SYLVICULTUEE. 



tree, on sunny slopes often mixed with Manzanita (Acrostaphylos 

 pungens). 



II. North Mexican forest of the moderately warm zone. 



This zone, very narroAv, should contain winter-bald broad-leaved 

 species. The dryness of the soil and of the air, however, allows of 

 their occurrence only on moist ground along rivers. Western Walnut, 

 Mexican Ash, Poplars and \Villows. The Pines are the leading 

 species of the zone, forming huge forests at altitudes exceeding G,000 

 feet elevation. Some of these Pines are northern sentinels from 

 Mexico, others outposts from the States. Most important is Pinus 

 Chihuahuana, in Mexico largely used for timber, up to 80 feet high, 

 three feet in diameter, three needles. Pinus Arizonica, a five-needled 

 pine, occurs at 6,000 feet elevation. Pinus reflexa, locally known as 

 White Pine, occupies moist dells at 8,000 feet elevation. Nut pines 

 at less6r elevations as low brush, notably Pinus edulis, monophjdla 

 osteosperma. 



C. The Pacific forest. 



Typical difference from Atlantic forest lies in the relative lack 

 (f broad-leaved woods — not in species, but in area. Tropical forest 

 is absent, possibly due to lack of moisture at low elevations in 

 Southern California. 



I. Pacific sub-tropical forest. 



Occupying Southern California. This zone is devoid of dense 

 forests, the nortliern edge excepted. ,!\vergreen Oaks, or rather 

 Winter Green Oaks (Quercus densiflora is leafless during dry sum- 

 nier) dot the ground in park-like groves. California Laurel (Um- 

 bellularia calif ornica) is a characteristic tree of this region, growing 

 up to 100 feet high. Impenetrable bush thickets cover hot aspects, 

 formed by Leguminosae, Labiatae, Compositae, Rosaceae, et(?. The rare 

 and beautiful Montery Cypress along the seashore. Sequoia sem- 

 pervirens is the biggest tree of the zone, found only at its edge in 

 the Coast Range. Pinus insignis known as Montery Pine is valu- 

 able on sand dunes. 



Pinus tuberculata (attenuata) occurs most frequently in even- 

 aged woods. Pinus sabiniana. Nut or Digger Pine, valuable for the 

 Indians, of Olive-like appearance, is mixed in the Oak parks and m 

 the Chaparal thickets. Another Nut Pine is Pinus parry ana, grow- 

 ing 30 feet high. Pseudotsuga macrocarpa on St. Bernardino range. 

 Eucalyptus and Accacia were successfully introduced from Austra- 

 lia, Oranges and Figs from the Orient. 



II. Pacific forest of the moderately warm zone. 



