Barrie D. Coate & Associates' SUGGESTED REPLACEMENT TREES FOR USE IN THE CARMEL FOREST

ABSTRACT: While the selection of specific tree species for specific locations in Carmel-by-the-Sea should be based “upon the individual species suitability to the microsite conditions imposed by man,” Monterey Pine (Pinus radiata), the “signature tree” of Carmel-by-the-Sea, grown from pine pitch canker “free” seeds, and Monterey Cypress, should be planted in locations without overhead power lines and planting sites at least 35 sq. ft. Coast Live Oaks can be planted under overhead power lines. The use of larger open spaces (at least 35 sq. ft.) is encouraged to allow the planting of Monterey pines in sidewalk sites. Topics, including, pest control and irrigation, are also discussed. The observation was made that there are “many old specimens of exotic species as well as newly planted exotic species specimens planted in both private and public spaces" in Carmel-by-the-Sea already. Note: A young Monterey Cypress located in a planting space opening at least 35 sq. ft. is on the north side of Ocean Av. in front of Harrison Memorial Library. A young Monterey Pine located in a planting space opening approximately double the minimum recommended size is on the east side of San Carlos St. between Ocean Av. & 7th Av. in front of Ron’s Liquors, although the material is compressed decomposed granite.


SUGGESTED REPLACEMENT TREES FOR USE IN THE CARMEL FOREST

Prepared at the Request of:
Mike Branson
City Forester
P.O. Box SS
Carmel, CA. 93921
Fax: 831/624-2132


Prepared by:
Barrie D. Coate
Consulting Arborist
August 30, 2007

Job #01-07-020B


Assignment
The goal of this document is to relate our findings during a two block intensive inventory and a city-wide cursory tree analysis to the potential reforestation of the Carmel forest. Based upon our findings combined with many years experience with microsite tree adaptation we provide a recommended list of trees for use in appropriate microsites in Carmel and a list of species which should be avoided for a variety of reasons.

For the purposes of this task we have divided Carmel into horticultural zones or typical settings based upon horticultural criteria, including:

• Proximity to the ocean (winds, salt air, soil depth)
• Practical use of the site (street tree, garden tree)
• Available area of aerated root zone
• Presence of power lines overhead
• Required truck clearance

Finally, I have offered suggestions for changes in the site preparation, plant selection, tree maintenance, and pest control measures which would enhance tree condition and longevity.

Even though the coastal commission would prefer that all new planting be of Monterey pine, Monterey cypress or coast live oak (the holy trinity, I’m told) there are already many old specimens of exotic species as well as newly planted exotic species specimens planted in both private and public spaces in town.

In an effort to comply with the wishes of the Coastal Commission and the CNPS (California Native Plant Society) and to enhance the benefits of the use of indigenous species I suggest that the three species be considered the first choice of replacement species in sites where their unfettered natural form achieves the desired structure.

Where topping a Monterey pine would be necessary under a high voltage line or lion’s-tail pruning a coast live oak would be necessary to retain a view, it makes these species inappropriate for those microsites, and a species with a structure and size more appropriate to the needs of the microsite should be used.

If it is not possible to provide sidewalk openings larger that 3 feet square in the business district, Monterey pine is inappropriate for use in that area.

Observations
The current large tree inventory in an area within four blocks north of Ocean Avenue is rapidly diminishing as the maturing naturally occurring Monterey pines die and are removed. Since this area is primarily composed of businesses and the space available for trees is minimal, trees are being removed more rapidly than they are replaced.

In the area one block south of Ocean Avenue the same phenomenon is occurring but in areas further south and north from those business areas, far more mature pines, cypress, live oak and a mixture of exotic species are encountered, both in quantity and variety because these residential sites allow more locations for trees within the properties as well as on street frontages, and the larger spaces result in longer tree life and better tree health.

Where street fronts in those residential areas are 20 feet wide, allowing an adequate planting zone and no power lines are overhead, the opportunity to install Monterey pines and Monterey cypress is presented.

Where these same species have power lines overhead, coast live oak could be used. Many private property sites have room for a tree as large as a Monterey pine or Monterey cypress but the homeowner may prefer an exotic species.

A very different and more stressful location may be seen in two other types of sites. One is the 2 to 3 foot square openings in pavement found in much of the downtown sidewalk areas. The other is the sloped sites in some residential location which are typified by a 3-4 foot wide strip between the pedestrian path in front of homes and the street pavement.

These sites are commonly bare of mulch or ground cover to hold rainfall in place and are sloped so that rain fall runs off before it has the opportunity to soak into the soil. In both of these locations, the trees are severely drought stressed because their root zone has retained very little moisture even during the rainy season.

