I summarize current knowledge about the ecosystem functions of wood decomposition
in forests with a particular focus on the effects of fungal wood decay types (traditionally
categorized into white-, brown-, and soft-rot) on the community composition of saproxylic
organisms, forest tree regeneration, and carbon sequestration. Deadwoods of different
decay types show markedly different physicochemical and biological properties. High
carbohydrate availability in white-rotted wood promotes the activities of nitrogen-fixing
bacteria; thus white-rotted wood is a good dietary source for many wood-eating invertebrates.
In contrast, brownrotted wood is unattractive to saproxylic communities due to the
high recalcitrance of accumulated lignin, low nutrient content, and low pH. Nevertheless,
some species have adapted to these conditions and form distinctive communities on
brown-rotted wood. Tree seedlings that are associated with brown-rotted wood are symbiotic
with arbuscular and ericoid mycorrhizal fungal species, but not ectomycorrhizal species.
Thus, the diversity of fungal communities associated with a variety of wood decay
types produces habitat diversity for saproxylic communities and promotes biodiversity
in forest ecosystems. Wood decay type also affects carbon sequestration in forests
as brown-rotted wood might be more instrumental in soil organic matter accumulation
than white-rotted wood. An important aspect of wood decay type is that the wood decay
activities of fungi can have indirect long-lasting cascading impacts on forest biodiversity
by altering the physicochemical properties of deadwood. Including the effects of wood
decay type in ecological models is thus important for predicting the long-term dynamics
of biodiversity, vegetation, and carbon cycling in forest ecosystems.