Soil Organic Carbon Distribution and Its Response to Soil Erosion Based on EEM-PARAFAC and Stable Carbon Isotope, a Field Study in the Rocky Desertification Control of South China Karst.

Xinwen Wang,Kun Cheng,Ziqi Liu,Kangning Xiong,Yuan Li

doi:10.3390/ijerph19063210

Abstract

Ecological restoration plays an important role in enhancing carbon sequestration ability in karst areas, and soil organic matter is one of the main carbon reservoirs in karst key zones. The serious soil erosion in karst areas leads to the loss of soil organic matter (SOM). However, the distribution characteristics of SOM and its response mechanism to soil erosion in the process of rocky desertification control have rarely been reported. In this study, soil samples of five restoration types (abandoned land, AL; grassland, GL; peanut cultivated land, PCL; Zanthoxylum bungeanum land, ZBL; forest, FS) were collected in typical karst rocky desertification drainage, south China. By measuring soil organic carbon (SOC), dissolved organic carbon (DOC), and δ13Csoc values and combining with spectral tools, the distribution and isotopic composition of soil shallow organic carbon in definitized karst drainage was definitized and the response of DOM spectral characteristics to soil erosion was explored. The results showed that three kinds of fluorescence components were detected by fluorescence excitation emission matrix (EEM)-parallel factor analysis (PARAFAC), C1 and C2 were humus-like, and C2 was protein-like. Abandoned could be a more suitable control measure for enhancing SOC quality in the karst regions of south China. The variation trend of SOC content, δ13Csoc values, spectral indexes, and the distribution of fluorescence components from the midstream to downstream of the drainage indicated the soil redistribution. This study provides basic scientific data for karst rocky desertification control and for enhancing the soil carbon sequestration ability of karst.

Highlights

Soil organic carbon pool is the largest carbon pool in terrestrial ecosystems and an important part of the global carbon cycle [1,2]
Dissolved organic matter (DOM) plays an important role in the biogeochemical cycle of carbon and other elements by influencing the adsorption, dynamic displacement, residence time, and microbial availability of soil organic matter, and it is the core of the study of carbon sequestration and nutrient availability in soil [1,7]
DOM characteristics are closely related to biogeochemical processes involved in periodic changes of soil [8,9], and soil erosion is an important factor leading to spatial changes of DOM [10]

Summary

Introduction

Soil organic carbon pool is the largest carbon pool in terrestrial ecosystems and an important part of the global carbon cycle [1,2]. Improving soil carbon sequestration ability is an important aspect of achieving carbon peak and carbon neutrality in China [3]. DOM can combine with soil particles and coexist with minerals, becoming part of the organic carbon pool [6]. DOM plays an important role in the biogeochemical cycle of carbon and other elements by influencing the adsorption, dynamic displacement, residence time, and microbial availability of soil organic matter, and it is the core of the study of carbon sequestration and nutrient availability in soil [1,7]. DOM characteristics are closely related to biogeochemical processes involved in periodic changes of soil [8,9], and soil erosion is an important factor leading to spatial changes of DOM [10].

Methods

Results

Discussion

Conclusion