Changes in vegetation types alter soil respiration under the erosion and deposition topography in karst trough valley

Abstract

Soil respiration is a critical component of the terrestrial ecosystem carbon cycle and is significantly influenced by soil erosion and deposition topography. However, the effects of erosion and deposition topography on soil respiration remain unclear, particularly within karst valleys with different vegetation types. Therefore, we selected five vegetation types (abandoned land (bare soil with sparse weed), grassland, sloping farmland (corn field), brushland, and forest) and conducted in situ monitoring to examine the impacts of vegetation types and erosion-deposition topography on soil respiration. Additionally, a structural equation model was developed to identify key driving factors. The results indicated the following. 1) The environmental factors, soil organic carbon content, soil water content (SWC), soil temperature (ST), and electrical conductivity (EC) at the erosion site are significantly greater than those at the deposition site. 2) The soil respiration rate at the erosion site was higher than that at the deposition site with the anti-dip slope showing the highest soil respiration rate (11.2 µmol·m^−2·s⁻¹) in the forest, followed by the valley depression and the dip slope. The average soil respiration rate peaked at 3.15 µmol·m⁻²·s⁻¹ in August and reached the lowest value of 0.27 µmol·m⁻²·s⁻¹ in January. 3) The relationship between the soil respiration rate and soil temperature exhibited an exponential increase. Additionally, the soil temperature and soil organic carbon content had significant direct effects on soil respiration with path coefficients of 0.71 and 0.25, respectively, whereas erosion and deposition topography and vegetation type had indirect effects. Our findings highlight the effects of erosion and deposition topographies and vegetation types on soil respiration in the karst trough valleys and provide a theoretical foundation for enhancing carbon storage and regulating the carbon cycle in the karst trough valley ecosystems.