How Old Is Our Forest?

The forest of Maine has gone through many life cycles since becoming established around 6,000 years ago. It still changes constantly. Trees die and new ones sprout up all the time.

Natural disturbances such as wind, insects, or disease kill some trees. When natural disturbances happen on a small scale, fallen trees create a gap in the forest, allowing sun to reach the forest floor. Young trees sprout up in the sun. The result is a forest of many ages, or an uneven-aged forest.

Large-scale natural disturbances create a different picture. Wind, insects, disease and fire can affect vast areas, resulting in the death of many trees. The result looks messy; some say it looks devastated, but the forest itself does not die. While there are exceptions, typically populations of young trees sprout up in the wake of most large-scale disturbances. The result is a “Baby Boom”, or even-aged, forest composed of trees of the same age.

Natural disturbances and human intervention shaped the forest of today. Both will shape the forest of tomorrow.

White pine is the most common conifer, or cone-bearing tree, in the southern part of the state and grows abundantly in even-aged stands on old farmland.

Between 1890 and 1920, Maine’s conifer forests were heavily cut to supply a national building boom. At the same time, a spruce budworm outbreak, beginning in 1912 and lasting until 1920, created a 

large-scale natural disturbance that reshaped the forest in northern and eastern Maine. These natural and human events combined to set in motion the cycle of natural regeneration, or sprouting up, of a young spruce and fir forest.

This even-aged spruce and fir forest reached maturity in the 1970’s, making it susceptible to spruce budworm once again since this pest favors mature trees. Industry stepped in and harvested large tracts of budworm damaged trees during the 1980’s in a move that triggered a contentious debate about clearcutting that continues today.

Nature also shaped the forest with large-scale weather events, including the 1938 hurricane, the 1947 forest fires and the 1998 ice storms.

European Settlement to the Present
Although Native Americans lit forest fires to encourage the growth of young trees and to drive game, the forest of 1700 was generally older than the forest of today. Trees covered almost all of Maine when European explorers arrived. During the next two and a half centuries, half the forest in the south central part of the state was cleared for farms. As a result, by 1880, only 68% of the state was forested.

After the Civil War, eastern farmers migrated west looking for better farmland and for employment in the city. Young trees sprouted up in abandoned farm fields, creating even-aged forests. In fact, most of the forests we see today in southern Maine were once fields.

The Forest Today and Tomorrow
Maine is once again almost 90% forested, but it is a different forest than the one prior to European settlement. Today’s forest is mostly made up of trees less than 100 years old.

Older trees do exist. In Maine, there are 93 old growth stands. Of these, 11 sites are larger than 50 acres and 37 sites are smaller than 10 acres.

For the most part, old growth forests remain because the sites are too inaccessible to log. Some have never been cut. But trees die 

over time even if they are not cut down, so old growth forests are composed of young, middle-aged, and old trees. Still, old growth stands have many trees 150 to over 200 years in age.

The forest continues to change. Large areas of spruce and fir clearcut in the 1980’s now support a young even-aged forest – thus potentially laying the groundwork for another budworm epidemic when the spruce and fir mature. And, as population growth in southern Maine fuels development, it is clear that some change is permanent.

Over time a forest is constantly changing.  As trees and plants change, so do the wildlife 
that inhabit and use them.

Find a small-scale forest disturbance near where you live. Look for standing dead or downed trees, including old and rotten trees. Look for patches of young trees in an older forest. What do you think caused the disturbance? How can you tell?

Forest Fact
The 5,000 acre Big Reed Pond Forest Preserve is the largest known expanse of low to mid elevation old growth forest in the state. Big Reed is a mosaic of different forest types: spruce-slope, mixed hardwood-conifer, maple-basswood-ash, beech-birch-maple, northern white cedar seepage forest, and northern white cedar swamp. Locate this preserve on a Maine map and find the elevation of Big Reed.

PLT Activity #40: Then and Now
Communities today are quite different than they were a hundred years ago – or even ten years ago. In this activity, students explore how each of us
affects and alters our environment.

PLT Activity #80: Nothing Succeeds Like Succession
Succession is a natural pattern of change or replacement over time of one species or community of species by another that occurs as a result of competition for limited resources. In this activity, students study the connection between plants, animals, and successional stages in local ecosystems.