Monday, April 18, 2011

Vernal Pools of Portland

This evening I'll be giving a short talk about forest ecology at the Maine College of Art, as part of their FOREST show at the ICA. If you're in Portland, please come and save me from talking to an empty room.

To get ready, Jess and I took a bike ride on Sunday to explore the woods near the abandoned city dump, where there are several vernal pools at this time of year.

Above: a small vernal pool in the right-of-way of an unbuilt city street - that's a manhole in the background.

Vernal pools are temporary wetlands that fill up with snowmelt and spring rains and typically dry out by the midsummer. That important distinction keeps fish out and allows niche species - mostly amphibians - to breed and develop without competition from other wetland species.

This is another vernal pool closer to Ray Street. It's been a cold spring and so there wasn't much sign of life, but we did find what looked like some salamander jelly:

When a big rainstorm coincides with the first warmish evening of the spring, salamanders will come out of hibernation and venture down to breed in the same pools where they themselves had been born. Here in Portland, that probably happened last week or during Saturday night's drenching rains.

Male salamanders will deposit gelatinous packets of sperm on submerged sticks (like the one above), and later, females will deposit their eggs on top to fertilize them. Within the next few weeks, these will develop into tapioca-like sacs of salamander eggs.

Near "Stepping Stone Lane," a street name that tells you all you need to know about this neighborhood. You can actually make out some of the foreclosure boxes through the trees in the background here.

As the pools dry out in the summer, the amphibians they've nursed venture out into the surrounding woods as adults. These pools literally nurse the species near the bottom of the forest's food chain, providing food for critters in a wide radius.

These pools near Ray Street are just a 20 minute bike ride from downtown Portland - and there are similar pools located in the woods behind Evergreen Cemetery and in the uplands of the Fore River Sanctuary. No matter where you live in the northeastern U.S., there's probably a vernal pool not too far away. Finding them is half the fun.

At this time of year, they're neat places to visit: it's as though the entire forest's fecundity is concentrated here in these big puddles of water. It's also nice to take off your shoes and socks and wade into the water (which is still cool, but not cold) for the first time in months.

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