Redwood Sorrel

The coast redwood understory is a fascinating place. Next up in our review is the native redwood sorrel, botanical name Oxalis oregana.

It’s called redwood sorrel because it prefers to grow on the redwood forest floor and it’s extremely common there, sometimes forming great expansive green carpets. It ranges mostly where redwoods do, following the coast from central California up through Oregon and Washington, and just barely into British Colombia.

Redwood sorrel is native herbaceous evergreen perennial that spreads by rhizomes (which are sort of underground stems) and seeds. It grows in dense patches, mostly about 8 inches tall, in moist, quite shady areas. Its leaves are each made up of three heart-shaped leaflets.

The leaves are actually really cool. Because these plants live in the deep shade under the great redwoods, they’ve adapted with super-sensitive leaves to photosynthesize with very little light. That would be problematic during mid-day in summertime when the sun is high enough in the sky to deliver direct light to the plants but the redwood sorrel have also adapted to close their leaves, like an umbrella, when the sunlight is too direct. They also use this folding technique to conserve water during dry times and to protect themselves from heavy rains during the wet season.

The plant blooms early spring through the end of summer. The small flowers are white to pink with five petals with lavender veins.

[Photo credits: Deanna L. Pierce, me, Ed Miller via iNaturalist, and Nick Doty via iNaturalist]

close up of redwood sorrel flower

redwood sorrel showing leaves closed in the sunlight

closeup of redwood sorrel leaves

carpet of redwood sorrel in front of redwoods

One Quarter

The CZU Lightning Complex fire is the most significant event to happen to the forest of the Santa Cruz Mountains since the clearcut era.

A while back I attempted to estimate the extent of damage by measuring the area of the fire and the total forested areas of the Santa Cruz Mountains using Google Earth’s handy area measuring tool. I came up with 17% (about 1/6th) of the forest impacted by this fire.

The only problems with my approach are that 1) I used Google Earth’s default satellite view to estimate the forest area based on color and it’s actually kind of difficult to distinguish forests from not-forest by eyeballing it like that. And 2) I used Google Earth’s somewhat crude polygon tool to create an imprecise outline to measure the areas so there was probably some error there.

Today, I decided to make a more serious measurement and so I did a bit of research and found the USGS’s National Land Cover Database. The NLCD uses Landsat satellite imagery to classify land cover. Adding that data layer to Google Earth, I was able to get a much better picture of the boundaries of the forest and even to see the composition of the forest from evergreen to mixed to deciduous.

Then, rather than using Google Earth’s crude measuring tool, I took screenshots from Earth and opened them in Photoshop where I could select color ranges and count pixels (pixel counts are found in the Histogram dialog.) This should be a much more accurate reading.

And here’s what I found. My initial calculation was close, but underestimated the size of the CZU fire damage. My first estimate was about 16% of the forest of the Santa Cruz Mountains in the burn area. With the new, hopefully more accurate approach, that estimate grew to 19% or almost 1/5th.

And with the NLCD data I was able to go a step further and focus in on just the evergreen stands which are primarily made up of coast redwood and Douglas fir. When I analyzed those areas I got an even larger number, 25%. A full quarter of the pure evergreens stands in the Santa Cruz Mountain was impacted by this fire.

Google Earth's satellite view of the Santa Cruz Mountains

NLCD 2016 Land Cover for the Santa Cruz Mountains

An Oak

This is an oak near the top of the mountain that I really like. It’s by no means the largest or the most majestic oak on my drive, but there’s something about its shape and where it sits on the ridge that’s held my attention over the years.

Oak tree against a blue sky

Sugar-scoops

Today’s walk through the coast redwood forest floor brings us to the adorable little sugar-scoop, also called lace foamflowers, botanical name Tiarella trifoliata. (Tiarella means “little tiara”.)

There are several varieties that can be found along the Pacific Coast from Santa Cruz up to Alaska, and inland as far as Alberta and Montana.

Our sugar-scoops are var. unifoliata. Rather than the more common three part leaves found in var. trifoliata, ours have a single-part, lobed, toothed leaf that looks kind of like a small maple leaf.

Sugar-scoops are a perennial herb that like moist shady stream banks and that’s where we find most of ours. They flower along a tall (one foot or so) stalk, primarily in June and July but occasionally starting as early as May and as late as September. The white flowers are bell shaped with five petals.

The name sugar-scoop comes from the shape of their seed pods which resemble tiny sugar scoops.

[Photo credits: me, Deanna L Pierce, Don Loarie via iNaturalist]

flowering sugar-scoop

sugar-scoop flower clusters along its stalk

close up of sugar-scoop flower

Progression

In the very early morning of Sunday, August 16th, a dry lightning storm started a bunch of fires all over the western slopes of the Santa Cruz Mountains. Five of those fires would become significant and eventually merge to form the CZU August Lightning Complex.

(There was a sixth nearby fire that you might be able to see as a small dot northeast of the complex perimeter, to the left of the “me” label. That fire was our initial worry because it was less than a mile from our house. However, before we were evacuated we were watching it closely and it didn’t seem to be growing. Turns out it wasn’t.)

From this progression map (in which I highlighted the first three days of fire growth) you can see that the southern-most fire, which was staffed well because of its proximity to residential areas, was completely contained and didn’t grow after that first day. The other southern fire over on the coast did grow some on the second day but it was apparently also well staffed. The three fires up north were woefully understaffed in these early days and burned pretty much unhindered.

On the third day, the fire absolutely exploded in size growing to over 40,000 acres and connecting four of the original fires into a giant “complex”. (We were evacuated late that afternoon.)

The fire would continue to grow over the next 34 days but it’s pretty wild to think that about half of the total burned area happened in the first 3 days of the fire.

(Thank you, Casey Dunn, for the maps.)

Fire progression map for the CZU Lightning Complex

Containment

The CZU Lightning Complex fire is now 100% contained at 86,509 acres (~135 square miles.)

Containment doesn’t mean the fire is out or even fully under control. It simply means they’ve established a control line around the entirety of the fire such that it should not spread any further.

At the height of the fight, there were almost 2,500 personnel working the fire. That number is down to 81 today. I think that does say something about the control they have over the fire though and I’m relieved to finally hear containment has hit 100%.

Fire Season

Summer is over, but fire season is not. Historically, according to CAL FIRE, fall is when we see the largest and most destructive wildfires. I’ve got my fingers crossed hoping we’ve seen the worst of it for this year. The rains can’t come soon enough.

Not A Nettle

Continuing our exploration of the coast redwood understory, also known as “our yard”, we have the California hedge-nettle (Stachys bullata).

This fairly common perennial herb is native and endemic to California, growing along the coast from about Mendocino in the north (though it really starts to flourish around the San Francisco area) all the way down through San Diego.

The California hedge-nettle is a member of the mint family and likes to grow in moist, shaded areas at lower elevations. It reaches about 3 feet tall and has large sandpapery leaves in opposite pairs up the stem. The pink flowers cluster up the stem in groups of six, blooming for about half the year from April to September.

It’s said that the leaves have medicinal properties and a poultice made from them speeds wound healing, and a tea can help with upset stomach.

Don’t be fooled by the name. The California hedge-nettle doesn’t grow in hedges and it’s not even a nettle. We do have stinging nettles (Urtica dioica) in the redwood forest, and they do look a bit alike, so be careful what you touch.

[Photo credits: me, joshuadavis5 from iNaturalist, and Deanna L. Pierce]

California hedge nettle stalk and flowers

California hedge-nettle leaves

Close-up of California hedge-nettle flowers