18 OUTLINE OF PLANT GEOGRAPHY 



Wherever man has settled, the original vegetation has been 

 more or less profoundly altered. Primaeval forests once covered 

 the sites of many a great city, and the sod of the prairies has been 

 broken and given place to fields of corn and wheat, and the 

 orchards and meadows of countless farms of the mid-west. 



In his earliest development primitive man only took from the 

 forest such food as he might find — fruits, nuts or roots, thus 

 doing no more to disturb the equilibrium of the plant association 

 than would be done by the foraging of any other animal; but as 

 soon as he developed the most rudimentary form of agriculture, 

 or attempted to provide grazing for animals, tame or wild, he 

 began a warfare with the vegetable kingdom which has continued 

 with increasing energy down to the present time. 



Such primitive races of man are to be found today only in a few 

 remote parts of the world. The Australian Blacks, and a few 

 scanty remnants of primitive races in various tropical countries, 

 still exist, but constitute only the merest fragment of mankind. 



At a very early period in his history, man practiced a primitive 

 form of agriculture, and so soon as he had brought under cultiva- 

 tion the cereals and other food plants, and had domesticated 

 sheep and cattle, a new era was opened, and he was able to migrate 

 far from his original home, carrying with him his cultivated food 

 plants. 



Forests were cut down to afford ground for cultivation or pas- 

 ture, and the native vegetation replaced by grain fields, orchards 

 and vineyards. Indeed the ability to carry with him food in 

 the form of grain and herds, alone made possible the great 

 migrations of mankind, both in former times and today. 



With the facilities for transportation developed during the past 

 century, migration has reached a stage absolutely unheard of in 

 previous history, and the influx of millions of men into previously 

 unoccupied regions is reflected in immense changes in the vegeta- 

 tion of nearly all parts of the world — far greater than in any pre- 

 vious period of the world's history. 



Forests have been swept away until the world is menaced with 

 a timber famine, and their place has been taken by crops of all 

 kinds, which are entirely alien to the country and completely 

 alter the appearance of the landscape. This disturbance of the 

 natural vegetation is not confined to the white settler alone, but 



