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- Welcome to the start
of our second day of the

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Forest Ecosystem Monitoring
Cooperative conference,

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focused on revealing a
changing forested landscape.

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Today, we are diving
into what we can learn

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through an intensive
study and manipulation

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in a small well-studied area.

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Our ability to manage
forest in the face of all

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the overlapping intersecting challenges

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is gonna require both depth and breadth.

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We're gonna need depth
in our understanding

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of why ecosystem function
the way that they do

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and breadth to understand
how that functioning

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varies across the landscape.

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As a region, we're fortunate
to have so many diverse efforts

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tracking both sides of this
coin, both depth and breadth.

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And so today I'm excited
to have with us an expert

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to walk us through one of our
longest running experimental

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sites in the Northeast.

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I invite all of us to begin to ponder

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how to take decades of research forward,

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so that we can address monitoring

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and landscape-scale management
issues that await us.

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I'm pleased to welcome
Dr. Charles Driscoll

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to the FEMC conference this year.

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Charles Driscoll is a distinguished
and university professor

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at Syracuse University.

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His work focuses on the
effects of disturbances

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on forests, urban freshwater
and marine ecosystems,

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including air pollution, such
as acid and mercury deposition

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land use and climate pollution,

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let me say and climate change.

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His current research
focuses on the recovery

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of use of forest watersheds,

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from acidic deposition,
co-benefits of carbon dioxide

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emissions controls, ecosystem restoration,

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and responses to climate
change, harmful algal blooms,

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atmospheric deposition,
watershed and surface water

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transport and biotic exposures to mercury.

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It's a quite a range.

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Dr. Driscoll's talk is titled;

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Effects of Changing Atmospheric
Deposition and Climate

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on the Structure and Function
of a Northern forest,

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long-term measurements and experiments

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from the Hubbard Brook Experimental
Forest in New Hampshire.

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Charlie, thank you for being here today

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and thank you to all of our attendees

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for joining us on a second day.

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And we look forward to your talk.

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- Thanks Jim, and good morning

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so as Jim said, I'm
gonna talk a little bit

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about Hubbard Brook,

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a little bit of background
information on the site.

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It's an intensive study site.

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It's been going since the
1950s, and talk a little bit

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about our research
approach and observations.

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I'm gonna highlight long-term measurements

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and experiments.

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We also do other types of approaches,

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but in the interest of time,

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I'm gonna just focus on those two.

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And I'm gonna touch on two
major issues that we focus on,

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air pollution effects and climate change,

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and then I'll close.

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So undoubtedly, many of you
are aware of Hubbard Brook.

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It's a US Forest Service
intensive study site.

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It's about 3000 hectares.

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It's located in Central New Hampshire.

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It was established in the fifties
to investigate the effects

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of forest harvesting on water
supplies in New England.

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It was a lot of conflicting
information at the time.

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So it was thought to be in
a place where experiments

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could be done and long-term
measurements could be made.

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So the focus was primarily
on water resources hydrology.

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Then in the sixties, Bob Pierce

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invited Gene Likens and Herbert
Bormann, Noye Johnson to

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take their students and their
research to Hubbard Brook,

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and that was the start of the
Hubbard Brook Ecosystem Study.

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So it was initiated in the early sixties

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and it started with measurements
of precipitation chemistry

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and stream chemistry and
some initial experiments.

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And so Hubbard Brook was
a site where acid rain

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was first reported in North America,

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and it's been since the late seventies,

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a National Science Foundation

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funded long-term Ecological Research Site.

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So this is what the Hubbard
Brook Valley looks like.

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It's a sort of a bowl-shape
area if you haven't been there.

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There are a series of
experimental watersheds

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and most of the work is done
at the experimental watersheds

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but valley wide surveys are also prominent

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within the research portfolio.

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So this is a list of the
experimental watersheds.

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They don't really have any exciting names,

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they're just numbered.

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They're moderately sized

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ranging from about 10 to about 70 hectare.

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And some of them have had experiments done

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but some of them are referenced.

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So I'm gonna show you results

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from two reference watersheds,

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watershed six which is a
biogeochemical reference watershed

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and watershed three,

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which is a hydrologic reference watershed.

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So you might ask why Hubbard Brook

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has two reference watersheds.

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I can't really give you
a good answer for that,

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it's just sort of a throwback

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to what has been done historically.

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I'm also gonna talk a little
bit about an experiment

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that we did in the started
in the late nineties

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and continue today, what we did

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at Calcium silicate in
addition to watershed one.

