Soil Ecology and Research Group
last update February 27, 2004
RESTORATION PLAN FOR THE PROPOSED
1. PALOS VERDES BLUE BUTTERFLY (GLAUCOPSYCHE LYGDAMUS PALOSVERDESENSIS) MANAGEMENT AREA AT THE PALOS VERDES NAVY FAMILY HOUSING AREA, SAN PEDRO, CALIFORNIA
|Photo by WildlifeWebsite.com|
The proposed Palos Verdes Blue Butterfly Management Area is situated in the former Palos Verdes Navy Housing Area located directly north of the Defense Fuel Supply Point, San Pedro in the southern section of Los Angeles. The facility is directly west of the City of Long Beach and within the city limits of both Los Angeles and San Pedro (Figure 1). Adjacent areas include residential neighborhoods, commercial businesses, schools, playgrounds, a golf course, regional park and an oil refinery facility. Pursuant to the Defense Base Closure and Realignment Act of 1990, the 1995 Base Closure Committee recommended the closure of Long Beach Naval Shipyard. Included in this closure was the Palos Verdes Navy Housing Area (Figure 2). After the residential units were vacated in 1997 the entire housing area was fenced off.
In August 1999, the Navy became aware that the former Palos Verdes Navy Housing Area sustains habitat for the federally endangered Palos Verdes blue butterfly (Glaucopsyche lygdamus palosverdesensis). To eliminate the effects of conveyance on the butterfly, the Navy agreed to retain 10.44 acres of habitat, out of a total of 57 acres, deemed essential to the butterfly. This Plan is aimed at providing guidance for the restoration and management of habitat within the former Palos Verdes Navy Housing Area for the endangered Palos Verdes blue butterfly population.
The proposed Palos Verdes Blue Butterfly Management Area, located in the former Palos Verdes Navy Housing Area, lies less than five miles from the coastline and is located in a marine climate area that is heavily influenced by ocean conditions. Fog belts often develop in the summer months during nighttime hours, dissipating by late morning. Temperatures range from 35º to 100º F, with winter and summer temperatures averaging 52º and 68º F, respectively. Annual rainfall averages slightly more than 12 inches with the majority of all precipitation falling during the winter months from November through March. The area has a Mediterranean climate with cool wet winters and warm dry summers. Because of this, the natural vegetation communities are comprised of species that are adapted to seasonal dry periods common to most of southern California, with the dominant plant community on the facility being coastal sage scrub.
Figure 1. Location of Palos Verdes Navy Housing Area and Defense Fuel Support Point, San Pedro.
The former Palos Verdes Navy Housing Area is located in the southeastern portion of the Los Angeles Basin, an alluvial plain approximately 50 miles long and 20 miles wide. It is a broad coastal plain of low relief that slopes gradually toward the Pacific Ocean, extending approximately 12 miles offshore as the San Pedro continental shelf. The housing Area sits on a small hill along the eastern edge of the Palos Verdes Peninsula that extends from Redondo Beach in the north to the Los Angeles harbor in the south.
Figure 2. Location of former Palos Verdes Navy Family Housing Area.
The soils found at the Housing Area and DFSP primarily consist of the Ramona-Placentia soil association. These types of soils normally have a 5-9 percent slope and are found only in the Los Angeles basin on moderately sloping terraces between sea level and approximately 1,300-foot elevations. Normally, natural vegetation associated with these soils consists mainly of grasses and forbs. The division is approximately 65% Ramona soils and 30 % Placentia soils, with the remaining 5% consisting of Hanford soils. Ramona soils are normally over 60 inches deep, well drained and have slow subsoil permeability. Color is usually reddish-brown with a surface layer of loam or sandy loam normally about 18 inches deep. Substrate is normally loamy to light clay loam. Stones and cobbles may occur up to 60% by volume in some areas with a water holding capacity of approximately 8-10 inches for every 60 inches of soil depth.
Placentia soils are normally over 18 inches deep, moderately well drained with low subsoil permeability. Color is usually brown to reddish-brown with a loamy to sandy loam surface layer up to 18 inches deep. The subsoil tends to be very dense which restricts the movements of both air and water, limiting root growth and development. Areas can have sub-soils composed mainly of gravelly deposits or even iron-cemented hardpan. Fertility is normally much lower than in Ramona soils.
