Changes in soil multifunctional properties in semi-arid environments are dependent on ecosystem health

Abstract

Mountainous and semi-arid habitats are considered very sensitive and fragile, due to their climatic conditions. Soil has different functions, and its physicochemical and biological characteristics can be indicators that affect these functions. In recent years due to human intervention, most of these areas have been destroyed and now some areas are either bare or have sparse vegetation. The presence of different percentages of vegetation coverage can be an indicator of ecosystem health, especially in areas affected by the human intervention. Carpinus orientalis Miller. − Quercus macranthera Fisch & C.A. Mey and Crataegus melanocarpa M.B. and Crataegus microphylla C. Koch. − Berberis integerrima Bunge. are the dominant vegetation types found in the forest and rangelands of semi-arid areas in Iran. This study aimed to investigate the impact of different intensities of vegetation cover degradation, ranging from heavy (0–10 % coverage) to moderate (30–40 % coverage) and light (60–70 % coverage) in comparison to undisturbed sites (control group with 90–100 % coverage) in northern Iran. A total of 15 soil samples from forest and rangeland habitats with four degradation intensities were collected from each site, within an area of 30 × 30 cm at the depth intervals of 0–10 cm, 10–20 cm, and 20–30 cm, with a total of 360 samples that were subsequently analyzed in the laboratory. Degradation of vegetation reduced soil moisture by 5 to 10 %. In general, increasing the intensity of degradation caused an increase in soil temperature in the studied habitats. The values of pH and EC decreased by about 0.5 units with the increase of degradation intensity in both the vegetation types, and showed a decreasing trend with depth. Soil fertility characteristics, including N, P, Ca, K and Mg, showed a significant decrease (about 3 to 5 %) with the increase habitat degradation in forest and rangeland covers. Furthermore, in the studied sites, soil fauna including earthworms, acarina, collembola, nematodes, protozoa (about 1–2 %) and soil microflora including fungi, bacteria (about 1 %) decreased with the increase in the intensity of degradation. The highest effect of degradation was found in the topsoil of the studied habitats. From the point of view of soil multifunctional indicators, results showed that high and moderate degradation intensities are clearly different compared with light and non-degradation intensities. In addition, the intensity of degradation in light degraded and non degraded sites did not show a significant difference, thus ecosystem restoration is associated with fewer challenges.