18 BULLETIN 244, U. S. DEPARTMENT OF AGRICULTURE. 
As a result of repeated burnings the density of natural stands is 
usually very variable. Occasionally second-growth stands have been 
protected by surrounding cultivated fields and the watchfulness and 
care of their owners. Such stands show striking regularity of tree 
density and much quicker wood production than unprotected stands, 
which is due to the influence of a protective mulch consisting of leaves 
( u pine straw"), twigs, and bark. 
REPRODUCTION. 
Few of the valuable pines in the United States reproduce as vig- 
orously as shortleaf . The regeneration is accomplished by seed and 
by complete sprouting during the period of early life when the tree 
is most susceptible to severe injury. Reproduction by means of nat- 
ural seeding is successful and heavy, because of the frequent and full 
seed crops, the lightness and short germinating period of the seed, 
and the high resistance of the seedling to unfavorable conditions of 
temporary shade and drought. 
Abandoned fields and openings made by lumbering, windfall (in the 
tornado belt west of the Mississippi), and fires are quickly occupied 
by shortleaf pine. Ten representative counties in western North 
Carolina contain 393,670 acres of old-field stands of mostly pure short- 
leaf pine. This is 14 per cent of the total area, or 27 per cent of the 
forested area, of the counties. Such old-field stands characterize the 
forest lands of the upland regions from Virginia southward and west- 
ward throughout the range of the species. The extensive pineries 
near Lakewood, N. J., are mostly pure stands of shortleaf (" two- 
leaf") pine of similar origin. (PL II.) In mixture with the inferior 
pitch pine in New Jersey and loblolly pine in the lower or outer por- 
tions of the shortleaf range, it has not successfully held its former 
place of importance. The cause lies chiefly in the much closer utili- 
zation of the shortleaf and the resulting relatively greater abundance 
of seed trees of the associated species. In the southern mixed hard- 
wood forest there has been a notable extension of the importance and 
commercial range of shortleaf. This has been due to the successive 
clearing, working, and " turning out" of fields and to the extensive 
ranging of hogs. The hogs consume practically all of the oak and 
hickory seed and at the same time prepare excellent seed beds for 
shortleaf pine by uprooting soil and humus in the fall of the year. 
Some seedlings, of course, are later destroyed by the same process. 
The results of these two agencies, operative for periods of 75 to 200 
years, have been cumulative and have produced marked changes in 
the composition and density of the forest in various parts of the 
South. 
On the National Forests of Arkansas natural reproduction is heavy 
except on the cool northern exposures, and the encroachment of 
