NOTES ON THE TAPPING OF THE CLUSTER PINES. 255 



inferior quality, and the extraction of resin does not 

 pay. 



The resin is abundant only when the pines are ex- 

 posed to the full influence of light, are in active 

 vegetation, and possess thick foliage. Accordingly, 

 thinning operations on a large scale are executed as 

 soon as the young pines are six or eight years old. 

 The thinnings are repeated every five or six years till 

 the forest has reached the age of twenty years, at which 

 time there should not he more than 240 to 280 plants 

 per acre. The extraction of resin may now begin on 

 the trees which are to be felled before the end of the 

 rotation of the forest. To this end from 200 to 250 

 trees are marked out for the next thinning operations 

 which are to be made at the end of five or six years. 

 After another thinning at the age of about thirty 

 years, only 100 or!20trees are left per acre. This num- 

 ber is progressively reduced to eighty and even sixty 

 until the forest is about seventy or eighty years old. 

 It is now time to begin re-planting operations, if the 

 object of the forest is merely the production of resin. 



Eestocking is obtained either by artificial planting 

 or sowing, or from the self-sown seedlings which 

 may have come up during the last few years. 

 According to M. Bloi Samanos, sowing is the means 

 usually employed in the Landes. The method he 

 recommends is to trace out parallel lines at intervals 

 of from four to six yards (according to the distance 

 required between two successive plants), to cultivate 

 them deeply over a breadth of at least two feet with 

 a pick or plough, and then to sow five pounds of 

 pine seed per acre, and harrow them in lightly. 



