THINNING AND PRUNING. 31 



The first of these, completely within the control of the for- 

 ester, is the browsing of cattle. This is highly injurious to a 

 forest in every state. It is destructive to the young trees, to the 

 lower branches of taller trees, and to the undergrowth, which, 

 in an old forest, is the hope of the future. Sheep and horses 

 are not less injurious than cattle. All should be entirely ex- 

 cluded from woodlands intended to be valuable as such, and to 

 renew themselves.* 



I have already spoken of priming. Where the object is wood, 

 it may be doubted whether any pruning is advisable, except in 

 the case that a branch of one tree materially interferes with the 

 growth of another. Plants receive food by their roots, and di- 

 gest and convert it to their various products, by and in their 

 leaves. Both roots and leaves should therefore be left to extend 

 and expand themselves as freely as possible ; the one to occupy 

 all the space just below the surface of the ground, the other to 

 gain all the air and light within their reach above. Whatever 

 checks this free expansion, has a tendency to lessen the product 

 of wood. 



On thin soil the roots cannot penetrate far, and a tree, sur- 

 rounded by others, will soon exhaust the proper nutriment 

 within its circle, and must then begin to fail. As soon as this 

 happens, it must be removed, and trees of other families must 

 be sown or planted in its stead. The proper treatment for thin 

 soils, is, therefore, a rapid alternation of crops. 



Most forest trees are injuriously affected by the sea-breeze, 

 and we generally find them stunted and dwarfed by its influ- 

 ence. The remedy is to plant numerously the hardiest trees 

 along the seaward border. Those that most successfully resist 

 the sea-breeze, are the sycamore or plane tree, the linden, the 

 poplars, particularly the balm of Gilead. and many of the pines. 

 Almost all trees may do it when growing in large masses. 



* Where a forest is to be renewed artificially, and where the trees are out of the 

 reach of cattle, there is no objection to their grazing among them. One consider- 

 able recommendation of the Duke of Athol's mode of redeeming lands by planting 

 larches, is, that the ground is improved for pasturage by the growth of grass under 

 the shade of the trees. 



