Island Scrub Oak Regeneration

Management Objectives:
To maintain or enhance the natural structure of Santa Catalina Island's plant communities. To provide detailed descriptions of stand structure, health, and regeneration of island scrub oak trees (Quercus pacifica) to use as a general model for restoration and maintenance management.

Monitoring Methods:
In a pilot study conducted in 2001, four permanent 30 meter by 6 meter belt transects were established within each of two areas supporting predominantly scrub oak habitat: the west end of the island near Howland's landing, and the northern-central portion of the island near the airport. These locations have the advantage that they differ in their stage of feral animal removal; the west end has had all feral animals except deer removed since the mid- to late-1990's.

For each individual rooted within the transect, each oak individual was mapped and the following variables recorded: age class, number of stems/trunks, basal diameter of the largest three trunks, overall health, acorn production, and animal/pest damage. For any seedlings or saplings, these additional variables were recorded: substrate (e.g. bare ground or litter), whether or not the individual is immediately associated with annual grasses, and whether or not it is growing under the cover of another species.

Here are some results from the pilot study:

Number of mature trees per plot ranged from 3 to 13.
Dead trees comprised an average of 26 percent of the trees in each plot, and was 100 percent in one plot (SOM4).
Saplings were found in only 2 of the 8 plots studied, with 1 and 4 saplings found (25% and 14% of all individuals, respectively).
Seedlings were found in 3 of the 8 plots studied, with one seedling found in each of two plots and 21 seedlings found in one plot.
The majority of trees had an acorn production class of 0 (no acorns), 1(a few seen after close scrutiny), and 2 (a fair number, acorns seen readily).
Very few trees had good (class 3) or bumper (class 4) crops of acorns.
Many trees were ranked as having good or very good overall health.
Fewer trees were ranked as poor or fair health, and none as excellent.