404 REPORT OF THE COMMISSIONERS OF 



perhaps, in spots, planted, with as little interruption in the canopy as possible for the 

 sake of the soil. The farmer cultivates his land by tillage — the forester by regulating 

 the light conditions of his forest, by encouraging certain beneficial species of trees and 

 soil animals. The forest is not a mere assemblage of trees. It is a great unity con- 

 sisting of the birds, the bees, the worms, and fungi, besides trees and many other 

 things, each of which plays a role of more or less importance. It is a great machine, a 

 series of wheels within wheels, all dependent upon one another, and all influenced by 

 one another's activities. 



The pine is not of course the only tree which plays the role of pioneer. There 

 are the poplars and birches in the North, which are the salvation of many burned-over 

 areas. Their seeds are carried long distances in immense quantities by the winds ; 

 they germinate quickly and soon clothe black unsightly burns with a coating of rich 

 light green. The blackness of these burned-over areas draws the sun to such an 

 extent that artificial planting with less hardy sorts could not be otherwise than failures. 

 Soon after they have become covered with poplars or birches, narrow lines may be 

 cut in the thickets and conifers planted. Owing to the shelter which these young 

 poplars, birches and cherries afford, the chances for the survival of the conifers are 

 good. In the course of time, spruce and pine work into these thickets naturally. 

 Later, maples and other trees find a foothold, and in the course of time there is formed 

 a mixed woods of conifers and many hardwoods. If these burned-over areas, 

 especially in sandy districts, are burned over repeatedly, it is of course a long time 

 before even the poplars, birches and cherry can gain a foothold. 



What may appear to the novice to be a weed, may be a shelter tree and soil 

 protector in disguise. A weed is a plant out of place, and any tree which serves tne 

 purpose of protection is decidedly in place in a region such as the sandy soils of the 

 Adirondack's, where much protection is needed against the rigors of winter and 

 drought of summer. When, however, this shelter tree begins to crowd or interfere 

 with the growth of a more valuable neighbor which is no longer in need of its services, 

 at that moment it becomes a weed. 



In irregular, open forests weeds are of course much more troublesome than in a 

 closed regular forest with a dense, even canopy. Even then the few shade-enduring 

 weeds are able to survive ; but these are ordinarily so few in number and so unobtru- 

 sive that they are of little consequence. 



Before considering the subject of soil-fixation I should define more in detail the 

 role played by micro-organisms in furthering forest growth. There has been discov- 

 ered lately a mode of life which is peculiar. It is called symbiosis or mutualism. It 

 is when two organisms are united for the good of both. It is not parasitism, because a 

 parasite is a robber who steals his food and gives nothing in return. Neither is it the 



