Soil Ecology and Research Group last update July 21, 2003

FINAL WORK AND MONITORING PLAN FOR
ENGELMANN OAK (QUERCUS ENGELMANNII) RESTORATION
ON MARINE CORPS AIR STATION MIRAMAR,
SAN DIEGO, CALIFORNIA

Executive Summary
Construction associated with the Rifle/Pistol Range in East Miramar on Marine Corps Air Station (MCAS) Miramar may impact up to nine Engelmann oak (Quercus engelmannii) trees. In accordance with the MCAS Miramar Integrated Natural Resources Management Plan (INMRP) impacts to Engelmann oaks require mitigation at a five to one ratio. Therefore, forty-five Engelmann oaks need to be established on MCAS Miramar at selected locations that meet the appropriate soil and vegetative conditions to support Engelmann oaks. Several possible restoration sites with the necessary conditions for Engelmann oak establishment will be located by the Soil Ecology and Restoration Group (SERG). Final approval for the sites will be given by the Public Works Department, Environmental Management, and Southwest Division.

Acorns will be collected from existing Engelmann oaks on the Station as soon as they are available and mature, in the fall of 2002 if possible. Seedlings will be germinated in deep (12-18") containers to allow for the proper development of the taproot. Acorns will either be germinated in soil collected from under a mature Engelmann oak, or in a potting soil mixture that mimics the deep, loamy clay in which they prefer to grow.

Approximately six months prior to scheduled out-planting, all sites will be treated with herbicide applied by a licensed pesticide applicator. Prior to placing the seedling into the planting hole, a handful of soil taken from beneath selected healthy Engelmann oaks will be placed in the bottom to provide necessary mycorrhizal fungi. Additionally, a fencing protector will be placed in the planting hole to a depth of approximately 8-10 inches to provide protection from possible gopher damage. The seedling will be installed and provided with approximately one liter of water through a deep pipe installed at the time the oak is planted. Due to potential die-off, additional seedlings will be planted to ensure a minimum of forty-five seedlings survive.

All seedlings will be monitored and maintained for four years after completion of planting. Maintenance will consist of supplemental watering and weed removal. Seedlings will be replanted yearly as necessary to ensure the success criteria of forty-five healthy oaks at the end of four years is met.

Introduction
Marine Corps Air Station Miramar, or the “Station”, is located in San Diego County, California, four miles east of the Pacific Ocean and thirteen miles north of downtown San Diego. Construction associated with the Rifle/Pistol Range in East Miramar on Marine Corps Air Station (MCAS) Miramar may impact up to nine Engelmann oak (Quercus engelmannii) trees. In accordance with the MCAS Miramar Integrated Natural Resources Management Plan (INMRP) impacts to Engelmann oaks require mitigation at a five to one ratio. Therefore, forty-five new Engelmann oaks need to be established at sites with the appropriate soil and vegetative conditions on the Station.

Background on Engelmann Oak
Engelmann oaks are only found in Southern California and the northern portions of Baja California, with more than 90% of the remaining stands located in San Diego County (Pavlick, et al, 2002). Most Engelmann oak woodlands occur between 2300 and 4200 feet and are usually found on southwest facing slopes and mesas dominated by grasslands or coastal sage scrub vegetation (St. John and Scott, 1997). Density of Engelmann oaks can range from 27 trees per hectare up to 147 trees per hectare (Barbour and Major, 1995). These oaks mix with coast live oak (Quercus agrifolia) woodlands. However, due to their ability to germinate and grow better at low moisture conditions, Engelmann oaks also tend to occupy areas between mesic canyon bottoms and sage scrub/grassland uplands. These oaks are often found in soil that is a deep loamy clay, however they also do well in areas with more sandy or rocky soils if there is some source of summer moisture such as a stream or intermittent stream (Pavlick, et. al., 2002). Drought and over-grazing, starting near the beginning of the 20th century, have altered the distribution of Engelmann oaks. This has resulted in many sites suitable for these oaks being currently unoccupied (Barbour and Major, 1995).

Methods
Prior to field work, pertinent literature will be reviewed to determine the best methods to collect, propagate, and maintain the oaks. This review will also include information on conditions for site selection. In order to find appropriate locations to plant the forty-five Engelmann Oaks, numerous areas around the Station will be surveyed. The Soil Ecology and Restoration Group (SERG) will select several possible sites, starting in the area of Green's Farm Road and working outwards to other areas with deep valley clay soils or with deep moisture conditions that can appropriately support Engelmann oaks(St. John and Scott, 1997). Surrounding vegetation that indicates deep soil moisture, including Quercus agrifolia, Malosma laurina, and Rhus integrifolia will also be utilized to determine which sites are most appropriate (St. John, and Scott, 1997). Table 1 and Figures 1 and 2 outline several sites appropriate for Engelmann oaks. These sites will be presented to the Public Works Department, Environmental Management Department, and Southwest Division for final approval. GPS coordinates will be taken around the edge of each site in order to place the site on a map and determine its overall size. Soil samples will be taken from areas that appear to meet the proper conditions in which these oaks prefer to grow, and soil texture and moisture results used to select the most appropriate sites.

Table 1.
Descriptions of Potential Engelmann Oak Sites.

Figure 1. Potential Engelmann Oak Restoration Sites Near Green Farms Road.

