I recently read an article in the Los Angeles Times Drought Trees 1 , Drought Trees that addressed the tremendous die-off of trees within California’s national forests. The aerial pictures in the article depict vast areas of red colored trees dominating the forest land. As the drought continues, the death toll on our national forest lands is approaching record numbers.
To date, scientists and U.S. Forest Service representatives estimate at least 12.5 million trees in California’s national forest have been killed due to drought. Unfortunately, scientists expect the die-off to continue as the state heads into the summer season, traditionally the driest months of the season and the months with the greatest fire threat. The last time researchers saw such a great die-off was during the drought period of 1975-1979, when an estimated 14 million trees died.
As a professional arborist, horticulturist and outdoor enthusiast, I find it incredibly sad and painful as we helplessly watch millions of trees die in our forest lands. Since childhood, I have loved camping throughout California, whether in the local San Diego mountains, the Sierras, or coastal California, the common denominator was the presence of trees, sometimes big trees. Oaks, pines, sycamores, redwoods, cedars, the list goes on, so many beautiful tree species whose survival is now being threatened by drought.
I first became aware of the effect of the drought on client trees two years ago and the problems have only increased in the urban forest and wild land trees. Oaks, pines and peppers on non-irrigated lands that survived for decades are now finally succumbing to the drought. The grinding, relentless drought has reached a point where water tables and soil moisture are too depleted for many trees to survive. Clients have called with questions why trees they have in the past ignored are now declining. Non-irrigated trees located in slopes or non-viewed areas that survived and flourished for decades are now in decline or dead. As turf irrigation is turned off trees decline and die.
Trees weakened by drought are being infested and killed by wood boring beetles.There has been an uptick in the beetle populations due to the dry drought conditions. A healthy tree exerts internal pressure and pushes sap out of the tree surface, in effect forcing intruders out of the tree. But when a tree is dried up, it cannot develop the sap flow and other natural defenses to ward off the wood boring insects. Trees weakened by drought become susceptible to invasion and colonization by beetles, killing the host then spreading to other weakened or even healthy trees.
As trees die-off from drought or killed off by beetles, millions of dead trees increase the likelihood of devastating summer wildfires. San Diego county has suffered some of largest wildfires in the state. Decades ago, I used to take my family to campgrounds in the Cuyumaca and Laguna mountains that were later destroyed in the Cedar and Witch fires back in 2003-2005. Even now, the standing dead, blackened, trees are a reminder of the terrible results of wild land fires.
In the past, “normal” spring weather resulted in green hillsides and mountains, with wildflowers and snowcapped peaks. That has not been reality for the past several years. Anyone can easily see the already brown, grey hillsides, it looks like the middle of the summer yet it is only May. The small amount of rain this past weekend, while a wonderful event, two days later you would never know it rained at all.
I have no recollection of the drought in the late seventies. I was a college student back then and drought was not something that registered on my horizon at the time. Now, after decades working in the landscape, arboriculture, horticulture and land development industries, this drought is frighteningly real and showing no signs of relenting. Mandatory water restrictions are affecting the lives of all Californians.
The real scary question for me, is this our new climate? I don’t want to see a California devoid of redwoods, oaks, sycamores and so many species I have grown up with and grown to love. Regardless of how much water we conserve, the trees in our forest lands are at the mercy of mother nature. The drought of the seventies killed millions of trees but that drought ended and millions of trees recovered and flourished. Lets hope for a similar scenario with the current drought and tree die back.