TERMS m FOUESTRY. 21 



Shelterbelt, n. Natural or artificial forest maintained as a protection from wind or 

 snow. 



Syn. : shelterwood, wind mantle. G., Waldmantel, Schutzmantel. F., rideau. 



A narrow shelterbelt in which true forest conditions do not exist, is a windbreak 

 when maintained as a protection against wind, and a snowbreak when maintained 

 as a protection against snow. 

 Shelterwood, n. See Shelterbelt. 



Shelterwood compartment system. See Stand method. 

 Shelterwood g-roup system. See Group method. 

 Shelterwood selection system. See Single tree method. 

 Shoot, »i. See Sprout. 

 Silvical, a. Pertaining to silvics. 

 SilTical rotation. See Eotation. 

 Silvics, n. 1 . The science which treats of the life of trees in the forest. 



2. The habit or behavior of a tree in the forest. 



Syn. : habit, silvicultural characteristics. 



Silvicultural characteristics. See Silvics. 



Silyicultural rotation. See Rotation. 



Silyiculture, n. The art of producing and tending a forest; the application of the 

 knowledge of silvics in the treatment of a forest. See Forestry. 

 G.jWaldbau, Holzzucht. F., sylviculture. 



Single tree method. That method of conservative lumbering in which reproduc- 

 tion from self-sown seed under the shelter of the old stand is invited by the 

 cutting of single trees. This cutting may be made throughout the forest, as in 

 some woodlots, or in definite portions of the forest in turn. See Forest management. 

 Syn.: selection method, selection system, shelterwood selection system. G., 

 Pliinterbetrieb, Planterwirtschaft, Femelbetrieb. F., jardinage, regime de la 

 futaie jardinee. 



Sing^le tree mixture. A mixture in which trees of different species occur singly. 



Site, n. See Locality. 



Slope, n. The gradient of the land surface. In forest description the following 

 terms are used to define the slope, each of which has its equivalent in percentages 

 of the horizontal distance and in degrees: 



Level = 0- 5%= .0- 3.0° 



Gentle = 5- 15%= 3.0- 8.5° 



Moderate = 15- 30%= 8.5-16.5° 



Steep = 30- 50% = 16.5-26.5° 



Very steep = 50-100% =26.5-45.0° 



Precipitous = over 100%=over 45.0"* 



Small pole. See Pole. 



Small-pole forest. A forest of small poles. 



Small sapling-. See Sapling. 



Small-sapling forest. A forest of small saplings. 



Snowbreak, n. 1. The breaking of trees by snow. 

 G., Schneebruch. F., bris de neige. 



2. An area on which trees have been broken by snow. 



3. .See Shelterbelt. 



