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New Leaves on Drought-Stressed Valley Oak

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Drought-stressed valley oak sprouting leaves following summer rains in Southern California

Sprouting new leaves as if recovering from a wildfire, this drought-stressed valley oak at Ahmanson Ranch benefited from the unusual amount of rain in Southern California during July and September.

Hilltop valley oak at Ahmanson Ranch, photographed in April 2011, prior to the drought in Southern California
Valley oak at Ahmanson Ranch

Between July 1 and October 1, the Cheeseboro RAWS, located on a hilltop about two miles away, recorded more than two inches of rain.

Here’s what the tree looked like in 2011, before the drought.

Update January 15, 2021. “The Tree” died in the Spring of 2020, when Ahmanson was closed due to COVID-19. Although scorched in the Woolsey Fire, it never recovered from the 2011-2015 drought, and that appears to have been the primary cause of death.

Some related posts: Ahmanson Valley Oaks Battling Drought, It Was So Muddy (Again) That…, A Two Mud Run Summer and Wet Winter Outlook for Southern California

nature, nature|trees, nature|weather, photography, photography|landscape, weather

Ahmanson Valley Oaks Battling Drought

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drought-stressed valley oak in Upper Las Virgenes Canyon Open Space Preserve (Ahmanson Ranch)

Following four rainfall years in which Downtown Los Angeles (USC) has cumulatively recorded less than half of normal rainfall and accrued a precipitation deficit of more than 30 inches, many of the valley oaks at Ahmanson Ranch (Upper Las Virgenes Open Space Preserve) are drought stressed.

The most obvious signs of drought stress in valley oaks and many other plants are a reduced number of leaves and reduced leaf size. In severely stressed valley oaks the foliage has the appearance of a tree that is recovering from a wildfire.

At Ahmanson the degree of stress varies widely from tree to tree. The “TV tree,” an aesthetically-shaped and often-photographed valley oak on the west side of Lasky Mesa appears to be showing a higher than average level of stress.

Valley oaks and live oaks cohabit the oak savannas at Ahmanson Ranch, but live oaks appear to be more drought tolerant. The lone Blue Oak at Ahmanson seems to be doing OK and has at least as much foliage as it did last year at the same time.

Update January 15, 2021. “The Tree” died in the Spring of 2020, when Ahmanson was closed due to COVID-19. Although scorched in the Woolsey Fire, it never recovered from the 2011-2015 drought, and that appears to have been the primary cause of death.

Some related posts: Ahmanson Blue Oak, The Color of Rain IV

nature, nature|weather, photography, photography|landscape, weather, weather|southern california

Winter Oaks, Summer Temps

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Valley oaks and clouds near sunset

These valley oaks have dropped their leaves, but if you were to go by the warm temperatures we’ve been having in Southern California, you might think it was Summer.

Including today, the high temperature at Pierce College in Woodland Hills, California has reached into the 80s each of the last six days. High temperature records for December 31 – January 5 have been broken at several locations. Among the records broken, yesterday San Gabriel recorded a high of 91, Camarillo 90, and UCLA 89.

It sounds sweltering, and it can be if you’re in full sun, but it’s not like a 90 degree day in July. Days are short, shadows long, and some north-facing slopes never see the sun. And it does cool down quickly. If you take a look at the overnight lows on those six 80+ days at Pierce College, you’ll see the temperature dropped to around 40-42 degrees.

On my run Tuesday afternoon, when the photograph of the valley oaks was taken, the temperature varied by as much as 20-25 degrees between some high and low points.

It has been great weather for running, but I’m ready for a change in the pattern and a little rain!