Spatial Distribution of Soil Organic Carbon and Total Nitrogen in a Micro-Catchment of Northeast China and Their Influencing Factors

Abstract

This study aimed to analyze the spatial distribution of soil organic carbon (SOC) and total nitrogen (STN) in a micro-catchment area comprising farmland and a gully with vegetation restoration (artificial forest and grassland) and their influencing factors. We surveyed a total of 52 topsoil sampling sites to measure the SOC and STN content, as well as topographical factors (elevation, curvature, slope gradient, and aspect), soil properties (bulk density, aggregate distribution, soil texture, and soil moisture), and land use and management. We used traditional statistical and geostatistical methods to analyze the spatial variability of SOC and STN. The results of this study indicate that SOC and STN content varied moderately across the entire micro-catchment area, with greater values in the west (gully head area) than in the east (gully mouth area). Additionally, SOC and STN were significantly positively correlated with soil water content, >2 mm size aggregate fraction, and elevation, but negatively correlated with <0.053 mm size fraction. Land use types also influenced the spatial distribution of SOC and STN contents, with the highest averages of SOC and STN content found at the edge of farmland road and grassland, respectively, and the lowest values in bare land. This study provides a valuable supplement to the understanding of SOC and STN in micro-catchment areas, and the research results also support the evaluation of the impact of gully erosion control on SOC and STN dynamics after vegetation restoration. Overall, vegetation restoration should be adopted for gully erosion control and sustainable agricultural development in the Mollisols region of Northeast China.

Spatial Variation in Responses of Plant Spring Phenology to Climate Warming in Grasslands of Inner Mongolia: Drivers and Application

“…While numerous studies have explored the impact of terrain on the relationship between SOS and climate change [ 6 , 13 , 23 ], there has been limited focus on the influence of soil factors on this relationship [ 39 ]. Since soil nutrients play a crucial role in plant growth [ 20 ] and the spatial variation in soil factors is significant [ 38 ], it becomes essential to consider the effects of soil factors on the correlation between SOS and air temperature. The results from our random forest model highlight the significance of SOC and SNC in influencing the response of SOS to average WST.…”

“…The soil factors also exhibit significant spatial heterogeneity. Altitude, gradient, and the roughness of terrain show significant correlations with soil organic matter and total nitrogen [ 38 ]. Therefore, the spatial heterogeneities of precipitation and soil factors may induce spatial variation in the sensitivity of SOS responding to climate warming.…”