Plant Community Descriptions
Since the area of concern was developed as a housing area, there are almost no clearly defined natural plant communities. Most of the vegetation is either residential lawns (16.8 acres) or steep embankments with an assortment of ornamental and/or exotic species (13.1 acres). There are also 6.4 acres of non-native grassland, 2.4 acres of non-native eucalyptus groves with a very sparse under-story of exotic grasses and shrubs, and one small strip (0.3 acre) of disturbed coastal sage scrub habitat along the southern perimeter. The remaining 18.7 acres are buildings and paved roads.
Listed Species Present
Currently a small population of the Palos Verdes blue butterfly, along with numerous Lotus scoparius host plants, are known to occur within the boundaries of the former Palos Verdes Navy Housing Area. It is in support of this population that the Palos Verdes Blue Butterfly Management Area is being established by the Navy.
Palos Verdes Blue Butterfly
The Palos Verdes blue butterfly (Glaucopsyche lygdamus palosverdesensis) is one of eleven subspecies of the silvery blue butterfly. It is single brooded with a flight period extending from late February to early May. Eggs are usually individually laid in the flowerheads of Lotus scoparius (deerweed) or Astragalus trichopodus var. lonchus (locoweed), the two food plants of the butterfly. When the larvae mature, they crawl into the leaf litter at or near the base of the food plant and pupate.
The butterfly inhabits coastal sage scrub and grassland with suitable resources for early stages (i.e., food plants) and adult nectar sources (such as Lotus, Encelia, Eriogonum fasciculatum, and several other coastal sage species). Host plants are known to have historically established after disturbances such as fire, landslides and impacts from digging and burrowing animals. Exotic grasses and fire control efforts have impacted the dynamics of post-disturbance succession and fragmented remaining coastal sage scrub habitat, leading to the reduction of Palos Verdes blue butterfly populations and its subsequent listing as an endangered species in 1980.
PALOS VERDES BLUE BUTTERFLY MANAGEMENT AREA
To help preserve the Palos Verdes blue butterfly population located on the former Navy Family Housing Area, a Palos Verdes Blue Butterfly Management Area has been established. The Preserve consists of approximately ten acres of land located within the boundary of the Palos Verdes Navy Family Housing Area (Figure 3). Most of the land proposed for the Preserve, currently surrounded by Navy family housing units, consists of highly disturbed coastal sage scrub habitat that has been impacted by the area previously being used for both recreation and as a disposal area. To provide suitable habitat for the Palos Verdes blue butterfly, restoration efforts, aimed at establishing fairly open coastal sage scrub habitat, need to be accomplished. In addition to these initial implementation efforts, ongoing maintenance efforts will be required to ensure that open patches are maintained where the two food plants necessary for the butterfly's continued existence can establish.
Figure 3. Proposed Palos Verdes Blue Butterfly Management Area.
The Palos Verdes blue butterfly depends entirely on Astragalus trichopodus var. lonchus and Lotus scoparius as the food plants for its caterpillars. Both these species exploit
disturbance areas and are normally found in gaps and open areas within the coastal sage scrub plant community. Historically these early successional species followed such natural occurrences as fire, landslides and animal burrowing. With the advent of human intervention (i.e. fire suppression, retaining walls and animal eradication through trapping and loss of habitat), this natural cycle of disturbance and growth has changed. Europeans have introduced many highly adaptable annual exotic grasses that flourish in these same open areas inhabited by both Astragalus and Lotus and compete with the native species for both water and nutrients. In addition, the suppression of fire has led to the development of coastal sage communities that have developed into continuous bands of vegetation, not only decreasing species diversity but leaving no open areas that are a requirement for such species as Astagalus and Lotus to develop.
To ensure the continued existence of the two species that serve as the food source for the Palos Verdes blue butterfly restoration efforts must have a two-fold approach. First, additional coastal sage scrub habitat must be established to provide the habitat necessary for the Palos Verdes blue butterfly to survive. In addition, this newly established habitat must be maintained on a continuous basis to ensure that gaps within these areas continue to exist to provide the open areas necessary for both Astragalus and Lotus species to survive. Since fire, in the form of controlled burns, is not an option at the Palos Verdes Blue Butterfly Management Area due to both residential housing and the adjacent DFSP, these open areas need to be maintained through mechanical means on a regular on-going basis.
