Introduction

    Valley Oak (Quercus lobata) is the largest of the world’s oak species.  It is endemic to California, and ranges from the Mount Shasta region of northern California to the Santa Monica Mountains in Southern California.  Decades of published studies have noted a long term decline in Valley Oak regeneration and recruitment throughout the species’s range.  

    The term “recruitment” refers to the transition from seedling to sapling.  The vast majority of Valley Oak seedlings do not survive past the first year, and thus never make the transition from seedling to sapling.  For this reason, researchers are often less interested in instances of Valley Oak germination, and more interested in conditions under which successful recruitment might occur.  In general, when a tree reaches 30 cm in height, it is said to have been “recruited” into the world of being a tree.

    Although many studies have been published which examine the recruitment problem in Northern and Central California, very little research has been published on the subject as it pertains to the species’s Southern-most habitat in the Santa Monica Mountains.  This project focuses on one site (Cheseboro Canyon) in Agoura Hills in the Santa Monica Mountains where Valley Oak recruitment is known to have taken place in recent decades (Figure 1).  The goal of this project is to use GIS Suitability Analysis to determine the existence of any local site-specific factors that could be having an affect on Valley Oak recruitment at the site.  Based on the results obtained, an attempt will be made to predict locations within the site where successful recruitment might be expected to occur in the future.

                 Figure 1.  Cheseboro Canyon study site in the Santa Monica Mountains