REFORESTATION ON THE NATIONAL FORESTS. 
3 
be so situated that the plantation will serve as an excellent object 
lesson. 
The economic importance of field planting or sowing, the expense 
attending it, the even greater proportionate expense of replanting or 
resowing parts of areas where the first operation failed, and the 
high percentage of mortality which is almost sure to attend ill-advised 
and hasty work have led to two stages in reforestation work on the 
National Forests; first, experiments conducted on a small scale; 
and, second, extensive field operations. Successful field planting or 
sowing on a large scale is not a simple operation. The task of plant- 
ing or sowing so many acres to forest trees or seed in a given period 
of time is merely a matter of providing the seed or nursery stock and 
employing a crew of sufficient size, but the success of the operation 
depends on much more than this. The object of experimental plant- 
ing and sowing is to determine the factors which make for success or 
failure. These in turn serve as a guide for reforestation operations 
on a large scale. Experimental planting or sowing is usually inten- 
sive and necessarily expensive. Practical reforestation on a large 
scale takes advantage of the facts learned through experimental 
work, and the foremost consideration is to make the costs reasonable 
and yet secure success. 
COLLECTION OF SEED. 
SEED CROPS, 
All planting and sowing must begin with the collection of seed. 
Trees, unlike some other plants, do not bear a good crop of seed every 
year. Conifers in particular are very irregular about this. A few 
cones are produced every year, but w^ith most species it is only at 
intervals of from two to five years, or more, varying with the species 
and the climatic conditions, that a heavy crop occurs. Years when 
seed of any species is produced in abundance are known as "seed 
years" for that species, and the intervening years are called "off 
years." During " off years " seed is produced only in small quanti- 
ties; it is difficult to obtain because of the concentrated demand for 
it by rodents and birds, and there is a smaller yield per bushel of 
cones. 
In a " seed year " the seed crop of any species is usually abundant 
throughout the tree's range, though much better in some places than 
in others. Even during an " off year " a species may produce some- 
where within its range a fair crop over a limited territory. The sea- 
son of 1910 was an " off year " for both Douglas fir and western yel- 
low pine, the two most important trees of the West, yet cones of 
sufficient quantity were collected in widely separated localities to 
furnisli 30 tons of clean seed of these species. Studies made to de- 
