Soil Ecology and Restoration Group

PLANT COMMUNITY RESTORATION

POINT LOMA NAVAL SUBMARINE BASE

SAN DIEGO, CALIFORNIA

ANNUAL REPORT 1999

Introduction
The Point Loma Naval Submarine Base (Subase) is located in San Diego, California on the east side of the Point Loma peninsula. Approximately 145 acres of the 295 acres occupied by the Navy is situated within the Point Loma Ecological Reserve established in 1996. Eighty-nine percent of the 295 acres on Point Loma is covered in either Diegan Coastal Sage Scrub or Southern Maritime Chaparral (Point Loma Natural Resource Management Plan 1994). These vegetation communities are rapidly disappearing due to an increase in development and the introduction of invasive exotic species such as Acacia cyclops (acacia) and Carpobrotus edulis (ice plant).

In October 1995, the Soil Ecology and Restoration Group (SERG) at San Diego State University formed a letter of agreement with the Department of the Navy to perform native plant restoration research on the Point Loma Submarine Base. From October 1995 through September 1998, experiments on surface amendments, erosion control methods and weed control were implemented over six sites encompassing 8000 m² of Coastal Sage Scrub and Southern Maritime Chaparral. SERG continued restoration on steep slopes and experiments in germination of coastal sage scrub vegetation seedlings October 1998 through December 1999.

Results of the 1999 research will enhance and expand the previous research implemented in 1996 through 1998. Details of procedures and research conducted in June 1995 through August 1998 may be found in the first and second Plant Community Restoration: Point Loma Naval Submarine Base San Diego, California submitted in May 1998 and May 1999.

Study site
The 1998/ 1999 restoration site selected by the Subase natural resource office and Southwest Division is located on the west side of Anne's Alley Drive and historical building number 154N (Figure 1). The site is bordered by a cement culvert to the south and west and a staircase to the north. The site is sloped 35 to 45 degrees with a northeast aspect. Native vegetation on the site consisted of a few Lemonadeberry (Rhus integrifolia) and Flattop buckwheat (Eriogonum fasciculatum). Exotic vegetation was primarily Eucalyptus sp. and exotic annual grasses such as Bromus sp. and Avena barbata. Some of the Eucalyptus trees had been removed and the site had been hydroseeded in 1997 by a contractor hired by the Subase.

Site preparation
Eucalyptus less than 10 feet tall were cut down and removed from the site. Also, Eucalyptus resprouting from stumps were cut and the stump treated with concentrated Roundup. All brush, consisting mainly of dead exotic grasses and tumbleweed (Salsola tragus) were removed from the site by hand. The slope was covered with jute netting anchored with three inch metal staples placed approximately 3 feet apart. The steeper sections of the slope (>40 degrees) were covered with coir netting using the same method as the jute netting. A drip irrigation system was installed by laying 1 inch PVC pipe along the top of the hill parallel to the slope. One-half inch polyvinyl tubing was connected to the PVC pipe and attached to the slope using 10 cm metal staples. One gallon per hour drip emitters were punched into the ½ inch tubing.

Research Addendum
In order to facilitate propagation of coastal sage scrub seedlings for further restoration on Point Loma, SERG has compiled a summary of germination and cutting methods for container seedlings grown for restoration projects over four years. These methods, listed in Appendix I, have been found to be the most successful for the listed species from seeds and cuttings collected on Point Loma.

((Figure 1))

Figure 1. Location of Anne's Alley restoration site on the Point Loma Naval Submarine Base, San Diego, California.

Container Planting
A total of 902 coastal sage scrub seedlings were grown in the SERG greenhouse at San Diego State University (SDSU) for the restoration site (Table 3). Seed was collected on the Point Loma Peninsula. While at the greenhouse, seedlings were initially watered three times a week and fertilized monthly. Water and fertilizer were reduced one month prior to planting and the plants were removed from under shade cloth. Seedlings were planted between December 1998 and March 1999 by creating holes for plants using either a power auger or a shovel.

Table 1. Coastal sage scrub seedlings planted on the Anne's Alley restoration site.

Maintenance and Monitoring
Seedlings were watered twice each month May through September 1999 with the drip irrigation system for one hour each time. A garden hose was attached to a water faucet in the parking lot above the restoration site and connected to the PVC pipe. Seedlings will be watered once each month June 2000 through September 2000, then the irrigation system will be removed.

Exotic vegetation was sprayed with Round up Pro by Habitat West Environmental Firm in May 1999. Hand weeding was also done twice each month in the summer while seedlings were being watered.

Seedling survival was measured in June and September 1999. Three soil samples were taken from the site in December 1999. Samples were sent to A & L Agricultural Laboratory in Modesto, California. The samples were analyzed for organic matter, phosphorus, nitrate, total nitrogen (TKN), pH and sodium.

Results
Overall percent seedling survival was 56 percent as of September 1999 (Table 2). Native percent cover on the slope was approximately 8 percent (Figure 3).

Table 2. Container seedling survival as of September 1999.

Figure 3. Anne's Alley restoration site in September 1999.

Results from the three soil samples on the site were averaged for each test (Table 3). Results showed high levels of organic matter and sodium on the site. Phosphorus, pH, nitrate and total nitrogen were average and consistent with other soil analysis results on Point Loma (Heffernan 1999).

Table 3. Results of soil analysis in December 1999.

Discussion
The propagation methods in Appendix I will be helpful in growing coastal sage seedlings for future restoration projects. It should save time and money by using the methods that worked the best for plants grown for previous restoration projects.

Percent survival at 56 percent was low, but above the 50 percent requirement. This low survival may be tied to the soil results and other vegetation in the area. The high levels of sodium may be more tolerable for some seedlings such as Lemonadeberry as compared to other species, such as Deerweed. In addition, the high levels of organic matter on the site are probably produced by the large Eucalyptus trees on the site. The Eucalyptus trees not only may have shaded some of the plant species too much, but are known to also produce chemicals which inhibit the growth of other species.

Primary exotic vegetation on the slope, other than the Eucalyptus trees, were tumble weed (Salsola tragus), exotic grasses and Australian saltbush (Atriplex semibaccata). Although the site was sprayed with herbicide in the Spring 1999, there was likely a large seedbank of these species. This was evident by the dead weeds removed from the site before installation of jute netting and the number of seedlings that continued to sprout throughout the summer.

Black sage and California sage are also sprouting from the hydroseed mixture. These seedlings are concentrated on the upper and lower portions of the slope. This was probably due to improper erosion control at the time of seeding and the seeds being washed down the slope by winter rains.

Conclusions and Recommendations
The propagation methods provided in this report may be added to in the future when new vegetation species are used on sites or when areas other than coastal sage scrub are restored. These methods may also be updated as germination experiments continue with hard to germinate species such as Mission manzanita (Xylococcus bicolor).

Although survival is low on this site, about half of the seedlings have become established and exhibited new growth. In addition, the supplemental irrigation during the summer months in the year 2000 will keep these plants alive until the next growing season in the Fall 2000. Removing the Eucalyptus from the site would be beneficial not only for the site, but also for the historical buildings to the east as the branches from the trees break off frequently during storms. However, the Eucalyptus are used by Herons and other birds on Point Loma for nesting and restrictions exist for the removal of the trees.

The exotic vegetation on the site should be sprayed and removed for at least another two years to reduce competition with the native seedlings. However, the herbicide applicator should be cautious of the native seedling that are sprouting from the hydroseed mixture. Because of the presence of exotic species in the area it is unlikely that total removal is possible, but further maintenance would allow container plants to grow enough to eventually inhibit the germination of exotic vegetation in the future.