(dramatic music)
-: Prairie systems and grasslands
around the world are owed to fire.
Now in this system we've done something in addition.
Not only did we change how fire functions
to control something like cedar,
it's increased more rapidly because we introduced
seed sources at an unprecedented scale.
There was no way for a rare plant
to produce this amount of seed
without us introducing that seed
to areas where it wasn't there before.
If you look back historically,
it was so difficult to get trees
established in these grassland ecosystems.
I mean they were such expansive,
inhabitable regions for trees,
and so people put in an extraordinary amount of effort
of planting unsuccessfully, bringing in water.
It was so hard to get established in the first place.
It wasn't thought that they could end up being
self-sustaining and propagating.
So that's often talked about as an adventive species.
An adventive species is one where we can establish it
through a cultivated practice,
but it doesn't spread and self-propagate on its own.
A hundred years ago, that's what cedar was thought to be.
So when we established windbreaks,
you can put in this windbreak for a local benefit,
and it won't have this spread and cost.
Bessey in the late 1800s said that
the only real negative of eastern redcedar
was to apple rust.
So you get these local benefits,
and the only real negative is apple rust.
So we can have this great benefit of a planted windbreak
that will add and increase the well-being of this region.
Well now, scientists over the last 60, 70 years
have been showing that that assumption is not correct.
If you only talk about local benefits,
you're ignoring what's come at a cost,
and that cost has changed since we started doing this
in the late 1800s, early 1900s.