58 CANADIAN roRWTRY ASSOCIATION. 



porting a long way north, and that they will flourish after they have been transported. 

 I think the northern limit of a tree might be called the limit beyond which it will not 

 ripen its seeds, and beyond which it can only be grown with artificial help. If it ripens 

 its seeds every year, or even once in many years, it may be said to be within its north- 

 ern limit. 



I have given special study to questions affecting the northern limits of our trees, 

 and have embodied the result in several published maps. On my revise.! maps I have re- 

 presented to within a possible error, in some places, of five miles, the present northern 

 limits of thirty of our species of forest trees, throughout the greater part of the Domin- 

 ion. I might explain this map to those of you who are not familiar with it. The limit 

 lines do not run parallel, east and west, but they seem to wander all over the map. 

 Although the prevailing direction is approximately east and west, some of them run 

 hundreds of miles north and south; others curve around 1 in a way that is very diffi- 

 cult to explain to any one who has not given the matter some study. I think that it 

 may be partly explained by the geological conditions which have submerged and after- 

 wards raised the level of the land, so that the old shore lines were constantly chang- 

 ing. 



I might just mention two trees to give you an instance of how trees may guide 

 us in forming some idea of the geological changes which have taken place in this 

 country. Take for instance the Banksian or jack pine, which rather shuns the pre- 

 sence of the sea, and the balsam poplar which seeks it. By using those two trees 

 alone as guides, we are able to point out what parts of the country were covered with 

 water a short time ago (geologically speaking). For instance, the Banksian pine is 

 found in the interior of the Labrador peninsula and all through the provinces of 

 Quebec and Ontario, at the greatest distances from the sea, and on elevated lands, 

 these elevated portions marking the islands and mainland that represented this con- 

 tinent a short geological time ago. The balsam poplar is found in the outer portions 

 of the Labrador peninsula, but not' in the centre. It is found around Hudson bay, 

 and to the westward. Whenever we come near the sea we find these trees. 



There is another point of great interest in regard to the distribution of trees, 

 that in certain regions or along certain zones you can find areas that contain a given 

 tree, and other areas which do not contain it. For instance, if you travel towards 

 Hudson bay, you do not go very far before you get beyond the limits of certain 

 species, such as the black ash, the American elm, and some others, but after crossing 

 the height of land, and going perhaps a couple of hundred miles beyond the last ex- 

 amples you had seen of these trees, you will suddenly come upon them again. This 

 shows that the climate is better adapted to them there, than the climate south of it, 

 on the height of land. 



There are many instructive circumstances which we might deduce from the 

 study of the distribution of trees. The Banksian pine is perhaps the only tree that we 

 can claim to be Canadian. It certainly does extend its limits into the United States 

 in some directions, but the occurrence of this tree may be said to be mostly within 

 the limits of Canada. All the other trees of Canada extend into the United States 

 very largely. 



