Microbial Diversity and Ecosystem Functioning in Deadwood of Black Pine of a Temperate Forest

Roberta Pastorelli,Alessandro Elio Agnelli,Alessandra Lagomarsino,Isabella De Meo,Alessandro Paletto

doi:10.3390/f12101418

Roberta Pastorelli, Alessandro Elio Agnelli + Show 3 more

Open Access

https://doi.org/10.3390/f12101418

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Journal: Forests	Publication Date: Oct 18, 2021
Citations: 12	License type: CC BY 4.0

Affiliation: Agricultural Research Council, Forestry Research Centre

Abstract

The present study provides a deeper insight on variations of microbial abundance and community composition concerning specific environmental parameters related to deadwood decay, focusing on a mesocosm experiment conducted with deadwood samples from black pine of different decay classes. The chemical properties and microbial communities of deadwood changed over time. The total carbon percentage remained constant in the first stage of decomposition, showing a significant increase in the last decay class. The percentage of total nitrogen and the abundances of nifH harbouring bacteria significantly increased as decomposition advanced, suggesting N wood-enrichment by microbial N immobilization and/or N2-fixation. The pH slightly decreased during decomposition and significantly correlated with fungal abundance. CO2 production was higher in the last decay class 5 and positively correlated with bacterial abundance. Production of CH4 was registered in one sample of decay class 3, which correlates with the highest abundance of methanogenic archaea that probably belonged to Methanobrevibacter genus. N2O consumption increased along decomposition progress, indicating a complete reduction of nitrate compounds to N2 via denitrification, as proved by the highest nosZ gene copy number in decay class 5. Conversely, our results highlighted a low involvement of nitrifying communities in deadwood decomposition.

Highlights

Lying deadwood—the dead trees and debris on the forest floor—is a natural and fundamental structural and functional component of forest ecosystems
The total N (TN) values significantly increased from decay class 1 to decay class 5 (Table 1), following an exponential trend (R2 = 0.93)
Dead black pine logs are proved to be an important habitat for fungi, bacteria, and archaea

Summary

Introduction

Lying deadwood—the dead trees and debris on the forest floor—is a natural and fundamental structural and functional component of forest ecosystems. It influences biological, physical, and chemical processes [1], and plays a key role in biodiversity and soil fertility maintenance [2,3]. Lying deadwood provides important habitats and nourishment for several saproxylic species [4], being an essential substrate for numerous insects and fungi [5]. Deadwood decay level is a key variable affecting deadwood-inhabiting fungi, bryophyte presence and diversity, and the dynamics of carbon release and sequestration. According to the deadwood classification system adopted in many national forest inventories (NFIs), five decay classes [8]

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