THE THEORY AND PRACTICE OF WORKING PLANS 41 



easier if the forest description data are well and carefully- 

 gathered. 



Where artificial lines are cut through, those running with the 

 prevailing storm direction arc called, in Germany, " Haupt- 

 Gestell '' (Main Frame) or '' Wirtschafts streifen " (Manage- 

 ment Stripe), those runnmg at right angles thereto, " Neben- 

 Gestell " (Accessory Frame) or " Schneussen "or " Schneisen." * 

 The former average 15 to 30 feet in width, the latter 6| feet 

 to 1 5 feet ; in this way they serve as a network of logging roads 

 and fire lines. The " Schneisen " serve also to strengthen 

 the stand against windfall; for along them develops the " wind- 

 mantle '' — i.e., the crowns of the trees on the border form an 

 impenetrable mantle and protect the interior of the stand from 

 windfall. This is especially important in spruce and similar 

 shallow-rooted species. As the lower branches show signs of 

 dying off, the strip is widened so as to let in the necessary addi- 

 tional hght and keep the wind mantle intact, until it reaches a 

 maximum width of 30 or 40 feet. These "Schneisen" are 

 then made the points of attack for the cutting series,! since the 

 stand to leeward of them has through its wind mantle ample 

 protection against the storms. 



Block divisions are always natural and are chosen on a large 

 scale — watersheds, drainage basins, are suitable units. The 

 single block may contain many thousand acres; its shape is 

 immaterial; the governing considerations are logging and mar- 

 ket conditions. The block is usually a main logging unit or 



* In Prussia the " Hauptgestelle " are 700 to 800 yards apart; the " Neben- 

 gestelle " are 350 to 400 yards apart. 



t Culling Series. — A cutting series or felling series is an aggregation of stands 

 into a proposed or actual sequence of felling areas — that is, areas on which 

 cutting operations are being conducted or areas designated for cutting. The 

 object of such a series is a distribution of felling areas for administrative reasons 

 or to secure a final satisfactory distribution or location of age classes, especially 

 to avoid damage by windfall and insects due to uniformity of stand and size of 

 felling area. It is intended to interrupt a regular sequence of age classes. It is 

 quite generally used abroad in spruce to prevent windfall and pine to prevent 

 insect damage. 



It is not used in broadlcaf forests or in any selection forest. 



