- [Joe Hanson] To you and
me these look like trucks, and well, technically
that's true. But on this patch
of Oklahoma prairie, they're more like
oversized sheep dogs, except the creatures
they're rounding up are a little bigger than sheep. They're bison. Using 4x4s to chase bison might
seem like a weird new sport, but what's happening here
could actually be the key to resurrecting
a lost ecosystem. [light music] A long time ago in the heart
of the North American continent existed a vast sea
of tall grasses and millions of bison. This tall grass prairie
stretched from Canada to Texas, an area encompassing
14 present-day states. But then, stop me if
you've heard this story, Europeans came with
their guns and plows, and both the bison and
the prairie disappeared. As little as 5% of this
original prairie exists today. The largest remaining protected
area of Tall Grass Prairie in the entire world is
here in Northeast Oklahoma. This 40,000 acre expanse is known as the Tall
Grass Prairie Preserve. From horizon to
horizon, it's all grass. - [Sam] These grasses are what
we call perennial grasses. So they live year to year, and there've been reports
of perennial grasses living as much as 50 years. - [Joe Hanson] Sam Fuhlendorf
studies grassland ecology. He's found these soil
and plant communities are surprisingly complex. Some of these grasses
roots reach 15 feet deep, making them a crucial piece of Earth's carbon
storage biosphere. And there's more biological
diversity here per square meter than in some tropical forests. - [Sam] We've tried
to understand the way this system would have
operated historically and restore it as
closely as possible. - [Joe Hanson]
Before it could be preserved, the prairie had to be restored. You see it, didn't
always look like this. Not long ago, this
was a cattle ranch. Ranches prioritize
economics over ecology, which in practice means putting
as many animals on the land as possible for as
long as possible. That can lead to
destructive overgrazing. So how did this turn into this? It started with this. - [Bob] These are grasslands
evolved with grazing, principally by bison. And so if you're trying to put
Humpty back together again, you start with some
of the bigger pieces, more important pieces. Bison were the primary
historical grazer. Boom! Let's put those guys back. - [Joe Hanson]
Bison were reintroduced to this preserve in 1993. Since that time, the
original herd of 300 has grown to upwards
of 2,000 animals. These bison love eating grasses and forage for up
to 11 hours a day. - [Bob] They are essentially
a stomach with four legs. - [Joe Hanson]
You'd think all that eating would destroy the prairie, but these grasses evolved
to cope with the grazing of migratory bison. In fact, they're actually
healthier for it. Grazing bison keeps certain
plant species under control and allow others to flourish. - [Bob] They're kind
of ecosystem engineers. And so that's one of
the principle reasons we bring them back and reintroduce them to
these native prairies. - [Joe Hanson]
This preserve is managed by the Nature Conservancy. Today, Bob Hamilton and his team are bringing in the herd
for medical checkups. Dogs could get injured,
so instead they use trucks to lead the bison
into the corral. - [Bob] You have to always
be watching for the ones that are trying to cut
and turn and blow past. Hey! Hey! - [Perry Voiceover] You
can have 300 of them going, and all of a sudden one
cow tries to dart out and the rest of
them try a follow. And you just, you never know. It looks like you're a
control, but you're not. - [Bob] At point sometimes,
you and your vehicle are in the middle of this swirl. Yeah. It's just chaos. Like a little bison
bomb goes off. One of their really driving
behaviors is this herd instinct. They want to be
with other bison. They have this very
synchronized movement. And so it's like, they're
moving a big organism. So as you're moving them, it's this real
synchronized turning. It's like a school of fish. [cages rattling] - [Joe Hanson]
These 2,000-pound patients don't care much for exams. Hey, bud. It's okay. We all get nervous
going to the doctor. Who's my brave little guy? - [Bob] Well looking for
any kind of injuries. Are they still in good
shape? Are they stable? If everything goes well,
the animal is only confined for about 45 or 50 seconds, then they're kicked out and
you're onto the next one. They are kind of a
quintessential wild creature. They've never been domesticated. And one of our policies is
to respect as best we can the wildness of that species. Our responsibility, as
I see it, to the bison is to maintain their health and kind of their proper
impact on the prairie. - [Joe Hanson]
