WORKING GROUPS 191 



group. Rotations in private forests are usually shorter. The average 

 is between 55 and 65 years and, where the production of mine props is 

 the chief objective, the rotations can be reduced to about 40 to 50 years. 

 With the new 4-year thinning cycle the present rotations may be slightly 

 reduced. 



According to the working plan for the forest of Biscarrosse, revised 

 January 7, 1910, the maritime pine has a 75-year rotation. The forest 

 is divided into fifteen periodic blocks. The growth data available show 

 that the maximum growth of the maritime pine is between 40 and 

 50 years; therefore a transitional rotation of 60 years has been recom- 

 mended. It is almost certain that as the humus in the different maritime 

 forests fertilizes the soil the growth will become more rapid, so that the 

 proverbial 70 to 75 year rotations may be generally reduced to 55 to 65 

 years. 



According to this working plan "The yield is estabhshed by area; 

 the surface of each periodic block is run over by a clear-cut regeneration 

 felling, exploited during the period having the same numerical order as 

 the periodic block. " 



Felling Cycles. — In the past the felling cycle was almost invariably 5 

 years, but sometimes 4 to 6 years. In the future it will usually be 4 years 

 (see p. 193). In the past the trees were resined for 4 years and felled the 

 fifth year. But in the forest of Carcans a 6-year period allowed 5 years 

 for tapping and the usual 1 year for felling. 



"Working Groups. — According to De Lapasse the past method of 

 management was as follows: 



"These forests are divided into working groups whose number varies from two to 

 six, according to their importance and size; working groups are estabhshed in long strips 

 parallel to the ocean, bounded by parallel fire lines, the first working group being placed 

 on the east side of the forest. In each working group the periodic blocks are numbered 

 in the order in which regeneration is fixed, from the north to the south. In each forest 

 the working plans have estabhshed a group without predetermined treatment, to in- 

 clude the dune and littoral zone, designed to form a shelter belt which protects the re- 

 mainder of the stand against wind action and sand coming from the west. 



"The scheme is very simple. During each 5-year period each periodic block (except 

 those to be regenerated and those including young growth) is run over by a thinning with 

 turpentine operations. The trees which are to be removed are, before they are cut, 

 tapped to death during a period of 4 years; simultaneously, the pines which have 

 reached 14 inches in diameter and above are tapped alive for 5 years. The oldest 

 periodic block in turn is regenerated by clear cuttings preceded by tapping to death 

 all the trees. These are felled during the fifth (see 'New Tapping Scheme,' p. 193) 

 and last year of the period. The periodic blocks of young growth are run over by or- 

 dinary thinnings without tapping. At the beginning of each period (every 5 years) 

 each working group is completely marked (and valued) to compute the material of the 

 clearcut regeneration fellings (to be sold standing) and the trees to be tapped alive where 

 the contractor receives only the resin." 



