Quercus species control nutrients dynamics by determining the composition and activity of the forest floor fungal community

Abstract

In forest ecosystems, microbial community structure and activity play an important role in C and nutrient dynamics and are strongly influenced by litter composition. Moreover, litter decomposition rates also depend on microbial activity. Fungi are a key component of the microbial community as they produce extracellular hydrolytic and oxidative enzymes that degrade organic polymers and mobilize inorganic nutrients. In this study, we examined how litter composition affects microbial activity and fungal community structure by comparing decomposing litter derived from sympatric Quercus castanea (Qc) and Quercus deserticola (Qd) in a deciduous forest in Mexico. Microbial N and P biomass were higher in the Qd litter than in the Qc litter. The differences in N and P were seasonal and were not observed at the end of the rainy season (October). The specific enzyme activity was higher in the Qc than in the Qd litter, mainly at the onset of senescence (May). At this time, phenol oxidase and β-glucosidase activities were significantly higher in the Qc litter than in the Qd litter; thereby the nutrient acquisition strategies of the microbial community differ in the litter derived from each Quercus species. Internal transcribed spacer sequence analysis of the fungal community indicated higher richness (24 operational taxonomic units: OTUs) in the Qc litter than in the Qd litter (18 OTUs). Six taxonomic orders of microbes were common to both types of litter, and the phylum Basidiomycota was most abundant in the Qc litter. The lignin and tannin contents were highest in the Qc litter, which also contained diverse fungal taxa associated with POX production. The findings of the present study suggest that the Quercus species control the organic nutrient mineralization by determining the composition and activity of the forest floor microbial community.