The restoration effort for the Palos Verdes Blue Butterfly Management Area will therefore be an ongoing process, and require a continuous input of both time and money. The most cost efficient method to accomplish such an effort is not to attempt to accomplish all implementation actions within the first year or two, but to establish, from the beginning, a smaller, but steady effort that includes both implementation and maintenance actions being accomplished on a regular schedule. If approached in this manner, i.e., establishing new habitat in 1-2 acre size areas per year, in conjunction with a maintenance program that centers on weed reduction and gap development, a long-term restoration program can be established with a reasonable long-term budget requirement. It is on this basis that this restoration plan is being developed. However, if budget constraints are such that money becomes available at a level to allow native habitat restoration to occur on a larger scale, such as the entire Management Area, such an opportunity should not be bypassed. Maintenance efforts are less costly than implementation and can more readily be folded into annual budget requirements.
The goals, methods and procedures outlined in this overall plan, and in all subsequent work plans detailing specific restoration efforts to be accomplished at the Palos Verdes Blue Butterfly Preserve, will be reviewed by a wildlife biologist familiar with the requirements of the Palos Verdes blue butterfly.
Ongoing Restoration Activities
For a native habitat restoration program to be successful, several activities need to be accomplished on a regular, ongoing basis to provide the means by which restoration efforts can be accomplished. These activities include: seed collection, to ensure the necessary native seed is available for the specific species desired; an ongoing seedling germination program to ensure that enough seedlings, both in number and in diversity, are available for restoration efforts as they become necessary; and weed eradication to provide the necessary open area required for host plant recruitment and survival.
An on-site seed collection program shall begin as soon as this restoration plan becomes effective and continue on an ongoing basis. Only seed collected from within the boundaries of DFSP will be used for restoration efforts conducted at the Palos Verdes Blue Butterfly Preserve. Seed is to be collected from a variety of different individual plants to ensure both genetic diversity is maintained and seed collection efforts do not adversely affect natural seeding recruitment for any one area. All seed collected is to be stored in a cool dry location and in containers designed to prevent access by rodents. A spreadsheet computer program will be established to maintain an accurate record for all seed collected, to include the following information: date of collection; location of collection site; scientific and common names of species collected; amount of seed collected; viability testing accomplished; and storage location.
Container plants should be grown and maintained in a variety of containers. For example, woody plants (trees, shrubs and sub-shrubs) and succulents can be grown in D-40 or half-high containers. D-40 containers are 40 cubic inches and have a rooting depth of 10 inches. Half-high containers are 4-6 inch diameter PVC pipe cut to 16 -18 inches in length. The rooting depth provided by these types of containers is equivalent to the rooting depth of most plants in undisturbed coastal sage scrub systems. The relatively large volume of these containers will give the shrubs and trees a competitive advantage over exotic weeds and enhance initial growth. Smaller shrubs should be grown in 10T containers (10 cubic inches, 8.5 inch rooting depth) or 3"x3"x10" plant bands which provide approximately 9 inches of rooting depth.
Proper hardening off of container plantings is important to survival in the field. Hardening off involves making sure that nursery-grown plants are exposed to full sun conditions for at least two months prior to installation at a restoration site. During the hardening off period, plants should also receive a dramatic decline in supplemental watering to enhance each plant's ability to more quickly adapt to natural conditions once it is planted at the restoration site.
Maintenance procedures, including weed removal and maintenance of open areas, will continue in perpetuity. To provide the open habitat necessary for the survival of the Palos Verdes blue butterfly open areas for the recruitment and survival of host food plants need to be continually maintained. Since there is, and will continue to be, a large weed seed bank adjacent to the Palos Verdes Blue Butterfly Management Area in the form of exotic annual grasslands that cover the underground tank areas located throughout the adjacent DFSP, weed control will be an on-going requirement. In addition, the use of mechanical means to maintain the openness required by the blue butterfly is also necessary since the natural means by which coastal sage scrub habitat is kept open, through fire, is not a viable option at the Palos Verde Blue Butterfly Management Area.
