Back in 2022, we dug a series of channels
to flood an area of
forest next to the Danube
River.
We did this to help a struggling
ecosystem that has been in
decline since the construction
of a dam, and the results were immediate.
For almost two years, these channels have
been bringing water to
this floodplain forest
twice a year, during the
spring and the summer floods.
But this year,
something unexpected happened.
The forest flooded in winter.
In January, the whole wetland was
suddenly full of water, and then the
water froze, creating
this strange and enchanted icy landscape.
It's really just a crust that's kind of
hanging sort of in
midair, and as you walk
on it, it breaks, but
there is no water underneath.
So in this video today, Adriana will put
on some ice cleats to walk
you through our slippery,
frozen, flooded forest, and we'll also
investigate this rare
phenomenon, because it turns out
that ice might be more important for the
health of this floodplain
ecosystem than we previously
thought.
Now, I guess you might be wondering why
we are so thrilled about
seeing this place flooded.
It's a floodplain after all, and the
water is supposed to be there, right?
Well, yes, but this floodplain was cut
off from its river by the
dam, and has been drying
out ever since.
If you want to know more about what
happened here, I invite
you to watch the first video
in this Flooded Forest series we have
here on the YouTube channel.
It will explain
everything in more detail.
What you need to know now is that the
floods that were once
natural here are now controlled
and timed by people.
The whole floodplain area is now fed
water from this
artificial channel through this
inflow here, and the water is distributed
to different places
through a series of channels,
including the ones we constructed with
our Slovak partners, Broz.
These human-controlled floods are done
twice a year, one in the
spring and one in the summer,
to help wetland species during a crucial
time of growth,
reproduction, and nesting.
But from time to time, the roles still
reverse, and the river calls the shots.
When the Danube brings exceptionally high
amounts of water, the
dam operators have to
release some of it into the old riverbed
to take the pressure
off the hydropower plant.
The mass of water can also push back up
the old river and fill
the floodplain from the
bottom.
This combined effect causes the water
level in the old Danube
to rise, and a flood is
born.
The kind of flooding is common in the
summer, when high rainfall
combines with the snowmelt
from the Alps, causing
water levels to rise rapidly.
Witnessing a flood like this in the
winter, though, is much rarer.
So basically, two
quite rare things happened.
There was a lot of the water in the
Danube, so our forest got
flooded, and then it was
freezing.
So basically, this beautiful crust of ice
formed over our
forest, and this is how we
ended up with this
incredible frozen forest.
The last time this forest flooded in the
winter was 18 years ago.
So you can imagine our excitement, and
especially Sigi's excitement.
He is the one responsible for restoring
this area, and this
forest is kind of like his
second child.
So when Adriana first went to visit the
forest, it was just for
the sheer joy of experiencing
this icy spectacle, and also capturing
some shots for you guys to see.
It's pretty cool to see
it frozen over like this.
I've never actually been
here in the winter before.
These are little icicles that are kind of
hanging beneath the
ice, like little polka
dots.
So you can see on this ice mark here on
the tree that the water
level was a lot higher
last week, but it's
been retreating slowly.
But after a day immersed in this icy
world, she was hooked and
wanted to know more about
this little-known phenomenon.
Coincidentally, the following day, the
Bratislava City Museum was
putting on an evening lecture
about ice floods on the Danube, and that
gave us some answers.
It turns out that ice and winter floods
used to be a common thing on the Danube.
Records from the past three centuries
revealed that the river
would freeze over very often.
It was pretty much a yearly occurrence,
and often the river would
freeze in its full length,
all the way from
Austria to the Black Sea.
The ice flows that formed on the river
could be several meters
high, and to fight it, people
deployed icebreakers and
sometimes even explosives.
For an instance, in the winter of 1947,
the Air Force dropped
250 kilograms of bombs on
the ice, just below the city, in an
attempt to break it,
but it had little effect.
People were fighting the ice because as
it accumulated, it
would often create a kind
of log jam that clogged up the river and
could cause flash flooding.
These ice floods were catastrophic and
could level entire
villages to the ground.
But the frozen river was also celebrated
as a natural part of
life because people used
to enjoy crossings in the river on
horse-drawn carriages called Eisweg.
Today there are still three icebreakers
around, named Brezno,
Krupina and Dunaj, but they're
not so busy these days, because the
winters on the Danube have changed.
The last big ice was recorded 70 years
ago, and 2017 saw the
last ice flows form on the
Danube.
Part of this is because of good
old climate change of course.
But the river itself also changed, it has
been modified to be
deeper and faster, making
it harder for the ice to form.
And although the flood that froze in our
flooded forest is really
interesting, it is quite
different from these
historical ice floods.
And the loss of these floods actually
opened some interesting new
questions about the meaning
of ice.
Remember when Adriana said that she
hadn't visited the
forest in winter before?
Well, that's part of the problem.
Ecologists tend to focus their research
on the growing season,
but what we know about
ecosystems in the summer cannot be
applied to them in the winter.
This leaves us with a whole season that
is significantly understudied.
So the truth is that we don't actually
know much about the
ecological role of ice in the
river and ecosystems, but those studies
that have looked into
this show that what happens
here during the winter has an effect on
how things unfold throughout the year.
Experimental studies from rivers in
Sweden show that areas
that are flooded and covered
in ice during the winter grow a richer
understory with more
species of wildflowers.
And more than half of all large rivers
are seasonally covered in ice.
And for these rivers, ice is a force that
has the power to both
create but also destroy.
So this scar here really gives you an
idea how much power
even a small amount of ice
can have.
It really took off the top layer of the
bark as it encased the tree.
Quite impressive.
Now imagine the power of large ice blocks
drifting through the
riverine landscape, eroding
soil, redistributing sediment and
scouring any vegetation
that stands in their way.
This might sound like a scene of
destruction, but where some
species are displaced, others
find opportunity.
It is often like this in nature, and this
constant change makes
the river floodplains
one of the most diverse and productive
ecosystems on earth.
So ice is probably more important for the
ecology of rivers than
we give it credit for.
But in addition to that, it might have a
significant effect on
our forests this spring.
So last winter the channels were
completely dry throughout
the whole winter, basically.
And we're hoping that because there is so
much water here now, if
the ground stays saturated,
then when we have the spring floods, we
should see an even bigger effect.
It is really exciting to be headed
towards the third flood
of this project with this
extra potential surprise in the back.
The impact that this project has had in
reviving this ecosystem
has been amazing to witness.
It has been an absolute
pleasure to be a part of.
And if you've enjoyed the ride so far,
please remember that you
could support our work and
projects just like this one
by becoming a Mossy Earth member.
We set up all kinds of impactful projects
that restore and
rewild nature, from native
oysters in Scotland to the rainforest of
the Amazon, all the
way to the coral reefs of
Indonesia.
We're really hard at work across more
than 20 projects to
help bring back wild native
ecosystems.
And becoming a member is cheap because we
want as many people as possible to join.
And when we put it all together, your
money goes a really long way.
And if this is a big step for you right
now, then please consider
subscribing to the channel.
It is a great zero cost
way to help us out as well.
I hope you enjoyed the walk
through the frozen forest.
But now I'm the one who is frozen, so
it's time to go home.
See you next time.
Ciao!