Northeast Forests Still Feeling the Effects of Colonial Farming, Study Shows

A walk through the woods in the Northeastern United States today reveals the same type of trees the colonial settlers encountered 400 years ago; however, the similarities end there, according to a new study published in the journal PLOS ONE.

"If you only looked at a tree species list, you'd have the impression that Northeast forests haven't changed," Jonathan Thompson, research associate at the Smithsonian Conservation Biology Institute and lead author of the new study, said in a statement. "But once you start mapping the trees, and counting them up, a different picture emerges. In some ways the forest is completely transformed."

The study draws on colonial-era tree records and modern US Forest Service data regarding a 9-state area from Pennsylvania to Maine, the results of which unveil major differences between pre-colonial forests and today.

Maples, for example, have exploded in numbers, increasing by more than 20 percent in most towns, the researchers found. Many other trees, however, have declined. Among those that have experienced the greatest degree of loss over the centuries were beeches, oaks and chestnuts, according to the study.

This is problematic, the researchers explain, for the wildlife that depend on tree nuts to survive the cold, long winters characteristic of the region.

The pine population, meanwhile, shifted more than any other kind of tree, with numbers rising in some places and dropping in others. The reason, says Thompson, has both ecological and economic roots.

"Pine is valuable for timber, but quick to return after cutting," he explained. "It has a social and environmental dynamism to it."

Overall numbers have fluctuated a great deal over the years, with more than half the forestland across the nine states being cleared for agriculture and timber during the 18th and 19th centuries. After the majority of these farms were abandoned during the 20th century, forests began to return: today approximately 80 percent of the Northeast is forested.

Some 200 years later, however, the effect of these farms is still the felt; in fact, more than regional climate, soil conditions and any other factor, the researchers say colonial farming had a greater impact on the modern forests than any other factor. The result is forest areas that are more homogenous and less responsive to small changes in temperature and precipitation.

"The overriding theme of this forest region is resilience in the face of multiple impacts," said David Foster, co-author of the study and director of the Harvard Forest in Massachusetts. "This is an important lesson for the future. If we do not replace forests with houses and pavement, they will endure future challenges as well."

This can be seen, according to Thompson, even in the daily life of a Northeasterner.

"The Northeast wants to be a forest," he said. "If you stop mowing your lawn, you'll get a forest. That's essentially what we did in the mid-1800s -- we stopped mowing fifty percent of the landscape. What happens ecologically in the wake of that? The Northeast is the first place where we've watched it happen."