Site Preparation Methods
Soil compaction and competition from non-native weed species are the two most important problems limiting the re-establishment of coastal sage scrub species on a disturbed site. Pre-planting site preparation is probably the most important phase of any coastal sage scrub restoration effort. The exotic plant species problem has been exacerbated in southern California by the occurrence of nitrogen deposition. The burning of fossil fuels, and especially through the use of the internal combustion engine, has led to a tremendous increase in atmospheric nitrogen. In southern California this is most easily recognizable in the form of smog. Precipitation washes this nitrogen into the soil where the non-native annual grasses readily absorb it, enhancing their growth. Native species, having evolved in a naturally low nutrient environment, are unable to increase their nutrient intake and therefore are out-competed for both space and water by the faster growing non-native annuals. However, if soil compaction and weed cover problems are not corrected before planting takes place, restoration efforts may fail outright or be only partially successful, no matter how much is later spent on remedial measures. For weed eradication/control (especially non-native grasses), it appears multiple-year treatments are required to sufficiently rid a site of weed seed to allow for establishment of native species.
The following methods can be used to alleviate the problems of compaction and exotic species prior to the reintroduction of native species.
Hand pitting is the process by which compaction is reduced through the use of hand tools such as picks, shovels and McClouds. This method is best for small sites and on hillsides that preclude the use of mechanical means. Workers use hand tools to open up small pits in the soil that allow water to infiltrate the soil and provide micro-catchments that collect organic matter, seed and inoculum. This initiates the breakdown of soil strength and leads to the natural de-compaction of the soil. This method will be used the majority of the time for the restoration sites at the Palos Verdes Blue Butterfly Preserve if compaction is determined to be a concern.
Various herbicides are available which can be applied to eradicate either all species on a site or specifically monocot or dicot species prior to planting. Broad-spectrum products kill all vegetation cover (native or non-native) while spot hand application is used to eradicate smaller populations of undesirable species within larger native cover areas. Repeat applications are usually required to achieve weed control because of the residual seed bank and differing phenologies of weed species. Herbicides work best during periods of active plant growth and therefore are not useful during the summer months. Herbicide use to eradicate weeds on a site prior to planting is better than disking because it does not require disturbance of the soil surface to work. Such soil disturbance usually stimulates the germination of new weed seed.
Care must be taken in the use of herbicides to limit their use to the species and areas designated for control. All pesticides specify in their labeling information on the correct application formulations of these products and the species for which they are registered for use. Spray drift is the most common cause of problems with herbicide use. Best Management Practices for herbicide use require that spray herbicides not be applied at periods when wind drift might cause damage to adjacent non-target vegetation. For this reason, the best time to apply such herbicides is in the early morning hours before the wind picks up for the day. Due to varying wind conditions, it should not be assumed that herbicides can be safely applied throughout a normal work day. If wind exceeds 15 miles per hour, it is important that the operator stop use immediately.
Finally, although there has been concern about the residual effects of herbicides
on the germination or growth of subsequent restoration plantings, field experience
to date does not appear to indicate that either broad spectrum or monocot-specific
herbicides inhibit the establishment of container plants or seedlings after
their use. Nevertheless, it is a good practice to avoid seeding areas immediately
after herbicide application, allowing
2-3 weeks or more after weed kill before seeding takes place. There may be some growth inhibitory effects on newly established native seedlings (not container plants) if pre-emergent herbicides are used too early in their growth cycle.
If permission is granted to use herbicide on the Palos Verdes Blue Butterfly Management Area, it would be most useful during the maintenance of restoration sites after implementation. Spot spraying could be used to reduce weed competition and, in conjunction with mechanical means such as the use of a weed-eater and hand removal, maintain gaps within the coastal sage scrub canopy. This will allow for the growth of both Astragalus trichopodus and Lotus scoparius, the food plants of the Palos Verdes blue butterfly.
Native Species Introduction Methods
Once site preparation is complete, a variety of methods can be used to reintroduce native propagules to a site. Besides the ones discussed below, natural seed invasion by wind and animal vectors will play a role for restoration site where established coastal sage scrub species communities exist along its borders. On the other hand, renewed weed seed invasion is also likely if a site is bordered by non-native species with wind born seed, which is the case for the Palos Verdes Blue Butterfly Management Area, thus leading to the need for continued maintenance after implementation procedures have been completed.
