FALLS VILLAGE — A sure sign of the change of seasons is a visit to the American chestnut saplings with Ellery “Woods” Sinclair.The hybrid, blight-resistant trees are part of a project to restore what Sinclair called “these magnificent, iconic trees” in the U.S. A group of about 20 people gathered at the site, off Undermountain Road in Falls Village, to take part in one of that weekend’s Housatonic Heritage walks, a series of informative hikes sponsored by the Upper Housatonic Valley National Heritage Area.Until the early 20th century, the American chestnut represented one in five hardwood trees in forests in the eastern United States, said Sinclair (the other four species being maples, oaks, birch and ash trees).And as settlers cleared fields, the chestnut, a light-seeking species, flourished.The chestnut wood was highly sought after for building, he continued.Because the trees grew tall and straight, they were used for ships’ masts and telegraph — later telephone — poles, and barn beams. And because the wood was highly resistant to rot, it was used for railroad ties, coffins and shingles.And the nuts — rich in protein and fats — were a major food source for wildlife and for settlers. In some areas, chestnuts were not a luxury item but a fundamental part of a subsistence diet.“During the Depression, families in Appalachia lived off these nuts.”In the late 1890s, Chinese chestnuts were imported for ornamental use and specimens were included in the collections of major botanical gardens.It was at the Brooklyn Botanic Garden that the chestnut blight was first spotted. A fatal chancre on the trees was spread by a fungus from the Asian imports, and the American chestnut had almost no resistance.By 1950, some 4 billion trees on about 9 million acres of eastern forests had been wiped out by the blight.The trees that have been planted in the Falls Village grove are 15/16 American chestnut, the result of careful breeding and selection. These trees will be intercrossed with other 15/16 trees, to increase blight resistance and American chestnut characteristics, Sinclair said.“The geneticists tell us we’ll have trees that are 95.7 percent American chestnut in two more generations,” he said.The ultimate goal: an American chestnut that is resistant to the chestnut blight.The project’s sponsors are the Connecticut chapter of the American Chestnut Foundation, Great Mountain Forest and the agricultural education department at Housatonic Valley Regional High School. The high school students do much of the field work at the site.Heritage Walks continue Oct. 1 and 2The Upper Housatonic Valley National Heritage Area (Housatonic Heritage) Heritage Walks will continue on Oct. 1 and 2. Guided educational outings will be offered throughout the Heritage Area, which includes 29 towns in Berkshire and Litchfield counties, from Kent in the south up north to Lanesborough, Mass. It encompasses 964 square miles of the upper Housatonic River watershed. The 2011 Heritage Walks feature short walks and longer hikes, walking tours of towns and historic buildings, nature and birding walks, tours of industrial site ruins, a canoe trip on the Housatonic River, a Native American history and culture walk, a sunset bagpipe serenade on a scenic hilltop and a country bike ride. Historians, naturalists and environmentalists will help participants explore the region’s rich historical, cultural, industrial and environmental history.The majority of the walks are free, and all are open to the public. Brochures have been distributed throughout the area, and are available at most libraries and post offices and many stores. Complete details are available online at www.heritage-hikes.org/ or by emailing the Heritage Walks coordinator at programs@HousatonicHeritage.org.