280 F. L. Bunnell et al. 



Meadows Basins Troughs 



Rims 



10x10°- 



>, o 

 ^ in 



^ »5xlO^- 



d 



1 



t^ 



J 



2x10 



xlO' 



■3 o 1 

 o 



DQ 



o> 



2x10^- 



□ Density 



I 



iBiomass 



-2x10 



FIGURE 8-9. 77?^ seasonal average density and bio- 

 mass and estimates of minimal productivity (sum of 

 positive changes in counts) of plateable bacteria in the 

 I- to 2-cm soil depth, 1973. (Benoit, unpubl.) 



and appears associated with fruiting of the basidiomycetes. 



A comparison of estimates of minimal fungal productivity with 

 mean biomass estimates (Table 8-3) indicates that minimal productivity 

 ranges from about 2 to 3.6 times the average biomass in the surface soil, 

 giving broad turnover rates of about 2 to 3.6 times per season, about 2 

 times the rates estimated by Hanssen and Goksdyr (1975) for Norwegian 

 sites. Turnover rates in the deeper soil are generally about 20 to 70% 

 greater. Although fungal biomass is low in the deeper soil layers, the ex- 

 isting biomass appears more productive than near the soil surface. This 

 latter observation may be a result of grazing microbivores consuming 

 more of the fungal growth near the surface (Chapter 11), a phenomenon 

 that may confuse comparisons between years as well. 



Estimated bacterial production is only broadly correlated with mea- 

 sured abundance among microtopographic units (Figure 8-9). Although 

 basins of low-centered polygons show low counts of plateable bacteria in 

 the upper soil, the population is relatively more productive than the more 

 abundant populations in wet meadows. Widden (1977) reported a similar 

 situation from Truelove Lowland: the more abundant bacteria of the 

 sedge meadow were less productive than the sparser bacteria on the 

 beach ridge. When dilution counts are converted to biomass, polygon 

 troughs and rims of low-centered polygons are the most productive mi- 

 crotopographic units. 



