Category Archives: nature|trees

Searching For Another Blue Oak In Upper Las Virgenes Canyon Open Space Preserve

Blue oak-like leaves of an unusual oak in in Upper Las Virgenes Canyon Open Space Preserve (Ahmanson Ranch).

After the Ahmanson Blue Oak in East Las Virgenes Canyon died this Winter, I started to search for another blue oak (Quercus douglasii) in Upper Las Virgenes Canyon Open Space Preserve (aka Ahmanson Ranch). Blue oaks are rare at the southern limit of their range, but I was hopeful that if there was one blue oak at Ahmanson, there might be another.

Valley oak leaves in Upper Las Virgenes Canyon Open Space Preserve (Ahmanson Ranch).
Valley oak leaves.

Typically, blue oak leaves are noticeably different than valley oak leaves. The Jepson eFlora describes the leaf margins of blue oak as being more or less entire, wavy, or more or less lobed. The leaves of the Ahmanson Blue Oak fit this description. Valley oak leaves are usually much more deeply lobed and readily identified.

Recently, while on a run, I noticed an unusual oak near the top of a service road on the western margin of Lasky Mesa. Its leaves are not deeply-lobed and are a bit more dusky than the usual valley oak leaf. But the tree doesn’t look quite the same as the Ahmanson Blue Oak. One difference is that the shape of the leaves is not as uniform as those of the Ahmanson Blue Oak. This might be due to the wet 2022-2023 rain season and the flourish of leaves that resulted. And, as with the Ahmanson Blue Oak, this oak was burned in the 2018 Woolsey Fire, and its trunk is partially hollow.

Blue oak-like leaves of the unusual oak on the western margin of Lasky Mesa.
Blue oak-like leaves of an oak on the western margin of Lasky Mesa.

Based on its leaves, the “West Lasky Mesa Oak” could be a blue oak, blue oak hybrid, or valley oak hybrid. A 2002 study of a mixed stand of blue and valley oaks found that appearance can be misleading. When DNA tested, four of the five hybrid-appearing oaks in the study were not classified as hybrids. Of the four trees deemed most likely to be hybrids, only one oak was intermediate in appearance.

Although it seems unlikely this tree would have been overlooked, I could find no specific reference to the oak in the various studies and surveys done of Ahmanson Ranch. Please get in touch with me if you can provide additional information about this tree or how a DNA analysis can be arranged.

Some related posts: Ahmanson Blue Oak, Ahmanson Blue Oak Succumbs to Climate Change

Upper Las Virgenes Canyon Trailhead Valley Oak

Large valley oak near the Upper Las Virgenes Canyon Trailhead of Upper Las Virgenes Canyon Open Space Preserve (aka Ahmanson Ranch)

This large valley oak lives near the Upper Las Virgenes Canyon Trailhead of Upper Las Virgenes Canyon Open Space Preserve (aka Ahmanson Ranch). There used to be several large valley oaks near the trailhead, but they were killed in the 2018 Woolsey Fire.

The trunk of the Upper Las Virgenes Canyon Trailhead valley oak.
The brim of the cap is about 7 inches wide.

This tree is as large as any of the valley oaks I see along the trails at Ahmanson. I estimate it’s diameter to be a little under four feet. That’s not large by Northern California standards, but it is still a sizable tree. Valley oaks have a tougher time here.

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.

Some related posts: Ahmanson Valley Oaks Finally Get Their Leaves, Ahmanson Valley Oaks Battling Drought, Ahmanson Blue Oak Succumbs to Climate Change, and Many More

Ahmanson Valley Oaks Finally Get Their Leaves

Cold weather delayed the leafing out of valley oaks at Ahmanson ranch until late March and early April 2023.

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.

Cooler than normal temperatures during January to March 2023 delayed the leafing out of these valley oaks in Las Virgenes Canyon.
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.

(Officially named Upper Las Virgenes Canyon Open Space Preserve, most users refer to the open space area as Ahmanson Ranch or simply Ahmanson.)

Some related posts: Revitalized Valley Oak at Ahmanson Ranch, Goldfields Are Blooming and Valley Oaks Greening, Valley Oak Leaf

Ahmanson Blue Oak Succumbs to Climate Change

Rare at this latitude, this blue oak at Upper Las Virgenes Canyon Open Space preserve succumbed to drought, fire, and above average temperatures.

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.

Related posts: Ahmanson Blue Oak, Ahmanson Valley Oaks Battling Drought, After the Woolsey Fire: Ahmanson Ranch, Fallen Oak, Valley Oak Savanna

Forest Run

Coast redwood along the Forest Trail in Malibu Creek State Park

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 in Malibu Creek State Park.
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.
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.

Some related posts: The Malibu Creek State Park Redwoods Are Dying; Malibu Creek State Park Redwoods: Fighting the Drought; After the Woolsey Fire: Malibu Creek State Park Redwoods, M*A*S*H Site and Bulldog Climb

Exploring the Santa Clarita Ultra & Trail Runs 50K Course

Bigcone Douglas-fir along East Canyon Mtwy fire road
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 (3747'), the highest peak in the Santa Susana Mountains.
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.

Entrance to the Narrows on the Towsley Canyon Loop Trail
Entrance to the Narrows in Towsley Canyon

Following an out and back up the canyon to the top of a prominent hill, the course continued on the Taylor Loop nearly to the Old Road, eventually circling back to the parking area at Ed Davis. At the parking lot my watch read a bit over 9 miles.

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.

A very green stretch of the Taylor Loop Trail
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.

The first of three short detours along fencelines on the way to Mission Point.
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.
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!