A Sherlock Holmes of the Forest Dies

By Richard Conniff

Editor’s Note: David Smith ’46, Ph.D. ’49, Morris K. Jesup Professor Emeritus of Silviculture at F&ES and one of the most revered and beloved professors in the history of the school, died March 7 (see obituaries, page 60). The following article saluting his career ran in the Fall 2003 issue of environment: Yale.

In the parking lot of an assisted living center, a frail, diminutive man sits on a bench at the end of a long garage. He has his cane propped upside down in front of him, one foot up on the crook, his hands folded over the rubber end piece, his chin resting on his hands. His eyesight is impaired, and the effects of a stroke keep him from venturing out into the forests where, not so long ago, he led students much younger than he to a point somewhere between exhaustion and illumination. But even at a distance, even in a parking lot, he still has a characteristic way of closely observing what other people scarcely notice.

“You see that little ridge off to the right there?” asks the man, whose name is David Smith, Morris K. Jesup Professor Emeritus of Silviculture. “That’s a remnant of the kame terrace. A huge chunk of ice got deposited over there as the last glacier retreated 15,000 years ago, and a river of melt water raged around it, dumping sand and glacial till to form the ridge.”

“How do you know all that?” asks a visitor, who has assumed until that moment that the whole thing was put there by a developer in the 1970s.

“There’s a kettle pond formed by the ice over there,” says Smith, “and that tree, the one growing just beyond the dumpster, that’s a scarlet oak. It likes to grow in dry soils.”

Smith, now 82 and recently honored with the establishment of the David M. Smith Scholarship Fund at F&ES, has spent a lifetime observing such details, beginning on his great-grandfather’s woodlot in western Massachusetts. When he announced his intention to become a forester, he recalls, his father allowed that he had gone to college to get out of the woods, then packed him off to the Yale School of Forestry. After earning his doctorate, Smith went on to become one of the most revered and beloved professors in the history of the school, teaching generations of students how to ferret out for themselves the secret details of how forests grow. Through his textbook, The Practice of Silviculture, “every forester in the world” also came to know Smith’s methods, says a colleague, with only slight exaggeration. Originally published in 1921 by one of Smith’s mentors at Yale, Ralph Hawley, the book has sold about 125,000 copies, not counting pirated editions in China and elsewhere. It has shaped the management of forests in areas as distant as Tasmania.

This last thought makes Smith proud and, since he is very much a New Englander, also rueful. His book (which he has handed down in turn to be written by students he once mentored) is explicitly about North American forests, and his chief argument is that every forest, and every stand within a forest, is different and deserves its own carefully considered style of management. The Practice of Silviculture was never meant to be a cookbook. He is quietly scathing on the topic of forests he has visited in Canada, where the clear-cutting was done according to actuarial yield tables, and the replanting regimen called for 500 seedlings per hectare, whether on rich Pacific coastland or the edge of treeless tundra. “There is no one way to do these things, no dogma,” he says. 

On the contrary, Smith’s students describe him as a sort of Sherlock Holmes of the forest, able to analyze a stand of trees and figure out from seemingly trivial clues exactly what it has been through over the past few centuries, what it is likely to do next and what sort of help it could use to get there. A hummock of dirt tells him that the 1938 hurricane uprooted a tree here. A bend in the stem of a spruce records the passing of an ice storm 20 years back. He sees each stand as a unique product of its soils, its microclimate and the animals that live there.

Sitting on the bench in the parking lot, for instance, Smith points to the fork high up in the trunk of a white pine tree, and recounts the life history of a weevil that specializes in eating the terminal shoots of the tallest pines, a diet that seems to him as exotic as “eating hummingbird tongues.” The weevils overwinter in the litter on the ground. “They look like tiny elephants. They have a snout, not that they use it for breathing.” When the weevil larvae devour the six inches of new growth at the top of the pine, the trunk forks and begins to grow again. A careful forester cuts the tallest and most vigorous white pines first, Smith suggests, to put the growth on slower trees that are less susceptible to weevils. The unfashionable economic value of the forest still matters to him, as he thinks it should in a world that gets two-thirds of its energy and much of its housing from wood. Another pine in the parking lot catches his attention because someone years ago trimmed the lower branches, to yield a straight and relatively knot-free 16-foot length of lumber. The senior center could sell that tree now for $50, he thinks. But wait another 30 years until the trunk thickens to two feet, and it could be worth $1,000.

