Love the Beauty of Your City? Thank the Landscape Architects who Made it Happen

I recently read a great article by Delle Willett of the North Park News entitled Landscape Architects:  Artists with the Earth as a Canvas.  The article focused on three local women landscape architects who have made significant contributions to enhancing the aesthetics and functionality to the City of San Diego.

While reading about the history of female landscape architects, I couldn’t help be reflect on my own background and education within the fielof landscape architecture and landscape contracting.  As a college student, my path began at UC Santa Barbara and completed with a Bachelor of Science degree from California Polytechnic University, Pomona.

I wrote and article correlating my own academic history with the three landscape architects discussed in the newspaper article.  For men or women interested in the field of landscape architecture, design, planning, horticulture, arboriculture and landscape contracting, or anyone who struggled to find their own passion and career path in college, I think you’ll enjoy the read.

Landscape Architects Making Significant Contributions to City of San Diego

Landscape Architects: Artists with the Earth as a Canvas.



PTCA Field Day a Great Success

Wow, just when I thought the PTCA (Professional Tree Care Association) annual seminar was the bomb, the following field day was just as great. While the seminar was an indoor event focusing on a variety of topics presented by outstanding industry professionals and educators, the field day was spent outdoor at beautiful Balboa park in San Diego.

The day consisted of a number of workshops organized into several different tracks that allowed participants to choose from a palette of presentations that provided something for everybody. Tree climbers and field workers loved the tree climbing workshop and training by Mr. Martin Morales. His workshop included climbing and positioning for safe work in trees, also taught about knots, ropes and equipment inspection, while providing new tips and tricks. I am way to old for climbing, but enjoyed watching guys in the trees, had an opportunity to meet Martin during an incredible lunch (carne asada). We were looking at a rigging holding a tree logIMG_0042, he immediately pointed out flaws and worn equipment, I would never have noticed. Fortunately we have educated tree climbers who understand the importance of proper equipment, training and safety.  Another track included Tree Risk Assessment best management practices (BMP’s) workshop taught by Mr. Ron Matranga and Dr. R. Bruce Allison. Since I consult and provide tree risk assessment as part of my practice, it was a great opportunity to learn about  best management practices involved with the new TRAQ (tree risk assessment qualified) versus the previous TRACE (tree risk assessment certification exam) methodology. Dr. Allison demonstrated new sonic tomography techniques for non-destructive testing of the interior of tree trunks, new cutting edge technology that is already an advancement from just two years ago. Using probes and determining the time for sound waves to travel through tree trunks and how the sound wave moves at different velocities around interior trunk decay will assist arborists to use in advanced tree risk assessment. As Dr. Allison noted, hopefully in the next few years, the cost will come down and we will have a pocket sized device and an app to use to help us understand what is happening with interior tree decay.

Sound wave technology, the next big thing?

Sound wave technology, the next big thing?

How serious is the problem

How serious is the problem

We all know about new invasive insects and diseases affecting our trees, new invasive species are being detected at a rate on one every 60 days, Dr. John Kabashiima provided the sobering statistic it is now one every 45 days! The gold spotted oak borer has decimated tens of thousands of Coast Live Oak and Black Oaks throughout California.

Six orange color dots help identify this pest, although the adult is rarely seen

Six orange color dots help identify this pest, although the adult is rarely seen

This pest has been spread throughout the state, particularly San Diego county by people using the dead wood for fire wood, transporting it in their vehicles where they unwitting spread the insect throughout the county. Don’t move infected wood!

Stop using infected wood for fire wood and don't transport the wood, you are spreading the disease

Stop using infected wood for fire wood and don’t transport the wood, you are spreading the disease

Take a look at some of these nasty borers and other insects, yikes!Nasty Borers

For pest control advisors and applicators, there was a pesticide application for trees demonstration and a safety workshop and tree identification workshop and quiz available to test your knowledge. Field guys loved the chainsaw sharpening and troubleshooting workshop presented by Mr. Paul Lasiter and Mr. Joe Garcia. Another great aspect for everyone was presentation of many workshops in Spanish and English, a very inclusive aspect that helped all of us enjoy the day.

