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The objective of this study was to characterise the effect of grazing on soil physical, chemical and biological properties of a semi-steppe rangeland grazed by goats and sheep in the Sahand Mountains (Iran) in order to develop effective soil conservation measures and sustain livestock production. Grazing was classified as light, moderate and heavy according to the stocking rate and utilisation rate of the vegetation. Soil sampling was conducted at depths of 0–10 and 10–20 cm for each grazing treatment. Soil physical and chemical properties were determined at both depths and soil microbial variables were evaluated at the surface layer. Increasing level of grazing significantly decreased all soil chemical properties at both depths except for pH and magnesium concentration. Increasing the level of grazing significantly decreased the soil moisture content and porosity at both soil depths. The highest values of microbial biomass carbon, total fungi and bacteria were observed on the light treatment. Grazing significantly affected soil properties unfavourably and reduced vegetation vigour and composition, jeopardising the sustainability of the ecosystem.

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Deadwood is a key component of forest ecosystems, but there is limited information on how it influences forest soils. Moreover, studies on the effect of thinning-derived deadwood logs on forest soil properties are lacking. This study aimed to investigate the impact of thinning-derived deadwood logs on the soil chemical and microbial properties of a managed spruce forest on a loamy sand Podzol in Bavaria, Germany, after about 15 years. Deadwood increased the soil organic carbon contents by 59% and 56% at 0–4 cm and 8–12 cm depths, respectively. Under deadwood, the soil dissolved organic carbon and carbon to nitrogen ratio increased by 66% and 15% at 0–4 cm depth and by 55% and 28% at 8–12 cm depth, respectively. Deadwood also induced 71% and 92% higher microbial biomass carbon, 106% and 125% higher microbial biomass nitrogen, and 136% and 44% higher β-glucosidase activity in the soil at 0–4 cm and 8–12 cm depths, respectively. Many of the measured variables significantly correlated with soil organic carbon suggesting that deadwood modified the soil biochemical processes by altering soil carbon storage. Our results indicate the potential of thinned spruce deadwood logs to sequester carbon and improve the fertility of Podzol soils. This could be associated with the slow decay rate of spruce deadwood logs and low biological activity of Podzols that promote the accumulation of soil carbon. We propose that leaving thinning-derived deadwood on the forest floor can support soil and forest sustainability as well as carbon sequestration.

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