An additional concern with the introduction of native propagules on the Palos Verdes Blue Butterfly Management Area are the restrictions imposed on the type of vegetation cover that can be established on the OU-1 landfill section of the Management Area. The landfill cap is compoased of three layers. The Foundation Layer consists of imported granular fill and ranges in thickness from 2 to 5 feet. The next layer, called the Barrier Layer, is composed of fine-grained, low-permeability material, mostly clayey silt and silty clay, intended to reduce water infiltration into the underlying material. This layer ranges in thickness from 1.5 to 2 feet. The upper layer is the Vegetative Layer. Its purpose is to improve the appearance of the landfill, protect the soil from erosion, control
infiltration by increasing transpiration, and, in this case, provide habitat for the Palos Verdes blue butterfly.
Due to the potential for infiltration into the underlying landfill from a breach in the barrier layer by roots, the plant palette on the landfill area will be limited to shallow-rooted sub-shrubs, grasses and herbaceous cover plants. In addition to the species limitations placed on the restoration of the OU-1 landfill area, an active maintenance effort to prevent deep-rooted species, such as laurel sumac or lemonadeberry, from recruiting onto the site will be required.
Hand Seeding (Broadcasting)
Considering the small size of the restoration efforts that are to occur at the Palos Verdes Blue Butterfly Management Area, and the fact that most sites will be located on slopes, hand seeding will be the preferred method for direct seeding. Hand seeding involves the broadcasting of native seed, mixed with an additive such as cactus mix, over a site by hand. Seed should be applied in double passes over a site to assure more even distribution. The seed can be spread either by hand or with the aid of a small mechanical spreading that can be carried by an individual as he walks the site. The advantage of this approach is that it places seed on the ground without any cover in as close to a natural process as possible. One disadvantage of hand surface seeding, however, is that animal vectors (birds, in particular) can invade a site and eat sown seed before it can germinate. Table 1 provides a suggested seed mix for direct seeding.
At the Palos Verdes Blue Butterfly Preserve, hand seeding should be used mainly on small areas, maybe several square yards in size or smaller, where container plants have not been able to establish. In other words, direct seeding will be most useful for "filling in" areas that are slow to be restored. The success of any seeding effort is almost always directly related to the amount of natural precipitation that occurs close after seeding has been accomplished. For this reason, the best time to hand seed is just before winter rains begin in late November or early December. Direct seeding should also be used only during those years that are predicted to be an El Niño event to ensure enough natural precipitation occurs for germination to be successful.
Suggested species list for direct seeding at Palos Verdes
Blue Butterfly management Area
|Scientific Name||Common Name||PLS #/acre|
| California sagebrush
The use of container plants to introduce coastal sage scrub propagules to a site has several advantages. First, it allows a much higher degree of control over where species establish and their composition. Secondly, it usually allows quicker development of cover. Thirdly, it often fosters native species reestablishment in non-native areas where they would have difficulty succeeding from seed. Finally, container planting allows the introduction of certain woody species to sites whose seed scarification or stratification
requirements limit or prevent their establishment from seed (e.g., laurel sumac). Table 2 provides a listing of suggested species for container planting.
Suggested species list for container planting at Palos Verdes
Blue Butterfly Management Area
|Scientific Name||Common Name|
prickly pear cactus
Container planting should be accomplished during the wet season, normally running from November through March or April. Planting should not begin until sufficient rainfall has occurred to completely moisten the soil, normally after one or two winter storms have passed through the area. Planting holes should be at least one-half to twice the size of the container holding the plant. This will help the roots move into the native soil by initially allowing them to move through backfill soil before entering native soil. If determined to be necessary, a handful of native soil, collected from beneath coastal sage scrub species from a less disturbed site, should be paced in the bottom of the planting hole before planting occurs to provide mycorrhizal spores. This procedure is discussed in more detail in the section concerning mychorrizal fungi. The planting hole should then be filled with water and allowed to drain before the individual plant is placed in the hole. Once planting is complete, a basin, approximately 18-24 inches in diameter, should be constructed to hold the supplemental irrigation water. Finally, the basin should be filled with water to serve as the initial watering for the newly planted species.
