Forests at Sea: Visiting Squam Swamp in Winter

You might never guess that the tail end of winter would be a great time to explore the forests of Nantucket, but it is!

On February 21st, a group of warmly dressed visitors met in the Squam Swamp Trailhead Parking Lot on Wauwinet Road. The objective: to explore the forest of Squam Swamp in winter. Kelly Omand, a Research Technician/Field Supervisor on NCF’s year-round Science and Stewardship staff, accompanied the visitors,  students and instructors of the UMass Boston Living Lab Program, which is linked with the UMass Boston Nantucket Field Station. The students are on-island for an entire semester, studying various topics ranging from eco-poetry to water quality and hydrology. The Squam Properties provide insight into some of the unique challenges and natural beauty of island life: including both Squam Swamp and Squam Farm, they comprise more than 500 acres of conservation land. Within their boundaries lie a mosaic of unusual wetlands, forests, and agricultural areas, networked with walking trails owned and maintained by the NCF for public use.

In winter, the trees are stripped of most of their leaves and the contorted, exposed trunks provide hard evidence of what a tree needs to do in order to survive on the island. Unless you’ve been away on a tropical vacation the last couple months, you probably don’t need a reminder: rather than typical winter “windy day” conditions(15-40 mph gusts), the weather morphed into a serious storm — gusts up to 90 mph for “Winter Storm Nemo” on February 11th. Then just a week later, a second powerful storm arrived, resulting in days of boat cancellations and serious damage which sent the Steamship Authority’s MV Nantucket car ferry into dry dock for repairs. There were large trees blown down in different parts of the island, and a house that was being moved was blown off its temporary I-beam structure. That’s a lot of wind! And it’s not just wind that the trees have to contend with: salt spray can “burn” the foliage during the growing season, and entire trees can be defoliated.

On our tour of Squam Swamp, students visited some of Nantucket’s largest “wild” trees. It’s true that there are many beautiful large street trees downtown–mostly American Elms, Ulmus americana, that were planted as street or garden trees. The surrounding buildings provide some shelter from the winds, allowing the trees to grow taller and straighter than other island trees–more like trees found in mainland forests. In contrast, wild-grown Nantucket trees grew on their own from seeds, or re-sprouted following extensive logging of the island, which occurred between the time of European settlement and the mid-1800s.

Students visited examples of Black Oak (Quercus velutina) and American Beech (Fagus grandifolia) which may have been cut at one time and then re-sprouted. These pioneering trees needed to “canopy out” very low to the ground in order to withstand the strong winds and still develop a large enough canopy to get enough food through photosynthesis. In winter, after all but a few marcescent leaves of oak and beech have fallen, you can readily view the forest’s unusual structure and observe the trees’ survival tactics.

Squam Swamp and Squam Farm provide plenty of dips and hollows that help shelter trees from the wind, and the richer moister soils found on that part of the island offer ample habitat for a mosaic of mixed deciduous forest, wooded swamp, and shrub swamp to grow back over the last 150 years. Most of the rest of the island, with sandier, drier soils and more wind exposure, is home to lower growing Scrub Oak (Quercus ilicifolia) and Dwarf Chinquapin Oak (Quercus prinoides). Pitch Pine (Pinus rigida) was re-introduced to the island in the mid-1800s along Milestone Road and has since spread to many areas. Open areas of coastal heathland and sandplain grassland are typical on the more exposed sites along the southern shore, where prescribed fire and brush-cutting are used as management tools to ensure habitat for many state rare and endangered species.

On the winter walk, students learned about the adaptations of Squam’s large old trees, navigating deer and pedestrian trails that meander among vernal pools, and even cross a bridge over a perennial stream (flowing water year round, a rarity on Nantucket). Some trees grow as clones, such as the Tupelo (Nyssa sylvatica) and Sassafras (Sassafras albidum). Groves of these species appear to be large stands of separate trees, but they are actually one individual made up of many trunks arising from a network of roots. Alongside one of the vernal pools, students learned how spotted turtles spend the winter tucked away underwater beneath the protective “cages” formed by partially uprooted Red Maples (Acer rubrum). The pools themselves, along with extensive mats of sphagnum moss, provide ideal habitat for spotted turtles and amphibians in the warmer months. Red Maples are generalist species, adapted to survive with “wet feet” or in uplands, and can even survive when partially uprooted in a storm.

Stopping beside a particularly gnarly Red Maple, UMass Professor Anamarija Frankik urged students to consider the amazing structure and function of these trees growing in the swamp. She explained that biomimicry researchers are studying trees’ ability to regulate water flow, conveying fluids from roots to canopy, so that human engineers may one day adapt these methods to the engineering of tall buildings. What human engineers accomplish with awkward pipes and pumps, trees all over the world accomplish with highly evolved cellular structures adapted to local conditions. Squam’s “weird trees”, 26 miles out to sea and punished by winds and salt spray, illustrate the flexibility of these remarkable yet common organisms; humans can learn a lot from their adaptations.

Leaving the forest, we stopped to check the branches of Beaked Hazelnut (Corylus cornuta), a common shrub of the forest understory. Click here to view the Hazelnut Fact Sheet. This species is one of the earliest plants to bloom on Nantucket, and usually its ruby-red female flowers appear in March, followed a couple weeks later by the opening of the dangling caterpillar shaped catkins, which are the male flowers. Last year’s peculiar weather brought early flowering of the Beaked Hazelnut (in February), but in this year’s colder conditions, the buds remained tightly closed; perhaps they will be emerging soon, to be discovered if you look closely on your next winter walk.