I learned a great deal of new information I never would have even considered without this great field day presentation. Have you ever considered how heavy a downed tree trunk is?  Well, there was a workshop on how to calculate the wood weight of felled trees, presented by Mr. Harvey Pedersen. Crane operators have to have a reasonable idea of how much a log or portion of a tree trunk weighs in order to safely lift it. Mr. Pederson presented wood weight calculations of various types of trees and an amazingly accurate method for estimating the weight of a log, which was then lifted by the crane which provided the true weight to compare against our estimated weights. How cool is that!

How much do those logs weight?

How much do those logs weight?

Just want to thank all of those involved in the PTCA Seminar and Field Day for a truly memorable event, a special thanks to our friend Dave Shaw

Dave kept us all entertained, what a great guy!

Dave kept us all entertained, what a great guy!


who once again served as the master of ceremony and kept us all entertained. Keep up the great work, looking forward to next years seminar and field day.

Learn more about the PTCA at

PTCA Arbor Essence

No, this is not a perfume, rather it is the title for this years PTCA Seminar and Field Day.  PTCA, known as the Professional Tree Care Association of San Diego, is a premier industry association for professionals within the tree care industry.  The association contains a wide diversity of professionals, including representatives from outstanding tree care and tree service companies, ISA (International Society of Arboriculture) certified arborists, utility arborists, board certified master arborist, ASCA (American Association of Consulting Arborists) RSA’s (Registered Consulting Arborist), and industry professionals from utility companies, San Diego Zoo, golf courses, private industries, landscape contractors, landscape architects, educators and more.

A common thread shared by all of these different professionals and educators is our love of TREES and desire to further improve our understanding of the field of arboriculture!  It is a comforting feeling sitting is a room with hundreds of people sharing our knowledge and experiences with trees, learning new information, meeting old and making new friends.

Each year, the PTCA sponsors the annual Seminar and Field Day.  The first day (today) featured an incredible diversity of speakers and topics, there is something for everyone.  Here is a sampling of todays speakers:

Ms. Leah Rottke, professor at Cuyamaca College spoke about what to plant now for upcoming changes brought about by climate change in Southern California, Ms. Pat Nolan, County Pathologist for San Diego County of Department of Agriculture spoke about invasive diseases  moving into the Urban Forest.  In the morning session, Dr. Tom Scott, Ph.D., Department of Earth Sciences, UC Riverside discussed Management of Oak trees in San Diego County followed by an afternoon discussion about the Gold Spotted Oak Borer research (GSOB) and update.  Mr. Ron Matranga, Board Certified Master Arborist from Atlas Tree Service provided an overview of the ISA Traq (Tree Risk Assessment Qualified) program and Mr.Randall Stamen, Esq., from Riverside, California delivered a sobering lecture about Arboriculture and the law, including tree risk assessment and case studies.  Mr. Brian Bishop of Bishops Tree Service discussed improving the efficiency of tree crews and Dr. John Kabashima, Ph.D., UC County Extension, Orange County gave an entertaining lecture about effective sampling for diagnoses of insect and disease problems.  All of that in ONE day!

Really looking forward to tomorrow, the field day featuring workshops in tree risk assessment and BMP (best management practices), insects and diseases of shade tree diagnoses, pesticide applications for tree demonstrations, safety and tree identification, electrical safety, wood weight calculations, improving efficiency and maximizing safety.  There will be a tree climbing workshop provided in Spanish and English.

If you are a tree, landscape, horticulture, educator, consultant, or expert witness and have not yet attended a PTCA field day, you are missing out on a premier educational and entertaining event.  Members of the ISA, ASCA and urban forest councils, city and jurisdictional representatives, recreational and utility companies all come together in a common bond of learning, teaching and sharing, not to mention fantastic networking opportunities.  Hope to see you at the next PTCA Seminar and Field Day!

Learn more about the PTCA at

Is Global Warming Affecting Redwood Trees in California?

I read a very interesting article in the L.A. Times concerning possible affects of global warming on both the Giant and Coastal Redwood tree populations in California. There might actually be some good news associated with global warming, recent scientific studies have documented growth spurts in both the coastal redwoods and giant sequoias.