Another typical area is the western street frontage on San Antonio Avenue and Carmelo Avenue. This exposure to salt laden consistent winds, combined with the shallow sandy topsoil, underlain by sandstone determines what plants best succeed.

Del Mar Avenue and Scenic Road are even more directly affected by these natural forces. Ironically some of the most successful species in these areas are indigenous to the coastal areas of Australia and New Zealand.

Conclusion
The definition of a typical area and recommended tree species replacement in this report is based to a great degree upon the ability of roots to obtain moisture, (consequently oxygen) because that, in the end is the most important single factor in plant success.

Obviously this reference must be modified by aesthetic and practical factors but availability of moisture and oxygen to roots remains essential if the other factors are to have any effect on successful tree growth.

Criteria for Plant Selection
The criteria each of the recommended species would be selected for are:
• 15 foot wide street frontage residential district
• 3 foot wide continuous parking strip
• 2-3 foot square parking strip opening, business district
• Overhead high voltage lines
• Oval, 8 foot long parking strip opening
• Unimproved median strip, residential area
• Residential, within 1 block of ocean
• Residential, within 4 blocks of ocean
• Residential, between 4 and 8 blocks of ocean
• Truck clearance (14 feet above roadway)

Wherever Monterey pine (Pinus radiata) grown from seed from trees free from pine pitch canker would be appropriate (without overhead power lines in planting sites with adequate root room) they should be used since they are the “signature tree” of the county and are so important to the wildlife and ambience of Carmel.

The current inventory includes:
• Blackwood acacia – Acacia melanoxylon
• Brazilian pepper – schinus terebinthifolius
• African yew pine – Podocarpus gracilior
• Japanese black pine – Pinus thunbergiana
• Aleppo pine – Pinus halepensis
• Italian stone pine – Pinus pinea
• Tarawa – Pittosporum eugenioides
• Sweetgum – Liquidambar styraciflua
• Scarlet gum – Eucalyptus ficifolia
• Holly oak – Quercus ilex
• Chinese elm – Ulmus parvifolia
• Deodar cedar – Cedrus deodara

California natives from other parts of the State
• Catalina ironwood – Lyonothamnus floribundus asplenifolius
• Island oak – Quercus tomentella
• Coast redwood – Sequoia sempervirens
• Incense cedar – Calocedrus decurrens
• Catalina cherry – Prunus lyonii

Indigenous Species
• Coast live oak – Quercus agrifolia
• Monterey cypress – Cupressus macrocarpa
• Monterey pine – Pinus radiata

Recommended Tree Species for Use in Carmel
The species suggested here for use in Carmel were chosen first for their adaptation to the environmental conditions found here, i.e.: regular wind, with high salt content, a very sandy topsoil, overlaying a shallow sandstone subsoil with just enough clay and silt to make it hydrophobic when dry and relatively low annual rainfall.

The species most well adapted to this combination of conditions are those which appear naturally near the ocean, in Australia, Chile, New Zealand, Greece, the Canary Islands and California.

Selection of a specific species for a specific location should be based upon the individual species suitability to the microsite conditions imposed by man. It should be clearly understood that the more severe the diversion from the species natural form, or location conditions are from the species natural occurrence and shape the more expensive will be the tree’s maintenance.

Pruning a tree up from the ground or topping it to avoid high voltage lines costs not only man hours (equals money) but reduces the trees vigor and often results in creation of structural defects.

As an example, a deodar cedar commonly develops a broad “skirt” of branches near the ground. If a tree with this structure is installed in a narrow sidewalk, where those broad, los branches impede pedestrian traffic flow, it must either be pruned to remove low branches, a practice which vastly reduces leaf surface and thus reduces vigor or the low branches must be tip pruned several times per year. In either case, a tree which did not develop a broad base would cost much less to maintain in that setting.

For this reason, the three preferred indigenous species may not be well suited to every microsite.

Recommendations
Planting site preparation for new tree installation.
1. Choose to provide a planting site with sufficient root room and oxygen access to allow use of Monterey pines in sidewalk sites rather than choosing a tree species tolerant of single site.

Options include;
a. Using larger open spaces (at lease 35 sq. ft.) for planting sites with excavation of entire space during planting.

b. Use of structural soil in 4’ x 4’ x 3’ deep planter spaces cost of material is $48 per cu. yd. if delivered in 25-ton loads or $82 per 48 cu. ft. planter hole.

2. New planting sites near the ocean
The shallow sandstone subsoil in many of the sites closest to the ocean makes it very difficult to get a large tree established.

Planter holes for trees installed in areas where the subsoil is encountered at 3 feet below grade or less must be prepared with a horizontal drain line from the lowest elevation.

The planter hole must be at least 3 times the width of the rootball, but no deeper than the rootball. A trench which begins at the bottom of the hole and runs laterally to a lower elevation in which a French drain is installed must be installed before the rootball is installed in the hole.

