Soil Ecology and Research Group last update October 29, 2002

WORK PLAN FOR
INVASIVE SPECIES CONTROL AND NATIVE HABITAT ENHANCEMENT
SUBASE ICE PLANT AND ACACIA ERADICATION
NAVAL BASE POINT LOMA

Introduction

In July 2002, the Soil Ecology and Restoration Group and Naval Facilities Engineering Command, Southwest Division entered into a Letter of Agreement for one year of habitat restoration. The restoration area is an integral part of land adjacent to Fort Rosecrans Cemetery on the western slope of the Point Loma Ecological Reserve, This area, once covered with native coastal sage scrub, is now disturbed with invasive plant species. Ice plant (Carpobrotus edulis) and acacia (Acacia sp.) are the most dominant invasives and need to be removed to prevent further loss of valuable native habitat. The five-acre portion shown in Figure1 is the site to be restored by the Soil Ecology and Restoration Group.

The intention of this plan is to repair the damaged ecological processes such as the water and nutrient cycles, thereby crossing the degradation transition threshold of the ecosystem and allowing self repair. The goal is the establishment of a self-sustaining native plant community and to prevent further encroachment of iceplant into the area. A process-oriented approach to the restoration of the site will focus on vegetation manipulation to increase the ability of the system to conserve essential resources. A benefit to this approach is that once autogenic repair has begun, further maintenance will not be required (Whisenant, 1999).

The means of ecological repair that will be implemented in this plan consists of the removal of invasive species, particularly iceplant and acacia, the installation of erosion control and the outplanting of native perennials. These measures will be taken in order to create a more natural and undisturbed area resulting in natural recruitment by native species. This will be accomplished by eliminating direct competition for resources, improving the quality of the soil, and allowing the native flora to utilize water and nutrients.

The primary task will be the eradication of iceplant, acacia, and other invasive species. This will be accomplished through herbicide application and manual removal. Several types of erosion control will also be implemented in order to discourage runoff and reduce soil degradation. Native perennials propagated from seed collected on-site and in the surrounding areas will be planted in an effort to mimic the distribution of plants in the undisturbed area surrounding the site. Botanical and soil monitoring will be conducted to determine the success of the project.

Site Preparation

Propagation and Monitoring
A reference site has been established on an undisturbed south-facing slope directly south of the area to be restored. A Releve' survey has been conducted and point-intercept monitoring was completed along a fifty meter transect. The data collected was used to create a desirable species palette for the restoration site. Survey results are presented in the appendix. Seed and cuttings of native perennials have been and continue to be collected from the restoration site, the reference site and the surrounding areas. Propagation has begun at the San Diego State University greenhouse for outplanting during winter 2002-2003.

The restoration site will be divided into five one-acre subplots as are shown. One permanent fifty meter transect will be established randomly in each subplot for point-intercept and quadrant monitoring. The transect is a fifty meter line from which data will be collected every half meter. A measuring stick will be placed every half-meter to determine and measure the vegetation at that point. Quadrant sampling will also be used to collect data. Along the transect line a one meter by one meter square will be placed every two and one half meters to determine both species present and species density. The protocol to be used is discussed in further detail by McClenaghan et al. (1997). Data collected will be used to determine total percent cover and the presence of annuals and exotic species on-site. Transects will be monitored once before implementation to establish base line data and every quarter thereafter to measure progress.
The quality of the soil is always an important aspect of any restoration project. Several types of soil monitoring will be conducted to assess below ground changes. Soils will be sampled onsite and at the reference site and analyzed at the Soils Laboratory at San Diego State University. Compaction onsite will be determined by measuring bulk density. Four random samples from each subplot will be collected once prior to implementation and twice thereafter, in January 2003 and at the end of the project in July 2003, to determine whether proper soil conditions are being achieved.

Non-native Plant Eradiction/Biomass Removal
Once base-line data for all monitoring have been collected, invasive species eradication will begin. The species that most threatens native flora, iceplant (Carpobrotus edulis), will be treated using two different methods of eradication. The first is Roundup-Pro, a glyphosphate-based herbicide that interferes with amino acid production and increases targeted plants' metabolisms (Kuhns 2000). This is the recommended means of iceplant eradication because of its effectiveness and because the agent is inactivated upon contact with soil and therefore does not affect the seed bank. Once treated with herbicide, the resulting mats of dead iceplant will be left onsite in the hopes that they will discourage erosion, act as an organic mulch, and aid in the retention of nutrients and water. The iceplant left to be treated with herbicide will be small patched so that minimal litter will be produced. The second method of eradication is manual removal. This form of eradication will be used in a very small portion of the site where iceplant is less abundant. Herbicide application is favored over manual removal because it prevents soil disturbance that may decrease the ability of native perennials to compete with invading species and contribute to runoff and erosion.

