CHAPARRAL. Deal 
AMOUNT OF SHADE PRODUCED. 
Chaparral cover may be roughly graded as heavy, medium, light, 
and scattered. In some cases where comparative studies have been 
made to determine the value of cover on different watersheds the 
amount of shade or the density of the chaparrai has been estimated by 
percentage. If these two methods are reduced to a common basis for 
comparison, heavy will equa! from 75 to 100 per cent of shade, 
medium from 50 to 75 per cent, hight from 25 to 50 per cent, and 
scattering less than 25 per cent. The surface total of shade, or 100 
per cent, is rare, and is likely to occur only where the chaparral con- 
sists of two stories; that is, of species of varying height forming two 
or more strata of cover. The heavy cover is, of course, the most 
desirable, provided that it is not of undesirable species. In the mock 
chaparral, where the cover is only temporary, complete shade is unde- 
sirable, since it will prevent the growth of forest-tree seedlings. 
The very heaviest chaparral is impassable to man, owing to the 
closely matted growth and the spines carried by some species. Some- 
times these dense growths are in large patches, with areas of more 
scattered growth between, so that by carefully selecting a route one 
may travel through the growth with comparative ease. 
The density and composition of the chaparral varies on different 
slopes. (Pi. III, fig. 2.) Altitude also has much to do with the 
development of the different species, and hence with the density of 
the cover. Notes on the density of the chaparral on different sites 
and exposures, at altitudinal intervals of from 2,000 to 3,000 and 
from 3,000 to 5,000 feet, were made during the course of a study of 
the chaparral on the Angeles National Forest. The results are given 
in the following table: 
TABLE 4.—Percentages of shade on selected plots of chaparral. 
PASADENA WATERSHED, CALIFORNIA, 1908. 











Slope. 
North. | South. East. West. 
No. of survey. | 
2,000 to | 3,000 to | 2,000 to | 3,000 to | 2,000 to | 3,000 to | 2,000 to} 3,009 to 
3,000 5,000 3,000 | 5,000 3,000 | 5,090 3,000 5,000 
feet. feet. feet. | feet. feet. | feet. feet. feet. 
| 
1h Joe eae a a ne ere 85 80 60 25 50 20 60 75 
OM ooo a fee oe ee 75 €0 7 75 85 95 iu 90 
eee so oS eo eis ee ee 80 40 40 50 70 | 60 35 70 
(Ns oie ae EEE ah eae in rl ee 90 70 SOR Beate 50 | 85 65 40 
Ne ak See e ser eee ere ee] eee GO 85 95 60. 85 60 90 
ie ve see A 90 60 | 50 | 60 65 90 40 35 
ee ee ae = ee es oe 59 | 65 SOREN Set 50 50 90 
ee Oe ae A i [re §5 35 O0u Sees G 90 90 
Ue ie re ES SO ee: SRS ee er ee 60 35 GOR sae 100 70 40 
[L() Ree aera eR ns ee Ee aN oe 2 95 60 Sd) | s-eee 65 30 80 
Til. Ss S82 SSRI Pe ek ae ae ont [ae 65 50 O)i| Rae ee se 80 35 60 
Ubi 2S oF SSE RE ae ee ea a ee aE [eee | | ae 75 OO) Rae Sr ee ee 65 55 
VS at Re Oe Eee ae | a ceo) 50 AD aE Res et ee eeu pen en } 55 90 



