Table XLIII. Microfungi and bacteria counts from soils on the hot 

 pipe and control sites. 



The soils in the disturbed site were taken in areas opposite and parallel to those sample 

 areas in the natural forest and over the heated pipe. From these comparative samples the effects 

 of the perturbation on the microfungi were assessed. Much of the data collected are still being 

 processed and correlated. Preliminary observations are as follows. 



A total of 150 species of microfungi were isolated from the two sites: 122 from the natural 

 and 83 from the disturbed area. There were 54 shared species of which, in the natural and the 

 disturbed areas respectively, 35 species occurred in a ratio of 2:1 and 19 occurred in ratios 

 ranging from 1:1 to 98:1. Seven species occurring in high density in the natural area were completely 

 missing from the disturbed area and conversely two high-density species occurred in the disturbed 

 area which were absent in the natural sites. Between the two areas considerable differences 

 were noticed in relative densities of major species components (Table XLIV). 



Abiotically and microbiologic ally the area disturbed has been changed drastically. The changes 

 are both qualitative and quantitative for fungi and bacteria. The extent to which there is species 

 change in bacteria populations has not yet been determined. There are obvious gross changes in 

 pH, organic matter and moisture content of these perturbed soils. More than likely an observed 

 change from acid to alkaline pH is the major cause for rise in bacterial biomass and concomitant 

 decrease in fungal biomass. In many taiga soils the pH changes from acid to alkaline with in- 

 creased depth. Turning soil in the disturbed College site could account for the marked change in 

 pH. Heating the soil below can cause upward migration of water and solute salts. This effect 

 could well account for the increased alkalinity. 



These chaises in pH will select for entirely different plant and microbial communities. The 

 absence of a litter layer is most probably causing some very profound ecological changes. During 

 metabolism, fungi excrete many organic acids. Litter contains many organic acids. These acids 

 in combination maintain a suitable pH for fungi and rapid turnover of organic material. The removal 

 of litter upsets this balance, resulting in loss of acidifying agents. These factors also could 

 account in part for the increase in pH and bacterial biomass. The absence of a litter layer together 

 with influx of fungi on non-sterilized seeds could account at least partially for changes in species 

 components. Changes in relative densities of major species components could be accounted for 

 by lack of certain substrates and removal of competition. The changes in pH would select for 

 certain fungal species. Two variants of the extremely competitive celluloytic Trichoderma viride 

 are completely absent from the perturbed sites but occur very commonly in the adjacent natural area. 

 The ecological lacuna is probably being filled by one of the high density species in the perturbed 

 area e.g. flO or f27. 



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