8 BULLETIN 308, U. S. DEPARTMENT OF AGRICULTURE. 
between the hard and soft layers in each annual ring oives the wood 
a very pleasing figured effect. 
Even under a high-power microscope the woods of the important 
southern pines appear strikingly similar though not identical in 
structure. With a view of bringing out the features helpful in dis- _ 
tinguishing the wood of shortleaf pine from the other important 
southern pines, a brief summary of characteristics is given in Table 5. 
TABLE 5.—Average physical properties of the important southern pines. 
ae ae Cubic Moisture content. 
Grain (compara- 
Width| tive width and Air- Green. Air-dry.2 
Species. of |number ofannual| Resin content. dry 
sap- SES per (45 
wood. inch).1 Green.| per yroa 
cent 
Ane Heart.| Sap. | Heart.| Sap. 
ture) 
Inches. Libs.) Gbs:\ Lbs. |B. chy. cba) Pei Pace 
Longleaf| 2to3| Narrowest | Veryabundant.| 52.5 | 43.5 | 39.0] 34.0] 95.5 15 15 
pine. aol rings): 
Slashipimes-|oitOGe| Wade! -<--s= 22 -|- dois - 52.5 | 45.0 | 41.5] 32.5 | 84.0 15 15 
Shortleaf| 3to4 VGomiedintd Moderate.......| 45.5 | 38.0 | 31.0] 31.0 | 88.5 15 15 
pine - (11 rings). 
Loblolly | 3to6| Widest G EINngs)-|-eee doa 54.0 | 39.0 | 36.0] 36.0] 82.0 15 15 
pine. 
1 Variable in ail species so that rapid-growing longleaf might be taken for any of the others. This order - 
prevails in the average. 7 
2 ee and sap will ultimately reach the same moisture content if thoroughly air dried under the same 
conditions. 
DURABILITY AND PRESERVATIVE TREATMENT. 
Shortleaf pine is only moderately durable in contact with the — 
soil. The presence of a large amount of resin, as in “ light wood,” 
is commonly thought to increase materially the natural durability of — 
the wood. Sapwood is much less durable than heartwood; it can not 
ordinarily be expected to last over two or three years, while good — 
heartwood may last seven or eight years. When not in contact with 
the soil or under conditions particularly conducive to decay, the wood 
has given good satisfaction. _ 
By proper preservative treatment the durability of short-leaf pine 
can be very materially increased. Wood preservation is discussed in 
a number of publications, among which are Forest Service Bulletins 
78, 84, 107, 118, and Circular 209. 
MECHANICAL PROPERTIES. 
The wood of shortleaf pine is strong and stiff and therefore very 
valuable for structural timber. It often contains the same number — 
of rings per inch and is very similar in wood structure to longleaf 
pine, which holds first place among the southern pines used for this 
