EMILY BERNHARDT: A ghost forest is a very clever name
for a kind of unfortunate new habitat type
we're seeing growing on the coast.
It's a place where you have a lot of dead trees.
Large areas of contiguous forest that are just gone.
RYAN EMANUEL: My emotional response
is to mourn the loss of those trees.
But scientifically, I say, what was the combination of stresses
that caused this particular stand of trees
to bite the dust?
MARCELO ARDON: We've been doing this now for close to a decade.
And in that time, we've already been seeing changes.
If these things are changing on a timescale where I can see it,
what's going to happen for this landscape by the time
my kids grow up?
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My name is Marcello Ardon, and I study
ecosystem ecology and biogeochemistry
of streams and wetlands.
EMILY BERNHARDT: And I'm Emily Bernhardt,
and I am a biogeochemist and aquatic ecologist.
RYAN EMANUEL: And I'm Ryan Emanuel, and I'm a hydrologist.
EMILY BERNHARDT: Believe it or not, back in 2004,
this was a really large 440 acre farm
that was purchased by a group of developers who decided
to turn it into a wetland.
Because we were studying this wetland restoration project,
didn't even occur to us that saltwater would get here.
And we recognized a year after the first intrusion event
happened, that we had gotten to near brackish conditions
in much of this wetland.
MARCELO ARDON: And that's what kind of led us
into this research of saltwater intrusion,
and trying to understand if the patterns we had seen
in this restored wetland were also
happening in the broader area of the Albemarle-Pamlico
Peninsula.
RYAN EMANUEL: The Albemarle-Pamlico Peninsula
is a landscape dominated by water.
EMILY BERNHARDT: So we have the Pamlico Sound the south
and the Albemarle Sound in the north.
We have the big Alligator River sort
of cutting down through the middle of this peninsula.
MARCELO ARDON: Ecologically speaking,
this used to be all dominated by wetlands.
Tends to have very organic rich peaty soils,
and it's system that would sequester a lot of carbon
in the soils.
RYAN EMANUEL: The Albemarle-Pamlico Peninsula
has a history of large scale commercial agriculture.
Vast tracts of land that are used for corn, soybean, crops
like that.
EMILY BERNHARDT: Really pretty late
in the '60s, '70s, and '80s, huge parts
of the coastal plain forested wetlands
were drained with sort of mechanized drainage systems,
canals, ditches, et cetera, to pump water off and keep
them dry enough to farm.
RYAN EMANUEL: No matter where you go on the peninsula,
you can see some type of artificial drainage
infrastructure.
MARCELO ARDON: You can even use Google Earth and Google Maps
and you can see some of these changes on your computer.
RYAN EMANUEL: Even though they were
made to drain water from the interior out to the estuary,
there's the potential for them to serve the opposite purpose.
You can have storms that push saltwater deep
into the interior, often through ditches and drains
that may not have flow control structures
or other protective measures.
EMILY BERNHARDT: Now when you have a drought,
the sounds get saltier, in part, because they're evaporating,
and in part, because they're not getting
fresh water off the landscape.
So you start to see the salts mixing up.
RYAN EMANUEL: You could actually have gradients of saltwater
that penetrate deep into the interior through these
ditches and drains.
One of the impacts of climate change
is a likely increase in the number and severity
of droughts, and the intensity of storms.
In both of those cases, we're actually
influencing different types of saltwater intrusions.
EMILY BERNHARDT: The thing that's actually happening,
is that salt is getting into a landscape
and killing individual organisms,
be they trees or microbes.
So it's actually happening at a very granular scale.
But what we want to know, and I think what most people want
to know, is how the coast of North Carolina
is going to change as a result saltwater intrusion.
Well, our team is a hydrologist, two biogeochemists, a plant
ecologist, and a social scientist,
all trying to think about how can we bring our expertise
to bear in it's really multi-layer difficult question.
RYAN EMANUEL: We're collecting data
from more than a dozen sites around the peninsula.
MARCELO ARDON: So we measure the water chemistry,
we measure the water level, nutrients
are there, how much salt is in there.
We also monitor the soils, the chemistry of the soil.
We look at the greenhouse gas emissions.
