City Meets Tree Preservation Goals with ISA Certified Arborist

A $28 million community improvements plan, known as Measure E was set in motion in 2009 to upgrade parks and construct community infrastructure in the City of Pleasant Hill (City).  While the plan included some much-needed modernization for the City, it was also important to preserve city-defining trees in the process.  These trees are treasured because of their historical, aesthetic, and biological values.  The City had to plan early and well with the help of an ISA-certified arborist to successfully complete the project and meet preservation goals.

How the Plan Began

The residents of the City approved a bond measure to fund a new Senior Center, Community Center, Teen Center, and park upgrades.  Park modernization projects had the highest potential impacts to trees.  Several of the parks slated for upgrade are located within the City’s rich “urban forest”: an assemblage of mature trees that contribute to the City’s unique character and identity.  The urban forest also provides important functions like shade, temperature regulation, air and water filtration, wildlife habitat, and visual aesthetics.  Tree protection was a high project priority and this urban forest was necessarily incorporated early into project planning to responsibly preserve trees.  Some “showcase” trees would even be focal points of the remodeled park and community buildings.

Arborist Survey

In order to design and plan a project with tree preservation in mind, existing trees were surveyed by an ISA-certified arborist.  The survey located all trees with potential to be impacted by the park improvements, and evaluated baseline conditions like size, health, and structural condition of these trees.  For Protected Trees – trees falling under the regulation of the City’s tree ordinance – additional baseline data were collected including estimated dollar values.  Results of the arborist survey enabled the planning and design team to spot potential problem areas early in the process.  Project plans are most flexible early in the process, and therefore any changes to plans are relatively simple and less costly.

ISA-Certified Arborist – Why Do They Matter?

ISA is the International Society of Arboriculture, and an ISA certification is designed to “help consumers identify qualified, knowledgeable tree care professionals” (ISA website).  To become ISA-certified, a tree care professional must be trained and knowledgeable in all aspects of arboriculture and meet certain prerequisites.  Requirements include three or more years of full-time, eligible work experience in arboriculture and/or a degree in an applicable field like forestry.  A code of ethics for ISA-certified arborists strengthens the credibility and reliability of the certification.


The arborist collaborated with the planning and design teams to provide detailed tree protection measures all the way through construction.  The specifications provide instructions to contractors – even on a tree-by-tree basis – who are tasked with tree protection in addition to their normal construction duties.  A daily, on-site monitor ensured that tree protection measures were correctly put into place during construction.  Monitoring not only enables a thorough record of tree-related actions and decisions made during construction, but also provides the opportunity to increase tree awareness by discussing tree protection with construction personnel.

In the End

Early and careful planning allowed the City to successfully preserve high priority trees within the landscape of their project.  Keeping in mind that tree preservation is only deemed successful as the trees continue to thrive, the City set off on the right foot toward successful tree preservation through collaborative planning, design, and construction oversight.