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So the backbone of work at Hubbard Brook

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is the small watershed approach.

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And this was the approach
that was initiated

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by Bob Pierce colleagues back,

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when Hubbard Brook was started.

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And it's a fairly simple idea.

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And so within areas of the
landscape, such as shown here

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measurements of precipitation are made and

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a gauging station is put in,

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which is anchored to a bedrock

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to try to collect all the water

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or most of the water
that feeds the system.

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So water balances can be done

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measuring the precipitation
inputs in the stream outputs

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and then, by difference
evapotranspiration could be obtained

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and what Bormann and Likens did

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to expand that was to take
these hydrologic measurements

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and superimpose on those
chemical measurements.

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But since that time, additional
things have been done.

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There've been vegetation
surveys, microbial assays.

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There's a lot of work done on

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insects and birds by colleagues,
largely from government

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and Wesley college, other
institutions, Buffalo Smithsonian.

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So we try to take an ecosystem approach.

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So this is just the slide
showing you a design

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of a bulk precipitation
collector, much like the ones that

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were done used back in the early sixties

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the first to measure acid rain.

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So the chemical inputs as
well as the water inputs,

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to the system and then a
gauging station at the base

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of the watershed.

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So this is the, what the gauging
station of watershed six.

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So a little bit of background
information about the forest.

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It is underlined by resistant
bedrock, low weathering rates.

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The area was glaciated
like much of the region.

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About 14,000 years ago, the
soils are rather a civics

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Spodsosols, although there
is variability depending

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on their position in the landscape.

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And we've learned quite a bit

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about that in, in recent
years, thanks to Scott Bailey

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from the Forest service and colleagues.

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The forest is largely Northern
hardwood, of the conifers

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at higher elevation and
humid continental climate.

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So this is a slide to show you a soil pit.

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So you can see that there is
a upper thick organic horizon

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which goes into the mineral soil and then

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down into seed horizon material,
relatively shallow soils.

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I've got a slide here
to show you a landscape

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of what one of the experimental
watersheds would look

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like if you, if you could do a cutout

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from the gauging station up
to the top of the watershed.

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So you can see the, the outlay of bedrock

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until here and the approximate
height of the canopy.

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So generally we have hardwoods in the

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in the lower elevation and
then there's a transition zone.

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And then it creates into
canopy or forest at the

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at the crest at the highest
elevations within the watershed.

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This is a very poor quality picture

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of what the forest looks like.

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And part of it, this
is a little bit perchy

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than we usually see, but
it's, you can get a sense.

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And this is a map of
the forest distribution.

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So I mentioned that we do
surveys across the whole Valley.

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We also try to extrapolate work

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at Hubbard Brook for the
greater Northern forest region.

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So this is color coded by
the types of vegetation,

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the reddish color which is the bulk

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of the area is Northern hardwoods.

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You can see Hemlocks prominent
by the base of the watershed

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along the, the channel of
the main Hubbard Brook.

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And then the greens you can
see are Spruce Fir forest

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at the highest, highest elevation.

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So we've been fortunate
that there've been some very

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important vegetation surveys
at Hubbard Brook dating back

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to Bob Whitaker's work in
the sixties at that time.

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This shows you a above
ground biomass over time.

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This is for watersheds six.

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We also had sort of Valley wide surveys.

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So you can see that early in the study

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the forest was strongly
grading growing pretty strongly

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and then starting in the early eighties

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that growth leveled off.

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And in recent years it's
been declining growth.

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There've been some fairly
significant climatic

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events that have happened
over the last 20 or so years.

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There was a significant ice storm.

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That may be some of you remember in 1998.

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I'll talk a little bit about that

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towards the end of the talk.

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And then more recently,
about five years ago

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there was a significant
microburst then both

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of those impacted the forest somewhat.

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And so we've surveyed the
distribution of vegetation

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at the sites.

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This shows sort of a
course level distribution

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of species.

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The upper panel represents
basal area of canopy trees

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and then the lower panel
represents sapling density.

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And so these are color coded
just to try to highlight some

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of the nature observations.

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The red represents sugar maple.

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So you can see sugar
maple is pretty prominent

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in watershed six have
a very strong dynamic.

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It was growing relatively
well early in the study.

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And then in the early eighties,
it's really been declining

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and that growth has been replaced
largely by American beach.

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And you can see beeches
suffered from peak scale

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like much of the Northern forest.

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So you can see a large increase

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in saplings starting in the 1980s.

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This slide show you
what they a strange look

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like at Hubbard Brook.

