Fungi are commonly recognized as the main decomposers of litter and wood, playing an important role in global carbon cycle. Saprotrophic fungi are functionally classified as brown, soft and white-rot types. Previous study has observed strong species identity effects of fungi in wood decay rates. However, the mechanisms driving these observations remain to be elucidated. 

In a study published in Soil Biology and Biochemistry, researchers from the Xishuangbanna Tropical Botanical Garden (XTBG) and the Kunming Institute of Botany (KIB) examined the effects of fungal diversity and composition on woody debris decomposition rates.

They further wanted to explore whether fungal communities in decomposing logs could explain the wood species identity effects, and lack of habitat effects, on wood specific gravity (WSG) loss.  

The researchers investigated successional changes in fungal diversity and composition in decomposing logs of two tree species across a disturbance gradient and their effects on WSG loss over three years in a tropical montane forest in southwest China. 

Regardless of wood species and habitat, the fungal species diversity was found to be consistently peaked at 18 months and significantly influenced by wood species identity. Fungal community composition varied significantly with time, wood species, habitat type, and termite presence.  

They observed lack of difference in decay rates across the disturbance gradient, due to the dissimilarities in fungal community composition among habitats. Termite presence reduced WSG loss, but the effect was mediated via the abundance of soft rot fungi, which increased through time. 

Their measurements showed that the fungal diversity only explained about 2% of the variance in WSG loss. The larger variation in WSG loss was explained by abundance of soft rot fungi and saprotrophs, up to 11%.  

"Our results suggest that changes in functional traits, rather than fungal species diversity, may better explain variation in WSG loss," said Dr. Gbadamassi Dossa from XTBG.