Soil biological quality as affected by vegetation types in shrublands of a semi-arid montane environment

Abstract

Mountain shrublands in semi-arid zones have a relevant effect in protecting water and soil, and conserving biodiversity. Nutrient availability in vegetation layers of semi-arid shrublands, may increase biomass production and litter accumulation rates that may affect the soil nutrient cycle through the positive feedback. However, the effect of semi-arid mountainous shrublands on litter quality and soil properties is poorly studied. To fill these gaps, we studied different vegetation types (i.e., Ulmus carpinifolia Gled., Berberis integerrima Bunge, Malus orientalis Ugl., Pistacia atlantica Desf., Amygdalus lycioides Spach., Rhus coriaria L., Cotoneaster kotschyi Klotz. and Juniperus excelsa M. Bieb.), to assess litter quality, soil properties, and C and N mineralization in Iran. Totally, 240 litter or organic horizon and topsoil (0–10 cm depth) samples were taken under the studied vegetation types. Based on analysis of variance and Tukey test, soil fauna (earthworms, acarina, collembola, nematode, protozoa), microflora (bacteria and fungi), microbial (basal and substrate-induced respirations, microbial biomass) and enzyme (urease, acid phosphatase, arylsulfatase and invertase) properties, as well as C and N mineralization were highest under deciduous species, especially U. carpinifolia vegetation type. Conversely, J. excelsa, as an evergreen species, decreased soil quality bio-indicators by decreasing litter quality and soil fertility in the high mountain vulnerable semi-arid sites. Based of heat plots of principal component analysis, soil biological and biochemical properties, especially enzyme indicators, created hot spots of soil quality under the studied vegetation types. As a conclusion, deciduous species are the hotspot's bioindicator in the mountainous ecosystems, indicating their potential role in enriching soil nutrient cycles.