THE FORMATION OF FORESTS 99 
braced from bank to bank. The water of the next 
rain will pass through, but the earth and débris will 
remain behind the brush dams until the gullies 
become practically filled. Then planting is easy. 
Along the shores of streams, bunches of brush in the 
form of bavins and fagots may be used to dissipate 
the action of the waves until willows or other trees 
may be used to hold the bank in place. The con- 
struction of these protective works which is prepara- 
tory to forest formation, often requires a great deal 
of skill and engineering ability. 
For the sake of convenience more than for any 
other reason, the formation of forests may be divided 
into two categories: the first, cases in which man 
prepares the seed-bed and sows the seed, or plants 
little plants; and, second, cases in which Nature sows 
the seed and where man simply aids her by preparing 
a seed-bed under the mother trees in such a way that 
natural regeneration follows. One is called artificial, 
and the other natural regeneration. Nature does 
most of the work in both eases. In fact, there is little 
that is artificial about it in the first ease. Man aids 
Nature a little more in one case than in the other. 
In one instance man sows the seed or plants the 
little plants, and in the other Nature does it, although 
in the latter man cuts in such a way that the mother 
trees will bear an abundance of seed, and wounds the 
