280 GEOLOGICAL SURVEY OF NEW JERSEY. 
have reached maturity regeneration is effected by a series of 
uniform successive thinnings. The number of thinnings depends 
upon the circumstances of the case. Success in the method 
depends primarily upon two conditions: First, the trees must be 
in condition to produce a good crop of seeds; and, second, the 
forest floor must be a favorable bed for germination. From that 
time on the forest must be gradually thinned and finally removed 
as tapidly as the condition of the young growth will permit, 
which varies with the species, climate, soil, etc. 
This system is only applicable to pure, even-aged forests. 
This is a disadvantage, however, because for several reasons the 
tendency at present is decidedly in favor of mixed growths. 
Pure growths, especially of conifers, are much more seriously 
injured by the destructive forces of nature, such as winds and 
insects, than mixed forests. An excellent form of forest from a 
silvicultural standpoint consists of a growth of conifers with an 
underwood of some kind of shade-enduring deciduous trees- 
The overwood is healthier and the soil is protected and 
enriched by the underwood. To produce this kind of wood it 
is necessary usually to resort to the clean-cutting system with 
regeneration by planting or sowing. 
The fourth system, coppice, is so simple that little explanation 
is necessary. ‘The crop is simply cut clean year after year, and 
the new crop is formed either from stump-shoots or root-suckers. 
Care should always be exercised in cutting the stump close to 
the ground, with a clean sloping top, so that there will not be 
the slightest opportunity for rot and so that the young shoots 
will be healthy and sound. 
In the choice of species for planting and for favoring in mixed 
growth we should not fail always to consider the silvicultural 
qualities as well as usefulness for lumber. Fashion often guides 
us in our choice of kinds, and we should not fail to bear in mind 
that modern devices of treating wood may completely change 
its appearance and durability. 
The species of trees which may be successfully grown in 
southern New Jersey I have divided into two groups—first, 
those which require good soils, and, second, those which will 
thrive on the poor sandy soils and swamp-lands of the Coastal 
Plain; and since the latter are the lands to which the forest will 
