Tag: ecologists

The Challenge of Managing Fragmented Forests

In the Great Lakes states, many of the original forests were cut down. They were cleared for homesteading, farming, and for the wood that fueled the age of steam. But over the past several decades, some of the forests have been growing back. Many of the new forests are confined to small patches or woodlots surrounded by farm fields. These woodlots are small havens for animals. But some foresters, biologists, and environmental groups are concerned that those forests are simply too small and too fragmented. The Great Lakes Radio Consortium’s Cristina Rumbaitis-del Rio prepared this report:

Transcript

In the Great Lakes States, many of the original forests were cut down. They were cleared for
homesteading, farming, and for the wood that fueled the age of steam. But over the past several
decades, some of the forests have been growing back. Many of the new forests are confined to
small patches or woodlots surrounded by farm fields. These woodlots are small havens for many
animals. But some foresters, biologists, and environmental groups are concerned that those
forests are simply too small and too fragmented. The Great Lakes Radio Consortium’s Cristina
Rumbaitis(rum-bite-us)-del rio (del-rhee-o) prepared this report:


(Natural sounds – walking through leaves underneath) & Thomas Grubb talking:
“This little woodlot is large enough to house one pair of downy woodpeckers and one pair of
white breasted nuthatches.”


Thomas Grubb is a Biology Professor at Ohio State University. Instead of lecturing to a classroom
today, he’s strolling through a small, private woodlot next to a cornfield in central Ohio. This is
one of the study sites where he looks at how forest fragmentation affects woodland bird species.


He says just as in many areas of the Midwest, Ohio’s forests are highly fragmented because
instead of having the forest concentrated in one big area, the forests are carved up into small
patches, scattered throughout a largely agricultural landscape. While 90% of Ohio was covered
with forest before European settlement, now less than a third of the state is considered forested.
And according to Grubb, this part of Ohio has even less forest.


“This plot is about 3% forested and that’s not much forest. This landscape is probably as little
forested as any you’re likely to find.”


Grubb and his students are working with woodlot owners to see if the size of a woodlot affects
the number of birds living there and their survival. He says bird survival is better in larger
woodlots than in smaller ones.


“One of the things we think is happening in these small woodlots, these permanent resident birds
that are there all winter- they can’t get out of the wind, and so they have tremendously high
metabolic rates trying to stay warm.”


Smaller woodlots may be colder than larger ones because there’s fewer trees to block the wind.
Smaller woodlots also have less food for birds, and in the winter birds may starve trying to get
enough food to stay warm.


(Natural sounds of leaves and birds)


“Oh that’s a Carolina Wren.”


Forestry officials, scientists, and environmental groups agree forest fragmentation is one of the
most serious problems facing Ohio’s forests. Fragmentation is a problem for a number of reasons
beyond the fact that it represents a loss of forest habitat. According to Ohio State University
Ecologist, Ralph Boerner, the smaller a forest patch is, the fewer number of species that can live
there.


“The smaller a forest patch, the less diverse it is. And you particularly lose species that need
large areas in which to gather food.”


Boerner says smaller patches may also have a harder time recovering from disturbances – like an
insect outbreak or a tornado.


“We also believe there is a link between how diverse an ecosystem is and how stable it is in the face of disturbnace, so when you lose diversity there’s the potential to lose stability, lose the ability to bounce back
from disturbance.”


Breaking up the forest into patches also isolates animal and bird species that can’t or won’t cross
agricultural fields to get from one forest patch to another, and that means less genetic diversity
because they can’t mate with animals outside of their forest patch. So some woodlots are just too
small for certain species to survive.


Fragmentation also makes managing forest land more difficult. Most of Ohio’s forested land is
privately owned. Ohio Division of Forestry official, Tom Berger, says this makes managing
almost an impossible task.


Well, you’ll have 10 people and they’ll have 10 different views on how to manage it or what’s
valuable to them and they all have that right.”


Division of Forestry officials can give landowners advice, but they can’t tell a landowner what
their priorities should be. Berger says this often means neighboring patches of forest are managed
for completely different interests. Berger wishes he had more tools at his disposal to get land
owners to manage their land collectively.


“I wish we could put together some programs or some incentives, monies available through the
state or federal government that would really encourage landowners to work together to form
blocks or units that would be managed in the same way.”


Managing isn’t the only challenge. Berger says keeping the land at least partially forested is
becoming a problem as people choose to build homes in woodlots, particularly in areas near
cities.


“Not only is the woods scattered that we have fragmented, but a lot of them continue to
disappear too, especially in the urbanized areas in Columbus and around the state.”


Ohio State University Biologist, Thomas Grubb, says there are may reasons for protecting
woodlots, but his favorite reason is because it’s a pocket of nature in a sea of developed land.


“This is worth preserving just because it’s like it is and we ought to just leave it alone. This enriches our lives.”


The average woodlot size in Ohio is 20 acres, and it changes hands frequently – every seven years on average. The small size and the quick turnover make it nearly impossible for the state to
encourage owners to establish any kind of useful management practices. That means there’s little
to be done to help keep the forests from further deterioration.