General coastal sage scrub species will be randomly planted throughout the restoration site. The two major host plants, Astragalus trichopodus var. lonchus and Lotus scoparius, will be planted in clumps. These groupings of host plants (5-10) individuals per grouping) will be scattered within the restoration site to provide a wide base of support for the blue butterfly.
Seedlings are especially susceptible to herbivory by rabbits, coyotes and other herbivores. In order to reduce plant loss due to herbivory, several materials can be used:
• Treepee - Recycled plastic in two-part cones with built-in wire pegs.
• Tubex Treeshelters - Double-wall plastic shelters. Stable, easy to install. Flared top.
• Tree Pro - Tree Pro shelters (8" to 6 feet) are made of polyethylene and can be assembled on-site. The top is flared to reduce damage.
• BLUE-X - The Blue-X shelters are made of rolled recycled X-ray film.
• Plastic mesh - International Reforestation Suppliers manufactures plastic mesh tubes for plant protection. The open mesh provides little protection from drying winds, however, the plastic mesh is photodegradable (different lifetimes are available) and if staked with bamboo can be left in place.
• Wire screen cages - 1/2"-2" wire mesh threaded over one to four 1/4" reinforcing bar stakes ("pencil rod"). These can be readily dismantled for reuse on other sites.
Treepee and tubex tree shelters will be used for smaller-sized species and plastic mesh and wire cages will be used for the larger, woody species.
The availability of sufficient moisture for plant growth is critical for plant establishment and survival. This need is always most crucial at the seedling germination and establishment phase for seeding efforts and is equally critical to transitioning container plantings from nursery to long-term field conditions. Because the southern California Mediterranean landscape experiences sporadic rainfall events during the winter growing season, and because low rainfall years are not uncommon, supplemental irrigation will be required to support plant establishment until root systems are sufficiently developed to survive under natural rainfall regimes. Supplemental irrigation for all restoration efforts involving container planting at the Palos Verdes Blue Butterfly Management Area should be accomplished through the use of a temporary drip irrigation that can be removed no later than two years after completion of implementation.
A drip system allows water to be provided directly to each plant. This minimizes not only the amount of water needed, but also minimizes the amount of water made available to the non-native exotic species, especially the annual grasses, that can out-compete the natives for both water and nutrients. The use of a drip system does increase the "up-front" costs of a restoration effort through both increased supplies and increased labor when compared to an overhead irrigation system. However, the irrigation equipment can be reused when it is removed from a site after 1-2 years and the labor costs are more than offset by the additional weeding maintenance resulting from the use of overhead irrigation procedures.
Fertilization is the introduction of additional plant nutrients to a restoration site to supplement those already present. If nutrients are lacking on a site (e.g., where mainly sub-soils exist) or if nutrient leaching is high (e.g., in sandy soils) the addition of supplemental nutrients may be required to allow native plantings to establish. For coastal sage restoration, however, such a practice is rarely recommended. Past studies have shown that most coastal sage scrub soils are naturally nutrient poor, particularly in nitrogen. However, the lack of nitrogen is not so much a disadvantage to native species as it is a detriment to the weed species that require high nitrogen levels to survive. Under natural conditions, nutrient poor soils provide a competitive advantage to native species over the non-native weed species and “improper” fertilizer applications could promote the abundance of non-native weed species to the detriment of the coastal sage scrub plants.
In contrast to what occurs "naturally" in coastal sage scrub communities, the Palos Verdes Blue Butterfly Management Area, along with most southern California restoration projects, will most probably experience the abnormal situation of an excess of nutrients, especially nitrogen, in the soil. This phenomenon is the result of atmospheric deposition of nitrogen caused by the air pollution found in and around the Los Angeles Basin and the ubiquitous exotic annual grasses that quickly breakdown each year providing nutrients for next years growth of exotics. Because of this situation, which enhances the spread of non-native exotic species to the detriment of natives, soil testing at each restoration site should be accomplished on a regular basis (once or twice each year). If nutrient levels are found to be higher than what is normally expected, remediation should be accomplished. This can be done through the addition of recalcitrant mulch, such as bark or wood chips, to the soil. This will provide an additional source of carbon for microorganisms, in particular soil fungi, which will enable them to increase in numbers and therefore take up the available nitrogen from the soil through the process known as nitrogen fixation. This will both decrease the amount of available nutrients in the soil and provide a "slow-release" process, caused by the re-release of nitrogen into the soil as the micro-organisms slowly die off, that will benefit the native species over the non-native exotics.
