JURA ZONE 31 



species are the holm oak, white oak, aleppo pine. On the sihcious soils of 

 the Maures and the Esterel maritime pine and cork oak form the predomi- 

 nant stand with a thick undergrowth of heather. In this region trees 

 rarely attain large size, but yield good fuel charcoal and tanbark. The 

 secondary revenue from truffles is in places as much as $38.60 per acre. 

 The prevalent northeast wind, known as the "mistral," is a source of 

 danger during the fire season. This is especially significant since in this 

 region there is much less rain than in the Parisienne. 



Mountains. — The mountains are divided into five main zones: (1) 

 Vosges, (2) Jura, (3) Alps, (4) Central Plateau, (5) Pyrenees. 



Vosges Zone. — The Vosges begins at 1,150 feet elevation. It is rich in 

 forests; fir, beech, and spruce are the dominant species at certain points; 

 oak and hornbeam disappear completely toward the summits. The spruce 

 continues with the fir to the highest altitudes. Much Scotch pine has 

 been artificially introduced. The zone extends to a maximum altitude 

 of 4,590 feet, but the average hmit of tree growth is at 4,100 feet. Be- 

 tween the maximum and minimum altitudes five types of stands have 

 been distinguished: (1) the Lorraine plain; here coppices of hornbeam, 

 oak, and poor quahty birch have led to an increase in the per cent of beech 

 in order to improve the soil. Where, however, the conditions are ex- 

 ceedingly bad, Scotch pine is being introduced. (2) Basses- Vosges ; here 

 silver fir is the typical species. (3) Hautes- Vosges ; on account of the 

 granitic formation it is well watered, but the forest area is much cut up 

 by farms and grazing lands. Here are found a number of protection 

 forests. Two less important subdivisions are: (4) where on the south 

 slope toward the Franche-Comte plains the schists give place to syenites 

 and porphyries and the fir is replaced by the oak. There was formerly a 

 good deal of coppice alternating with field crops in this region and there 

 is still much simple coppice grown for bark production. The fifth (5) 

 (la Vosge), also relatively unimportant, is apparently an island of varie- 

 gated sandstone where high forests of oak and beech predominate on 

 the fine-grained sand. 



Jura Zone. — Exceedingly rich mountain forests are found in the 

 Jura. They are less extensive than in the Vosges but much richer. In 

 the Vosges the soil is silicious, while in the Jura it is calcareous. The im- 

 portant commercial Jura species are silver fir and Norway spruce. In 

 this region there are four subdivisions, based on altitude: (1) The first 

 plateau really belongs more to the plain than to the mountain region, but 

 fir has been introduced. (2) In the second region, with an altitude of 

 1,640 to 1,970 feet, the fir is mixed with spruce. The best fir forests of 

 France are found on the rich soil above this first escarpment on Jurassic 

 formation. The forests of Levier and La Joux (Fig. 2) are world famous. 



