34 HARPER: PLANT POPULATION OF MICHIGAN 
richer regions of southern Michigan, Ohio, etc., than they do. 
While the fireweeds are flourishing, seeds of the original conifers 
are being brought in in the regular manner, and by the time the 
birches and aspens have run their course the conifers that have 
Fic. 3. Scene in large tamarack swamp with a few feet of peat, about four 
_miles north of Douglas Lake, bordering a sluggish stream flowing into Carp Lake. 
Trees in background all or nearly all Larix laricina. (See Gates, 1913, pp. 64-66.) 
Open space in foreground evidently severely burned several years before. Woody 
plants in it mostly Larix seedlings, Salix pedicellaris, Betula pumila, Rhamnus alni- 
folia, Chamaedaphne, Alnus, Lonicera canadensis and Ledum. Evergreens in the 
minority; little or no sphagnum. (This view was taken a mile or more from the 
stream, and near the south edge of the swamp, where it is bordered by clayey hills 
mostly cultivated. Toward the stream the percentage of evergreens increases con- 
siderably.) 
been growing up in their shade may be ready to dominate the 
situation again.* 
Since the best pines have disappeared the lumbermen have 
attacked the hardwood forests also, and much hemlock has been 
destroyed for tan-bark. The slash left from these operations is 
subject to fire too, but the fireweeds on hardwood land are not 
quite the the same as on pine land. Sambucus pubens and Rubus spp: 
* So ine many papers have been written about the effects of fire in ‘boreal coniferous 
forests that it would not be worth while to attempt to cite them here, but references 
t© several of them can be found in Bull. Torrey Club 35: 349. 1908, and in Pop. Sci. 
Monthly 85: 341. 1914. 