Mycorrhizal fungi are present in most native coastal sage scrub soils. However, most coastal sage scrub species are only facultative users of mycorrhizal fungi and do not require their presence to establish on site (St. John 1995). These fungi grow into the root tip cells of the plants and form a symbiotic relationship with them which allows the fungi to obtain some of its nutrient needs from the plant and helps the plant obtain phosphorus, which can sometimes be difficult for plant roots to extract. In general, mycorrhizal populations are eliminated from highly disturbed sites through the removal of topsoil and other soil disturbance activities. However, if appropriate native species are reintroduced to a site, it appears the associated mycorrhizal fungi will return in 1-5 years (Nelson and Allen 1993). There is currently a debate over whether it is useful to introduce mycorrhizal fungi to coastal sage scrub restoration sites. Experiments done with coastal sage scrub species and non-native grasses where mycorrhizae were introduced showed that non-native grasses may obtain a competitive edge because they put on more top growth while native species increase root growth (Nelson 1995). A few practitioners feel that no restoration can be truly successful without mycorrhizae (St. John 1995).
There are several techniques currently in use for the reintroduction of native mycorrhizae to a restoration site. The most common technique involves using salvaged topsoil from other natural areas lost to development. Since there will be no topsoil salvaging at the Palos Verdes Blue Butterfly Management Area, this procedure will not be used. The second technique involves the collection of soil from around the root systems of on-site coastal sage scrub species. The mycorrhizal symbionts are then isolated (at a laboratory facility) from these samples and cultivated for inoculation onto the restoration plants. Such a process is expensive and not cost efficient and is therefore not recommended for restoration efforts at the Palos Verdes Blue Butterfly Management Area. The use of commercially available inoculum to supplement restoration efforts, though practiced by several restorationists, is also not recommended since it introduces exotic species of fungi into the site.
Mycorrhizal inoculum procedures for restoration projects at the Palos Verdes Blue Butterfly ManagementArea will be as follows. Prior to planting each seedling, a handful of soil, gathered from underneath a coastal sage scrub plant in a less-disturbed area, is placed at the bottom of the planting hole. As the roots of the seedling grow through this native soil, native mycorrhizal spores in the soil will attach to the roots and develop. This will provide the native mycorrhizae needed to help each native plant compete for both nutrients and water. There are numerous areas on the adjacent DFSP that can serve as sources of supply for mycorrhizae through this method.
Hopefully weed seed will have been significantly reduced in the soil bank before planting, but weeds will still need to be controlled afterwards, particularly during the early stages of native plant establishment. Hand weeding, mechanical weeding and selective herbicide applications are used to achieve this purpose. Herbicide can be useful in certain situations, even after a site has been planted. For example, if there are few native monocots on a site, the use of a monocot specific herbicide may significantly decrease competition from non-native annual grass species. Likewise, pre-emergent herbicides can be used after initial perennial plantings have established to eliminate regenerating annual weed species. Spot spraying should be used to control weeds in and around newly planted coastal sage scrub seedlings and to maintain the open areas necessary for the Palos Verdes blue butterfly Management Area. Herbicide application should be timed to occur before weeds set seed to prevent an increase in the seed bank.
Hand weeding, focused on the most competitive and controllable species, can also be used after planting. This approach also needs to be timed for removal of weed species before they flower or set seed. It is important to focus weeding efforts at the time of year and on the areas which will benefit most. The highest priority for weeding should be placed during the late winter and early spring months when most annual weed seeds germinate, though weeding should still occur on a quarterly basis to ensure control of exotic annuals is maintained. These weeds should be removed before they flower and set seed. Also, focused weeding around either container plantings or larger seedlings will give priority to the largest and fastest growing plants most likely to succeed.
