Discerning ecosystem changes over the last
a great puzzle trying to figure out how an ecosystem works."
"For me, it's about solving a big mystery," says Cathy
Whitlock, describing her work as a paleoecologist at Montana State
University. Whitlock studies the environments of the past, using
pollen and charcoal remains from deeply buried lake sediments to
understand how plant communities and climates have changed through
time. Information about how ecosystems looked and operated
thousands of years ago, she hopes, will also help society prepare
for the future.
Whitlock has long been intrigued by the
recent geological past. An avid hiker, she often uses her time on
the trails to ask herself, "How did the ecosystem get to be like
this? What explains the mosaic of trees?" She studied geology as an
undergraduate at Colorado College and as a graduate student at the
University of Washington, where she focused on "the younger side of
geology" — the 20,000 years following the last ice age. After
14 years as a professor and researcher at the University of Oregon,
Whitlock moved to Montana State University last July.
understand the past, Whitlock and her graduate students wade into
present-day wetlands, bogs and lakes, located throughout the
coastal rainforest of Oregon, the Northern Rockies and the northern
They take samples at these longtime study
sites by maneuvering a long sediment-coring "barrel," which looks
like a metal pipe, into the muck and mud. Then, they muscle the
barrel out of the sucking lake sediment, securing a sediment core
just a meter long and 5 inches wide.
The cores are taken
into the lab, sliced into sections about as thick as Oreo cookies,
and examined under a high-resolution microscope. Each section
represents approximately a decade of deposition, and contains a
mixture of lake sediments, including charcoal and pollen from a
variety of plant species. Whitlock's practiced eye readily picks
out pine pollen, which is shaped like miniature Mickey Mouse heads,
and she can also distinguish the pollen of white pines from that of
two- and three-needle pines.
By identifying pollen and
dating charcoal deposits, Whitlock pieces together vegetation and
fire patterns. For example, her research indicates an abrupt and
widespread arrival of lodgepole pine in the Northern Rockies 11,000
years ago. "It suggests a rapid warming, and a shift towards more
fires," she says. At the same time, Douglas-fir was appearing
across the Pacific Northwest, spreading throughout the region in a
matter of a few centuries. "When the climate warmed, it was
suddenly everywhere," she says. "It is remarkable to think that our
most common trees were once so sparse that we can't locate their
whereabouts during the glacial period."
environmental transformations may foretell the future. Increased
greenhouse gas concentrations will likely cause deeper droughts and
warmer temperatures in the West. As Whitlock's evidence suggests,
forests respond dramatically to such climatic shifts: While
high-elevation trees such as whitebark pine may decline, other
species may thrive in new places. "The future for lodgepole pine is
probably bright," she says. "It's a real weed."