REPRODUCTION OF ROCK PINE. ule 
the chief cause must be found in the failure of the seed to develop. 
Whether or not this in turn is due to the cutting of neighboring trees 
and a consequent decrease in the opportunity of fertilization can not 
be said with certainty. 
It should be remarked, however, that the lack of young seedlings 
immediately beneath the trees does not show that the entire crop. of 
the corresponding years failed, since a large part of the seed are 
released before the cone falls and may be borne a considerable dis- 
tance by the wind before they reach the ground. 
Notwithstanding the lack of very small seedlings which was ob- 
served, and the large proportion of defective seed found in the cones 
of three successive seasons, there is no reason to believe that a perma- 
nent deficiency in reproduction is likely. The presence of many 
seedlings 4 years old and over militates against such a conclusion. 
It is well known that the seed production of trees is generally 
periodic and that heavy crops are usually several years apart. And 
even in years of abundant seed production germination may fail for 
want of the necessary attendant conditions. 
The precipitation of this region is scanty—only about 15 inches 
annually on the average—and it is also extremely variable. Thus 
it may easily happen that plenty of seed are set in a favorable season, 
but the second year required to mature them is dry and they are lost 
or the seed may mature, yet reach a soil so inhospitable that they 
can not germinate. In other words, plentiful reproduction is depend- 
ent upon a succession of moderately moist seasons or upon the coinci- 
dence of a good seed year with fovarable conditions for germination. 
In spite of these difficulties, however, there is no doubt of the ability of 
the pine to reproduce itself in the course of time, provided a sufficient 
number of seed trees are left and the ground is not exposed to fire nor 
overgrazed. 
In numerous situations good reproduction can be found. This is 
especially true of north and east slopes, where there is always more 
moisture than on other exposures. The best conditions for the pro- 
duction of pine seedlings are found where there is no sod, but a loose, 
bare soil or one covered lightly with leaves and litter. North of the 
Niobrara conditions are generally more favorable and the seedling 
growth better than south of it. In Sioux County, for instance, the 
reproduction on many areas is very satisfactory. Young seedlings 5 
vears old and over were noted in great numbers at the base of the 
rocky cliffs, on the hillsides, and even in the prairie sod. On a north- 
west exposure, at the base of a precipitous bluff from 50 to 75 feet 
high, 903 young pines from 8 inches to 22 feet in height were found 
on an area 45 by 47 feet. The seeds from which these grew must have 
31149~— No. 66—05 M 3 