Since the 1970’s, taking corings from trees more than 1,000 years old, scientists claim certain coastal redwoods have experienced the fastest growth ever. “The forests are not experiencing detrimental impacts from climate change” stated Emily Burns, science director at the Save the Redwoods League.

A variety of factors besides climate change could explain the increased growth rates said professor Stephen Sillett of Humboldt State, one of many researchers. Scientists established 16 research plots in old growth redwood and sequoia forests throughout their respective ranges. They took pencil width corings from 78 redwoods, studied the tree rings and developed a chronology dating back year 328. They also took corings from sequoias, analyzed the rings and dated the trees back to 474!

The data revealed redwood trunk growth in recent decades has “shattered” all records. The global warming records and effects on regional precipitation are less clear, indicating highly variable precipitation but overall no significant decline in the recent study areas. One theory is old giant sequoias might be growing faster because rising temperatures have extended the growing season in the Sierra Nevada.

Other theories include redwoods receiving more sun due to reduced fog in coastal climates yet still getting the precipitation they require or getting more sunlight due to a reduction in air pollution in north coastal areas from reduction in wood processing plants.

A great side benefit of the research was discovery of an ancient tree that corings revealed the oldest coastal redwood on record, 2,500 years old, besting the previous record holder by 300 years!!

When is comes to climate change, Professor Sillett added “I’m more worried about humans than I am about redwoods. I think they’re going to hold their own”. Very glad to hear this positive redwood assessment although a bit concerned about the human race.

Click to read the full article Is Climate Change Affecting Redwoods?

Oak Tree Failure Kills Counselor at Camp Tawonga

Camp Tawonga Tree Failure

My son Jake called yesterday very upset, telling me about an oak tree falling and killing a counselor at Camp Tawonga near Yosemite, CA.  My son graduated with a degree in Environmental Studies and Economics from UC Santa Cruz last June and worked the summer at Camp Tawonga.  He loved working there and returned for some part time work last fall.

What was chilling was his description of the exact location where the tree fell, he said he often sat nearby the spot and even sat under the tree!  He knew the counselor, Annais Rittenberg from UC Santa Cruz, where he also took the environmental field course his senior year.  Needless to say, he is shocked by what happened.

As a certified arborist, I provide tree risk assessments, a process of tree investigation and analysis that rates a tree defects and determines the hazard potential of a tree part or whole tree failure.  I have worked with plaintiff and defendant attorneys concerning tree failures and accidents, yet this accident struck very close to home.  I keep thinking about how that easily could have been my son under that oak tree when it failed.

Who knows if this failure could have been predicted?  My son mentioned how the area where the tree was located was irrigated daily throughout the summer, he said the tree trunk split and fell.  Was there root rot, cavities, or decay in the trunk?  Was the crown showing signs of stress?  Would a risk assessment have determined the tree was structurally unstable?  Maybe yes or no, I certainly don’t want to speculate, as I do not know the facts.

Tree failures resulting in human fatalities are very low, yet it only takes one failure to change lives forever.  My heart and sympathies to the family for the terrible loss.

This should serve as a reminder to camps, recreational facilities, golf courses, R.V. parks and manufactured housing communities to inventory and inspect your tree assets on your property, common spaces and even notify homeowners of endangered trees on their private lots or property.  Facility owners who take proactive measures to inspect, inventory, assess and maintain their tree assets increase the chance of detecting and minimizing tree related accidents before they happen.


Unsure of What Plants to Select for Your Landscape or Garden?

