Tag Archives: vernal pools

landscape, places

vernal pool side trip

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On the recent outing to The Tunnels we took a little detour to view some vernal pools adjacent to Del Mar Mesa.

The area is a patchwork of land administered by several agencies. But the basic message at most of the parcels is: Sensitive Habitat, Keep Out.


Unfortunately, to the basic American pioneer mindset, “Keep Out” is a message to be resisted. The barricade to the right of this photo is fairly famous locally in commemorating the lengths that some people will go to in order to circumvent a regulation that they perceive to be too draconian. On a dark and stormy night (or it might have been in broad daylight on a clear morning, I’m not sure of the details) a vandal stole a bulldozer and drove it here to tear out the barricade. The vandal wasn’t able break through, but the barrier still shows the signs of the struggle.

Other fences were more easily defeated.

On the day we were out the rangers who were with us spent most of their time talking to the occasional hiker and the frequent mountain biker, explaining that the area was off limits. I guess the lifespan of a fence closing off a trail popular with mountain bikers is right up there with the lifespan of biology lab fruit flies. Most of the cyclists are respectful, but there are a few libertarian rednecks with wirecutters out there.

Once common in the county the vernal pool habitat is now one of the rarest. A nice flat spot that collects winter rains is also a nice flat spot to build your subdivision.

Today, in many of the pools that are left, you can watch the accelerated seasonal cycles. Tadpoles are pretty common, trying their hardest to reach amphibian puberty before the pool dries up.

Much less common are these, San Diego fairy shrimp, Branchinecta sandiegonensis, a critter that’s on the federal endangered species list. Your almost more likely to find them in vehicular tire ruts than in natural vernal pools.

Spike rush, Eleocharis montevidensis, emerging from the translucent water. It’s a common vernal pool plant.


And with this plant we return to the federal endangered species list. This is San Diego button celery, Eryngium aristulatum var. parishii. You’ll find it in standing water, like these plants. But it’s also happy setting up household adjacent to the pools, growing so prolifically that you’re likely to be surprised that it’s endangered. It’s one of those classic cases where a plant is rare mainly because its habitat is being obliterated.

Okay, okay, these photos are probably a little artsy and not particularly useful for identifying the plant…

I don’t begin to profess to know everything there is to know about these environments, but it’s pretty cool to check them out when you get the chance.

More information:
[ at the California Chaparral Institute ]
[ City of San Diego Vernal Pool Inventory ]
[ My April 25, 2010 trip to Miramar Mounds National Natural Landmark ]

landscape, places

miramar mounds national natural landmark

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Last week I participated in a trip to Miramar Mounds National Natural Landmark that I helped organize for a group of us from the local native plant society. Only a few visitors get to visit every year, so we were lucky to have the opportunity. JoEllen Kassebaum, Botanist for Marine Corps Air Station Miramar, interpreted for us.

Detail: Pogogyne abramsii

Several endangered species call the Landmark home. The best-known is probably San Diego mesa mint, Pogogyne abramsii, a plant with extremely limited distribution.

San Diego button celery Ernygium aristulatum var. parishii (the green plants)

San Diego button celery is another endangered plant found on the Landmark. Both these species live only in vernal pools. The issue isn’t so much that the plants are wimps. Give them a little depression filled with water for a few weeks and they thrive. They’re endangered because the gently rolling terrain that favors the creation of vernal pools is also easy land to develop. (Sad to say, my house probably sits on land where vernal pools were found sixty years ago.)

Downingia with annual hairgrass, Deschampsia danthonioides

The superstar of the pools last week, however, was the toothed calicoflower, Downingia cuspidata. The way it grows only in the pools creates a really cool effect when it blooms. The land around the pools is whatever color the chaparral is, but the pools become this solid mass of soft lavender.

Lots and lots of Downingia cuspidata in bloom

Downingia, up close and personal

Sorry for sharing so many of the downingia photos, but the displays were way too amazing not to!

And there were other things blooming away. Here’s a small sampling.

Owl's clover, Castilleja densiflora, growing more at the edges of the pools and not so much in them
A Brodiaea (filifolia?) growing on the pool edges, along with one of the goldfield species

Bladderpod, Isomeris arborea, growing high on the mima mounds separating the pools

Bounded by freeways on two sides, a city landfill on another, and runways of the Marine airbase to the north, it’s an unpromising location for 400-plus acres of rare vernal pool habitat. The Landmark, dedicated in 1972, remains a part of MCAS Miramar. The land isn’t technically a preserve–national security interests could cause the land to be withdrawn back into military use. But the same reasons that make this an unlikely location for a nature destination–the freeways, the dump–also make it a compromised location for military activities. We can keep our fingers crossed that it remains dedicated to preserving these rare resources.

gardening, landscape, my garden

after the rain delay

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The rain last weekend cleared out long enough for us to install the shade panel we’d constructed.

The fence you see faces north by northwest. Anything growing in the bed is in total shade for several months. About this time of year, though, the sun swings north, and things start to get sun exposure in the later parts of the day. We removed the termite-munched patio cover that shaded the delicate plants last fall–it had to go–but suddenly time was of the essence in restoring shade.

This is where a few shade denizens live in the bed…

…along with John’s collection of orchid cactus, Epiphyllum, that he’s amassed over the years. We also have a small assortment of hanging tillandsias and some tropicals, including a few surviving orchids from my rabid orchid-growing days two decades ago.

This weekend has turned rainy again, filling many of the holes in the shade screen with water. It’s slowed down moving the plants to their new home, but I won’t complain about the water we’re getting.

We’re already two inches ahead of the entire rainfall for last season (July 1, 2008 to June 30, 2009). And last month’s rain accumulation alone, 5.4 inches, came close to the 5.5 total for all of 2009. Still we have a couple inches to go before we can even claim an average rainfall year.

This season’s rain is filling up vernal pools after several years of disappointments. Friday I stopped by some pools with a biologist to scope out a potential field trip for the local native plant society. Vernal pools are among the most threatened habitats locally. The occur on our mesa tops, areas that prove irresistible to developers because they’re flat and require less soil preparation than canyon bottoms or slopes.

Young plants were everywhere, including those of San Diego mesa mint (Pogogyne abramsii), a plant on several endangered species lists. If the rains keep up, it looks like it’s going to be a great year for them.