88 NATURAL REGENERATION 



say, one-fifteenth of the forest. Under the same conditions it is pos- 

 sible to make the openings 2 to 4 acres in area. The diameter of the 

 opening is usually at least one-half the height of the neighboring trees. As 

 soon as the regeneration starts it is necessary to open up around it in 

 order to give it sufficient Ught for development, always bearing in mind, 

 however, that too wide openings, which become choked with brush, 

 are consequently expensive to clear. This hole-selection method has 

 been apphed to aleppo pine, but until experiments in Algeria in the 

 Oran Conservation are completed by Conservateur Laporte, no final 

 decision can be reached as to the best method of treatment. It is very 

 significant, however, that near Marseilles the working plan calls for 

 the shelterwood system, that is, progressive feeUngs, but the local in- 

 spector preferred the method as described in the following statement 

 furnished the author personally: 



"The aleppo pine is the only coniferous species of the calcareous regions of the Medi- 

 terranean Provence. Besides this species there is only the holm oak and the pedunculate 

 oak treated under coppice and furnishing nothing but firewood. In the Department of 

 Bouches-du-Rh6ne the aleppo pine ordinarily forms almost pure stands or mixed with a 

 small per cent of oak (.0 to 15 per cent). 



"The forests of aleppo pine occupy the lower mountains where the altitude ranges 

 from sea level to 2,600 feet. The calcareous soil is generally on steep slopes, which are 

 usually rugged. There are numerous rock benches and stone slides with but Uttle 

 vegetation. The climate is characterized by hot and dry summers. The average 

 annual rainfall is 20 inches at Marseilles to 28 inches at Areasque (in the center of the 

 small moimtainous forest situated to the northeast of Marseilles) . The average number 

 of rainy days is 85, chiefly in autmnn and spring. During 1912 there was an almost 

 complete drought for two months — July and August. 



"The aleppo pine is admirably adapted to these conditions, which any other indige- 

 nous species would not be able to stand. It is essentially light-demanding, endures 

 drought, and is vigorous. It has a very light foUage and is easily regenerated by natural 

 means. But while it stands heat and prolonged droughts, its growth suffers neverthe- 

 less, and its remarkable thrift when near water . . shows it can thrive on fresh 

 soil. The young seedlings suffer from drought if the roots are not well into the soil; 

 they are often burned by the sun in the summer if it is especially hot and dry. On cer- 

 tain rocky slopes where the stand is open it is difficult to get regeneration imder the old 

 trees; on the other hand, the soil should not be allowed to run wild, since it must be pro- 

 tected against the heat of the sun; cuttings must be light. 



"The treatment by regular high forest (shelterwood) with a rotation of 60 years and 

 with the division of the forest in three periodic blocks (each to be regenerated in turn 

 within 20 years) has been followed in a number of forests for 50 years. But the looked- 

 for regularity has not been obtained on the arid and rocky soil which one finds on most 

 of the area under management. 



"Uniform stands have been obtained only on several areas where the soil was deeper 

 and richer; these are the exception rather than the rule. In reality most areas treated 

 by the shelterwood system have always remained in a transition stage. On the contrary 

 the selection system is adapted to the regional conditions. Forests of more than 741 

 acres are divided into working groups whose area ordinarily does not exceed this. Each 

 working group is divided into a certain number of felling areas, usually 10 to 16, which 



