On the Planting of Forest-Trees. 267 



sisting principally of starch, which is so abundant in the Norway 

 pine as to be used by the natives of that country in scarce seasons 

 for making bread. Thus a new layer of wood is formed every 

 year, covering that which was produced the year before, while the 

 inner layer of the alburnum is converted into heart-wood. A new 

 bark is also produced, while the old is thrust outwards, and is 

 either exfoliated, as in the birch and plane-tree, or forms that 

 deeply furrowed mass of dead matter which encrusts the elm, oak, 

 and other trees. The office of the pith is not known, but as it is 

 always found in the annual shoots and twigs, it is probably essen- 

 tial to the buds and leaves. 



I trust that the above brief description of the organs of trees, 

 and the functions they discharge, will not be deemed irrelevant in 

 a work of practical instruction, for I am confident that it is only 

 by the diffusion of this kind of knowledge, the evils of mismanage- 

 ment, to which I have before alluded, can be effectually arrested. 

 We have enough of practice without knowledge in this important 

 department of rural economy, as the present condition of most of 

 our woods and plantations sufficiently testifies, and it is therefore 

 hiofh time to adopt a practice founded upon knowledge. It is 

 well known what fatal errors were committed in surgery before 

 anatomy was understood ; and most of the sylvan doctors have yet 

 to learn the physiology of trees. 



In speaking of the different kinds of trees, I shall premise a 

 few observations upon the natural causes which determine their 

 localities. The distribution of timber-trees, like that of all the 

 other vegetable tribes, depends upon two principal causes, climate 

 and soil. Climate is equally the effect of latitude and elevation; 

 accordingly, we find trees of similar kinds, if not identically the 

 same, growing on the elevated sides of the Andes and other lofty 

 mountains within the tropics^ and by degrees descending, as the 

 latitude increases, to lower situations, until they are found occupy- 

 ing the low plains on the banks of the Lena and Coppermine 

 rivers near the Arctic Circle. 



While climate effects the general distribution of trees by means 

 of temperature, the localities of different species of trees in the 

 same climate are determined in a great measure by the nature of 

 the soil ; most deciduous and soft-leaved trees require a much 

 larger quantity of potash than those of the pine tribe ; and such 

 trees are therefore found in low situations, on secondary and 

 tertiary strata, and diluvial plains, the clays of which abound with 

 that substance, while the pine tribe, which require but little 

 potash, principally occupy the light sandy levels and the sharp 

 thin soils of mountainous regions. It is not therefore the mere 

 firmness or openness of the soil which determines the production 

 of particular trees, but the presence of those substances which 



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