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So the headwater streams

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and the experimental
watersheds are generally first

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and the second order streams.

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So I mentioned early on
that Hubbard Brook is part

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of the long term ecological
research program funded

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by the NSF involves I think
28 sites that are found

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throughout the US and
some areas outside the US

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there are two sites in Antarctica.

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And so this is a
conceptual model that we've

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developed to sort of set the

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the underpinning for the work
that's done at Hubbard Brook.

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There are three major drivers
of change that we look at

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and our major theme is a disturbance

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within the Northern forest system.

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And some of those disturbances
are atmospheric deposition

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and climate change and then changing biota

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and changing biota is sort of a catch all

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for a number of types of disturbances.

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It could result from forest harvesting.

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It could result in

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the input of path, pests

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so a variety of things.

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And so those, those
disturbances can influence

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and change what we call
the geo-physical template

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of the watersheds.

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So this represents the, the soil

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the overall structure of
the, of the watershed.

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And then, a lot of the
focus research is done

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on looking at functional responses

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and these include vegetation,
biogeochemistry, hydrology

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00:13:08,950 --> 00:13:13,290
and food web, so insects, birds,

256
00:13:13,290 --> 00:13:14,123
mammals

257
00:13:15,000 --> 00:13:17,450
large herbivores are all included in the

258
00:13:17,450 --> 00:13:19,600
in the food web work.

259
00:13:19,600 --> 00:13:21,440
And some of these have feedbacks

260
00:13:21,440 --> 00:13:23,970
particularly in terms
of changing biota and

261
00:13:23,970 --> 00:13:28,233
and influencing this geo-physical
template that we focus on.

262
00:13:30,080 --> 00:13:32,410
So to try to answer our research questions

263
00:13:32,410 --> 00:13:34,860
we try to use a variety of tools.

264
00:13:34,860 --> 00:13:37,150
We conduct experiments.

265
00:13:37,150 --> 00:13:41,490
We do long-term measurements,
we do modeling exercises

266
00:13:41,490 --> 00:13:43,713
and we do gradient studies.

267
00:13:45,930 --> 00:13:48,350
So I'm gonna transition now
to talking a little bit about

268
00:13:48,350 --> 00:13:51,330
one of our focuses services
in that air pollution

269
00:13:51,330 --> 00:13:52,890
or acid rain.

270
00:13:52,890 --> 00:13:56,710
And that's been a big theme
for the work at Hubbard Brook

271
00:13:56,710 --> 00:14:00,880
for a long time, and continues
to be a theme, although the

272
00:14:02,290 --> 00:14:05,700
acid rain has changed markedly
over the, over the decades.

273
00:14:05,700 --> 00:14:07,580
And we've been fortunate enough to capture

274
00:14:07,580 --> 00:14:09,670
that what Hubbard Brook was

275
00:14:09,670 --> 00:14:11,520
measurements were first
made at Hubbard Brook.

276
00:14:11,520 --> 00:14:14,110
They were the values were relatively high

277
00:14:14,110 --> 00:14:16,750
that was near the peak of acid rain.

278
00:14:16,750 --> 00:14:20,550
And then the change
started in 1970s with the

279
00:14:21,490 --> 00:14:23,440
1970 Clean Air Act amendments.

280
00:14:23,440 --> 00:14:27,483
And it's had changed over time
with various rules that have

281
00:14:27,483 --> 00:14:30,580
have been implemented and continue today.

282
00:14:30,580 --> 00:14:34,220
So this is a slide showing
you some of that change.

283
00:14:34,220 --> 00:14:36,300
The y-axis shows the volume way

284
00:14:36,300 --> 00:14:39,373
to concentrations of sulfate and nitrate.

285
00:14:40,350 --> 00:14:43,410
These are annual values
in precipitation in bulk

286
00:14:43,410 --> 00:14:45,420
precipitation at Hubbard Brook.

287
00:14:45,420 --> 00:14:47,920
And along the x-axis is the driver

288
00:14:47,920 --> 00:14:50,750
which are the national, these
are national scale emissions

289
00:14:50,750 --> 00:14:53,680
of sulfur dioxide and nitrogen oxide.

290
00:14:53,680 --> 00:14:55,730
And you can see this a
pretty strong relationship.

291
00:14:55,730 --> 00:14:58,250
So these highest values
represent the earliest

292
00:14:58,250 --> 00:15:00,110
measurements that Hubbard Brook.

293
00:15:00,110 --> 00:15:03,560
And then with time, the
emissions have declined.

