AbstractWork described in this thesis was undertaken to determine the effect of wood on behavioural aspects and growth of fungi and bacteria in pure culture and soil.
It was shown that sapwood blocks of lime (Tilia vulgaris) end pine (Pinus sylvestris) strongly influenced hyphal extension patterns of several wood inhabiting fungi when placed to one side of developing colonies, by eliciting either positive or negative chemotropic responses. A method was developed to measure and quantify these responses and statistically analyse them. then such fungi were grown in the presence of wood blocks treated with organic or CCA preservatives, only those preservatives with a volatile component influenced tropic responses. CCA treated blocks, even when leached, had no significant effect on the chenotropic response.
Aqueous extracts of sapwood of several wood species were shown to elicit positive chemotactic responses in a number of flagellate wood and soil inhabiting bacteria. Chenotaxis was also demonstrated to amino acids and sugars, such responses being greater, at the concentrations used in this investigation, to compounds with a nitrogen component.
Nitrogen contents of soils at IRG test sites were determined and found not to correlate with published decay estimates. It was considered that refinement and standardisation of soil sampling procedures was required in further studies.
Both fungal hyphal lengths and bacterial numbers were shown to increase in soil within 3mm of decaying wood, and such increases correlated with mass loss and nitrogen content of wood. Dehydrogenase activity in soil was significantly correlated with biomass presence, and both biomass increases and enzyme activity were inhibited in the presence of pine and in wood impregnated with CCA.
The presence of plastic barriers about wood in soil inhibited mass loss, nitrogen accumulation and dehydrogenase activity in wood and dehydrogenase activity in soil contiguous with such barriers. It was proposed that barriers acted as a prophylactic against the chemostimulation of soil microbial populations and microbial transfer from soil to wood.
|Date of Award||Nov 1983|