The Basics on Landscape Design, Tree and Shrub Selection for Southern California Landscapes

I am most definitely a native SoCal.  Born in the San Fernando Valley in Los Angeles, educated at UC Santa Barbara and California Polytechnic University, living in San Diego for many decades, I have lived in Southern California my entire life.
Yes, we complain when we have hot spells, (last summer was ridiculous), Santa Ana winds, and the fog, but overall, we have the best climate in the world for growing plants.  Whether for ornamental landscapes or vegetable gardening, we a blessed with a climate and environmental conditions that allow us to grow an incredible variety of trees, shrubs, ground covers, turf, vegetables and fruits pretty much 365 days a year.
Walk or drive throughout our neighborhoods and check out the incredible plant diversity.  We are very accustomed to the trees and plants that surround us.  However, if you are from the midwest, east coast or other parts of the country or the world, you are most likely amazed at the variety of plant material.  Botanical gardens and arboretums from Santa Barbara to San Diego boast incredible displays of plants from around the world that flourish in our mild Mediterranean climate.
We have neighbors recently moved to San Diego from Kansas City.  They purchased a home and want to landscape but are completely baffled about what to plant.  Obviously, the trees and shrubs they were accustomed to in Kansas City were very different from what is available for landscaping in San Diego.  I offered some suggestions to help simplify the plant selection process.
There are many approaches one can take to designing and installing an ornamental landscape for their home or place of business.  Using a landscape architect to design a planting and irrigation plan is an excellent choice, however it can be costly.  Landscape contractors can provide design services as part of a design build contract, however you might feel uncomfortable about possible conflict of interest, and whether the contractor is truly knowledgeable about plant material and design.  Then, there are the millions of property owners trying to do it themselves.  This article is for you!

Where to Start?

Don’t get caught up with or distracted by endless design themes and details.  If you have a certain theme in mind, fine, then you most likely already know the kinds of plant material you want to use.  I prefer to design and select plant based on the site environmental conditions matched to the cultural requirements of each plant to be used in the landscape.  What does that mean?

What are Environmental Site Conditions?

The first step in selecting plant material is determining your specific site conditions.  There are many factors that affect plant growth and they are reflected in your site.  Analyze your location and be able to answer the following questions:

  1. Does the site face the north (full shade), east (part shade part sun), west (part sun – full sun), or south, (full sun).  Determining the site sun exposure is one of the most important environmental conditions.
  2. What are the temperature extremes.  Does the site receive cold weather extremes such as frequent frosts, freezes, snow or hail?  Does the site receive intense heat?  Determine the temperature extremes as well as the average seasonal temperature for your location.
  3. Is the site near the coast where it will receive constant salt air and sea breezes?
  4. Is the site windy, contain microclimates, protected by a structure?
  5. Is the soil a heavy, poorly drained clay or lighter, well drained loam, or sand?
  6. Is the soil structure friable and fertile or dry and compacted?
  7. Does the site drain well or is water trapped onsite or on top of a perched water table or spring?
  8. Are there rodent or pest or disease problems?
  9. Are there physical site constraints such as overhead or underground utilities, concrete or masonry improvement?

These are just a sampling of typical environmental site conditions that affect plant growth.  The more you know about the site to be landscaped, the better informed you will be in order to make appropriate plant selections.
In the next installment, I’ll discuss plant cultural requirements and the importance of selecting plant material with cultural requirements that match the site environmental conditions, a key to successful landscape project!

What Will be the Development Future for Balboa Park?

Like many citizens of the City of San Diego, I have been closely monitoring proposals for the redevelopment of Balboa Park.  For those who might not be aware of this  situation, the Plaza de Panama  committee plan proposed changes to Balboa Park including removing vehicles and free parking within the park where they are now allowed and replace that with paid parking structures.  Included in the plan is construction of a 400 foot bridge extension and freeway like transition road from the historic Laurel / Cabrillo bridge for visitors to access the new parking structures.  The idea was to finish construction in time for the centennial celebration of 1915 Panama-California Exhibition, the reason Balboa Park first came into existence.

SOHO, (Save Our Heritage Organization), filed suit two years ago to block the city from proceeding with the proposed design.  On February 4, 2013, SOHO claimed a great victory when Superior Court Judge Timothy Taylor ruled the City Council violated municipal code and utilized “faulty logic” in approving the Plaza de Panama Committee plan last July, 2012.  Judge Taylor ruled the City “abused its discretion” in approving the project and ruled to set aside the project’s required Site Development Permit.

