Effects of fertile islands on soil organic carbon density and labile organic carbon distribution in elm (Ulmus macrocarpa Hance)-dominated sparse wood grasslands in southeastern Inner Mongolia, China

Abstract

In semi-arid savanna grasslands, the sparse distribution of trees often forms what are commonly known as fertile islands. However, the effect of these trees on soil organic carbon (SOC), microbial biomass carbon (MBC), and dissolved organic carbon (DOC), remains poorly understood. In this study, the spatial distribution patterns of SOC, MBC, and DOC were investigated across soil profiles (0–5, 5–10, 10–30, 30–50, and 50–100 cm) at three distances from the tree trunk in an elm-dominated savanna ecosystem in Northeast China. Our results suggest that SOC, MBC, and DOC were significantly influenced by both the distance from the tree and the soil depth. The research provides evidence that elm trees can form fertile island effects, thereby enhancing the contents of SOC and labile organic carbon fractions.

Keywords:

• Fertile islands
• labile organic carbon
• soil carbon density
• under canopy
• vertical and horizontal distributions

Acknowledgments

We thank Jingshi Li for her considerable help with the laboratory analyses, and the anonymous reviewers and the editor for their valuable comments and suggestions.

Disclosure statement

The authors declare no conflicts of interest.

Additional information

Funding

This research was funded by the National Natural Science Foundation of China (Nos. 41977074, 41401262, and 32071858), the Shenyang Scientific & Technological Project (No. 23-407-3-12) and the Natural Science Foundation of Liaoning Province (2024-MSBA-88).