Figure 2. Potential Oak Restoration Sites in West Sycamore Canyon.

Collection and Germination
Acorns from existing Engelmann oaks located on the Station will be collected as soon as they become available, during the fall of 2002 if possible. Station personnel will be contacted to find any known or likely locations of Engelmann oaks and these areas will be surveyed in order to find existing oaks. Aerial photographs taken of the base will also be examined to further pinpoint possible oak locations. Once an Engelmann oak is located on the Station, GPS coordinates and a picture of the tree will be taken. If no acorns are found on the Engelmann oaks located on the Station, Station personnel will be contacted to decide whether acorns from other specified locations in San Diego County will be acceptable. If acorns are found, the tree from which they are on will be documented and acorns gathered once they are ripe. Acorns will be gathered preferably from the tree as soon as they can be removed easily from the caps. If this is not possible, acorns will be collected from the ground below the tree. It is preferable to collect acorns from the tree as these have less chance of being damaged by insects than those collected from the ground (McGreary, 2000). Once collected, acorns will be stored in plastic bags and cold stratified in a refrigerator until they begin to germinate (approximately one month).

Once the acorns begin to germinate they will be moved to the SERG Greenhouse located at San Diego State University. Seedlings will be germinated in deep (12-18") containers to allow for proper development of the taproot. After 6 months of growing, the oaks will be transferred to the SERG shade-house at Alliant International University. Half the acorns planted will be started inside the greenhouse and then moved outside after three months. The other half will be started outside the greenhouse under shade cloth. Greenhouse conditions should encourage plants and their roots structures to grow at a faster rate. However, this may also cause the taproot to grow too quickly and reach the bottom of the planting container before the oaks are able to be put into the field (McGreary, 2000). Starting acorns inside and outside of the greenhouse will determine if the rate of root development in these two conditions has any effect on the long term survival and success of the Engelmann oaks.

Acorns will either be germinated in a potting soil mixture that mimics the deep, loamy clay in which they prefer to grow, or in a four to one mixture of potting soil to soil collected from under a mature Engelmann oak. Soil found under oaks contains mycorrhizal fungi necessary for oaks to survive and can be used as a natural innoculum (St. John and Scott, 1997). Planting some acorns into soils with the mycorrhizae and others in soil without will determine whether the mycorrhizal presence is beneficial at the initial stages of germination and growth. It will also determine whether such initial innoculation has any effect on the long term survival and success of Engelmann oaks.

Site Preparation and Planting
Once seedlings have reached the size to be out-planted (when the tap-root has grown the length of the container, a minimum of one year), site preparations will begin. Approximately six months prior to scheduled out-planting, all sites will be treated with herbicide, applied by a licensed pesticide applicator, to reduce competition for water and nutrients between exotic annuals and the oak seedlings.

Prior to placing the seedling into the planting hole, a handful of soil taken from beneath a healthy Engelmann oak will be placed in the bottom of the hole in which the seedling will be planted. As the seedling's taproot grows through this added soil, it will provide the oak seedling, an obligate mycorrhizal species, the inoculum needed to survive.

Oak seedlings will be planted prior to or during the rainy season. Holes for the seedlings will be made through the use of a hand auger. A fencing protector will be placed in the planting hole to a depth of approximately 8-10 inches to provide protection from possible gopher damage. The above ground portion of the fencing will protect the seedling from grazers such as rabbits and deer. An additional protector such as a treepee or tubex may also be utilized to give shade to the seedling until it outgrows the container. Once the planting hole has been prepared, the seedling will be installed and provided with approximately one liter of water. The water will be supplied through a deep pipe installed at the time the oak is planted. The deep pipe irrigates the plant below the surface of the soil, causing the roots to grow downward and tap into the available groundwater. Deep pipe irrigation also reduces crown rot caused common in oaks by keeping the surface soil around the base of the plant dry. Due to potential die-off, at least forty-five additional seedlings , for a total of ninety seedlings, will be planted to ensure a minimum of forty-five seedlings survive. Each oak will be marked with a tag to denote the different conditions in which it was initially grown (with oak soil innoculum or not, and started inside the greenhouse or not).

Monitoring and Maintenance
All seedlings will be monitored and maintained for four years after completion of planting. Maintenance will consist of supplemental watering and weed removal. Watering will be done every week the first eight weeks after transplanting has occurred, and then once each month for the first year following planting. Watering for the first two weeks will include surface and deep pipe watering. Watering monthly will be done solely by use of the deep pipe to discourage crown rot and fungal infections common with oaks as well as reducing weed growth that would compete with the oaks.

Weed removal will be done from an area approximately fifteen feet in diameter around each seedling through use of an herbicide or through mechanical removal. This will decrease the amount of competition with non-natives for water and nutrients (St. John and Scott, 1997). Mulch may also be spread around each seedling within the fifteen foot radius to decrease the amount of weeds.

Monitoring will consist of determining percent survival, seedling growth (plant volume), and rating each seedling’s health on a scale of one to five (one being almost dead and five being robust). Mychorrhizal soil analyses may also be done to determine that mycorhizae are present and to determine if the number of spores are increasing through the four years after planting.

Success Criteria
Success criteria for this project is that forty-five healthy Engelmann oaks will be established at the end of the four year monitoring period. If oaks die off below the necessary forty-five during the four years, additional seedlings will be replanted to meet the established criteria.