Key to the ruling was according to municipal code for historic sites, the City was required to find that the project site would otherwise have “no reasonable beneficial use” in order to have the permit approved.  Obviously, Balboa Park has a great deal of “beneficial use” without the permit issuance, which the City seemed to ignore in their decision to proceed with the committees recommendation, perhaps the reason Judge Taylor deemed City Council had “abused it discretion”, used “faulty logic” and held that “the critical finding by the City Council is so lacking in evidentiary support as to render it unreasonable; it must therefore be set aside”.

Balboa Park is a rare and extraordinary site located in the urban center of San Diego.  This has been a free “peoples park” for locals and tourists for generations.  Supporters of the Plaza de Panama project contend it would reclaim the park from cars that currently drive through the park to reach parking lots.  Opponents to the plan claim while one small area of cars would be freed up, the remainder of the park would be dominated by traffic, new buildings and acres of concrete parking lots.  Tranquil Alcazar Gardens would become an automobile, bus and delivery zone.

With so much as stake for one of San Diego’s most important, historic and enduring landmarks, why has the City of San Diego failed to find an agreeable compromise?  Balboa Park is a historic resource that should be protected and sensibly improved to benefit  ALL the citizens of San Diego, not just special interest groups or donors such as Mr. Jacobs, who pledged to donate $30 million for improvements, but only using the Plaza de Panama plan, in other words, the philanthropic donation had political strings tied to it.  Not much of a philanthropic gesture in my opinion.  If Mr. Jacobs is truly interested in improving Balboa Park for ALL citizens, tourists and park visitors, he donation should not be tied to a specific design.

While I have spent a career working in land development, I am also a proud citizen of San Diego and I do not want to see the historic Cabrillo bridge turned into a freeway, and do not want to see the western historic architectural facade of the existing buildings destroyed because of a poorly conceived traffic circulation plan.  There are better alternatives available and the City Council needs to stop considering free donations with strings attached as the reason for choosing one alternative plan over another.

Balboa Park was conceived and developed as a free park for all citizens to enjoy.  That was the original intent, we should honor that objective in careful deliberation about the future of how to thoughtfully redevelop the park for future generations.  Lets not rush to a limited decision so we can have a park renovated in time for the centennial.

Click to read the full SOHO article, SOHO Wins! Balboa Park Saved!

Construction Development Versus Oak Trees: Can the Two Co-Exist?

I had the good fortune to be selected as the project arborist for a portion of the San Diego Gas and Electric Sunrise Power Link Project. This is a high voltage energy transmission project bringing an additional source of electricity to the San Diego County area and supplementing the California energy grid. The transmission lines bring energy from the desert southwest into and through San Diego County backcountry.

The portion of the project I consulted on is known as the Suncrest Substation, located at the edge of the Cleveland National Forest just east of Alpine, California. Beta Engineering was the design/build general contractor awarded the contract for constructing the substation for SDG&E. Since the substation was located three miles from the nearest paved road, a three mile construction and operations access road needed to be developed.

In order to build the access road, SDG&E obtained road easements with private land owners to grade and build the access road. However, due to the presence of hundreds of existing Coast Live Oaks and Engelmann Oaks, the property owners required a certified arborist be present before and during construction to make recommendations and implement best management practices to preserve and protect the oak trees during road grading and construction.

Beta Engineering selected Rappoport Development Consulting Services LLC as their independent certified consulting arborist for the Suncrest Substation construction project.

The following article describes the project and how Jeremy Rappoport, an ISA certified consulting arborist designed and implemented best management practices for oak tree construction preservation.

Construction Development Versus Oak Trees:

Can the Two Co-Exist?

Rappoport Development Consulting Services LLC recently completed a project providing independent certified arborist consulting services for Beta Engineering, a design build general contractor awarded the construction contract for the Suncrest Substation, a portion of the San Diego Gas and Electric Sunrise Power link Project. The Suncrest Substation is located east of Alpine, California adjacent to the Cleveland National Forest, approximately 40 miles east of San Diego.

The substation project included developing a 2.5-mile access road for constructing the substation and for ongoing operations and maintenance once completed. The access road runs 2.5 miles through private land used for ranching and recreation. The rugged hills and mountains contain many native California plant species and areas of relatively undisturbed native habitat.

