1856.] The Absence of Trees from Prairies. 27 Z 



forests, they contain no very old trees except in the ncighboihood of the 

 Baltic and Black seas, and in all other places the timber they furnish is 

 very defective in durability. The dry rot prematurely attacks nearly all 

 the Russian ships, permitting few of them to last longer than ten or 

 twelve years, and their great liability to decay is a very serious draw- 

 back to the naval power of this extensive empire. Even on this continent, 

 the timber of the Atlantic coast is much more durable than that of the 

 Mississippi valley, and the number of hollow trees appear to increase as 

 we retire from the sea- board. 



As the same state of things is productive of degeneracy as well as 

 disease, it would be reasonable to expect, that it should frequently cause 

 trees to disappear from the soil in places remote from the ocean. This 

 would be most likely to occur when the soils have great fertility ; for in 

 this case, they supply more nutriment to trees than can be converted 

 into wood by the action of the leaves. Accordingly, extensive plains in 

 the interior of continents should, in course of time, become destitute 

 of woods except in places where the soil is comparatively barren, or 

 along the banks of rivers, where they are favored by mists or heavy 

 dews. Such peculiarities are to be witnessed in the AVestern prairies of 

 this continent, the pampas of South America, and the steppes of Central 

 Asia. "Whenever meteoric influences are favorable to their health, trees 

 have the advantage over annual plants in disputing the possession of the 

 soil, and there the forest acquires an extensive dominion over the land ; 

 but the case is reversed on extensive plains ; and here the herbaceous 

 plants are successful in resisting the encroachments of the forest. 



It has been generally supposed that the absence of trees, in these 

 localities, is due to human agency ; that the prairies were once cleared 

 and cultivated, and that the growth of the forest was subsequently pre- 

 vented by fires. But the Western prairies afford no monuments of the 

 skill of an agricultural people of former times; while the extensive 

 pampas of South America were, according to Humboldt, always avoided by 

 the Indians, and contain not a single vestige of ancient civilization. The 

 steppes of Central Asia are likewise destitute of wood, though the forest 

 has established its dominion along the coast and around the mountains 

 of that continent. It may, indeed, be possible to convert prairies into 

 wood-land, by selecting hardy plants, by placing them at sufficient inter- 

 vals to permit the expansion of their foliage, and by always introducing 

 seeds from other regions to compensate for the effects of local degeneracy ; 

 but it is doubtful whether all these precautions will enable the wood to 

 attain a proper degree of strength and durability to supply those local- 

 ities with timber. i 

 18 



