Vine maple turns first at Alsea Falls, and the creek runs cold

Vine maple is the first thing to turn in the Coast Range here, and it turns in the shade, low down, while the bigleaf maples above it are still green. Walking the same 200 m of trail every ten days is how I keep the two from blurring together.

Two scores, one drainage

• Vine maple, twelve tagged stems: 3.1 out of 5. Seven stems were at 3 or above; the most advanced, at the top of the bank where the soil is thinnest, was at 4.
• Bigleaf maple, eight tagged trees in the same 200 m: 1.6. None was above 2, and the two largest, both in deep soil by the creek, were at 1.

Vine maple grows in the understory and roots where its stems touch the ground, so it layers and spreads; a bigleaf maple stands alone in the open with its roots in deeper soil. The understory plant is colder at night, and its leaves are thinner. The fortnight between them is not a mystery, but I cannot yet say how much of it is the site and how much is the species.

What the creek says

The creek fell below 10°C for the first time this autumn: 9.8°C at 10:20, against 11.6°C on 20 September. That matters for the fish in this drainage — 10°C is roughly where coho and chinook begin to move in from the mainstem, and it is also where the last of the summer's algal growth shuts down.

One coastal giant salamander larva, 14 cm, under a stone in the riffle below the second bridge. The licorice ferns on the vine maple stems have started to unroll, which they do on the first wet week rather than on any particular date.

What to check next time

• Rescore both sets of tagged stems on 14 October. If the gap holds near a fortnight, that is a result; if it closes, the site is doing the work and not the species.
• Take the creek temperature at the same riffle every visit; the date it passes 10°C is worth having for ten years.
• Look for the first coho in this reach, which will be the sign the fish read the same number I am reading.