Field Trip: Squam Swamp

This is a Nantucket Conservation Foundation property of 294 acres on the northeastern end of the island. The Foundation, which keeps a substantial portion of the island free of the monstrous SUV-scaled houses now built there, has produced an excellent paper interpretive guide to the mile-long trail. Hardwood forests are rare on Nantucket now, but the island had a lot more before Wood Age peoples from Europe cleared it for construction and fuel and to make way for agriculture starting in the 17th century. (“Wood Age” is my own coinage here; they were replaced by those Coal/Oil Age peoples also known as us.) A relatively uniform woods like this should be familiar to anyone who’s ever been on a highway on the eastern end of this country. The similar-sized trees here — oaks, mostly, but also hickories, beech, tupelo, maples — tell you that this land was also once cleared; a mature forest would have trees with a greater variety of sizes as old giants fall and open up the canopy to saplings waiting for their chance. Vernal pools, a rare-for-the-island running stream, and sphagnum/peat bogs testify to the swampiness of the terrain. Plants adapted to water-saturated soils, as well as high acidity in the peat, and animals adapted to intermittent water abound. Areas of higher elevation show how soils dictate habitat as well, as trees that can not survive with flooded roots congregate on the well-drained upland soils. The lumpy landscape was created by the last ice-age and subsequent weathering of kettles (valleys) and kames (hills), with clays beneath, which help to explain the presence of moving and standing water. Fiercely windswept, the island’s woodlands do best as “sunken forests,” protected in the old kettles. The vernal pools, which dry up in summer, are vital to the life-cycle of reptiles, amphibians, insects, and other invertebrates like fairy shrimp, all dependent of fish-free fresh waters.

The marvelous complexity of interactions between soils, weather, time, plant, and animal communities add layers of meaning to the landscape you walk through. An American Holly (Illex opaca), one of the very few evergreens here. The fruits are eaten by more than twenty species of birds, although the infrequent hollies in this patch are usually not fertilized because of their isolation; the separately male and female trees are be too far apart. The trees, which are slow growing and long-lived, may have gotten a start in these woods because their seeds arrived via bird-droppings. Under the best conditions, the seed’s covering takes from 16-months to three years to break down before the seeds can germinate. The fact that the leaves remain means that the trees can provide shelter for animals year around, something you’ll also readily see (and hear!) on New York streets as birds cluster in evergreens.

This was my first walk through this woodsy swamp. With spring awakening, I looking forward to getting back in there soon to see the forest wildflowers and ferns and hear the migratory birds and spring peepers, and perhaps catch a glimpse of a rare spotted turtle.

For a lot more about the island’s natural history, I recommend looking to the articles by Sarah Oktay, the managing director of the Nantucket Field Station.