294
00:15:03,560 --> 00:15:07,039
And within there's a very
strong, direct relationship

295
00:15:07,039 --> 00:15:10,800
between the sulfate concentrations
and to a lesser extent

296
00:15:10,800 --> 00:15:14,661
the nitrate concentrations
and precipitation

297
00:15:14,661 --> 00:15:16,900
pretty remote area at Hubbard Brook.

298
00:15:16,900 --> 00:15:20,070
So this is a real national success story

299
00:15:20,070 --> 00:15:21,670
and it's continuing to play out.

300
00:15:22,740 --> 00:15:25,960
I've got a dash line to show
you what, back in the day

301
00:15:25,960 --> 00:15:28,280
back in the seventies and eighties

302
00:15:28,280 --> 00:15:31,940
we projected back would
be a pre-industrial

303
00:15:31,940 --> 00:15:36,880
or circa 1870 values
of, of sulfated nitrate.

304
00:15:36,880 --> 00:15:39,730
So we're approaching those values now and

305
00:15:40,800 --> 00:15:44,450
there's discussion about reducing

306
00:15:44,450 --> 00:15:45,760
air pollution even further.

307
00:15:45,760 --> 00:15:47,950
There was some rollbacks in
the Trump administration,

308
00:15:47,950 --> 00:15:51,272
but, you know I'm guardedly
optimistic that there'll be some

309
00:15:51,272 --> 00:15:54,180
improvements in air
quality, largely focusing

310
00:15:54,180 --> 00:15:59,180
on carbon mitigation from the
electric electricity sector.

311
00:15:59,910 --> 00:16:01,080
So one of these has shown

312
00:16:01,080 --> 00:16:03,470
for a couple of years
ago, the clean power plan

313
00:16:03,470 --> 00:16:06,890
which was an Obama administration proposal

314
00:16:06,890 --> 00:16:09,030
they give you an idea of
what might be achieved.

315
00:16:09,030 --> 00:16:10,440
And we could even go further

316
00:16:10,440 --> 00:16:13,913
with some ambitious proposals
that are proposed today.

317
00:16:15,470 --> 00:16:18,220
So not only would we be seeing
changes in precipitation

318
00:16:18,220 --> 00:16:20,560
but we've seen changes in
stream water chemistry.

319
00:16:20,560 --> 00:16:23,980
So this is a fairly complicated figure

320
00:16:23,980 --> 00:16:25,860
but it gives me an opportunity to brag

321
00:16:25,860 --> 00:16:27,670
about some of the long-term records

322
00:16:27,670 --> 00:16:31,030
which go well beyond when
I started at Hubbard Brook.

323
00:16:31,030 --> 00:16:33,200
So this is a panel showing you

324
00:16:33,200 --> 00:16:37,410
for watershed six, the water
budget, the sulfate budget

325
00:16:37,410 --> 00:16:40,160
and the lower panel is the nitrate budget.

326
00:16:40,160 --> 00:16:42,190
I'm not going to talk
right now about water.

327
00:16:42,190 --> 00:16:45,290
I'll wait, talk a little
bit more about that later

328
00:16:45,290 --> 00:16:47,190
but if we look at the sulfate and nitrate

329
00:16:47,190 --> 00:16:49,680
we can see some evidence of the response

330
00:16:49,680 --> 00:16:52,990
of ecosystem to those changes in inputs

331
00:16:53,940 --> 00:16:57,160
from acid rain that I talked
about a few minutes ago.

332
00:16:57,160 --> 00:16:59,540
So I'm showing you the annual volume

333
00:16:59,540 --> 00:17:02,440
or the annual flux, excuse
me, for sulfate here.

334
00:17:02,440 --> 00:17:05,640
And the precipitation
values are shown in red

335
00:17:05,640 --> 00:17:09,290
and the stream values are shown
in sort of yellowish green.

336
00:17:09,290 --> 00:17:11,470
And you can see that
they were high back when

337
00:17:11,470 --> 00:17:13,770
the measurements were
started in the sixties

338
00:17:13,770 --> 00:17:16,600
and they have really gone
down quite a bit today

339
00:17:16,600 --> 00:17:19,280
and continue to go down.

340
00:17:19,280 --> 00:17:22,910
The nitrate story's a
little more complicated.

341
00:17:22,910 --> 00:17:25,270
The values were stuck
really sort of increasing

342
00:17:25,270 --> 00:17:27,840
in the early sixties and then leveled off.

