This winter’s atmospheric rivers, and the often violent winds that accompany them, have taken a toll on Del Mar’s trees. In the last month, three large Torrey Pines have fallen, including a tree on Via Alta—which landed on a power line, resulting in a significant power outage for area neighborhoods. Extreme weather patterns —along with invasive beetles, drought, and development pressures—are threats to our urban forest at a time when we need our trees more than ever. The carbon sequestration, cooling, wildlife support, aesthetics, and quality of life benefits of trees are substantial. They also add significantly to our property values.
The consensus among arborists is that a confluence of factors—torrential rains, fierce winds, damage to roots, and weakening from disease—can cause a mature tree to fall. Torrey Pines—with their considerable lateral and deep roots—are not more likely to fall in a storm. According to Mark Wisniewski, who served as Del Mar’s arborist for many years, problems usually start with damage to the roots.
“Tree roots are opportunistic,” he says. “They grow where there is sufficient soil, moisture, air and minerals. Torrey Pines are well adapted to Del Mar—roots can grow 20 feet deep or more and laterally, many times the spread of the tree’s canopy. If there are no natural or constructed obstacles and if the roots have not been damaged due to construction activity, a Torrey Pine can thrive and live for decades.”
When I ask him what residents with large Torrey Pine trees on their property can do to ensure their health and help preserve our urban forest, he says to keep an eye on the tree and look for tell-tale signs that could indicate something is amiss—such as soil movement at the base of the tree or die-back in the crown. Large trees should be examined annually by a certified arborist.
A recent photo taken by Wisniewski of a tree on Hidden Pines Lane shows both the complicated root structure and the resilience of Torrey Pines. The tree—which he has been watching for 20-25 years—appears to be emerging from sandstone, with both lateral roots and deeper growing roots that probably followed deep cracks in the sandstone. Over time—due to erosion and as the deep roots grew in diameter—the sandstone rock broke away and exposed the roots, he explains.
We in Del Mar are lucky to have such a robust and adaptable signature tree.