David Foster is no ordinary forester. To begin with, there’s his professional moniker: paleoecologist. It means that he is an environmental historian; he studies ecology in the context of history. Long-range history. Very long-range history. He can tell you (for example) what was happening in the Manuel F. Correllus State Forest about 15,000 years ago — and also 60 years ago.
In 1983, Mr. Foster became a professor of forest ecology at Harvard University, and for the past 19 years he has been the director of the Harvard Forest, an observation forest created in 1907 at the suggestion of the university’s dean of sciences. Harvard Forest is also the locus of a number of experimental and research projects focused on the natural history of the New England region. And in his role as Harvard Forest director, Mr. Foster has turned his attention to the Vineyard.
About 15 years ago, Harvard Forest began a study of the coastal landscape of southern New England, Long Island and Block Island. Rather than looking at individual islands or land masses, as other studies have done, the Coastal Research Project sought to gain an understanding of the region as a whole, and especially how it was different from the rest of New England.
“We want to use the past to inform the present and help inform the future,” he explained on a Sunday morning walk at the Polly Hill Arboretum, where he will give a talk tomorrow night. Although Mr. Foster, and Harvard itself, are policy-neutral regarding how to implement what has been learned, “Our overriding thinking is: It’s not enough to have a good understanding of the ecology of plants and animals — you have to inform all of that by history. You can use history to understand what shaped the land in the past.
“The project incorporates geology, archaeology, history, ecology and paleoecology, looking at the way the plants and animals would have changed over time, and trying to synthesize all that. Over time there’s been about a dozen professionals working on it,” he said.
The research has in turn offered insights to help guide land management for the present and future.
The project is funded by the Andrew Mellon Foundation and the National Science Foundation, as well as Harvard Forest monies. Most of the research has been wrapped up, including the Vineyard research, and Mr. Foster and his team are in the process of synthesizing all the data into a coherent whole. But Tim Boland, the director at the Polly Hill Arboretum, called Mr. Foster to come look at caterpillar damage in the woods behind the arboretum. “So this trip gives me a chance to regroup and look at the Vineyard again as we’re trying to look at the broader situation,” he said.
The broader situation is very broad, indeed. In the last year, Mr. Foster and his team have developed a long-term project to examine the last 15,000 years. “Were there any periods when there were any really dramatic changes in the landscape under natural conditions?” he asks, as an example of what they’ve been trying to learn. “What we find is that there are these episodes where, in a very short period of time, things will change from being dominated by one type of tree to another type of tree “ — with such changes driven by very rapid climate changes (very rapid in geological terms, meaning in about a century) often exacerbated by other issues such as drought.
He gave an example: 5,000 years ago the southern coast of New England had been dominated by oaks, but then abruptly (i.e., in less than 200 years) became dominated by beeches instead. “What drives that? That particular period [of change] was driven by major drought,” Mr. Foster explained. However, “There could be other things happening — like insect outbreaks. And today, you go out in the woods and what you see are dead oaks . . . with an understory of beech trees.
“So what’s happening now, on a very small scale, is an analog to what happened thousands of years ago,” he said, explaining that one tree is beginning to flourish in response to another one’s faltering. In other words, climate change on its own does not alter things as significantly as climate change with severe disturbances thrown into the picture — pathogens, insects, droughts, floods, fires.
As we can tell just from looking around, the beech-tree domination was short-lived; after about a thousand years oaks regained, and maintained, dominance. The only huge expanse of beech trees now is a 2,000-acre beech forest in the middle of Naushon. “It looks like a beech forest you’d see in Denmark,” Mr. Foster said. “That may be a remnant, an example of what happened.”
But beeches may be about to enjoy a serious renaissance. During the walk behind the arboretum, Mr. Foster examined the caterpillar devastation done to the oak trees, but he did not respond to it like most.
“People look at this and they say, ‘Oh, nature is damaged — we need to fix it.’ And yet, how do they usually fix it? They usually fix it by going in and creating more damage,” he said. “For example, by cutting everything down. You’ve got all these dead trees, and the natural inclination any place else would be to come in and cut them all down, because if you get in while the wood is still sound, you can make something from it. Here, though, there’s no viable timber industry, and that works out well, because from an ecological perspective, probably the best thing to do is just leave it.”