343
00:17:27,840 --> 00:17:30,580
And then with air pollution
controls in the late nineties

344
00:17:30,580 --> 00:17:34,380
and early two thousands,
largely directed towards nitrate

345
00:17:34,380 --> 00:17:36,810
you can see that they've had dropped down

346
00:17:36,810 --> 00:17:38,520
and you can see that there's a, the green

347
00:17:38,520 --> 00:17:39,960
which is the stream water chemistry.

348
00:17:39,960 --> 00:17:43,640
You can see a longterm
decrease, but unlike sulfate

349
00:17:43,640 --> 00:17:46,310
it doesn't follow the
pattern maybe somewhat

350
00:17:46,310 --> 00:17:48,170
but not particularly closely.

351
00:17:48,170 --> 00:17:50,270
And in particular there
are these large peaks

352
00:17:50,270 --> 00:17:52,810
that we see interspersed
throughout the record

353
00:17:52,810 --> 00:17:55,243
but I'll talk a little
bit about those later.

354
00:17:57,260 --> 00:17:59,280
So we've seen, also affects

355
00:18:00,260 --> 00:18:02,810
one of the effects that
we've seen that is on other

356
00:18:03,810 --> 00:18:07,530
aspects of chemistry,
Cations, calcium magnesium

357
00:18:07,530 --> 00:18:11,020
aluminum is a biggie because
aluminum was a toxic substance.

358
00:18:11,020 --> 00:18:13,230
And so this is a plot
of some of these cations

359
00:18:13,230 --> 00:18:16,570
calcium magnesium sodium
potassium is a function of the

360
00:18:16,570 --> 00:18:19,400
flocks of sulfate plus nitrate.

361
00:18:19,400 --> 00:18:23,260
So sulfate plus nitrate
represents strong acid anions

362
00:18:23,260 --> 00:18:25,600
largely input from the atmosphere

363
00:18:25,600 --> 00:18:27,580
and they've changed over time.

364
00:18:27,580 --> 00:18:30,210
And so in order for a solution to maintain

365
00:18:30,210 --> 00:18:33,590
its charge balance there
has to be mobilization

366
00:18:33,590 --> 00:18:37,680
of these cations to meet the
charges associated with these

367
00:18:37,680 --> 00:18:40,130
anions and negative chargers.

368
00:18:40,130 --> 00:18:43,370
And so you can see some
corresponding relationship

369
00:18:43,370 --> 00:18:46,350
that pretty strong relationships
for all these cations.

370
00:18:46,350 --> 00:18:49,480
Although the nature of the
relationship is different.

371
00:18:49,480 --> 00:18:51,610
They're all strongly correlated.

372
00:18:51,610 --> 00:18:53,520
Their fluxes are strongly correlated

373
00:18:53,520 --> 00:18:55,310
with the Fluxes of anions.

374
00:18:55,310 --> 00:19:00,310
And so the, a triangle upside
down triangles, potassium

375
00:19:00,550 --> 00:19:04,360
that's a strong nutrients,
strongly retained by the forest

376
00:19:04,360 --> 00:19:08,860
but the other cations, magnesium
in green, sodium in blue,

377
00:19:08,860 --> 00:19:11,040
and particularly calcium in red

378
00:19:11,040 --> 00:19:12,560
are pretty strongly correlated

379
00:19:12,560 --> 00:19:15,490
with the inputs of those anions.

380
00:19:15,490 --> 00:19:18,500
So as we add in acid rain that leaches

381
00:19:18,500 --> 00:19:21,910
out these nutrient Cations and the source

382
00:19:21,910 --> 00:19:24,670
of the available nutrient
cations is largely

383
00:19:24,670 --> 00:19:26,220
exchange sites from soil.

384
00:19:26,220 --> 00:19:30,470
And so this over time, over
decades depletes these cations.

385
00:19:30,470 --> 00:19:33,890
And so the amount of available
Cations critically calcium

386
00:19:33,890 --> 00:19:36,940
is less available today than it was back,

387
00:19:36,940 --> 00:19:38,470
you know, decades ago.

388
00:19:38,470 --> 00:19:42,053
And that has implications
for the ecosystem.

389
00:19:42,890 --> 00:19:45,240
There are two species

390
00:19:45,240 --> 00:19:48,330
of trees that have been
particularly impacted by acid rain.

391
00:19:48,330 --> 00:19:50,130
The first is red spruce.

392
00:19:50,130 --> 00:19:53,350
A lot of the great work was
done actually in Vermont

393
00:19:53,350 --> 00:19:55,680
working out the mechanisms for red spruce

394
00:19:55,680 --> 00:19:57,770
it's a little bit complicated.

