Intrinsic growth rate and cellobiohydrolase activity underlie the phylogenetic signal to fungal decomposer succession

Abstract

During litter decay, different fungal decomposer genera reach their highest relative abundance at different times. We tested the long-standinghypothesis that this “peak decay stage” of fungi is related to the activity of their fungal extracellular enzymes that break down various plant biopolymers and related as well to the growth rate of fungi. Using 50 decomposer fungal species, spanning a range of peak decay stages, we measured (1) the activity of four polysaccharidases and two oxidases generated by each species, and (2) fungal species’ growth rates. We found that the activity of cellobiohydrolase and growth rate were negatively correlated with peak time point for filamentous fungi; fungi peaking early had greatest cellobiohydrolase activity and fastest growth. No relationships were found between peak decay stage and enzymes or growth for yeasts. These data suggest growth and resource use are important factors shaping succession during decay by the main fungal decomposers, but as-yetuninvestigated traits may explain the remainder of the variation in succession.