The Volen Center focuses on a wide variety of complex
systems and Dr. Perlman proposed that ecosystems represent
another type of complex system worth studying. If we consider
just a single place on the Earth’s surface—such as eastern
Massachusetts—it quickly becomes clear just how many factors
have affected the ecological landscape that we see today.
It is relatively easy to see many of the ecological and
geological histories that have created our region. For
example, with little effort one can find throughout the
Boston area examples of Roxbury Puddingstone (or conglomerate),
a rock formation that dates from the pre-Cambrian time
over 500 million years ago, when multi-celled animals
were first appearing on the planet. However, our region
is not uniform in its geological history. The eastern
half of the state arose from the southern continent Gondwana
or island arcs near Gondwana, while the western half of
the state developed from the northern continent Laurentia.
In addition, although the bedrock of most of the state
is hundreds of millions of years old, Cape Cod is some
of the youngest land on the planet: it was deposited by
the most recent glaciers to cover our region. When the
glaciers eventually withdrew about 12-14,000 years ago,
they left behind the Cape as piles of sand and rock that
had been brought in from the north. Thus, within a space
of less than a hundred miles we find three very different
geological origins strewn across the state.
Once the geological changes settled down, and as the
glaciers withdrew, the most recent set of ecological changes
(those we can see best) began. As the glaciers receded
and left the barren landscape that would become Massachusetts
uncovered, the land was first colonized by plants and
lichens similar to those of today’s Artic tundra. Just
a couple of thousand years later humans began to colonize
the area; because humans inhabited Cape Cod less than
2,000 years after it was formed, nearly all of the Cape’s
existence has included humans as a major influence.
The single most striking ecological feature of the eastern
Massachusetts landscape since the glaciers left has been
drastic change. As the edge of the glaciers moved further
north, a series of plant communities migrated into the
region and then passed on to the north. After the tundra
plants passed through, the land was covered by a succession
of spruce forests, pine forests, and deciduous forests.
About 5,000 years ago the hemlocks that had been a dominant
part of the forest suffered a rapid and calamitous decline
that lasted a thousand years, and chestnut trees, which
became dominant over much of the region, only arrived
about 3,000 years before present. Just 2,000 years later,
Native Americans began practicing agriculture in earnest
across much of the region, and several hundred years later
Europeans began to write their own ecological changes
on the landscape, clearly most of it by about 1850. From
the written history of the nearly 400 years since European
settlement, we also know that our region is regularly
buffeted by massive hurricanes that knock down large swathes
of forest, opening the landscape up for regrowth and regeneration.
In short, the unbroken, untouched forest primeval of our
histories and imaginations was not even fully assembled
until the era of the Trojan War, and it has never been
as unchanging and pristine as we once thought.
In the past century and a half, as the wave of farming
moved west, our forests began to recover so that today
most of Massachusetts is heavily forested. Human commerce
has vastly increased the rate of movement of plants and
animals across the planet. However, we have seen Chestnut
blight turn one of our most magnificent tree species into
a band of tiny, shrubby fugitives that exist for a few
years until they succumb to the fungus; the Dutch elm
disease has wiped out the American elms that graced our
forests and so many of our city streets; and many other
exotic caterpillars such as the gypsy moth and winter
moth attack the deciduous trees of our forests.
Although Massachusetts is not known globally for its
biological diversity, even this brief look gives a sense
of the ecological and geological complexity of our small
corner of the world. Our forests—even the small Sachar
Woods of the Brandeis campus—reveal this history to those
who take the time to look.