For the Great Lakes Radio Consortium, I’m Cristina Rumbaitis-del Rio.

GAUGING MANKIND’S ECOLOGICAL FOOTPRINT

In the wake of the World Summit on Sustainable Development in Johannesburg, South Africa, there’s been a lot of talk about how to balance human needs with the health of the planet. Ecologists have been trying to measure the impact of humans on the environment for a number of years, with some sobering results. The Great Lakes Radio Consortium’s Daniel Grossman went to the New York Botanical Garden recently to gauge mankind’s ecological footprint:

Transcript

In the wake of the World Summit on Sustainable Development in Johannesburg, South
Africa, there’s been a lot of talk about how to balance human needs with the health of the
planet. Ecologists have been trying to measure the impact of humans on the environment
for a number of years, with some sobering results. The Great Lake Radio Consortium’s Daniel Grossman went to the New
York Botanical Garden recently to gauge mankind’s ecological footprint.


[Rain forest sounds, misters, tinkling of water, rain falling on leaves]


To get a good sense of the impact humans are having on earth, you could travel for weeks
on intercontinental plane flights, river boats and desert jeeps. Or, as Columbia University
biologist, Stuart Pimm suggested, visit a botanical garden. There, under the glass and
ironwork of a conservatory, Pimm says you can see a resource that humans are
over-using – Earth’s most important resource, its plant-life.


“We’re sitting in the rain forest here at the New York Botanical Society. And it’s a riot of
green.”


Professor Pimm says here beneath the misters in the Tropical Rain Forest Gallery is a
good place to start a whirlwind tour of Earth’s greenery. The air is heavy with moisture
and sweet-smelling.


“Rain forests are some of the most productive parts of the planet. They grow extremely
quickly and they are therefore generating a lot of biological production.”


What Pimm calls biological production most of us know as plant growth. Biologists say
all this green growth in tropical forests and elsewhere on Earth is the foundation upon
which all life rests.


“Everything in our lives is dependent upon biological productivity – everything that we
eat, everything that our domestic animals eat.”


And everything that every other animal eats as well. In a recent book, Pimm painstakingly
tallies up how much biological productivity we use. He starts with the rain forest. In the
last 50 years, loggers and settlers have cut down 3 million square miles of lush tropical
forests. Much was cut down for subsistence agriculture, a purpose Pimm says it serves
poorly.


“Although the tropical forest looks rich and productive, it is a very special place. And
when you chop that forest down the areas that replace it often become very, very much
less productive.”


[Sound of walking around conservatory]


Pimm speaks of the toll on greenery of cities and roads and of land converted to farming
in temperate regions such as the U.S. Midwest. Then, trekking along the botanical
garden’s gravel paths, he leaves behind the tropical mists and steps into the dry heat of a
Southwestern desert. Deserts and other dry lands are not very productive, but they
account for a substantial fraction of Earth’s land surface. Most of it is grazed by flocks of
sheep, goats, camels and cattle, often causing severe damage to vegetation. When these
uses are added to the other impacts of humanity on earth’s bounty, the results are
surprisingly large.


“What silence has shown is that we are taking 2/5ths of the biological production on land,
a third from the oceans. And that of the world’s fresh water supply, we’re taking half.”


[Fade out sound of conservatory. Fade up sound of Texas frogs.]


[Sound of plane engines]


Frogs and toads croak out a spring mating ritual in a concrete drainage ditch. Nearby, a
pilot practices maneuvers in a small plane occasionally drowning out the amphibian
serenade. Living in culverts, sharing the night with droning engines, these wild animals
are never completely free of human influences. From his Stanford University office,
Professor Peter Vitousek says wherever you look, the din of human activities is
interrupting and crowding out other species. Vitousek made one of the first attempts to
tally the impact of people on plant productivity in 1985.


[Frogs fade out in time for Vitousek’s act]


“The message to me was that we are already having a huge impact on all the other species
because of our use of the production of Earth and the land surface of Earth. That’s not
something that our models predict for some time in the future or something that we’re
guessing at on the basis of fairly weak information. It’s something that we’re clearly
doing now. That’s already happening.”


Many ecologists say this conclusion is beyond doubt. What they can’t say is whether
human domination of so much of nature’s output is good or bad. University of Minnesota
Professor David Tilman says as a member of the human race himself, he appreciates the
comforts in clothing, shelter and food our lifestyles buy us. And he acknowledges that the
survival of our own species is probably not imperiled – at least for the moment – by the
destruction of others. Still, he wonders if someday we’ll regret today’s resource intensive
practices.


“I think the more relevant question to me is, ‘Are we doing this wisely?’ ‘Are we wisely
appropriating the resources of the world?’ So, my concern is that we live in a balanced
way – a way that is sustainable through generations – that we leave our children and
grandchildren the same kind of world that we have.”


An expert on the impacts of agriculture, Tilman says we’re using up more resources than
can be replaced. He says if we don’t grapple with these important issues now, by the time
the human population reaches eight to ten billion or so people later this century, it might
be too difficult for us to do enough to save the planet’s life as we know it today.


For the Great Lakes Radio Consortium, I’m Daniel Grossman.