Acacia (acacia sp.) found within the restoration site will be cut down, chipped and deposited at the Submarine Base mulch pile for future use. Other invasive species found on site will be removed by hand, treated with herbicide, or cut and herbicide applied to the resulting stump, depending on the size of the plant and presence in each situation. Due to the large amounts of iceplant found on site, it will be removed from the Base and disposed of properly along with other large biomass. Because of the high potential of iceplant resprouts (Bosard et al. 2000), the site will be closely monitored and any re-emerging invasive species will be removed throughout the length of the project.

Erosion Control
Erosion control will most likely be required due to the steep incline of the slopes that compose the majority of the site. Straw wattles will be installed in various areas along declines to prevent sheet flow and run-off. Punched straw and check dams may also be utilized if it is deemed necessary in smaller problem areas. All debris that is currently on the project area will be removed and the disturbed ground beneath will be evaluated to determine if erosion control will be necessary and what types would be most effective. The Soil Ecology and Restoration Group is not responsible for removal of the disassembled tower at the north end of the restoration site. Coconut blanket and jute netting will be placed on the larger open areas on slopes where iceplant has been manually removed.

Revegetation

Outplanting
The second phase of the project will be the revegetation of the site with native perennials. Planting will take place throughout the entire five acres, in the dead iceplant mats, and in areas where the iceplant has been manually removed. Special consideration will be taken in planning the species distribution. California sagebrush (Artemisia californica) and California buckwheat (Eriogonum fasciculatum) have been favored in the species palette and will be planted throughout the site. Due to the topography of the site, species that have proven to do well on slopes such as common deerweed (Lotus scoparius) and bush rue (Cneoridium dumosum) will be planted through the entire five acres. Larger species found in the areas surrounding the site such as laurel sumac (Malosma laurina) and lemonade berry (Rhus integrifolia) will be emphasized along the eastern site perimeter to act as a natural barrier from the cemetery and protect the site (Table 1).

Table 1.
Proposed Plant List and Method of Propagation

Holes will be dug with shovels and post-hole diggers. Each hole will be approximately 18 inches deep and 10 inches wide. Each plant will receive two gallons of water at the time of outplanting. A basin will be constructed around each seedling to collect and hold water during natural rainfall events and supplemental irrigation. Each seedling will receive a plant protector device to discourage herbivory. Treepee shrub shelters will be used on smaller species and plastic mesh will be installed with bamboo sticks around species that would outgrow the treepees to allow for a more natural plant morphology. Evidence of herbivores and browsing will be documented to determine the effectiveness of the plastic mesh plant protectors.

Maintenance
Maintenance of the site will consist of supplemental irrigation of the outplantings by hand watering, drip/irrigation line, and the monitoring of re-emerging invasive species and subsequent eradication or removal. At the time of each visit to the site, all invasive species will be identified, recorded, removed, and properly disposed. Monitoring of the permanent transects will be used to determine whether the dead iceplant mats favor or discourage the establishment of invasive species. The outplanted seedlings will receive supplemental irrigation one time per month from the time of outplanting until May of 2003. The seedlings will be watered once every two weeks from May 2003 through September 2003. Results from previous coastal sage scrub restoration efforts have demonstrated the need for supplemental irrigation throughout the first summer. Following the first summer, outplantings will be able to survive with natural precipitation. Each outplanting will receive at least one gallon of water at the time of irrigation. Supplemental irrigation will discontinue at the end of September 2003 and irrigation lines will be removed.

Schedule for Implementation

The timeline (Table 2) includes both fieldwork and paper work to be completed. This project was initiated in July 2002 and is scheduled to continue through September 2003. Site preparation has begun and is scheduled for completion by the end of September 2002. Revegetation will occur October 2002 through January 2002. Maintenance and monitoring will continue until September 2003. Quarterly reports will be submitted on the first day of the month in which they are due. An Implementation report will be submitted within thirty days of the completion of revegetation and a final monitoring report will be submitted within fifteen days of the completion of the project.

Table 2.
Proposed Timeline of Activities