lichen species (Placidium squamulosum and Peccania terricola) and a moss species (Grimmia ovalis) could change major soil chemical and nutritional properties in an arid area under different parent rocks. Triplicate BSC-free surface soil and soil associated with the above-mentioned BSCs were sampled from 13 different sites with sedimentary and igneous parent rocks in an arid area in Isfahan, Iran. Soil properties including pH, electrical conductivity (EC), organic matter (OM), calcium carbonate equivalent (CCE), total nitrogen, available phosphorus, and available potassium were determined in all the samples. The results indicated that the presence of lichens and mosses significantly changed the soil chemical and nutritional properties. Specifically, the content of total nitrogen, organic matter, and available potassium in the soil environment increased under the activity of these biological crusts developed on both sedimentary and igneous formations. Additionally, these biological crusts resulted in a significant reduction in soil pH, CCE, and available phosphorus. The electrical conductivity of soils slightly increased due to the activity of biological crusts. In general, biological crusts including both chlorolichen (Placidium squamulosum) and cyanolichen (Peccania terricola) species, as well as a moss species (Grimmia ovalis) appear to create a unique microenvironment in terms of biochemical and nutritional conditions, which is substantially different from those typically observed in drylands.