384 George E. Nichols, Vegetation of Northern Cape Breton. 



are afforded by well-drained swampy areas which have been 

 converted into meadow-land. Here sedges and grasses pre- 

 dominate and the vegetation approximates more or less closely 

 that elsewhere described as characteristic of open, well-drained 

 swamps. Grazing cattle and sheep may bring about the intro- 

 duction into a swampy area of plants not previously present and 

 they may appreciably retard succession, but otherwise they do 

 not seriously modify the conditions. Aside from instances such 

 as those just outlined, any changes in the vegetation and suc- 

 cession in the swamps which are attributable to human activity 

 have been largely due to logging and fire. The former agency 

 may have resulted in the removal of the original forest cover, 

 where one was present, but beyond this has had little retrogres- 

 sive effect on the vegetation in the areas concerned. The 

 influence of fire is much less in swamps than on uplands, since 

 the very wetness of the substratum may prevent the complete 

 destruction of subterranean plant organs. In general, the 

 association-types of secondary hydrarch series appear to differ 

 little from those of the primary series as described elsewhere. 