Smith passes on his encyclopedic knowledge of the forest in a slow, soft voice, without the slightest hint of showiness. He has a knack for the quaint Yankee turn of phrase. “We’d sit around tearing apart some paper,” says Matt Kelty, a former student who now heads the Department of Natural Resources Conservation at the University of Massachusetts. “Then he’d say, ‘Well, we’ve learned that we can smell a rotten egg.  Now we have to see if we can learn to lay a good one.’” Chad Oliver, Pinchot Professor of Forestry and Environmental Studies at F&ES, recalls Smith’s description of a colleague who ventured opinions too quickly: “He has a mind like a 10-cent mousetrap. He’ll snap at anything.” Apart from the quaint phrasing, Smith also fit the New England image by being notably frugal, fueling his field trips on Dinty Moore stew, among other practical economies. But Kelty also recalls one time on a field trip when a student stricken with flu was mortified at having to stay back at the camp. At the end of the day, Smith forbore from Dinty Moore, and brought him chicken soup instead. “He worried about people,” says Kelty, who also recalls that the day he arrived at Yale for his graduate teaching fellowship, Smith wanted to write him a personal check to tide him and his bride over until his teaching stipend arrived. E.H. Harriman Professor of Forest Management Graeme Berlyn, who taught a course with Smith, adds: “He unerringly did the right thing for people, provided good counsel, believed in treating everybody fairly. People always felt they could trust the guy, both students and faculty.”

Smith’s New England background was the key that enabled him to open up what he calls in his book “the little world of the stand.” A gypsy moth infestation had ravaged the family woodlot, and in 1946 Smith went up to Massachusetts to organize a salvage sale. It was a “typical seemingly incomprehensible mixed forest,” he says, a layer cake of white pine, oak, maple and hemlock. Foresters then operated on the simplistic premise that big trees were old trees, and small trees young. But Smith knew this stand too well to accept that. He knew, for instance, that the chestnuts had come out as a result of blight in 1915, a salvage sale that paid his mother’s college tuition. He also knew that his great-grandfather had run a sawmill there through much of the 19th century, and that the family house had eaten up the rest of the forest for firewood. So everything he was looking at had grown up since about 1880. Big trees and small alike were roughly the same age. The variation among them was a product not of age but of other less obvious factors, the hidden patterns of growth and shade tolerance of different species. This epiphany helped Smith develop the field now known as “forest stand dynamics,” a major contribution to forestry.

In 1949, the Yale faculty expressed its trust in Smith with the dubious honor of asking him to apply his thinking to the school’s own forests, or as one of them put it: “See what you can do about the mess up in Union.” The 7,840-acre Yale-Myers Forest in Union, Conn., was so hopeless the faculty wanted to get rid of it. Most of it was derelict pasture scooped up by George Myers, a wealthy F&ES alumnus, who prided himself on never paying more than $15 an acre. The new forest that had sprung up there had also been decimated by the 1938 hurricane. Smith and a small staff of foresters had the unlikely job of restoring Myers and the school’s other New England forests to health and making them pay for themselves in the process.

“We’d walk around looking for something we could harvest without sacrificing the future, and we didn’t have much success,” Smith recalls. “We got a lot of exercise. For the next 10 years, I just sort of stalled around.” At Yale-Tuomey Forest in New Hampshire, his ability to thin out branchy, weevil-damaged “cabbage pines” was limited by demand from a local factory making wooden buckets, the only market for such short lengths of useful lumber. While he was thinning the forests and slowly improving the stands of old-field pines, Smith also oversaw the development of research in the forest to help create a more scientific basis for forest management. The Yale forests became self-supporting by 1965, and at about the same time, Smith began advising the Baskahegan Company on management of its 100,000-acre commercial forest in northern Maine.

“He taught us to pay attention to how the forest naturally develops and to adapt our management to the forest, instead of the other way around,” says Roger Milliken Jr., president of Baskahegan. “He told us that in forestry, the trees are both the product and the factory. The key is to keep the trees that are capable of being factories for high-quality stands. It’s the opposite of short-term thinking, where you take the best and leave the rest. You really had the feeling when you were in the woods with Dave that he thought like a tree. He really understood what the trees wanted to do and how we could work with that for both economic and ecological rewards.” Baskahegan is now widely regarded as one of the best forests in Maine.