DESTRUCTION AND REPRODUCTION OF FORESTS. 



211 



a tendency to prevail, to the exclusion of 

 others. For reasons which will be after- 

 wards stated, this last stage is rarely attain- 

 ed by the burned forests, in countries be- 

 ginning to be occupied by civilized man. 



In accounting for the presence of the 

 seeds necessary for the production of the 

 second growth, we may refer to the same 

 causes which supply the seeds of the smaller 

 plants appearing immediately after the fire. 

 The seeds of many forest trees, especially 

 the poplar, the birch, and the firs and spruces 

 are furnished with ample means for their 

 conveyance through the air. The cottony 

 pappus of the poplar seems especially to 

 adapt it for this purpose. The seeds of 

 the wild cherry, another species of frequent 

 occurrence in woods of the second growth, 

 are dispersed by birds which are fond of 

 the fruit ; the same remark applies to some 

 other fruit-bearing species of less frequent 

 occurrence. When the seeds that are dis- 

 persed in these ways fall in the growing 

 woods, they cannot vegetate, but when they 

 are deposited on the comparatively bare 

 surface of a barren, they readily grow ; and 

 if the soil be suited to them, the young 

 plants increase in size with great rapi- 

 dity. 



It is possible, however, that the seeds of 

 the trees of the second growth may be al- 

 ready in the soil. It has been already stat- 

 ed, that deeply buried tubers sometimes 

 escape the effects of fire, and, in the same 

 manner, seeds imbedded in the vegetable 

 mould, or buried in cradle hills, may retain 

 their vitality, and being supplied by the 

 ashes that cover the ground, with alkaline 

 solutions well fitted to promote their vege- 

 tation, may spring up before a supply of 

 seed could be furnished from any extraneous 

 source. It is even probable that many of 

 the old forests may already have passed 

 through a rotation similar to that above de- 

 tailed, and that the seeds deposited by for- 

 mer preparatory growths may retain their 

 vitality, and be called into life by the favo- 

 rable conditions existing after a fire. This 

 is a point, however, requiring for its esta- 

 blishment a series of experiments which I 

 have not yet been able to undertake. 



If, as already suggested, forest fires in 

 the uncultivated state of the country, be a 

 provision for removing old and decayed 



forests, then such changes as those above 

 detailed, must have an important use in the 

 economy of nature, since by their means 

 difierent portions of the country would suc- 

 ceed each other in assuming the state of 

 " barrens," producing an abundance of 

 herbs and wild fruits suitable for the suste- 

 nance of animals which could not subsist 

 in the old forests ; and these gradually be- 

 coming wooded, would keep up a succession 

 of young and vigorous forests. 



Sdiy. The progress of restoration may be 

 interrupted by successive fires. These are 

 most likely to occur soon after the first burn- 

 ing, but may happen at any subsequent 

 stage. The resources of nature are not, 

 however, easily exhausted. When fires 

 pass through young woods, some trees al- 

 ways escape ; and so long as any vegetable 

 soil remains, young plants continue to 

 spring up, though not so plentifully as at 

 first. Repeated fires, however, greatly im- 

 poverish the soil, since the most valuable 

 part of the ashes is readily removed by 

 rains, and the vegetable mould is entirely 

 consumed. In this case, if the ground be 

 not of great natural fertility, it becomes in- 

 capable of supporting a vigorous crop of 

 young trees. It is then permanently occu- 

 pied by shrubs and herbaceous plants ; at 

 least these remain in exclusive possession 

 of the soil for a long period. In this 

 state the burned ground is usually consid- 

 ered a permanent barren ; a name which 

 does not, however, well express its charac- 

 ter, for though it may appear bleak and 

 desolate when viewed from a distance, it is 

 a perfect garden of flowering and fruit-bear- 

 ing plants, and of beautiful mosses and 

 lichens. There are few persons born in 

 the American colonies, who cannot recall 

 the memory of happy youthful days spent 

 in gathering flowers and berries in the burnt 

 barrens. Most of the plants already refer- 

 red to as appearing soon after fires, conti- 

 nue to grow in these more permanent bar- 

 rens. In addition to these, however, a 

 great variety of other plants gradually ap- 

 pear, especially the Kalinia august) folia; or 

 sheep laurel, which often becomes the pre- 

 dominant plant over large tracts. Cattle 

 straying into barrens deposit the seeds of 

 cultivated plants, as the grasses and clo- 

 vers, as well as many exotic weeds, which 



