Are our woods healthy?

First in a series

By DEBORAH E. LANS

GHENT–Simply take a walk in the woods these days and the toll of the heavy winter and spring storms will be obvious. Trees uprooted, downed branches, large and small, everywhere. It all looks a bit chaotic. Which prompts the question: are our woods healthy?

The question is important because forests are important. They provide us with oxygen, jobs, water, nourishment and fuel, help to prevent erosion and conserve soil, and filter pollution, improving air and water quality. At a time of climate change, they remove carbon from the atmosphere and store it. (Only the oceans sequester more carbon.) Logging is an important industry, and wood products are central to our lives. Woods provide homes for a diverse array of animals, plants and insects – 80% of all terrestrial biodiversity. Not only is a walk in the woods a source of pleasure but studies show that time spent in forests benefits a host of conditions such as cardiovascular disease, respiratory illness, diabetes and mental health.

New York State is 61% forested, and the eastern side of Columbia County in particular boasts many heavily-wooded areas. As is true state-wide, much of the local forest is privately owned.

Our woods have many stewards, and they, in turn, have many views on the question of health.

To an ecologist like Charles Canham, a scientist with the Cary Institute in Millbrook and author of “Forests Adrift,” the question prompts another question: what is the definition of forest health? He explains that forests are ever-changing. In the 12,000 years of our postglacial history forest composition has changed, but never so much as in the past 400 years, since Europeans arrived and cleared some 85% of the area for agriculture by 1900.

In turn, in the 20th and 21st centuries, as agriculture has diminished, the forests have regrown and their composition has changed. Of course, the forests are younger. The numbers of red and sugar maples have increased dramatically and are now the most abundant species, whereas “pre-settlement” oaks dominated.

In turn, those changes have “cascading effects.” The array of “ecosystem services” a forest provides varies with its composition. For example, as maple trees predominate over oaks, the likelihood of fire spread diminishes. That is so because maple leaf litter decomposes more quickly than oak leaf litter, leaving less combustible material during the hot months. But oaks (through acorns) provide a far more valuable food resource to small mammals than maple seeds.

In an interview with The Columbia Paper, Cornell’s Bernd Blossey echoed the thought that change for forests is different: “Forests think in long time spans. So, there are many definitions of health, or none. The real question is whether the forest is different today than if there had been no humans, because change is always a part of any environment.”

Accordingly, Dr. Blossey would define forest health by asking whether the species currently in place have the ability to thrive in their location?

In answering that question with a “maybe” both Drs. Canham and Blossey cite a number of threats to current forest species: climate change, pollution, the proliferation of white-tailed deer and invasive pests and pathogens, land development and changed forestry practices, the effects of which are cumulative and interrelated. The long-term effects of these threats are unknown but lead scientists to believe that forests will continue to exist, but in changed composition and form.

In an April 2024 paper “Where have all the flowers gone? A call for federal leadership in deer management in the United States,” Dr. Blossey summarized the current state of the woods by saying, “Forests in the United States continue to lose biodiversity and many fail to regenerate due to high deer (family Cervidae) abundance. Declines in biodiversity and overall ecosystem health due to high deer populations increases the prevalence of wildlife and human diseases associated with increasing tick abundance and decreases forest resilience and the ability to deliver the benefits provided by healthy ecosystems.”

Likewise, a paper by U.S. Forest Service scientists issued in 2023 to summarize the results of a 12-year study of 39 eastern national parks from Virginia to Maine found “widespread regeneration debt” – a term that refers a lack of tree regeneration in the form of seedlings and saplings. The scientists found that eastern forest resilience – the ability of the ecosystem to experience disturbances but still maintain its basic functions, composition and structure – is threatened by the many compounding stressors the woods face, to the point that we can expect to see forest loss. The study concluded that 70% of the forests surveyed were suffering or were highly likely to suffer regeneration debt

So, what are the stressors? Topping the list are white-tailed deer. Because of hunting, driven in turn by the demand for leather, deer were virtually eradicated in the area in the 1800s. But, conservation efforts since then have succeeded to the point that Dr. Canham estimates the deer population now is at least double, and in some areas 10-15 times, that of the pre-European era.

Deer browse on the forest understory (seedlings, saplings and flowers) and, in our area, have all but erased the traditional and formerly abundant carpets of trilliums, lilies, orchids and other “charismatic wildflowers,” according to Dr. Blossey. In their place, species that deer dislike – sedges, ferns, garlic mustard, Japanese stiltgrass – have proliferated, to the point that the landscape has become impenetrable to seedlings; as Dr. Blossey puts it: “there are no safe places to start to grow, no safe passage, no hotels.”

Eli Arnow, who is chairing the Forest Health Task Force formed by Chatham-based Partners for Climate Action to provide education about forest threats and improvement, recently returned from a trip to Canada’s Gatineau Park. The park still has deer predators like wolves and the winters there are still severe enough to control the deer population. As a result, “the woods have not endured fifty years of crisis-level deer activity” and native plants abound. Mr. Arnow “was blown away by the health of the woods and the abundance of spring ephemerals in bloom – trillium, false Solomon’s seal, bellwort, orchids.”

It is not only the health and diversity of the woods that are threatened by the deer. White-tailed deer host the black-legged tick, which is the vector for Lyme disease, babesiosis and anaplasmosis. A study by Connecticut Department of Energy and Environmental Protection scientists found that where deer populations are significantly reduced, so too are tick infection and human cases of Lyme disease. Indeed, in an experiment where a controlled deer hunt reduced an area’s deer population by 87% (from a density of 39.8-54.5 deer per square kilometer to 10 or under) the incidence of reported Lyme disease dropped by 80%.

The woods also suffer from imported pests, like the emerald ash borer that has decimated the ash tree population, the Hemlock woolly adelgid, beech bark disease, Asian jumping worms, spongy moths. Pests and pathogens enter the country on wood pallets and in potting soils and mulch and spread from there, disrupting soils, encouraging erosion, and threatening species health.

What are other stressors and what can we do to address these threats? The next story will suggest some possibilities.