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to do, while the ground would be kept moist and in a state 

 favourable to the decomposition of vegetable matter. It 

 is desirable therefore to frame regulations regarding such 

 forests, deciding the minimum to be preserved of the 

 number of trees per acre, due regard being of course paid 

 to age, species, altitude, and locality. For these reasons 

 it is highly important that all such forests, whether private 

 property, commons, or belonging to the State, should be 

 placed under the control of the State. 



The different trees have naturally a different effect as 

 regards conservation of water and production of food and 

 shelter for fish, as I will here briefly point out. To simplify 

 matters we may divide all forest trees into two large groups, 

 the deciduous and the evergreen trees. The deciduous 

 trees, of which, as far as Great Britain is concerned, the oak, 

 elm, beech, plane, larch, willow, and poplar are the most 

 prominent, have a decided advantage over the evergreens. 

 I need not here enlarge upon the fact that the full 

 shady foliage during the summer is far more effective in 

 preventing a large evaporation, and that the branches of 

 the trees of this group are more spreading than those of the 

 other. The energy of life seems to be far greater in these 

 trees towards effecting our objects, and for direct border 

 trees to a watercourse they are undoubtedly the best suited. 

 The great amount of foliage and branchlets yearly thrown 

 by these trees forms a very prominent factor in the economy 

 of nature, and their decaying vegetation is full of teeming 

 life and food for fish. 



That this group is eminently suited for water conserva- 

 tion, was illustrated in a forest in Denmark, where an area 

 of firs and pines was cultivated with beech and oak. After 

 a lapse of about fifteen years a millstream, which during 

 the time of the evergreen trees had dwindled down con- 



