Before the arrival of Europeans to North America, it is estimated that 95% of Vermont was covered by forests. These forests would have been made up of a mix of hardwoods, like maples and beech, and softwoods like white pine and hemlock. By the late 1800s as much as 80% of this forested land had been cleared by settlers. People used the wood for a number of products including homes, potash, fuel, railroad ties, and fences; but much of the area was simply cleared to make way for agriculture. In the 1800s sheep farming became a major industry in Vermont as textile mills in southern New England needed the wool. The sheep boom lasted many decades, reaching a peak of about 1.7 million sheep in the mid-1800s, until a reduction in tariffs and the expansion of ranching out west made Vermont wool less competitive with other products. Without a strong sheep industry farmers tried other ventures, both old and new, but the erosion and flooding that resulted from the lack of trees and groundcover made farming difficult, to the point where many families left the state to try their luck elsewhere, abandoning their farms. Since that time Vermont's forest have made a comeback by overtaking many of the farms and pastures that had been deserted; today about 80% of Vermont is dominated by forested lands. In the park now, there is a patchwork of late successional mixed hardwood forests, fields, wetlands, and plantations. All these areas are closely monitored by the resource managers in the park; they not only observe water quality and forest health, but also ensure the park is safe and accessible to visitors.
The Marsh-Billings-Rockefeller NHP holds the distinction of being the oldest professionally managed forest in the United States and many of the forest stands throughout the park are still harvested for their wood. Frederick Billings, who bought this property in 1869, worked to replant Mt. Tom after years of massive deforestation left the hills in this area devoid of trees. Billings would plant many different species on his property but his signature tree was the Norway spruce. In 2006, the National Park planted a new Norway spruce plantation near the mansion to continue the legacy that Frederick Billings and his family started. Today, plantations of Eastern white pine, Scotch pine, Red pine, European larch, and Norway spruce can be found on the property.