Sunday, June 28, 2009

Dunes, for when the tide is high.

Today when we got to Boundary Bay the tide was all the way in, so son and I went for a walk on the dunes. Dunes are interesting, dynamic habitats, scoured by winter storms and subject to intense sun, strong winds, and high salinity. Understandably, the plants are oddballs--with spreading roots or deep taproots for anchorage and water access, creeping habits for wind resistance, thick cuticles that reduce water loss, and gummy surfaces that hold sand and create complex surfaces analogous to hair or spines--which also reduce water loss.

I worked at this park a decade ago, and I wondered which plants I would remember. I cheated in a couple cases; I had to read the signage, although I did recognize the large-headed sedge, Carex macrocephala, scattered among the grasses.

Here it is, showing the large fruiting spikes. It's nice to find a plant whose name makes sense in both languages. Especially a sedge.

This one is entire-leaved gumweed, Grindelia integrifolia. Its name refers to the sticky white latex that coats the bracts that surround the flowers. Yes, it's very sticky.

This sprawling, sage-bushy, somewhat succulent plant is silver burweed, Ambrosia chamissonis, also known as Franseria chamissonis. It is fragrant, smelling like cinnamon or nutmeg if crumpled.

A final view of the dune. In the foreground is beach pea, Lathyrus japonicus. In the mid-ground, somewhat bluish, is dunegrass (Elymus), and interspersed are splendid water- and weather-worn logs. The logs are important to dune ecology, I would imagine, for the physical structure and microhabitats they provide. Someone should look into that. (I bet someone already has.) I, in the meantime, will study the tide tables.


Karen said...

Beach pea I've seen, but not the other ones (or if I did, I didn't know their names). The logs... well, I wonder how many of them fell off barges or escaped from logbooms, and how many got there via natural causes. If you find a treatise on driftwood as habitat, maybe it would contain that info too? I am terrible at tide tables, usually rely on others to tell me when the super low ones will be happening. We had a good minus tide last week but the beach was covered in sea lettuce so not too much was visible.

Hugh said...

Re those particular logs, I don't know the source; I expect it isn't natural. But no matter where they come from, logs from mature trees are big. Someone studying driftwood ecology (a new discipline, perhaps, invented by you and me) would have to consider them. Would have to hang out at the beach. It would be awful.

For tides I use this site:

I use the table for Blaine, because it's on Boundary Bay. It has never let me down (when I bothered to check).

Wanderin' Weeta said...

You made me curious. I Googled "driftwood ecology" and "driftwood as habitat" and came up with a book:
From the forest to the sea by Chris Maser. (1994)

Looks interesting, and it's only 83 bucks, used!

Kim and Victoria said...

Sandunes are interesting places. Here in Idaho we have the Bruneau sand dunes which is the tallest single-structured sand dune in North America.

Hugh said...

WW, only $83! I better find my library card. But it does indicate that there's a body of work on the subject. Somebody got a PhD in logs.

K&V, I had never heard of the Bruneau dunes, so looked them up. What interesting, photogenic things. I wondered if they were where Napoleon Dynamite's grandmother broke her coccyx, but then read that motorized vehicles weren't allowed (a good thing).

Karen said...

Hey, thanks for the tide chart link - I bookmarked it and will try to learn not to be such a nimnull about remembering to check it before a beach run. Yes, I like the new discipline, but I am not a scientist, only a casual observer. Perhaps I could write the funding grants and organize the annual conferences while you handle the actual data collection? Then again, I wouldn't want to miss out on the extra, expenses-paid beach time. Hm.