Canopy effect of Quercus Douglasii H. & A.

The purpose of the present study is to gain some insight into the complex of factors that create the canopy effect with emphasis on the microenvironment that is associated with the vegetative differences. Data recorded weekly included the measurement of plant growth, precipitation, air temperature, soil moisture, and soil temperature. Other studies involved pH, bulk density, permanent wilting percentage, moisture equivalent, field capacity, organic content of the soil and. plant distribution. The determination of all factors involved was not possible in the two growing seasons studied, but accrued data suggests certain ecological relationships. The investigation was undertaken at the San Joaquin Experimental Range (SJER) near O'Neals, California, 25 miles north of Fresno. The SJER is situated on the east side of the San Joaquin Valley in the Sierra Nevada foothills. The natural vegetation is typical of the foothill woodland community (as recognized by Munz, 19&3) consisting of trees 15-70 feet tall in an open woodland with scattered brush and grassland between the trees.