Along with coast live oak, the valley oak is one of the iconic species of oak-grasslands at Ahmanson Ranch. In the past 20 years, valley oaks at Ahmanson Ranch have been more severely impacted by drought, fire, and rising temperatures than live oaks. In the not too distant future, the valley oak may become a relic at Ahmanson, much like the blue oak that died earlier this year.
According to preliminary NWS reports, Downtown Los Angeles (USC) recorded average monthly temperatures well below normal in November 2022 and January thru March 2023. March was particularly cool, with an average high of about 64 degrees and an average low of about 50 degrees.
Besides high heating bills, Southern California’s unusually cold Winter affected several seasonal processes, one of which was when the valley oaks at Ahmanson budded and grew new leaves.
The leaves of valley oaks at Ahmanson Ranch typically turn in mid-December, and the trees usually begin to leaf out during the latter half of February. Depending on the tree’s microclimate, the emergence of new leaves may vary by a week or more.
Valley oaks in Las Virgenes Canyon in early April 2023.
The earliest I’ve photographed a valley oak at Ahmanson sprouting new leaves was February 3, 2015. Last year, a valley oak had new leaves on February 10, 2022.
The latest I’ve seen valley oaks sprouting new leaves is this year — from about March 20, 2023, in favored locations to April 4, 2023, in cooler areas such as Las Virgenes Canyon.
Prior to this year, the latest I’ve photographed a valley oak at Ahmanson with new leaves was March 9, 2009.
When I rounded the corner on the Lasky Mesa Trail, I could hardly believe my eyes. The Ahmanson Blue Oak was gone. Where there had been a sprawling oak, there was nothing.
Crossing an eroded section of trail and walking over to the edge of the old roadbed, I looked down the slope. Much like this valley oak along Rocky Peak Road, the entire Ahmanson blue oak had fallen from its hillside perch near the bottom of the canyon.
Oaks in the oak-grasslands of Upper Las Virgenes Canyon Open Space Preserve have had a tough time with climate change. The five-year drought from July 2011 to October 2016, increasing temperature, and the 2018 Woolsey Fire have combined to kill a large number of trees.
This blue oak was one of very few found at the southern extent of its range.
The nasal bellowing of a bullfrog shook the morning, but didn’t disturb the mirror-like surface of Century Lake. I had paused along the Forest Trail in Malibu Creek State Park to take in my surroundings. Here and there glimmers of sunlight reflected from the base of the reeds along the opposite shore. Birds called, flowers bloomed and Nature continued to work in its wonderous way.
Canyon sunflower along the Lookout Trail.
My run had started at the Cistern Trailhead on Mulholland Highway and then wandered about the Reagan Ranch area. The Lookout and Yearling Trails had been thick with mustard and badly overgrown. The plants had been wet with dew, and my black sleeves and shorts had been liberally sprinkled with the bright yellow flowers. A few ticks had also hitched a ride, but were removed before they could bite.
It had been a relief to get back to the Cage Creek Trail and descend to the Crags Road Trail and Malibu Creek. The logs extending across the creek from the washed out bridge had been rearranged, making it easier to cross.
Log crossing across Malibu Creek on the Crags Road Trail, near the Forest Trail junction.
No other trail in the Park is quite like the Forest Trail. The trail isn’t part of a loop, doesn’t connect to other trails, and is only a half-mile long; but it feels like a trail you might find in Big Sur, Santa Cruz or the Bay Area. The forest is comprised primarily of coast live oak, California bay, and sycamore, but at several spots along the trail you’ll find coast redwoods.
Coast redwoods are not endemic to Southern California. All but one of the Forest Trail redwoods were planted over 100 years ago. The trees were severely impacted by the 2011-2015 drought, and only a few have survived. Even so, they are easy to spot — the large, deeply-furrowed, copper-brown trunk of a coast redwood is unmistakable.
Note: There is some poison oak along the Forest Trail, and this year some was protruding onto the trail.
Bigcone Douglas-fir along East Canyon Mtwy fire road.
I hadn’t seen a hiker, runner, or mountain biker since turning off East Canyon Mtwy fire road. That was about 2 miles ago. I checked my watch — it read 18 miles. Had I’d made a wrong turn?
Today’s plan was to do the first 25 miles of the Santa Clarita Ultra & Trail Runs 50K. A week ago I’d run the first (blue) and third (yellow) sections of the course, and today’s run would theoretically combine the first (blue) and second (orange) sections.
Oat Mountain from the Towsley Canyon Loop Trail
So far, the run had gone well. It had started with an extended version of the popular Towsley Canyon Loop in Ed Tavis Park. After climbing up oil-rich Wiley Canyon to a view point at an elevation of about 2450′, the course descended a series of long switchbacks, and passed through a gap in Towsley Canyon known as the Narrows. A mile down the canyon from the Narrows I’d used segments of the Elder Loop and Taylor Loop trails to run over to Lyon Canyon.
After switching from a bottle to a pack, I’d run on the Old Road over to the East Canyon Trailhead. From there the course followed East Canyon and Sunshine Canyon fire roads to Mission Point. The climb up to Jones Junction gains about 1300′ in 3 miles, then it’s another 1.5 miles over to Mission Point (2771′), the high point on the course.
Green along the Taylor Loop Trail.
One of the highlights of the run up East Canyon was the very healthy-looking Bigcone Douglas-firs higher on the road. Now relegated to the cooler climes of steep, north-facing mountain slopes, the species used to be far more widespread in Southern California.
On the way to Mission Point, the views of the San Fernando Valley from the crest were outstanding, and gave a perspective of the Valley I had not seen before. Apart from having to detour along fence lines bordering private property, and continuous gunfire in a section of the canyon that is near a popular gun club, the run to Mission Point was excellent.
Detour around private property on the way to Mission Point.
Returning from Mission Point there was another part of the course I needed to do — an out and back on Weldon Mtwy. Which brings me back to mile 18 of today’s run. After turning off East Canyon Mtwy on what I thought was Weldon Mtwy, I had expected the fire road to loose elevation relatively quickly. But that wasn’t happening.
Instead of running down a canyon, I was running along a ridge — a long ridge. Below and to my right was what looked like a landfill. Below and to my left I could see the Old Road and Santa Clarita. They seemed a long way down.
Mission Point, Three Trees and the San Fernando Valley.
There were several ways I could have checked where I was — my watch has maps; my phone had maps; and I had a map in my pack. But I wasn’t in trouble and was already two miles down this road — whatever it was. If I wasn’t on Weldon Mtwy, it would still be a trail I hadn’t done.
After a couple of “I’ll just go a little farther down and see what I can see” episodes, I eventually turned around and headed back up the fire road. When I got back to East Canyon Mtwy, I checked the yellow pole marking the junction of the fire roads — it was marked “WELDON.” Later, I checked my track and found I had turned around a half-mile from the Newhall Pass Trailhead. Now I know.
Overall, I’d enjoyed the course, and decided I would register for the 50K. But registration closed early, and now I see the event has been postponed until November. Oh well, I still got to run in a new area and check out some interesting trails!
Revitalized by December’s copious rainfall and temperatures in the mid-80s in February, this valley oak at Ahmanson Ranch has produced a lush crown of new leaves.
(Officially named Upper Las Virgenes Canyon Open Space Preserve, most users refer to the open space area as Ahmanson Ranch, or simply, Ahmanson.)
