Defining Old Growth Forests

Because of the challenging topography, long history of state acquisition of land, and constitutional protections, the Adirondack Park has preserved the largest collection of old growth forest on the east coast (Kershner 2004).  Conservationists and naturalists have long sung the praises of “old growth” forest stands as a representation time before the destructive power of man forever altered the shape of this continent.   With previously logged stands in the Adirondack Park approaching 150 and 200 years of age since human intervention, only trained biologists can recognize the fingerprint of humanity on these “secondary growth” forests (Kershner 2004; Ziegler 2004).  Is old growth exclusively indicative of forests where we have not interfered? Can we never recover what we have lost?  Or is old growth simply characterized by two-centuries’ unimpeded development?  According to Bill McKibben, the beauty of the Adirondacks is not found in the purity of its old-growth forests but in the recovery of its secondary forests, which are becoming increasingly indistinguishable from the old growth (McKibben).  But how indistinguishable are old growth and secondary growth forests? Let’s find out!


In the past couple decades, scientists have gathered a laundry list of qualifications for old-growth forests, including but not limited to: (a) very few, if any, early successional species such as paper birch and white pine; (b) average forest net-growth at or near zero, i.e. no expansion of forests; (c) the forest must be significantly older than the average interval between major natural disturbances; (d) the dominant canopy trees generally reach their average life expectancy; (e) the dominant tree species must be capable of reproducing themselves; and (f) the forest’s current annual growth rate is less than its lifetime average annual growth rate (Leverett 1996).

The significance of this rigorous scientific definition is the lack of a specification for “virgin conditions,” i.e. no human interference!  While many conservationists and foresters hold that true old-growth forests cannot have felt the presence of humanity within its lifetime, this would restrict the existence of old-growth forests in North America to basically nothing (Kershner 2004).  According to Barbara McMartin, the definition of old-growth “provides a way of describing forests that avoids the logical incongruity of the term ‘almost virgin’” (McMartin 182).  Unsatisfied with the list of qualifications generally agreed upon by the scientific community for old-growth, Barbara McMartin set off into the field to qualify old-growth forests in the Adirondacks from a historical and ecological perspective.  With the wealth of her research concerning logging in the Adirondacks, McMartin predicted that most of the old-growth in the Adirondacks would be characterized by the presence of spruce, but what she found surprised her…

Identifying and Measuring Old Growth: 

Old growth forests have been around for hundreds of years, but nearly 95 percent of the known old growth forests in the Northeast were discovered in the last two and a half decades (Folwell). Until recently, very few scientists spent any time identifying and measuring old growth forests because they assumed they simply did not exist after the Northeast’s extensive history of logging. Though scholars are focusing more attention on these forests today, there is still little consensus among scientists as to the actual acreage and locations of old growth forests left in the Adirondack Park. The disagreement primarily results from the lack of a common definition of an old growth forest. Some researchers such as Barbara McMartin, classify old growth forests as unlogged areas. This definition lead McMartin to estimate that there were at least 200,000 acres of old growth forest in 1994. On the other hand, Jerry Jenkins, the writer of The Adirondack Atlas, defines old growth forests as land that was never logged or seriously affected by disturbances such as severe storms or fire. Jenkins’ more stringent definition led to his 2004 estimate of 586,000 acres of old growth forest, which would make up roughly 9.6% of the Adirondack Park. Even though Jenkins’ definition is more limiting than McMartin’s, his estimate is nearly three times as large as hers due to the extra twenty years of identification and research he could leverage. This illuminates the rapid rate at which old growth forests were discovered in the Adirondack Park over the past few decades.

 Future of "Old Growth":

One of the most commonly accepted meanings of an “old growth forest” is a forest that existed before European settlement and has not been seriously altered since. This definition functions well for today, but as old forests begin to die out naturally and younger forests mature to have the same characteristics as the original old growth forests, the definition of “old growth” needs to evolve as well. The characteristics of old growth forests develop gradually over time, so as the land becomes far enough removed from logging, even forests that were previously logged can demonstrate the same characteristics as traditional old growth forests. If we do not alter the definition of old growth to include these new forests, legislators and environmentalists will not be able to protect the land. In the National Council for Science and the Environment’s report on old growth forests, the committee members summarize the impending problem perfectly, writing, “Unless some younger forests become older forests, one day in the future there will be no ‘old growth” (Members, Commission).

Works Cited:

Folwell, Elizabeth. "Discovering Adirondack Old Growth Forests." Adirondack Life.

Kershner, Bruce, and Robert T. Leverett. The Sierra Club Guide to the Ancient Forests of the Northeast. N.p.: Sierra Club, 2004. Print.

Leverett, R. T. 1996.  Davis, M.B. (ed.), Eastern Old-Growth Forests: Prospects for Rediscovery
and Recovery, 3–17. Washington, D.C.: Island Press.

McMartin, Barbara. The Great Forest of the Adirondacks. Utica, NY: North Country, 1994. Print.

Members, Commission. Beyond Old Growth: Older Forests in a Changing World. Rep. Washington DC: National Council for Science and the Environment, 2008. Print.

Ziegler, S.S.  2004.  Composition, Structure, and disturbance history of old-growth and second-
growth forests in the Adirondack Park, New York.  Physical Geography 25(2): 152-169.