The Negative Effects of Tourist Trampling on the Soil Physical Properties and Microbial Community Composition in a Natural Oak Forest

Abstract

Tourist trampling is a serious disturbance affecting the soil structure and microbial community in forests. However, it is still unclear whether the response of soil microorganisms to trampling is attributed to the alterations in soil physical (soil bulk density and total porosity) or soil chemical (total nitrogen and soil organic carbon) properties. To determine the response and mechanism of soil microbial community composition to tourist trampling, we conducted a field experiment including four levels of trampling intensity (control, mild, moderate, and severe) at the Baotianman forest ecotourism area. With increasing trampling intensity, soil bulk density showed a substantially increasing pattern, whereas soil total porosity, total nitrogen, and soil organic carbon showed a decreasing trend. Compared to the insignificant change under mild trampling, moderate and severe trampling significantly decreased soil bacterial PLFAs (phospholipid fatty acids) by 46.6% and 57.5%, and fungal PLFAs by 36.3% and 61.5%, respectively. Severe trampling showed a significantly negative effect (−4.37%) on the proportion of soil bacterial PLFAs. Changes in soil bulk density and porosity induced by trampling, rather than total nitrogen and soil organic carbon, played a greater role in regulating soil microbial community composition. These findings suggest that soil microbial community composition and biomass are significantly influenced by the changes in soil texture and aeration conditions caused by tourist trampling.