To reach the future substation site, the access road had to be constructed on land containing many native oak trees, including Quercus engelmannii andQuercus agrifolia. The Engelmann oak and Coast Live Oak, both native to California, thrive in the hills, canyons and mountains in eastern San Diego County.

The Engelmann and Coast Live Oaks ranged from 50 to 250 years old, with some magnificent Engelmann specimens displaying 42-inch diameter trunks.

While the Engelmann oaks appeared in relatively good health, the Coast Live Oaks (Quercus agrifolia) showed symptoms of Gold Spotted Oak Borer (GSOB), infestation including crown thinning and dieback, with major trunk and vascular system damage. Fortunately, the Engelmann oaks did not display any signs of bark beetle infestation.

In an effort to minimize tree loss due to construction impacts, the road was surveyed and redesigned several times. Even with the best efforts of the design team, many oak trees had to be removed for construction. Additionally, there were several hundred oak trees adjacent to the construction zone and road easement that would be impacted by construction activities.

Since Beta Engineering was the GC responsible for grading and improving the access road, they were also responsible for protecting and preserving oak trees immediately adjacent to the construction zone. Beta Engineering was required to provide an experienced, certified consulting arborist to implement an oak tree construction preservation plan and provide monitoring and recommendations throughout the access road construction time period of approximately one-year.

Beta Engineering selected Rappoport Development Consulting Services LLC as the certified consulting project arborist. The first site visit revealed beautiful, relatively undisturbed natural terrain. Since the access road was built within an easement on private land, much of the area has been protected by development, resulting in large oak trees and other native species including Ceanothus, Manzanita, Rhus and Malosma.

Pre-Construction Panning

Pre-construction tree protection planning is mandatory to achieve success in the design and implementation of a protection plan. The scope of the assignment was:

  • Review and amend the existing tree inventory with current site data.
  • Analyze grading, improvement and tree survey exhibits, determine and rate the extent of adjacent construction impact to the trees.
  • Design best management practices (BMP’s) and specifications to minimize construction impacts.
  • Provide field inspections and observations prior to and throughout the construction period. Make job site recommendations as required.
  • Develop a final report summarizing the results of the project.

Using an existing tree inventory and survey maps identifying tree locations, pre-construction field inspections compared this information with the survey stakes located in the field. Current field status was updated in the tree inventory, including digital photographs and the tree condition.

The importance of pre-construction planning is crucial for a successful tree protection plan. Tree protection best management practices generally work far better when implemented before heavy equipment and grading operations begin.

With a complete understanding of the field and tree conditions and upcoming construction schedule, RDCS LLC developed best management practices for the general contractor to implement and distribute to their sub-contractors and consultants.

General pre-construction recommendations included erecting barriers and fencing to define the workspace from the tree protection zone. A primary concern was protecting the root zone from mechanical damage and soil compaction. Warning signs were specified at regular intervals. Crown and canopy pruning specifications were designed and implemented to achieve vertical and horizontal clearance for large trucks and equipment while avoiding mechanical damage to oak tree limbs and branches.

Best management practices to minimize impacts to the oak trees during construction included placing mulch layers to reduce soil compaction, adjustments to changes in grade to minimize root disturbance and root pruning to reduce mechanical damage to roots caused by grading equipment. During the summer months, the trees canopies were rinsed by water truck to remove accumulated dust from construction activities.

Grading Impacts:

Due to site topography, the access road was constructed along slope side contours. To achieve a level roadbed through a hillside contour, one side of the road was a cut resulting in a 2:1 upslope from the edge of road to the top of slope. A concrete lined brow ditch was constructed at the top of the slope.

The other side of the road required a fill slope that resulted in a down-slope from the edge of the road to the bottom of the slope.

There were several storm drain crossing that conveyed water under the road in storm drain culverts to the downhill side of the road where the water “day-lighted” out of the toe of slope and ran in free flowing creeks. Therefore, construction impacts were anticipated where storm drain inlets and outlets were constructed.