And then we've also started measuring greenhouse gases
from trees.
Is the tree functioning like a chimney?
So is it taking gases that are being produced
by microbes in the soil and releasing them out
into the atmosphere?
Or is it more like a cork?
And is it actually helping to keep gases
that the microbes are producing in the soil within the soil?
RYAN EMANUEL: All of these things
are monitored continuously at a handful
of sites around the peninsula.
But we also have hand-held tools that we
can use to make spot checks as we drive around broadly.
EMILY BERNHARDT: What we would really like to do,
is link what we're seeing with vegetation,
areas where we know there's salt water intrusion occurring,
to what we're seeing in the soil.
So yes, there's salinization here,
this is what the trees do when that happens.
We really wanted to have a little bit more control.
And if you want to have control as a scientist, what you do,
is an experiment.
So we're adding salt alone, and salt
with nutrients, and nutrients alone,
and we're trying to understand if we
keep doing that, what happens.
Do leave seem stressed?
Are they water stressed?
If we can start to see those things from space,
we could detect salt water stress at a much larger scale.
MARCELO ARDON: Using geospatial data,
we can try to see if what we see in these small places
are going to apply to a much larger area.
RYAN EMANUEL: We're currently using digital elevation models
to assess how vulnerable the landscape is to salt water
intrusion.
We're using these algorithms that
tell us how water concentrates and flows across the surface,
and how connected or disconnected different parts
of the landscape are to one another.
Combining those metrics in ways that
allow us to come up with an estimate of vulnerability.
And when I look at those maps, I get
a sense of the magnitude of this problem.
Some of those salts can stay behind in the soils.
So you may see reduced yields in crops.
And there are forests nearby.
That could be one of the factors that leads
them to become ghost forests.
We think that ghost forests are spreading
throughout the Albemarle Pamlico Peninsula
and throughout many parts of the eastern US.
The pace of sea level rise and the intensity
of human modification of the landscape
have accelerated that process.
I've worked on a project where the change is happening at
such a rapid time scale.
MARCELO ARDON: It is possible that we might not fully
understand this problem before it's too late.
So this area is actually one of the highest sea level
rise rates in the country.
EMILY BERNHARDT: You could be very fatalistic
and say, just let it go underwater.
And I think that would be unfortunate if that's
the decision that we make.
There's the enormous standing stock of carbon in the trees
and the soils of all these coastal wetlands that could
be lost back to the atmosphere.
And then there's the biodiversity loss.
If we lose these so fast, we're just
going to lose this really important eco region.
Where we can be hopeful, is that there
are a lot of things that we could
do to manage this landscape differently than just
abandoning it to the sea.
RYAN EMANUEL: One of the things we
hope to do with our research, is to provide decision-makers
with tools that they can use to potentially mitigate
some of the effects of saltwater intrusion
that are caused by ditches and drains.
MARCELO ARDON: Rather than being an on or off switch, where
it has to be either we build a ditch or we plug it,
can we find ways where we allow water to move in one direction,
but not maybe allow it to move in another direction?
Or even maybe trying to figure out
if there are maybe crops that would be more salt
tolerant that are growing out here.
And the same thing for these wetlands.
So restoring it to what used to be here historically
is probably not going to be the smartest idea.
And starting to think about what species are going to do well,
can we use those species for restoration?
If you have ecological collapse, you're
going to have agricultural collapse.
But I tend to be an optimistic person.
And so I hope that people that are making
the decisions to make changes are going
to hear what we have to say.
RYAN EMANUEL: If we do nothing and we continue to farm,
we continue to build infrastructure
as if these forests and these systems are not
going to change, then we might be
in for some really rotten surprises in a few decades.
EMILY BERNHARDT: I think humans can have a huge impact on both
whether new ghost forests develop,
whether current ghost forests expand,
and also what happens now, once a ghost forest exists
on the landscape.
Do we leave them?
Could we manage them in a way that we might actually
move more rapidly into a sort of a salt marsh ecosystem?
I think there's a lot of interesting decisions
that we could begin to make.
They're not going to be forests in those places probably again,
but they might be something equally
interesting and beautiful.
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