304 THE BOOK OF FORESTRY 
Index Forest. That forest which in density, volume, and incre- 
ment reaches the highest average which has been found upon a 
iven locality. Measurements of such a forest provide a standard 
or comparison with other forests of the same age and composition, 
grown under similar conditions. 
Intermediate. A tree class having the crowns shaded on the 
sides, but free to light at the top. 
Intolerant. Incapable of enduring heavy shade. 
Jack Chain. An endless spiked chain, which moves logs from 
one point to another, usually from the mill pond up an incline 
to the sawmill. ; 
Jam. <A stoppage or congestion of logs in a stream, due to an 
obstruction or to low water. . 
Key Log. In river driving, a log which is so caught or wedged 
that a jam is formed and held. 
Landing. A place to which logs are hauled or skidded prepara- 
tory to transportation by water or rail. A rough and tumble landing 
is one in which no attempt is made to pile logs regularly. 
Layer. A shoot which, while attached to the plant, takes root 
at one or more places and forms a new plant. 
Lift. To pry up seedlings from the seedbed so that they may 
be pulled by hand for transplanting. 
latter. That portion of the forest floor which is not in an 
advanced state of decomposition. | 
Loam. Friable, mellow, rich soil containing much humus. 
Locality. An area, considered with reference to forest-pro- 
ducing power; the factors of the locality are the altitude, soil, 
slope, aspect and other local conditions influencing forest growth. 
Log, To. To cut logs and deliver them at a place from which the 
can be transported by water or rail, or, less frequently, at the mill. 
Log Rule. 1. A tabular statement of the amount of lumber 
which can be sawed from logs of given lengths and diameters. 2. 
A graduated stick for measuring the diameter of logs. The num- 
ber of board feet in logs of a given diameter and length is shown 
upon the stick. 
Logging Sled. The heavy double sled used to haul logs from the 
skidway or yard to the landing. 
Lumber. To log, or to manufacture logs into lumber, or both. 
Lumberjack. One who works in a logging camp. 
Many-aged Forest. A forest through all parts of which many 
different age classes of trees tend to distribute themselves. When 
all age classes are thus distributed, the forest is all aged. 
Market. A unit of measurement used in northern New York; 
a log 19 inches in diameter at the small end and 13 feet long. 
Marking Hatchet. A hatchet for marking trees. A raised die 
is cut on the head for stamping the face of the blaze. 
Mature Forest. Forest so old that growth in height is practi- 
cally at an end, and diameter growth is decreasing. 
Mean Annual Increment. The total volume of a tree or stand 
divided by its age in years. 
Merchantable Length. The total length of that portion of the 
stem which can be used under given conditions. 
