Studies into Fungal Decay of Wood In Ground Contact—Part 1: The Influence of Water-Holding Capacity, Moisture Content, and Temperature of Soil Substrates on Fungal Decay of Selected Timbers

Abstract

This article presents the results from two separate studies investigating the decay of wood in ground contact using adapted versions of laboratory-based terrestrial microcosm (TMC) tests according to CEN/TS 15083-2:2005. The first study (A) sought to isolate the effect of soil water-holding capacity (WHCsoil [%]) and soil moisture content (MCsoil [%WHCsoil]) on the decay of five commercially important wood species; European beech (Fagus sylvatica), English oak heartwood (Quercus robur), Norway spruce (Picea abies), Douglas-fir heartwood (Pseudotsuga menziesii), and Scots pine sapwood (Pinus sylvestris), while keeping soil temperature (Tsoil) constant. Combinations of soil mixtures with WHCsoil of 30%, 60%, and 90%, and MCsoil of 30%, 70%, and 95%WHCsoil were utilized. A general trend showed higher wood decay, measured in oven-dry mass loss (MLwood [%]), for specimens of all species incubated in soils with WHCsoil of 60% and 90% compared to 30%. Furthermore, drier soils (MCsoil of 30 and 70%WHCsoil) showed higher MLwood compared to wetter soils (95%WHCsoil). The second study (B) built on the first’s findings, and sought to isolate the effect of Tsoil and MCsoil on the decay of European beech wood, while keeping WHCsoil constant. The study used constant incubation temperature intervals (Tsoil), 5–40 °C, and alternating intervals of 10/20, 10/30, and 20/30 °C. A general trend showed drier MCsoil (60%WHCsoil), and Tsoil of 20–40 °C, delivered high wood decay (MLwood > 20%). Higher MCsoil (90%WHCsoil) and Tsoil of 5–10 °C, delivered low wood decay (MLwood < 5%). Alternating Tsoil generally delivered less MLwood compared to their mean constant Tsoil counterparts (15, 20, 25 °C). The results suggest that differences in wood species and inoculum potential (WHCsoil) between sites, as well as changes in MCsoil and Tsoil attributed to daily and seasonal weather patterns can influence in-ground wood decay rate.

Temperature sensitivity of termites determines global wood decay rates

“…(2) Precipitation-sensitivity: Microbial activity and substrate access are dependent on moisture [37][38][39][40] . We predicted microbial decomposition will be highest in humid locations.…”

“…These results suggest that while precipitation shapes the discovery phase, it does not affect the decay phase of termite decomposition; however, the strong temperature and precipitation interaction effect on discovery means that termites increase overall decay most in tropical seasonal forests and savannas and subtropical deserts (Figure 1C). Further, even though microbial abundance is highly sensitive to precipitation [37][38][39][40] , temperature was a stronger driver than precipitation of microbial-driven decay, perhaps mediated through its effects on enzyme kinetics 36 .…”

Modelling the Material Resistance of Wood—Part 3: Relative Resistance in above- and in-Ground Situations—Results of a Global Survey

“…The progress of decay in-ground is less affected by the wetting ability of wood, since wood mainly stays permanently wet when it is exposed to soil [86][87][88]. Wood that has undergone non-biocidal treatments, aimed at the exclusion of moisture from the cell walls, are therefore often not recommended for use in soil contact where intermediate re-drying is not possible.…”

Enhanced water uptake in the longitudinal direction by shiitake mycelium in shiitake cultivation logs: water content distribution in logs measured by magnetic resonance imaging

“…It has been found that the presence of brown rot fungi changes the penetration of liquid water into a piece of wood (Frankl 2013 ). Some papers present results on the observation of the decay of wood buried in the ground (Marais et al 2020 ), fungal decay resistance by coating (De Vetter et al 2009 ), the effects of soil and wood water content on fungal decay (Brischke and Alfredsen 2020 ), and the aging of the coating and cracking of the surface increasing the permeability of the wood (Ekstedt 2003 ).…”