Analysis of Microbial Diversity and Greenhouse Gas Production of Decaying Pine Logs

Abstract

In Sustainable Forest Management, decaying wood plays an important role in forest biodiversity, carbon balance and nutrient cycling. The management of this important component of forest ecosystems is limited by the fact that little is known about relationships between substrate quality and community structure of wood-inhabiting microorganisms. During decomposition, carbon stored in deadwood is lost either in the atmosphere or in the soil, but to our knowledge, limited information on the quantities of CO 2 and other greenhouse gases (GHG) emitted is available.In the present research we investigated the correlation between the decay of logs, the decomposer microorganisms and their activities, in terms of GHG production and enzymes, in a black pine (Pinus nigra Arnold ssp. nigra) degraded forest. The decomposition of deadwood was visually assessed using a five-class system, and for each decay class four wood samples were collected. CO 2 , CH 4 and N 2 O potential production from each decay class was measured in closed systems by means of gas chromatography. Enzyme activities related to carbon, nitrogen, sulphur and phosphorus cycling were measured fluorometrically. The composition of decomposer microbial communities (fungi, bacteria and actinobacteria) was assessed by using polymerase chain reaction-denaturing gradient gel electrophoresis fingerprinting. CO 2 production and enzyme activities were significantly higher in the last decay classes of deadwood. The molecular approach highlighted differences in microbial community structure both at species and abundance levels, depending on the rate of decay.

Assessing the forest-wood chain at local level: A Multi-Criteria Decision Analysis (MCDA) based on the circular bioeconomy principles

“…Generally, on the long-term period it would be a good practice to leave at least 5% of deadwood, -particularly logs with minimum diameter above 30 cm -because they are of primary importance both for biodiversity (e.g., saproxylic species) and for preservation of soil fertility (Nordén et al 2004, Pastorelli et al 2017.…”

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

“…The cultivation-independent molecular methods, generally including the direct extraction of total microbial DNA, have been the most common approaches to determine microbial diversity in various environments [32]. Among these, the polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) fingerprinting has already been used to provide indications on the relative changes in deadwood and litter microbial community composition as decomposition progressed [33][34][35][36][37]. The best approach to identify and quantify specific microbial groups and/or enzymes related to processes of the C and N cycles is to use real time PCR of marker genes of the respective microbial groups (e.g., 16S rDNA genes) or that encodes the process-related enzymes [38][39][40].…”

Chemical and microbiological changes in Norway spruce deadwood during the early stage of decomposition as a function of exposure in an alpine setting

“…This is in line with the fact that the wood samples at the south-facing slope were characterized by a higher microbial biomass (based on dsDNA). Accordingly, the dsDNA yields were positively correlated with most of the previously mentioned enzymes (data not shown) at the end of the monitoring period, probably because of more suitable conditions (i.e., higher nutrient availability) for microbial growth as wood decay progresses (Gonzalez-Polo, FernandezSouto, and Austin 2013; Pastorelli et al 2017;Petrillo et al 2015Petrillo et al , 2016. In fact, the increase in fungal abundance after 104 weeks was also accompanied by an increase in the C-related enzyme activities in the P. abies wood blocks, suggesting the higher activity of the wood-inhabiting fungi at this stage of decay.…”