By DELLE WILLETT | Uptown News
When landscape architect Tomas Herrera-Mishler came to San Diego four years ago to be CEO and president of the newly formed Balboa Park Conservancy, he was astounded that the park didn’t have an updated tree inventory.
The last one was done by hand 20 years ago, taking seven years to do. Not having any of the technology that we have now, it was shelved, and the information was never updated, attributable to a lack of manpower in the city of San Diego’s Parks & Recreation Department.
Shortly after Herrera-Mishler arrived, with the help of a steering committee of industry experts, key stakeholders, and Parks & Rec staff, funding was identified to update the inventory, resulting in the hiring of Davey Resource Group, Inc.
We all know Balboa Park as a place with museums, restaurants and gardens. But it’s really more than that. It’s San Diego’s arboretum, an urban forest with immense, widespread influence. Its diversity of tree species helps filter air and water, control storm water, conserve energy, and provide animal habitat and shade. And by reducing noise and providing places to recreate, it strengthens social cohesion, spurs community revitalization, and adds economic value to our communities.
Also, it is helping realize the San Diego Climate Action Plan, which has a lofty goal of 15% tree canopy by 2020 and 35% by 2035 for the whole city. (Balboa Park is at 30% but the city as a whole is at 5-6%.)
Using the data collected from the inventory, the objective is to develop and implement a management and reforestation plan for Balboa Park that includes replanting trees on an annual basis; increasing species diversity; experimenting with new plant introductions; propagating trees of historic and horticultural value; conserving unusual, rare and endangered trees; removing hazardous trees; maintaining and protecting trees; and interpreting park horticulture.
“The incredible value of this new survey has given us a real understanding of the condition of the park,” said Herrera-Mishler.
To direct the inventory and nine other projects, the conservancy brought in Jackie Higgins, a landscape architect skilled in management information technology and restoring climate-appropriate and native California landscapes. The tree inventory was managed under her leadership and oversight, focused on establishing a baseline of data for the park.
Using GIS and GPS, the Davey team conducted the tree inventory from June 2017 to April 2018, identifying 15,515 trees throughout the park, producing up-to-date real-time information on each tree.
The Davey team collected around 20 attributes per tree including GPS location, age, site information, species, size, condition, health maintenance, diameter at breast height (DBH), a photo of every tree, age of the urban forest and recommendations/tasks.
The conservancy also commissioned another baseline study of the economic impact of the park that identified the tangible economic benefits to the San Diego region.
For example, currently the forest’s carbon storage is equivalent to annual carbon emissions from 5,770 autos, and the annual carbon emission from 2,370 single-family houses with a carbon storage value of $1,060,000. (Cash values determined by the U.S. Forestry Service.)
Explained Higgins, “These 1,200 acres help to balance out the concrete jungle that we live in. Not only do we have to make sure that we are accounting for appropriate canopy cover for our parks, we are essentially taking on the burdens of all the other areas that can’t have a canopy or other benefits that go along with that, for example, carbon sequestration, air filtration and purification, and stormwater mitigation.”
“We’re making progress,” said Herrera-Mishler. “One of our goals is increasing the diversity of the trees in the park.”
Having a broad diversity of trees is paramount for resilience from climate change and sickness. Twenty years ago, there were 348 different tree species in Balboa Park. Today there are 448, exactly 100 more. That’s astounding, Herrera-Mishler said. “And so now, with new technology, we are able to track exactly what species are doing well in San Diego with modern growing conditions. That’s a valuable data set to share with the rest of Southern California.”
Herrera-Mishler, who is especially interested in historic landscapes, said “This urban forest is 100-years-plus [old] now, with Kate Sessions starting the process [in] the beginning of the last century. We now know precisely where the heritage trees are, the survivors that have weathered drought and climate change and air pollution and urbanization and smog and all those things.”
Herrera-Mishler thinks it’s important to note that tree plantings in the park have always been public/private partnerships. Since the park’s very beginnings, regular folks have planted trees at their own expense, some successful, some not. Today, every one of the newly planted trees is being monitored by teams of volunteers called Tree Stewards, who are trained to work with other conservancy volunteer groups to plant the trees according to a very rigorous standard, working alongside other groups and representatives from Parks & Rec. Currently there are 40 Tree Stewards who monitor trees on a real-time basis, checking soil moisture at the base of a new tree, helping to insure the survival of the trees. With more funding, the Tree Steward program can expand to monitor all 15,515 trees.
So far, in the 500 new trees they have planted in the last two years, through a grant from CalFire, there’s a 98.4% survival rate. The success attributable for this rate is that Parks & Rec helped to get irrigation to the trees and the Urban Corp works with Tree Stewards and other volunteers to help with the installation of the trees.
Said Herrera-Mishler, “The conservancy is thinking about the park as a ‘forever’ asset for the community. It’s really cool when your timeline is forever.”
Anyone interested in Balboa Park’s trees and urban forest can Google “Open Tree Map” and download the Open Tree Map app and choose “San Diego Tree Tracker Map” within this app. Those interested in becoming Tree Stewards should visit balboaparkconservancy.org/project/tree-stewards/
Many cities have notable urban forests including Austin, Atlanta, Charlotte, Denver, Milwaukee, Minneapolis, New York City, Sacramento, Seattle, Washington D.C. and St. Louis. These cities are doing inventories with various other methods of gathering data.
— Delle Willett has been a marketing and public relations professional for over 30 years, with an emphasis on conservation of the environment. She can be reached at firstname.lastname@example.org.