Decomposition of Leymus chinensis root residues in restored grasslands increased soil faunal abundance

Abstract

Background and aims

In the context of ecological restoration, the decomposition of plant residues is an important process for the return of soil nutrients in grasslands, with soil fauna playing a crucial role in this process. However, little is known about how different grassland types affect the decomposition of Leymus chinensis plant residues and changes in soil faunal communities.

Methods

We conducted a study in the Songnen grassland of Northeast China and selected Medicago sativa communities of restored grasslands and L. chinensis and Phragmites australis communities of natural grasslands. Using litterbags with 4-mm mesh, we examined the decomposition of L. chinensis plant residues and soil faunal community changes across grassland types from June to September 2023.

Results

We observed that the overall average decomposition rate of L. chinensis root residues reached 41.51%, which was significantly faster than the decomposition rate of L. chinensis leaf litter. The decomposition rate in the restored grassland was 46.05%, which was significantly higher than that in the natural grasslands. In restored grasslands, the decomposition of L. chinensis root residues was associated with a high diversity of soil fauna, particularly in terms of individual numbers. Moreover, we found that grassland type was the primary factor affecting soil faunal community differences. Our findings indicate the decomposition of L. chinensis litter in restored grasslands increased soil faunal abundance, with soil moisture, soil organic carbon, and available nitrogen being key factors promoting soil faunal activity.

Conclusion

Our findings highlight that the chemical properties of litter (e.g., C:N ratio) serve as pivotal drivers of L. chinensis root residue decomposition, with soil fauna playing a critical mediating role in this process. Under restored grassland conditions, the decomposition of L. chinensis litter enhanced soil faunal abundance through favorable soil organic carbon content, available nitrogen levels, and optimal moisture regimes. Therefore, grassland restoration plays a critical role in nutrient retention and biodiversity enhancement.