ECOLOGY OF ISLE ROYALE. 189 



limited number of species which are individually abundant; numerous 

 local faunae. Contains the characteristic desert fauna of North America. 

 Influenced markedly by glaciation only at the extreme north, and 

 possibly in the Great Basin, but certainly by the great fresh water 

 lakes formerly occupying this basin (Wickham '04, '05). An old (pre- 

 ■Glacial) center of origin, preservation, and center of dispersal. 



3. The Southeaste^rn Humid Hardicood Forest Area. This area in- 

 cludes much of eastern United States east of the plains (exclusive of 

 southern Florida), and north to the Canadian conifers. The Coastal 

 Plain (and possibly the Mississippi Embayment area) may form a sub- 

 center through the influence of its conifers (Schwarz '90; Chittenden 

 '00, '01). 



Local lists within this center: Summers '74; Schwarz '78; Ulke '02; 

 Dury '02, '06. cf. LeConte '78a. 



Characterized by the abundance of forest insects, particularly those 

 infesting hardwoods; species of extensive range; few local fauna; a 

 large number of species found in a given locality, often but few in- 

 dividuals. 



An ancient centre of origin, preservation and dispersal. Glaciated 

 on the north, and post-Glacially repopulated, as was also the Coastal 

 Plain and Embayment, with the elevation of the Coastal Plain. 



4. The Transcontinental Conifer Area. This area includes the re- 

 mainder of forested North America, and includes all of the higher 

 mountain ranges. Its relation to the Coastal Plain conifer belt has 

 not been determined. 



Characterized by conifer feeding beetles, Cerambycids, Scolytids; 

 numerous Carabids and Staphylinids, and thus shows a decided subarctic 

 ■circumpolar affinity. Few endemic elements and local faunae. Ex- 

 tensive range of species, except in the high mountains. Largely a new 

 land surface through glaciation; largely repopulated at a relatively 

 late date; apparently characterized by dispersal or diffusion of forms 

 rather than for their origin or preservation, except the mountain areas 

 of the United States, which wei*e areas of preservation and origin. 



The very different history of its eastern portion, with much more 

 extensive glaciation, is to be contrasted with the moderate western gla- 

 ciation. The differences in the character of the forests is also marked; 

 the giant western conifers are to be constrasted with the smaller con- 

 ifers of the Northeast. The Mackenzie Basin and the Plains mark the 

 line of division between these subcenters. This division is so marked 

 that it may yet necessitate a complete severing of the transcontin- 

 ■ental conifer belt. (cf. Murray '70, pp. 32-33.) 



a. The Eastern Canadian Conifer Fauna. 



This includes Canada east of the Rocky Mountains, north to the tree 

 limit and the interior of Alaska; northeastern United States; and 

 southward on the Appalachians. 



Characterized by forms of extensive subarctic range, very few 



■endemic elements or those peculiarly American; individuals abundant, 



variety moderate; beetles feeding on conifers, birches, and aspens. T^e- 



€onte '50, '59, '78b. There is a possibility that this fauna has North 



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