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ihrougliout the preat distance of 4,000 miles v,-e find the same group of trees. 

 Again in tlie great triangular area of the North-west, between the United States 

 boundary, the llocky Mountains, and the Laarentian region, embracing over G00,00() 

 square miles, very little diHereuce could he observed in the climate, the soil, or the 

 general level of the country, antl hence the same groun of trees — only about half a 

 dozen in all — are found throughout this immense tract. In striking contrast -svith 

 tills is the fact that on the same farm lot in the south-western part of the province 

 of Ontario one may ol'teu count as many as lii'ty diilerent trees. The richness in 

 variety of the native trees of Ontario and the adjacent States is owing to the 

 fertile suil and the favourable conditions as to summer temperature, constant mois- 

 ture, and the absence of intense cold in the winter. The writer exhibited a map 

 showing the northern and westi'rn limits of the principal forest trc's of the Do- 

 minion east of the Itocky Mountains. From this it appears that the ri.nge of .species 

 is not according to the moan annual temperature or ])recipitatiiiii, but rather to the 

 absence of extremes of heat and cold, and great dryness. For tlicse reasons a 

 number of the trees of the province of Quebec and northern Ontario do not range 

 west into Manitoba, although the annual means of temjierature and i)ieci))itation 

 are nearly the same in both. This map also shows in a striking manner that the 

 northern limits of our various forest trees are l)y no means parallel to one another^ 

 although locally some groups may be nearly so for a certain distance. Some of 

 them pursue extraordinary or eccentric courses, which are diilicult to account for. 

 The most remarkable of these is the white cedar, which in the central part of its 

 trend reaches James' Bay, but drops suddenly to the south at the Gulf of St. Law- 

 rence in the east, and on reaciiing the longitude of the head of Lake Superior iu the 

 west. Yet the climate and other conditions appear to be the same for some distance 

 both east and west of these lateral boundaries. An outlying c<jlony of the white 

 cedar is found at Cedar Lake near the north-western part of J.ake Winnipeg. 

 Colonies or outlying' p.Tlches of other trees have been noted in ditierent localities, 

 such as of the basswood a?id sugar-maple at Lake St. John, north of Quebec, of the 

 grey elm on the Missinaibi lliver, near James' J5ay, and of the hemlock spruce at 

 Thompson, near the west end of Lake Superif)r. 1 iivers and lakes, by supplying heat 

 and moisture and warding off summer frosts, often promote the growth of trees on 

 their immediate banks which are not found elsewhere in the surrounding country. 

 Instances of this may be seen along the North Saskatchewan, where the negundo,, 

 green a^h, grej' elm, white birch, alder, &c., thrive only on the river banks. In 

 the cold regions, the white .spruce grows to a much larger size on the shores and 

 islands of rivers flowing north tl'.an elsewhere. It has been found that exotic fruit 

 trees and other introduced plants can be successfully cultivated around the shores 

 of the larger lakes, especially on their southern sides, which will not grow at a short 

 distance inland. On the other hand the inuuediate proxiraitv of the sea, with a 

 lower summer temperature than the land, is unfavourable to the growth of timber 

 in the north. The habits of some trees are much modilied in difl'erfut latitudes. 

 Species which grow in warm dry .soil in the north may be found in cold, heavy, or 

 wetland in the south. The larch, balsam, white cedar, white pine, white birch, 

 &e,, are examples of this tendency. Some species extend far to the outh of their 

 general home along mountain ridges, while others seem to refuse to follow such 

 lines. The existence of extensive swamps, the shelter of hills, or the elevation.? 

 which they aflbrd, are therefore to be regarded among the minor elements govern- 

 ing the distribution of trees. 



The peculiarities in the outline of the northward limit of the white cedar and 

 other species of trees may throw some light on questions as to the direction from 

 which they have migrated or been dispersed. In some cases which the author has 

 studied, the trees appear to have reached the most northern limit possible. For 

 example, in its most northern range, the first tender leaves and shoots of the black 

 «8h are blighted almost every year by the spring frosts ; the trees are of small size 

 or stunted in height, and only occasionally bear seed. Sir John Richardson 

 mentions that on the barren grounds, outlying patches of dying spruces were some- 

 times met with far out frr -1 the verge of the main forest, and that he saw no 

 evidence of young trees .«• ^-iging up beyond the general line of trees ; from which 



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