The use of mechanical procedures, such as bush-wackers and weed-wackers, will be necessary to maintain the open areas required by the Palos Verdes blue butterfly. This should occur on a quarterly basis, in conjunction with weed control activities. All branches cut down should be removed from the site and not allowed to build up over time. Small twigs and leaves should be left behind to provide necessary nutrients to the soil, but the larger branches need to be removed to maintain the openness of the site that is advantageous to the blue butterfly. Litter directly beneath all coastal sage scrub plants, but especially under Astragalus trichopodus and Lotus scoparius, should never be removed since it is in this litter that blue butterfly larvae pupate and adults emerge from the following year.
Maintenance procedures, including weed removal and maintenance of open areas, will continue in perpetuity. To provide the open habitat necessary for the survival of the Palos Verdes blue butterfly all restoration sites need to be continually maintained. Since there is, and will continue to be, a large weed seed bank adjacent to all restoration sites in the form of exotic annual grasslands that cover the underground tank areas located throughout DFSP and adjacent to the Palos Verdes Blue Butterfly Management Area, weed control will be an on-going requirement. In addition, the use of mechanical means to maintain the openness required by the blue butterfly is also necessary since the natural means by which coastal sage scrub habitat is kept open, through fire, is not a viable option at the Palos Verdes Blue Butterfly Management Area.
Monitoring for each restoration site will begin immediately after completion of implementation and continue for a minimum of five years. During these five years, each site will be monitored for percent cover and species richness. Photo-documentation, covering all aspects of restoration activities, will be accomplished for each restoration effort.
Botanical monitoring shall focus on quantitatively measuring the cover development of restoration plantings and will be conducted annually in the spring (April-May) at the peak of the growing season. To determine/evaluate coastal sage scrub species cover, the point-intercept transect method will be used. One hundred points are sampled along a randomly placed 50-meter (m) tape at 0.5 m intervals starting at 0.5 m and ending at 50 m. A one meter long, 1/4 inch round steel bar is placed vertically at each sampling point, consistently on the same side of the tape. There shall be one transect for each site that is three acres in size or less. Though unlikely, if a site is larger than three acres, two transects will be established and monitored.
All live species that come in contact with the bar, or in the case of overhanging vegetation, intercept the upward projection of the bar are counted. If no vascular plants are intercepted at a sample point, it is recorded as "bare." Total cover is based simply on how many points are covered by vascular plants, regardless of the number of plant species overlapping a given point. In other words, total cover is based on how many points are not recorded as bare of vascular plants. Since several plants often overlap a single point, the sum of individual species covers is generally more than the total cover (McClenaghan, et.al. 1997).
Percent cover is determined for a species simply by dividing the number of points covered by that species by the total number of sample points. Total cover is similarly determined. Relative cover for a species is determined by dividing the percent cover for an individual species by the sum of the percent covers for all species (not by total cover).
Species richness is an estimate of the number of species present in an area. Species richness shall be determined by direct species counts by walking through the restoration and reference areas and compiling species lists.
Success criteria for restoration efforts at the Palos Verdes Blue Butterfly Management Area are outlined in Table 3. The parameters described in Table 3 are established to ensure restoration efforts are progressing satisfactorily.
Success criteria for coastal sage scrub restoration at Palos Verdes Blue Butterfly Management Area.
|Year 2||Year 3||Year 4||Year 5||Year 6|
(total native species cover)
(number of native species)
(total non-native cover)
A detailed work plan shall be submitted to Navy Facilities Engineering Command, Southwest Division within 60 days of acceptance of this Restoration Plan. The work plan shall at a minimum include an introduction, environmental setting, site information, proposed methods, design, proposed plant palette, expected results, and schedule with milestones and dates for completion of the work. The work plan is to be reviewed by a wildlife biologist familiar with the Palos Verdes blue butterfly.
An annual report shall be submitted to Navy facilities Engineering Command, Southwest Division by 1 August. The report shall review progress and status of all current restoration projects either being implemented or monitored. At a minimum, the annual report shall contain the following:
Table of Contents
III. Project Location
IV. Site Description
a. Existing Conditions
b. Source of Damage to the Site
V. Methods and Materials
a. Methods for implementation of restoration
b. Maintenance and monitoring procedures
IX. Management Recommendations