The Microflora 



265 



Laccaria sthatula and Galerina subannulata), no one of which is restrict- 

 ed to this microtopographic unit. 



Higher fungi inhabiting the wet meadow also show little specificity; 

 only 1 of 13 species recorded appears restricted to wet meadows, while 10 

 of the 19 species recorded from wet meadows and polygon troughs are 

 common to both microtopographic units. Rims of low-centered polygons 

 and tops of high-centered polygons show similar overlap, with 12 of the 

 23 species recorded being common to both (Figure 8-1). In all other com- 

 parisons there is a clear lack of common species; usually fewer than 10*^0 

 of the species recorded from a pair of microtopographic units are com- 

 mon to both. Much of the difference in commonality appears associated 

 with gradients in soil moisture and aeration and vascular plant assem- 

 blages. A relatively high percentage of the species on the extremes of the 

 moisture gradient are found in only one microtopographic unit, e.g. 31% 

 in troughs and 32% on tops. Similarly, a comparison between tops of 

 high-centered polygons and polygon troughs reveals only 1 of 35 species 

 in common. This species, Galerina subannulata (Sing.) Smith and Sing., 

 is ubiquitous and found in all microtopographic units sampled. 



Broad trophic distinctions exist between the meadow-trough com- 

 plex and the rim-top complex (Figure 8-2). About 50% of the species in 

 each complex function as decomposers of dead plant material. Almost 

 all the mycorrhizal forms are restricted to the rim-top complex, where 

 the proportion of dicotyledonous plants in the vascular vegetation is 

 higher than in the wet meadows or polygon troughs. Conversely, the epi- 

 phytic fungi are restricted to the meadow-trough complex. Among the 

 basidiolichens, Omphalina hudsoniana is found only on rims and tops 



Meadows Troughs 



Rims 



._ I5|- 



c 



3 



? 



ir 



10 



o 5 



Q. 

 V) 



15- 



10- 



5- 



I5h 



10 



L 



I5h 



10 



Tops 



I 



SMB "SMB SMB SMB 



^SoprophytJc(S) ^Mycorrhizal(M) BBasidiolichen(B) 



FIGURE 8-2. The usual trophic status of higher fungi 

 within different microtopographic units. (Data of Miller 

 and Laursen.) 