Due to slope cuts and fills, the existing oak trees were threatened with several impacts. The trees on the cut slope side of the road would suffer from mechanical damage to their roots from grading and brow ditch cuts into the slope. Many trees contained low scaffold branches that would be damaged by grading equipment. Tree impacts on the fill slope side of the road included root disturbance and suffocation by placing fills soils over the existing surface grade.

During grading construction, very heavy grading equipment would result in soil compaction in the adjacent tree root zone.

Construction Monitoring and Supervision

In addition to developing and implementing best management practices for oak tree preservation, another project assignment included supervising the grading sub-contractor responsible for oak tree crown and root pruning activities. The grading contractor sub-contracted the tree pruning work to a professional tree service. The grading contractor utilized in house employees for root pruning laborers.

Rappoport Development Consulting Services LLC supervised both above grade crown and canopy pruning and well as below grade root pruning. With the advent of the raptor-mating season, all tree crown pruning had to be completed no later than December 31, 2010. Gaining vertical vehicular access road clearance was the main objective and reason for crown pruning. Therefore, crown pruning included skirting up low lying limbs to achieve seventeen feet vertical clearance from the future finish road surface. Horizontal clearance required pruning back any growth to prevent encroachment into the right of way. Crown reduction and selective limb removal were the main crown pruning techniques used to satisfy access specifications. One had to be experienced in reading survey stakes to understand where the finished road surface would be in relation to the existing tree limbs.

Due to the age and maturity of the oaks, many trees had very large scaffold branches ranging up to sixteen inches in diameter. Unfortunately, several large limbs had to be removed to achieve the required clearances. In those instances, cuts were carefully selected and made well outside the branch collar to provide as much protection for the tree to compartmentalize the wound. Dead wood was removed as required.

The root pruning work included both mechanical and hand trench excavation starting from the outside edge (drip line) of an individual tree crown or a stand of oak tree canopies. The trench was located between the outside edges of the grading work adjacent to the trees. Most of the tree rooting occurs in the upper twenty-four inches of the soil profile. Therefore, the trench specifications were approximately eighteen inches wide (wide enough to accommodate a laborer and shovel) with an average depth of thirty inches. In some cases the trench excavation extended to thirty-six inches. Approximately 80% of the roots were encountered above twenty-four inch depth.

The goal with root pruning is to avoid construction and mechanical damage to the root system by trenching and cutting roots prior to heavy equipment making grading cuts that would severely damage adjacent tree roots. Once the root pruning is employed, grading equipment can then excavate and pull the cut roots out without mechanically tearing the roots, thereby minimizing root disturbance and tree shock.

The objective was to expose roots, cut and remove roots crossing through (perpendicular) to the trench. As the trench deepened, roots up to six and eight inches in diameter were cut throughout the entire trench profile. Large diameter roots were cut with a sharp chainsaw, smaller size roots were cut with sharp tree loppers. Once all of the roots were cut, the trench was backfilled and grading proceeded up to the trench cut.

Monitoring and Data Collection

The tree crown pruning started in December of 2010 with grading operations beginning in February of 2011. Root pruning began with grading and was completed by March of 2011. Oak tree monitoring began prior to construction in November of 2010 and the final monitoring occurred prior to paving in September of 2011.

During the access road design, the consultant team rated potential damage to the tree based on the percentage system below:

Status of the Tree:

% Damage to the Tree:

Preservation Category:

1. Save the treeNo damageTree is considered preserved
2. Save the tree, minor pruning requiredUp to 25% damageTree is considered preserved but affected
3. Save the tree, major pruning requiredOver 25% damageTree is not considered preserved
4. Remove the tree100% damageTree is considered a loss

The consultant team defined tree damage as any physical alteration of the tree caused by proposed construction, including branch and root pruning, grading within the root zone, removal of one or more multiple trunks. The determination of the percent damage is a judgment made by the arborist at the site during construction and the amount of disturbance to the individual trees and considers roots, trunks, branches, and crown.

Tree monitoring was implemented based on seasonality and for job specific construction events. All of the monitoring utilized visual observation and digital photographic record keeping. While monitoring, many types of data were collected. Much of the data was relative, comparing the tree health and condition from the original tree inventory to the current monitoring event.

