Deadwood decomposition is a fundamental forest process that regulates carbon and nutrient cycling and supports biodiversity. Previous studies have suggested that fungal and bacterial communities may drive differences in wood decomposition rates between bark-covered and bark-removed logs. However, it remains unclear whether bark effects are driven by microbial biomass or by community composition only.

In a study published in ISME Communications, researchers from the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences and their collaborators found that bark plays a key role in shaping fungal communities during tropical tree decomposition. The presence of bark alters fungal community composition and assembly processes during wood decomposition in a tropical forest, but it does not change overall fungal or bacterial biomass.

The researchers conducted a two-year common-garden experiment using logs from five tropical tree species. They compared logs with intact bark with logs from which bark had been removed, sampling at 0, 18, and 24 months of field exposure. They used high-throughput sequencing to characterize wood-inhabiting fungi, phospholipid fatty acid (PLFA) analysis to measure microbial biomass, and chemical analyses to track changes in the wood over time.

They found that bark presence significantly altered fungal community composition. Logs with bark removed had a higher relative abundance of Ascomycota (including soft rot fungi), whereas bark presence favored Basidiomycota, particularly white rot fungi, during early decay. Overall, soft rot fungi had the highest relative abundance, followed by white rot fungi and brown rot fungi.

Furthermore, they found that bark status had no direct impact on total microbial biomass (fungi + bacteria), but its dynamics was closely correlated with wood physicochemical properties (e.g., carbon, nitrogen contents, and moisture levels). During decomposition progression, fungal biomass gradually declined while bacterial biomass increased, indicating a microbial succession from fungus-dominated to bacterium-dominated communities.

In bark-removed treatments, fungal community assembly was dominated by turnover over time, whereas bark presence shifted assembly toward nestedness at advanced decay stages, suggesting a transition toward more deterministic, habitat-filtered assembly.

In addition, the results showed that wood mass loss was significantly associated with degradation of lignin/cellulose and moisture content, which themselves were influenced by bark.

“Bark is not just a passive barrier. It actively shapes the fungal communities that colonize wood, influencing which decomposers establish and how they function. However, our results show that the overall effect of bark on wood decomposition may depend not only on fungal activity but also on wood physicochemical properties,” said Gbadamassi G.O. Dossa of XTBG.

Fungal community on tropical dead wood. (Image by Gbadamassi G.O. Dossa)

Published: 06 September 2026