He noted that in response to the absence of an over-story of oak leaves, the beech, sassafras and catbrier are all growing like mad. “In the short term, the catbrier is going to be a real problem. But in the long term, the beeches can grow, and beech creates much denser shade than oaks, and eventually that will suppress the catbrier — if the catbrier doesn’t all grow up the beech and overwhelm it. Beeches are so much more shade-tolerant than oaks — they can grow in their own shade,” he said. “That’s why all throughout this forest there are small beeches scattered about; there aren’t a lot of small oaks. So the beeches can get established, and in this situation it’s great — the beeches will really take off with all this sun.”
He pointed out that catbrier, which is an enormous annoyance usually associated with woodland, is not actually common in well-established forests — most so-called weedy species such as catbrier are in areas that used to be pastures. “You go out in the middle of the sandplain, in the state forest, and you see very few invasive species, because those areas have always been forested,” he said.
But to return to the 15,000-year study: A standard practice in paleoecology is taking long sediment-core samples from lakes and ponds. Mr. Foster and his team have taken two such samples already. The first is from Harlock Pond in Seven Gates Farm, an area in the glacial moraine close to the ocean; the other is from Duarte Pond (the Duarte Pond off Stoney Hill Road in Oak Bluffs) on the outwash, which is flat and sandy.
“The differences are in the soil but also the terrain,” Mr. Foster pointed out. “The outwash is dry and burns a lot; hilly terrain is moist, richer, there is almost no history of fires. So we expect, and get, a different history from each sample.” Later this summer they will be taking a final sample from Icehouse Pond, which is between the two in both soil and terrain.
What do Mr. Foster and his team do with what they learn from their collected data? Since Harvard Forest gets major funding from foundations that expect them to do fundamental science, their first obligation is to get their research out in scholarly journals; their secondary obligation is to hand as much of the material off to those who can use it (state agencies, conservation agencies and the like), and then finally: “Our third obligation is to transfer it into accessible information. When we did all the work on the state forest [several years back], we did a paper that we tried to write in an accessible tone to start with,” he said. They gave the paper to organizations on the Island who would find it useful — and then gave all the extra copies to local bookstores to hand out to the general public.
Now the push is on to make the research results of the Southern Coastal Project accessible and interesting to the public, too. Mr. Foster’s presentation tomorrow night at Polly Hill is part of that push. He will talk about how different factors and forces have shaped where we are today.
The talk will include a little about archaeology, a little history, a little geology. For example, he’ll talk about the role of fire on the Vineyard over the course of the Island’s human habitation. How important has fire been, relevant to other human activities (land-clearing, or farming); how did the European settlers’ use of fire differ from the Wampanoags’; how does all of this variation shape our understanding of what fire can do in land management? Mr. Foster is not the kind of speaker who will conclude: “Therefore, we should do (insert suggestion here) with fire in the future . . .” He prefers to pose questions rather than preach answers, to ask the audience to work on it.
After all, he said, “There are many histories to any given field or forest — which history do we want to manage for? The pre-European landscape? The landscape of the 19th century, when deforestation was at its height and sheep were more numerous than people? Or do we want to manage for the future, taking into account climate change? There is no right answer to that question. Different organizations on this Island and elsewhere have different answers. I think the Vineyard is blessed by having a great combination of large and small conservation organizations that are all extremely knowledgeable in their ecology and their history. The Vineyard is distinctive in the way that all that information is used so well.”
Of course, there have also been organizations that manage without an understanding of history, but “what the history of conservation has shown is that you run into problems if you try to make nature do something it has never done before,” Mr. Foster said. “You could try to manage for something that is difficult if not impossible. If you go out into the middle of the state forest, you can find big depressions in the flat terrain. They represent a previous manager’s attempt to create duck ponds. He did that because he was trained to think about diversity, and he thought, well here’s a featureless flat plain, it needs diversity. So they dug out these large depressions and lined them with clay [and filled them with water]. And the clay has collapsed and the ponds have drained, and nobody tries to do that anymore.”
But learning from past experiments is not always that simple. Also in the middle of the state forest are big plantations of nonnative plants, especially spruce. When you plant nonnative species, you attract unusual organisms — and so the forest is now home to birds that it did not previously attract. Some management theories would argue that the spruce plantations should be cut down, because they are nonnative. “But now they support this unusual and cool collection of birds we would not otherwise have, so now we have to support them,” Mr. Foster said.
In other words, history guides, but it cannot dictate. “Because Native Americans burned the land, does that mean we should burn it? History gives you a lot of information but it doesn’t necessarily give you all the answers for the future,” he said.