Impact of fallen wood on soil protists in the subtropics

The general aim of the study is to provide insight into the importance of functioning maintenance of forest ecosystems. Specifically, the aim of the study is to assess the response of soil protist diversity, composition and co-occurrence network to varying degree of decomposition of fallen wood when compared to conventional soil.

A total of 24 samples of soil and fallen wood were collected from subtropical broad-leaved forests in China. Here we use a correlative approach to link the community of soil protists with fallen wood at different decomposition stage and compare with fallen-wood-free soil. The indicators of protists community were assessed using DNA metabarcoding of the 18S rRNA (Illumina sequencing).

The biodiversity of soil protists tended to increase as decomposition advanced and pronounced difference was found between severe and moderate decomposition stages (P < 0.05). The decomposition of fallen wood had a significant effect on the composition of the soil protist community (Adonis: R² = 0.24, P < 0.01), and enhanced the complexity and stability of the co-occurrence network of soil protists. Soil protists exhibited a stronger association with fallen wood (11 significant linkages), compared to soil (7 significant linkages). Fallen wood decomposition indirectly affected the soil protist community through multiple ways.

Retention of fallen wood helps maintain the richness and interaction of soil protists. Future research directions should focus on specific mechanisms for how fallen wood decomposition affects protists. Our work may contribute to better guide forest management policies in China.