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Wood rotting
Wood rotting
Wood rotting fungi could spread in this period. They should not be confused with the mycorrhizal fungi which live in roots, these rot the dead wood aerobically. They are the ones we are most familiar with. As we walk through woods in autumn, we see their fruiting bodies. Their mycelium would travel have helped bind the surfaces offering further structure for more springtails to live in and feed on.
De-lignification
De-lignification
"The evolution of lignin degradation in basidiomycete fungi was traced via phylogenomic methods and relaxed molecular clock estimates to the Permian (Kohler et al 2015), offering support for a fungi-mediated decrease in coal formation following the Carboniferous" (Floudas et al 2012). This is known as the 'evolutionary lag hypothesis' that is rejected by Nelsen et al 2016, who say that there was not as much lignin (in previous Carboniferous period) about as previously thought, and anyway there would have been organisms around to deal with it.
Here, we are the low rate of anaerobic decomposition of the plants was the main problem. De-lignifcation needs air, and had yet to evolve widely, which is what happened in Permian period.
The major ligninolytic enzymes are laccase, lignin peroxidase, manganese peroxidase, and versatile peroxidase…Numerous microorganisms such as bacteria, fungi, actinomycetes, and cyanobacteria have been reported which are capable to degrade lignocellulosic waste and other wood containing fibers" (Kumar and Chandra, 2020). There has been much study of the natural depolymerization of lignin by white- or brown-rot fungi, which produce extracellular oxidative enzymes, including laccase and peroxidases. (Lee et al., 2019)
The bacterial community of lignin degraders described till date comes under three classes such as actinomycetes, α- -proteobacteria and γ-proteobacteria. Various ligninolytic bacterial strains isolated from lignocellulosic-waste containing sites includes aerobic Azotobacter and Citrobacter and facultative anaerobe Paenibacillus sp (Bugg et al., 2011)
To Do..Check out white rot fungi and their relation with which soil animals?
The earliest definitive fossil record of basidiomycete white rot is from Triassic conifer wood (Stubblefield & Taylor 1986)
"An earlier evolution of fungal-mediated lignin degradation is indicated by Devonian-to-Permian woods infiltrated with fungi and possessing damage consistent with white rot decay or other forms of fungal degradation of lignified tissue" (Raymond et al 2001, Stubblefield & Taylor 1986,, Stubblefield et al 1985, Dieguez & Lopez-Gomez 2005)". (Nelson et al 2016) [nothing more up to date?]
Wood & Soil
Wood & Soil
Presumably the broken-down wood was incorporated into the soil. This is one of the most important processes on earth – dead wood into soil. Deadwood is an important element of any properly functioning forest ecosystem and plays a very important role in the maintenance of biodiversity, soil fertility, and carbon sequestration. The rate of decomposition and incorporation depends on the nature of the deadwood and the climate, generally where warmer the faster.
“Decaying wood is an important structural and functional component of forests: it contributes to generate habitat diversity, acts as either sink or source of nutrients, and plays a preponderant role in soil formation. Thus, decaying wood might likely have measurable effects on chemical properties of the underlying soil. We hypothesized that decaying wood would have a stronger effect on soil as decomposition advances and that such effect would vary according to wood quality…decaying wood, through its effect on SOM and nutrient dynamics, contributes to the spatial heterogeneity of soil properties in a subtropical forest, and can affect process of soil formation and nutrient cycling” (Zalamea, Gonzalez and Ping, 2007)
Types of decay
Types of decay
Wood-decay fungi act aerobically and can be classified according to the type of decay that they cause. The best-known types are brown rot, soft rot, and white rot. It is most likely that the main fungi then would have been brown rot. Brown rots primarily decay the cellulose and hemicellulose (carbohydrates) in wood, leaving behind the brown lignin. Wood affected by brown rot usually is dry, fragile, and readily crumbles into cubes because of longitudinal and transverse cracks occurring which follow cellular lines, or across cells, respectively. The decay commonly forms columns of rot in wood. Brown rots generally occur in conifers as heart rots.
Some – like Armillaria mellea would also invade conifer stems. When bark is removed, white or cream-colored mycelial plaques—the vegetative part of fungi—are present between the bark and wood of roots and trunk near or slightly above the soil line.
Logs & Soil
Logs & Soil
Various projects have analysed the soil under dead logs in different soil conditions to find out how they affected soil carbon. One study found there are significant carbon improvements under oak logs in a broadleaf forest but none under spruce logs in a Sitka spruce forest. They put this down to any inputs of carbon being masked by the already high,75+%, carbon in that forest litter. I think most of us would presume decaying logs add carbon to the soil – in a variety of forms.
More to it
More to it
However, there is more to it than that. “It was shown that the relative abundance of two groups of polyvalent cations: Ca2+, Cu2+, Zn2+, and Pb2+ on one side, and Al3+ and Fe3+ on the other, were affected differently by advancement of log decay. More divalent cations were available in the soil influenced by younger logs, and decreased as decomposition increased. While trivalent cations were more available near the older logs as decomposition advanced” (Zalamea, Gonzalez and Ping, 2007).The energy for electron transfer in soil would have increased dramatically in this period, leading to all sorts of possible combinations. Some of the deadwood breaks down to humus, offering a range of possible compounds.
While dead trees to soil would have been going on before, this period with the advancement into drier areas would be have enabled more aerobic breakdown of logs by fungi than had existed before, providing more food for soil inhabitants...
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