By Tim Clancy, for Let’s Talk Plants! January 2025.
Got Growspace?
Crowded cities are numerous around the world. A town most of us have probably not heard of is Gutenberg, New Jersey. With a population of ~62,000 in less than 1 square mile it is number 9 on the list of the world’s most populous cities. Number one on the list with a population of ~111,000/sq. mile is Manilla in the Philippines. Crowding happens for many reasons and may be unavoidable in certain situations. Trees can also be crowded by all sorts of things - including other trees.
CalTrans exits each have unique numbers. These start with Exit 1A (Camino de la Plaza) at the border of Mexico and the United States. At the other end is Exit 796 at the California/Oregon border. In between is exit 42 (possibly being renumbered as 41B) at Encinitas Blvd., in Encinitas, CA. Exit 42 underwent a redesign about 7 or 8 years ago. Thirsty plants were removed and replaced with more drought aware plants.
The main feature plant at Exit 42 is the Coast live oak. Or should I say several Coast live oaks. Coast live oak, Quercus agrifolia, is a sturdy California native and an important tree in the history of the West. The list of eco-services provided by this tree is impressive along with the human uses. One could make an argument that it is the most important species of tree to the native Californians.
Along with its impressive service to mankind (food, fuel, shelter), its size is also something to be marveled at. It can reach a height of 70 feet and an equal spread. Also, a fast grower at about 2 feet a year, it doesn’t take long to put on some size. And once it gets to its mature size it slows growth and goes into long term survival mode. Many specimens have been encountered that are more than 400 years old. A fast growing long lived native plant is a superstar and the coast live oak may be the top botanical superstar in Southern California.
The landscape architects for CalTrans specified Coast live oak for Exit 42. It seems that in their enthusiasm for the tree they got a little excited and created a design that uses many, many more trees than is necessary or even botanically recommended. On the Southeast corner of Encinitas Blvd., and the off ramp, there are about 15 trees where literally one would suffice. It will be interesting to see how this situation evolves in the coming years. Will the trees be size controlled by pruning? Will there be a phased removal as the trees grow bigger and conflict with each other?
There are a couple trees showing signs of stress and are beginning to decline on the Southeast corner. It’s difficult to determine the reason(s) for the decline from the vantage points I can legally access. My best guess at this time is the trees are water stressed. Even though these trees are drought tolerant, they do need supplemental irrigation in an urban setting such as this one.
Even with the over-planting, in about 5 years Exit 42 should grow into an aesthetically pleasing pseudo-grove of stately trees.
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