For many years, the ancient maples lining the road near my house and in the woods below were festooned with sap buckets in early spring. Now, the buckets have been replaced with plastic tubing. But these woods are still one of the best places in my neighborhood to find wildflowers in late spring. Here, the purple and white flowers of hepatica rise on hairy stems above leathery, lobed leaves, and rows of white-and-yellow pantaloon-shaped Dutchman’s breeches wave in the breeze. The shiny leaves of wild leeks carpet the forest floor beneath towering maples, white ash, scattered basswood, and an occasional butternut. In autumn, one can find the doll’s-eye-like white fruits of white baneberry, another wildflower of rich woods.
This patch of Vermont sugar woods is classified as a rich northern hardwood forest. This type of forest tends to form on lower slopes, benches, and in ravines where organic matter and nutrients that have washed downhill collect, and on other terrain where there is calcareous bedrock. Because of their deep, moist, humusy soils, these woodlands support a greater diversity of plant species and are more productive than the average northern hardwood forest. A study comparing forests in Vermont and New York found that a typical rich northern hardwood forest contained an average of 48 species of wildflowers and other herbaceous vegetation in a quarter acre, while other hardwood forest types had only 27 species.
In these rich northern hardwood forests, trees grow quickly and tend to be tall and straight. Sugar maple and white ash dominate, and basswood is common. Black cherry, white pine, bigtooth aspen, and yellow birch grow where natural or human disturbance has created openings. Common shrubs include striped maple, alternate-leaved dogwood, and maple-leaf viburnum. In addition to the wildflowers previously mentioned, these forests also feature blue cohosh, wild ginger, wood nettle, and maidenhair fern.
Because of their high biodiversity, the conservation of rich northern hardwood forests is one of The Nature Conservancy (TNC) in Vermont’s priorities, according to Jon Binhammer, TNC’s director of land protection. Areas of calcareous bedrock that support these forests are uncommon in the Northeast, and many were cleared for agriculture. Remaining patches tend to be small – finding a rich northern hardwood forest of more than 100 acres is unusual. Some of the largest and finest examples of this forest type grow in the Taconic Mountains, which run along the border of southwestern Vermont and New York south into Massachusetts and Connecticut, and where limestone and marble occur frequently in the bedrock. Near Manchester, Vermont, TNC has assembled the Equinox Highlands Natural Area, which includes land on Mount Equinox and Mother Myrick Mountain. Together with a conservation easement TNC co-holds on adjacent land, it protects the largest, contiguous rich northern hardwood forest in New England – more than 2,000 acres.
These prime growing sites are sought after by loggers and foresters. Trees grow to exceptional height and quality, and both basal area and annual diameter growth are high. TNC wants to help foresters and landowners “treat these forests with care and consideration for the future,” said Binhammer. To that end, TNC has created an 18-page booklet entitled “Managing Rich Northern Hardwood Forests for Ecological Values and Timber Production, Recommendations for Landowners in the Taconic Mountains.” Developed by a group of ecologists, foresters, and conservation planners, the booklet is designed for landowners and foresters interested in managing for ecological values as well as for timber production. Most recommendations are also applicable to rich northern hardwood forests beyond the Taconics.
In general, the booklet recommends an uneven-aged management system that emphasizes growing high-quality trees and sustaining high proportions of sawtimber. It suggests less frequent entries to harvest trees and mimicking small-scale natural disturbances through single tree selection and small group selection, treatments that create small canopy gaps. Overall goals are to maintain a variety of age classes, a multilayered canopy, and old, large-diameter trees.
The booklet also encourages the retention of standing dead and downed trees to provide wildlife habitat, as well as maintaining buffer zones around sensitive areas such as seeps, vernal pools, and rare species. Logging roads should be positioned to allow water and soil nutrients to disperse and gradually move downslope, a process critical to the perpetuation of this natural community. In addition, the booklet includes suggestions on methods to minimize the spread of invasive species and excessive browsing by deer. Specific recommendations are given for maximum diameter, stand structure, stocking level, crown closure, and cutting cycle.