And bison aren't the only thing these prairies need to survive. They also crave fire. Bob's team burns as much as a third of
the preserve each year. That may sound like a lot, but it mimics the
ancient seasons of fire that were once common
on these primaries. - [Bob] These native prairies
have evolved with fire. If you remove fire
from the prairie, it fairly quickly
converts to a woodland. - [Sam] Many people think
fire destroys stuff, but in some of the cases
of landscapes like this, it eliminates the
dormant vegetation and it allows the new
growth to do better than it would, if the old
growth had been there. It kind of cleans the
slate periodically and allows the prairie to
truly express its growth and really be highly productive and very well suited to a bison. - [Joe Hanson] This prairie
is thriving once again, proof that the
recipe of wild bison plus seasonal fire
actually works. But okay, let's get
real for a second. We can't return all
the Midwest to prairie or restore bison to
their former glory. But the biggest benefit
of this experiment could be a bit of
new found insight. By understanding how
natural systems work, we can use that knowledge
to restore them. Here on the prairie it turns
out that the species of grazer might not be as important
as the way they graze. - [Bob] If you manage cattle in a more wild type environment, you can get a lot of the
same ecological impacts as you can with bison. - [Sam] Cattle will almost
never manage that way. So it's like bison are
allowed to be bison, and so that's what makes them
really different from cattle. - [Joe Hanson]
So allowing cattle to be a little more like bison could be one key to
restoring damaged grasslands around the world. - [Bob] We do control
the world now. And so it's ultimately
our decision on whether and some
of these ecosystems are going to persist or not. If we were to lose the prairie, we would lose an important
part of our collective history. Open space is freedom,
oh man, it's freedom. [light music] - [Joe Hanson] Hey guys,
you want to hear a joke? What did the buffalo
say to their kid before they left for college? Bye, son! Bison? Get it? Keep those comments coming. We love reading them
below every single video. Keep liking, sharing
these with your friends, and make sure subscribe
here on PBS Terra, so that you don't
miss our next one. All right, see you guys. ♪
I never understood why America didn't just keep Bison as their main livestock.
I cannot for the life of me remember where I read it, but I remember an article about a large tank training area in the Soviet Union. All the tanks driving about unintentionally simulated the herds of large animals that lived there in n prehistoric times, and a whole load of rare plants and insect populations bloomed because of it. Then the cold war ended, and it all went back to modern grassland.
Grasslands on the Great Plains have been here for much longer than human beings.
https://en.wikipedia.org/wiki/Great_Plains
"During the Cenozoic era, specifically about 25 million years ago during the Miocene and Pliocene epochs, the continental climate became favorable to the evolution of grasslands."
Enjoyed that. Thanks for sharing.
Also, for what it's worth, grasslands are going to do much better in the future unpredictable climate. That's not to say that we don't need to manage all ecosystems if we want to fight climate change; forests, grasslands, jungles, they all need to be managed much better.
https://climatechange.ucdavis.edu/news/grasslands-more-reliable-carbon-sink-than-trees/#:~:text=Unlike%20forests%2C%20grasslands%20sequester%20most,in%20woody%20biomass%20and%20leaves.&text=When%20fire%20burns%20grasslands%2C%20however,more%20adaptive%20to%20climate%20change.
"Unlike forests, grasslands sequester most of their carbon underground, while forests store it mostly in woody biomass and leaves. When wildfires cause trees to go up in flames, the burned carbon they formerly stored is released back to the atmosphere. When fire burns grasslands, however, the carbon fixed underground tends to stay in the roots and soil, making them more adaptive to climate change."
Been going on in banff national park for a few years
This reminds me of a TED talk https://www.ted.com/talks/allan_savory_how_to_fight_desertification_and_reverse_climate_change?utm_campaign=tedspread&utm_medium=referral&utm_source=tedcomshare
Take a gander at the Sandhills of Nebraska - many ranchers are good stewards of the ground with grazing as the land will then take care of you. Drastic overgrazing is a short term benefit for long-term detriment, many ranchers have finally caught on.
There's a similar episode of the PBS Nature on the reintroduction of beavers to certain native areas and how their dams preserve water (and plant life) in dry landscapes.