3. If small planter holes (less than 27 cu. ft.) must continue to be used, choose only species which will tolerate the restricted conditions.

Planting site improvement for existing plantings
4. Where the site allows expansion from an existing 2 or 3 foot square into a 35 sq. ft. elongated space or in the narrow steeply sloped sites between the sidewalk and street.

a. During winter excavate the soil in portions of the expanded area which are 5 times the trunk diameter away from the trunk to 2 feet deep. Replace the soil removed during excavation with a premixed import soil containing 3 parts sandy loam, 1 part 0-1/4 inch volcanic rock, 1 part 0-1/4 inch fir bark, combined with recommended label rates (2-lb./cu. yd. of mix) of Broadleaf P4 humectant.

b. In a 15 foot wide right of way between private property and the street. Use radial trenching in water according to enclosed schematic.

c. In a median strip in residential area.

Use radial trenching in winter between trees according to enclosed schematic.

5. Old mature Monterey cypress near the ocean.
a. These trees gradually decline as they reach over-maturity, especially if they are over pruned, removing too much foliage from an already weakened tree.

A combination of crown restoration (WCISA Pruning Standards enclosed) and soil injected Greenbelt 22-14-14 fertilizer in October can rejuvenate those individuals with enough foliage remaining to recover.

6. Pest Control
Coast live oak trees in Monterey County have been badly damaged for several consecutive years by California oakworm larvae (Phryganidia californica).

This insect is not commonly present annually over a period of year, being a cyclical insect commonly with a 10-13 year cycle.

If it defoliates a healthy tree once or even several times per year every 10-13 years, the trees typically suffer no permanent damage.

Unfortunately, when trees which have been overthinned by over zealous interior pruning are stripped of foliage buy this insect in several consecutive years, they become weak and often begin a spiral of decline abnormally early in their lives.

The insect may produce a first generation of larvae in June and July, laying eggs for the second generation which hatch from July through September. The second generation adults lay eggs in October and November that produce some over-wintering larvae.

Recommendations
I suggest that the first generation larvae be sprayed in mid July to reduce the second generation population using Astro systemic insecticide. This is a pyrethrin insecticide which is very safe.

In years of unusually severe infestation it may be necessary to treat again in August.

7. Pine trees Turpentine beetle (Dendroctonus valens) is a common pest in old Monterey pines which are drought stressed. The tan “chewing gum like” exit tube the adult beetle creates at the base of the tree is evidence of its presence. Finding one pitch tube at the base of the tree should serve as a warning that the tree is stressed and under attack.

One irrigation per week with ten gallons of water per inch of truck diameter for one month, followed by a monthly irrigation will usually be sufficient to allow the tree to defend itself from this beetle.

If you find 6 or 8 pitch tubes it is probably too late to save the tree.

8. Pine pitch canker (Fusarium subglutinans pini).
You are all more intimately familiar with this disease than I, and know that there is little that can be done for an infected tree but wait for it to decline.

9. Planting Procedures
If a tree is not properly installed it will probably not survive past the first few years and possibly not even the first year.

If the investment in installation does not result in a vigorous young tree, developing roots in the fill soil around the rootball within the first year and producing vigorous new growth each year, the investment in the tree and the installation was a poor investment.

The following instructions, if followed will consistently produce vigorous, healthy long lived trees, but finding a contractor who will follow the directions and finding time to inspect installations to be sure all of the instructions are being followed may be difficult.

10. Irrigation
Newly installed trees of any species must have water applied directly on top of the rootball.

Water moves directly down, not laterally into container soil, so the newly installed tree is entirely dependent on water applied directly on the rootball, not next to the rootball.

If possible, a QuadraBubbler or OctaBubbler should be provided for each tree, but if irrigation is not available at the site, weekly irrigation by hose for the first year will be essential to success.

Respectfully submitted


Barrie D. Coate

Enclosures:
Assumptions and Limiting conditions
Glossary of Terms
Suggested Replacement Species charts
WCISA Pruning Standards
Pruning: a case against routine thinning, Bruce Hagen, Western Arborist Mag, Fall 2005
City Trees & Property Values, Kathleen Wolf, Arborist News, pages 34-46
Root Renovation Radial Trenching
Structural Soil Specifications
Tree Planting Detail
Poor Water Movement in Soil diagram
Water Management of Transplanted Container Plants, UCCE, August 1982
California oakworm, A Field Guide to Insects & Diseases of California Oaks, pages 14, 15
Astro Insecticide
Romeo Fertilizers: Greenbelt 22-14-12/controlled Release Fertilizer 18-6-12
OctaBubbler Irrigation System
Broadleaf P4
Screw Tight: The Reddy Stake System
Site Pictures