In the roughly fifteen thousand years since glaciers receded from New England, forests returned to the land. They evolved and diversified, adapting to the changing conditions. The earliest peoples arrived not long afterwards and lived for thousands of years in New England. In the 1500s and 1600s, when European explorers first visited what was to become New England, they found the finest temperate forests they had ever seen; they came from areas of Europe where forests had already been mostly felled or were exploited regularly.
The New England forest at that time was for the most part natural and primeval, with the exception of coastal regions and some river bottomlands, where indigenous populations were centered. Native people did some burning and clearing of the forest, particularly in coastal areas, but research has shown that these activities were quite limited in most of the upland forest.
The primeval forest was produced by natural processes, and therefore was as resilient and well-adapted to natural disturbances as it could possibly be, since those disturbances were exactly what had shaped the evolving forest. Native human populations were relatively small and localized; their impact on the forest was correspondingly small, and they moved often, which allowed forests to recover.
In the last four centuries, human impact on the land has been far more intensive and far-reaching. Most of New England forests south of Maine were cleared for agriculture by the mid-19th century, and others were heavily logged at least once, if not multiple times. Most forest organisms were eliminated from the cleared land and replaced with crops and grasses, vastly affecting the genetic diversity and adaptability of our forests.
In the last 150 years or so, with the reduction in farming here after the Civil War, once-cleared farmland has rapidly returned to "second growth" forest. But not all the original species of plants, animals, and fungi have returned; and many have not flourished in their former ranges or numbers. And that's a very important point- the resilience of a forest greatly depends on the number and diversity of species it contains. Why? Because, by Nature's design, there are often multiple species that perform the same or similar functions, which protects against the loss of any one of them (for example, several insect species may pollinate a particular plant species). Also, the multiplicity of species means a greater gene pool, which is key to adaptability.
Our second-growth forests are a degraded version of their ancestral primeval forests, and can be deficient in, or completely lacking, a number of species, and genetic diversity of those that remain is not what it could or should be. 
In a natural, old native forest, things are kept in check by the diversity of
species; no one species can run rampant and overwhelm the others. An old
forest maintains a high degree of adaptability and resilience; biological processes continue in a stable way. Non-native, invasive plant species are effectively repelled.
Many second-growth forests are gradually recovering. However, by continually disrupting them with management activities, we create opportunities for unwanted, invasive species to enter. A great number of such non-native species have taken hold here in the degraded second-growth forests, and they have a serious, deleterious effect. You can see them in many of our forests... plants such as Euonymus ("burning bush"), Japanese barberry, Glossy buckthorn, Multiflora rose, Asian bittersweet vine, Garlic mustard, Autumn olive, Japanese knotweed, and many others, can just completely overtake woodlands. Introduced insect organisms (eg, hemlock woolly adelgid, emerald ash borer, spongy moth (formerly gypsy moth), winter moth, etc, etc) are killing millions of trees. Less visible are the introduced fungal diseases that have virtually destroyed some of our most cherished tree species... Dutch elm disease, Beech bark disease, American chestnut blight, Butternut canker... to name a few. And then there are the highly destructive, non-native, invasive earthworms that destroy the forest duff layer and most of the plant and amphibian life dependent on it. Sounds pretty depressing, huh? Well, yes, it really is.
Forested land continues to fall to suburban development, timber harvesting, ill-conceived and subsidized solar farms, and other projects that are not forest-friendly. More than 99% of New England no longer has any original forest cover; much less than a mere 1% is "old growth".
Cut, cut, cut
A second reason given to create more early-successional forest is that "young-forest wildlife species are declining". The vast clearing of original forest for
agriculture (along with excessive hunting and trapping) affected numerous animal species; some declined sharply or
were extirpated from the region (eg, wolves, bears, cougars, wolverine, fisher, beavers, certain bird species,
etc, etc). At least one, the passenger pigeon, went extinct. Some species became advantaged and benefited greatly (eg, open-land
bird species). When farm abandonment caused a sharp rise in young forest
150 years ago, certain species thrived (particularly some game animals, and birds with wide geographic ranges). Those of us
who grew up in the mid-to-late 1900's may tend to think that large populations of deer, grouse,
and rabbit are normal, and may want to see them continue.
But they're not the norm, just an anomaly that never would have
occurred had the land not been cleared. When some species decline, others benefit; that's just how
things go.
New England's original forest was uneven-aged, due to intermittent disturbances caused by damage from insects, storms, and diseases. There was always some amount of young-forest habitat that supported young-forest species, but there was far more old forest than exists today. The current decline in some species' numbers is indicative of Nature restoring its preferred forest composition, and the species are not endangered. There's currently already a far greater percentage of young forest here than old-growth; it occurs along the edge of every road, trail, powerline, pipeline, golf course, and water body that borders, or is within, forest land.
What we don't have enough of is very old forest. Some of our second-growth is on its way there, even up to approximately 150 years old. For most forest trees, those are young-adult, not geriatric, years. In the northeast, white cedar is known to live over 1,000 years (actually, over 1,650). Red cedar, black gum, eastern hemlock, tulip poplar, and red pine can live 500 to 1,000 years. Many species, including oaks, sycamore, white pine, and red spruce can live up to 500 years. Those numbers may climb higher as we learn more. For example, scientists recently discovered that bald cypress trees in North Carolina live far longer than 2,000 years as previously thought; the known max is now up to nearly 2,700 years.
But a forest is more than just trees. The complete community of plant, animal, and fungus species is critically important; it is the combination of all those organisms, from microbes to moose, that make a forest work. Old trees are just one aspect (albeit the most obvious one) of an old forest. Additionally, the forest floor duff layer, which is the primary rooting and seed germination zone, can be compacted and/or eroded by machinery and other human activities.
In other situations, a third reason given to cut is "to increase forest health, resilience, and vigor". But what is forest “health?” There is no forest more "healthy" or resilient than naturally growing old forests, complete with their genetic lineage, structural complexity, and vast spectrum of species and interactions. They got that way by developing and adapting for thousands of years. Trying to hasten or improve on long-running biological processes by cutting more trees is wishful meddling at best, which is what got us into this situation to begin with. More interference in the necessarily-long process of forest recovery is not helpful, it only delays it further. With our continued disturbance to the forest, we encourage the drying of the forest soil and the introduction and proliferation of even more destructive invasive species. We also further impoverish its gene pool.
Wood and paper products come from trees, so we obviously must continue to harvest trees. But the life-sustaining ability of our planet relies heavily on the existence of large areas of old forest. What we should strive to do is designate some forests to be wisely managed woodlands, and a substantial amount of forest land to be managed primarily by Nature, with no significant interference from us. We must not continue to think that just any plot of land with trees on it is capable of sustaining itself, or us.
The climate connection
One of the theory's co-developers is Russian atmospheric physicist Anastassia Makarieva of the Petersburg Nuclear Physics Institute. She recently visited the United States and we were able to film her talking about the Biotic Pump mechanism. It's quite fascinating.
Which brings us to this:
A new film
We have completed a new one-hour film, "The Return of Old Growth Forests", that describes the characteristics and (just some of) the importance of old-growth (and recovering old-growth) northeastern forests.
