Short-term impacts of trampling on selected soil and vegetation properties of alpine grassland in Qilian Mountain National Park,China

Abstract

Understanding the impacts of human trampling on ecological environment is necessary for the utilization and management of recreational areas. Qilian Mountain National Park is one of the first pilot areas of the national park system in China, which is also the most popular tourist destinations suitable for hiking and camping. However, there have been very few studies on human trampling in the Qilian Mountains region. We conducted a controlled trampling experiment to explore the short-term impacts of different trampling intensities (0, 50, 200, 500, and 1000 passes) on soil and vegetation in a grassland in the park. At 0–5, 5–10 and 10–20 cm soil depth, some selected soil properties were measured. Human trampling had negative impacts on surface soil properties, aboveground plant cover and height in the study area. At 0–5 cm soil depth, compared to the control site, bulk density, soil organic matter and soil penetration resistance respectively increased from 0.66 to 0.79 g/cm3, 5.5–6.5% and 9.64–13.7 kg/cm2 after 1000 passes. Soil saturated hydraulic conductivity, water holding capacity and total porosity decreased from 0.29 to 0.23 mm/min, 31.62–24.07% and 46.22–34.67%, respectively. Soil properties were degraded both on the topsoil(0–5 cm) and midsoil(5–10 cm), with the greatest degradation occurring at 1000 passes, followed by 500 passes. The total vegetation cover and mean vegetation height decreased significantly with increasing trampling intensities. After different passes, the relative vegetation cover and height showed a curvilinear decrease. A reasonable threshold of visitors should be controlled between 500 and 1000 passes to ensure the quality of the landscape. Our findings suggest that human trampling of highly sensitive and fragile alpine grasslands has a significant impact and may further impede their function. Therefore, it is urgent to protect the ecological environment of alpine grasslands.