292 RELATION OF FORESTS TO THE 



maple, the first three being the leading species, but these have now 

 been succeeded by the beech, which at present is the tree which 

 greatly predominates. It is a tree more inclined to be exclusive 

 than any other broad-leaved tree, but it is being encroached upon 

 again by the fir. And is there not a cause 1 There is ; and Vaupell 

 seems to consider that man is unconsciously — and to his own dis- 

 advantage — helping forward the encroachment of the Goths and 

 Vandals on the nobler races at present in possession. And the views 

 advanced by them may subserve our present aim. 



In regard to the removal of fallen leaves he remarks : — " The 

 removal of the leaves is injurious to the forest, not only because it 

 retards the growth of trees, but still more because it disqualifies the 

 soil for the production of particular species. When the beech 

 languishes and the development of its leaves is less vigorous, and its 

 crown less spreading, it becomes unable to resist the encroachments 

 of the fir. The latter tree thrives in an inferior soil, and being no 

 longer stifled by the thick foliage of the beech, it spreads gradually 

 through the wood, while the beech retreats before it aaid finally 

 perishes." And in connection with this he adverts to the fact that 

 " The leaves belong to the soil. Without them it cannot preserve its 

 fertility, and cannot furnish nutriment to the beech. The trees 

 languish, produce seed incapable of germination, and the spontaneous 

 self-sowing, which is an indispensable element in the best systems 

 of sylviculture, fails altogether in the bared and impoverished soil." 



Thus may the succession of firs to beeches, if it should ultimately 

 occur, be satisfactorily accounted for. And in a corresponding way 

 may some of the previous successions of difierent kinds of trees be 

 accounted for : I say not in the same way but in some corresponding 

 way ; and in some corresponding way may much of the grass and 

 herbage which previously covered the forest ground have given way 

 to the forest trees, not because the conditions were absolutely un- 

 favourable to them, but because being also favourable to the growth 

 of trees, and perhaps comparatively more so, or otherwise simply in 

 virtue of their more sturdy constitution, these having gained a footing 

 maintained it, and the others were overpowered. Now one of the 

 conditions determining this was a particular distribution of the 

 rainfall both as to time and space, which was essential to the 

 growth of the trees which then existed, and but for whch the grass 

 and herbage would have been left in undisturbed possession. 



Such is in part the eSect of the distribution of the rainfall on the 

 distribution of forests. 



