By Susan Shea
Hikers climbing the highest peaks in the northeast will traverse various vegetation zones along the way. On the peaks, you will likely encounter plants so hardy that many also grow in the Arctic, thousands of kilometers to the north.
Many hikes begin in a northern deciduous forest, which is dominated by beech, yellow birch and sugar maple. As hikers gain altitude, they will notice the evergreen branches of red spruce and white trunks of paper birch added to the mix of hardwoods. At an elevation of about 2,500 to 2,900 feet, the forest usually changes into red spruce and balsam fir. Emerald mosses cover the ground, and lichens hang from trees and cling to bark. Look under the trees for the blue fruits of the blue pearl lily and the red clusters of ostrich berries.
These higher elevations have colder temperatures and a shorter growing season than lower terrain. When air masses hit a mountain range, they rise and cool quickly, causing water vapor to condense into clouds. Fog is frequent and rainfall is high. The moister soils are more acidic and less fertile. Conifers have an advantage here over most deciduous trees. By keeping their needles in winter, conifers can begin photosynthesis in early spring while they are still surrounded by snow.
Above 3,500 feet (or higher in some locations) the climate is more severe and trees cannot reach their full size. Black spruce and balsam fir form a stunted subalpine forest called Krummholz, derived from the German words krumm (krumm) and holz (wood). These dwarf trees grow very slowly in a dense thicket that is only a few meters high and bend and twist into bonsai-like shapes in response to wind-driven ice particles and snow load. Black spruce can form stretched mats in which branches develop roots that can grow into new trees.
Above the tree line is the alpine meadow or tundra – a plant community similar to that in the Arctic. Alpine tundra is rare in the Northeast and only occurs on the highest peaks of Maine, New Hampshire, Vermont, and New York. According to the Eastern Alpine Guide by Mike Jones and Liz Willey, the major alpine areas are on Mount Washington and other parts of the Presidential Range in New Hampshire and Mount Katahdin in Maine. Almost two-thirds of Mount Washington’s alpine plant species also grow in the Arctic. Mount Mansfield supports Vermont’s largest alpine meadow, and New York’s Adirondack Mountains are home to smaller patches of alpine tundra.
Lichen and moss are scattered on bare rock above the tree line. These pioneering plants help soil formation by collecting dust and nutrients, and the lichens secrete acids that dissolve the rock. Sedges, grasses, rushes and wildflowers grow in hollows and pockets of earth between the rocks. Alpine plants have special adaptations that allow them to thrive in harsh mountain climates. Many, like the white-flowered Diapensia, form low, dense pillows or mats that protect the inner part from the wind. Pillows also collect soil, store moisture and stay several degrees warmer than the surrounding air. The waxy leaves of Diapensia and the woolly leaves of Labrador tea minimize water loss and increase frost tolerance. Most alpine plants are perennials that develop flower buds by the end of summer and store excess carbohydrates in their roots so they can bloom as soon as conditions allow the following spring. Many alpine plants reproduce mainly through rhizomes (runners) and avoid the challenges of sapling establishment.
Many alpine plants are on state lists of threatened and endangered species. Mount Mansfield, for example, is home to 34 rare plant species. Climate change is a major threat to alpine plant communities and affects, for example, the timing of snowmelt and flowering. Studies have shown that as the climate warms, trees move uphill, potentially reducing alpine habitat. Loss of vegetation and soil due to trampling by hikers is another serious threat. Hikers can help protect alpine plants by staying on trails, walking on rocks if possible, and leashing their dogs.
Susan Shea is a naturalist, author, and conservationist based in Vermont. The Outside Story is commissioned and published by Northern Woodlands magazine and sponsored by the Wellborn Ecology Fund of the New Hampshire Charitable Foundation.