The main categories in the tree-monitoring log examined items such as:

  • Tree category designation
  • Whether crown pruning occurred
  • Whether root pruning occurred
  • Trunk or root damage occurred
  • Spring defoliation and flush
  • Crown and leaf appearance
  • Comments on edge condition, wound response, presence of Gold Spotted Oak Borer (gsob) and general appearance
  • Photographic identification number

Comparisons between monitoring events examined:

  • Reaction to crown and root pruning
  • Signs of crown decline or dieback
  • Signs of new buds and growth
  • Spring flush, color and density
  • Leans or stability issues from root pruning
  • Overall tree health, vigor or decline
  • Current construction impacts
  • Punch list and corrective actions

The oak tree preservation and monitoring program was designed to minimize construction impacts to the trees and monitor the tree response over a period of time. The program did not include tree risk assessment for structural integrity, risk to the construction workers, the public or property, nor did the program address recommendations for the tree Owners to correct noted existing deficiencies.

The project construction timing may have benefitted the trees. The crown and root pruning occurred during the winter months, a time of slow metabolic activity for the oak trees. The grading disturbance began in early spring, approximately the same time many of the Engelmann oaks dropped their old leaves from the previous season and began their spring flush of new growth. The weather also cooperated in that San Diego county experienced above normal rainfall for the year, resulting in elevated water tables for the trees, keeping soil moisture conditions relatively high, even throughout the hot, dry summer months.


Of the 369 trees inventoried and monitored during the program, no trees were lost. However, at least three to five trees exhibited signs of crown decline and foliage discoloration. Symptoms of tree decline from construction impacts may take up to three to five years to fully manifest. Therefore, full knowledge of successful survivorship will not be known for another two to three years.

That being said, it was very encouraging to see these ancient oaks survive at least during the heavy construction phase. Pruning cuts on limbs from four to twelve inches in diameter showed signs of healing and minimal evidence of decay. The trees dropped their foliage in the spring and displayed a nice spring flush of growth by the June monitoring. Yellowing and discolored foliage with browning of tips and margins was a typical foliage symptom. The fact the trees put out a healthy spring flush following crown, root pruning and grading operations, followed by a successful growing season was a positive sign.

Trees that appeared stressed in March re-foliated and displayed improved general health in June. More importantly, the trees survived throughout the hot summer months and did not defoliate as of observations made in September of 2011.

The ultimate success of the oak tree preservation program cannot be fully assessed until a sufficient time period has elapsed whereby the trees exhibit typical healthy growth patterns without signs of increasing or ongoing decline. The minimum elapsed time period for a final health assessment would be three years from date of construction impacts or March of 2014. This would provide three full years of “non disturbed” growth and allow trees to either fully recover or decline. Trees that continue to decline after three years most likely have entered the “tree death spiral”, a condition whereby the tree is unable to recover from injuries incurred during construction and are a total loss.

Unfortunately, the contract with Beta Engineering expired and the continuing status of the oak trees is no longer available to RDCS. Based on current survivorship and tree health, upwards of 369 Quercus engelmannii and Quercus agrifolia were persevered due to protection and preservation best management practices.

While final results will not be known for another year or so, the oak tree preservation program was determined to be a major success by both the general contractor and the client, San Diego Gas and Electric.

It was very gratifying to see the various project stakeholders acknowledge the importance and value in preserving as many native oak trees as possible balanced with the project transmission and sub-station objectives. While a certain percentage of the oaks may fail from the construction impacts over a period of time, a great majority of the trees were saved through careful preservation and protection best management practices.Therefore, the answer to the question, can development and oak tree preservation co-exist, I believe the answer is yes.

The importance and value in preserving and protecting trees has gained awareness with the “green movement” and creating sustainable environments. Tree benefits and their inherent value figure prominently in construction and development projects. Hopefully, public, owner and agency awareness about the positive value of saving, preserving and protecting native and heritage trees will continue to grow.

We all need to be responsible stewards of our planets diminishing resources. Knowing these oak trees survived during construction of a major electrical transmission and substation construction project and will be seen by future generations is a very rewarding experience.