NORTH AMERICAN FOREST TREES IN BRITAIN. 157 



spread over the British Isles in the dry, warm continental 

 climate that prevailed at the beginning of the neolithio period ; 

 but it has, with the advent of our present humid, cool climate, 

 gradually disappeared from all parts of the islands, except in 

 the great mountain massif of the Scottish Highlands. It is at 

 the present time distinctly a tree for use in certain districts only, 

 characterised by a low annual rainfall and much sun in late 

 summer and autumn, as in Speyside and Deeside in the north, 

 and in the sandy heaths of the south and east of England. In 

 such districts it regenerates freely, and attains a great height, 

 producing a satisfactory volume of timber of good quality. 



Our own foresters in their early introduction of the spruce, 

 larch, silver fir and sycamore from the continent of Europe 

 were distinctly improving on nature. All these trees were 

 largely used in plantations in the eighteenth century. The 

 movement towards extensive use of exotic trees was accelerated 

 by the discovery in the early part of the nineteenth century of 

 the trees of the Pacific Coast region of North America, where, in 

 a climate absolutely similar to our own, the highest and most valu- 

 able type of coniferous forest on the planet has been evolved. 



The North American forests deserve careful study, as they 

 comprise three great regions,^ which are absolutely distinct in 

 climatic conditions. These are : — 



I. — Eastern region, which is the largest, and extends from 

 the edge of the Rocky Mountains region eastwards 

 to the Atlantic. 

 II. — Rocky Mountains region, which comprises that great 

 mountain range, with its ramifications and foothills 

 down to the plains on either side, and includes roughly 

 the Yukon, eastern part of British Columbia, Alberta, 

 Montana, Idaho, Wyoming, Nevada, Utah, Colorado, 

 Arizona and New Mexico. 

 III. — Pacific Coast region, which extends from the western 

 boundary of the last region to the coast, and includes 

 Alaska, the western part of British Columbia, 

 Washington, Oregon and California. 



^ See map given by Sargent as frontispiece of Manual of the Trees of North 

 America (1905). I have omitted, as unimportant, three small districts on this 

 map, one in the extreme south of Florida, where the vegetation is tropical, 

 and two narrow bands lying along the Mexican boundary, where the trees are 

 similar to those of Mexico. The Eastern division and the Pacific Coast 

 region are each subdivided by Sargent into a northerly and a southern area. 



