San Bernardino District. 631 
on the western and southern slopes in the chaparral formation are due to 
local conditions of moisture supply, such as streams, springs, etc. 
The species which enter into this type of forest are below the 6,500 foot contour 
and their percentages: Cercocarpus ledifolius (as tree), Juniperus californica (as tree 4 per cent), 
Juniperus occidentalis (1 per cent), Pinus monophylla (93 per cent) and Yuccas (2 per cent), while 
above the 6,500 foot contour the following trees are found: Abies concolor (IO per cent), 
Cercocarpus ledifolius (15 per cent), Juniperus occidentalis (25 per cent), Pinus monophylla 
(38 per cent), Pinus ponderosa (ro per cent), with yuccas and scattering oaks forming two per cent. 
The composition of this type of forest in the San Jacinto Mountains is on the eastern 
slope where the pifüion belt (Pinus monophylla Facies) begins at an elevation of 2,500 feet 
Pinus monophylla (99 per cent), Fraxinus velutina (= F. pistaciaefolia), Populus trichocarpa, 
Quercus californica (Q. Kelloggii), Q. chrysolepis, Salix lasiandra and Yucca arborescens, whi 
on the southern and western slopes are found Pinus monophylla (8 per cent), Pinus quadri- 
folia (90 per cent), Quercus chrysolepis, Q. Wislizeni, Populus trichocarpa, P. Fremontii and Salix 
lasiandra. Between the 3,500 foot and the 4,800 foot contour lines the stands attain their maxi- 
mum density, On the San Jacinto range the growth thins out and soon ceases above the 
4,800 foot contour. 
Subhumid Forest Belt. The second type of forest covers subhumid tracts. 
The growth is open and park-like, consisting in the San Gabriel Mountains 
between the 5,500 foot and the 9,000 foot contours of Adies concolor (25 per 
cent), Zidocedrus decurrens (3 per cent), Pinus attenuata, P. Coulteri, P. flexilis 
(t per cent), P. Lambertiana (6 per cent), P. monophylla, P. fonderosa (20 per 
cent), Pseudotsuga macrocarpa (40 per cent). In the San Bernardino Range 
the subhumid type is best developed between 5,000 and 9,500 feet and it is 
of an open character. The composition of the forest between the 3,000 foot 
and the 6,000 foot contour is formed by: Adses concolor (6 per cent), Pinus 
ponderosa (64 per cent), Pseudotsuga macrocarpa (14 per cent), Quercus [3 species) 
and other trees, while between 6,000 and 8,500 feet occur Adses concolor (30 
per cent), Zidocedrus decurrens (4 per cent), Pinus Coulteri, P. Lambertiana 
(8 per cent), P. Murrayana (ı per cent), Pinus ponderosa (52 per cent), occur 
with Dseudotsuga and oaks (Quercus californica, O. chrysolepis 3 per cent). 
The oaks thin out and disappear at 8,000 feet, as do the alders, sycamores 
and willows at short distance above the 6,000 foot contour line. 
Pinus ponderosa Belt. In the San Jacinto Mountains the Pinus ponde- 
rosa type of forest is developed between 5,000 and 9,000 feet. Between the 
6,000 and 8,500 foot contours the following trees are found: Abtes concolor 
(30 per cent), Zibocedrus decurrens (8 per cent), Pinus Lambertiana (25. per 
cent), P. Murrayana (5 per cent), P. ponderosa (30 per cent), Ouercus califor- 
nica (= O.-Kelloggü), O. chrysolepis and Cercocarpus ledifolius. 
e find in the higher valleys Symphori- 
= 
o 
This forest is largely free from undergrowth, but w 
R us californica var. tomentella, Cornus ut- 
a 
della lanceolata, Streptanthus campestris, Arabis arcuata, 
Hosackia nevadensis and Pedicularis semibarbata. 
