THE MICROBIOLOGICAL CONDITION OF WOOD OF LIVING BALSAM FIR AND BLACK SPRUCE IN QUEBEC

Abstract

Determinations of bacterial and fungal microfloras were made on 2% malt agar slants from wood samples of a living balsam fir, by following standard techniques for the isolation of decay fungi. Comparative studies with other microbiological sampling techniques and with different media have demonstrated (i) the general suitability of the standard method for ecological studies of wood-inhabiting microorganisms, and (ii) the validity of negative results obtained in previous isolation studies with the standard method. These findings reveal the pith column as a major center of bacterial activity in balsam fir, with relatively low activity recorded for the heartwood, and none at all in the sapwood. There is evidence that a similar situation exists in living black spruce, although the level of microbiological activity was much lower in the heartwood of this species, and bacteria almost nonexistent. Isolation studies conducted over the past 3 years in Quebec revealed that 40% of 132 living balsam fir trees and over 90% of 42 living black spruce trees sampled had sterile heartwood and sapwood. Retinocyclus abietis (Crouan) Groves and Wells was the only fungus isolated from both heart-wood and sapwood of the two species.