395
00:19:57,770 --> 00:20:01,010
And so what the thinking is is

396
00:20:01,010 --> 00:20:04,480
that high levels of acid rain interact

397
00:20:04,480 --> 00:20:07,860
with a canopy and reach
membrane background, calcium

398
00:20:09,190 --> 00:20:12,760
and that predisposes the tree, the needles

399
00:20:12,760 --> 00:20:17,710
of the trees to low temperatures
and freezing damage.

400
00:20:17,710 --> 00:20:22,340
There's also a, a soil
component of that as well

401
00:20:22,340 --> 00:20:26,640
because some of the calcium
is supplied from from soil.

402
00:20:26,640 --> 00:20:28,660
sugar maple make those a
little bit different sugar.

403
00:20:28,660 --> 00:20:30,870
Maple requires large amounts of calcium.

404
00:20:30,870 --> 00:20:34,090
And so its effect is
largely soil mediated.

405
00:20:34,090 --> 00:20:37,610
It could also be influenced by
aluminum high concentrations

406
00:20:37,610 --> 00:20:39,980
of aluminum can impair water uptake

407
00:20:39,980 --> 00:20:43,683
in a nutrient uptake
from, for sugar maple.

408
00:20:45,300 --> 00:20:48,807
So we were interested in
really sort of sorting out

409
00:20:48,807 --> 00:20:52,420
the role of calcium in this process.

410
00:20:52,420 --> 00:20:56,477
And so back in 1999, we
initiated an experiment.

411
00:20:56,477 --> 00:20:58,700
One of the watersheds at
Hubbard Brook watershed

412
00:20:58,700 --> 00:21:00,930
one where we added calcium silicate

413
00:21:00,930 --> 00:21:04,170
or Wollastonite to the watershed

414
00:21:04,170 --> 00:21:07,280
and to try to put back what
we thought was the quantity

415
00:21:07,280 --> 00:21:09,780
of calcium that had been
leached historically

416
00:21:09,780 --> 00:21:11,370
from acid rain.

417
00:21:11,370 --> 00:21:15,890
So the base saturation, we
guesstimate, well, we, we

418
00:21:15,890 --> 00:21:17,630
we measure today is 10%

419
00:21:17,630 --> 00:21:20,840
and we thought historically,
it was about 20%.

420
00:21:20,840 --> 00:21:24,240
So we added enough calcium
to try to bring that back

421
00:21:24,240 --> 00:21:25,670
to what historical values.

422
00:21:25,670 --> 00:21:28,390
So it wasn't really a,
a fertilizer treatment

423
00:21:28,390 --> 00:21:30,100
but it was really an experiment to look

424
00:21:30,100 --> 00:21:33,160
at the impacts of lost calcium.

425
00:21:33,160 --> 00:21:35,130
So the theoretical calculation is

426
00:21:35,130 --> 00:21:37,800
for the watershed size is about 30 times

427
00:21:37,800 --> 00:21:39,820
but being a good engineer, I don't know

428
00:21:39,820 --> 00:21:41,420
if Jim said that I was an engineer

429
00:21:41,420 --> 00:21:43,580
but I'm actually an engineer by training.

430
00:21:43,580 --> 00:21:46,700
I added a 50% safety factor.

431
00:21:46,700 --> 00:21:49,470
And so we actually had a
little bit more 45 tons

432
00:21:49,470 --> 00:21:51,920
and it was applied by, by helicopter.

433
00:21:51,920 --> 00:21:54,670
I've got to fly to illustrate this.

434
00:21:54,670 --> 00:21:57,340
So this shows the whole operation.

435
00:21:57,340 --> 00:22:01,250
The material was mined
in Gouverneur in New York

436
00:22:01,250 --> 00:22:06,250
at Wollastonite mine, it
was ground up to relatively

437
00:22:06,390 --> 00:22:09,670
small particle size of 10 microns

438
00:22:09,670 --> 00:22:12,000
hard to apply that directly to the forest

439
00:22:12,000 --> 00:22:13,920
because it would be
dispersed all over the place.

440
00:22:13,920 --> 00:22:16,850
So we shipped it to Illinois
where it was pelletized looks

441
00:22:16,850 --> 00:22:21,150
like BB size shape particles
that was then shipped back

442
00:22:21,150 --> 00:22:24,400
to New Hampshire where it
was applied by helicopter.

443
00:22:24,400 --> 00:22:27,620
This material that binds these particles

444
00:22:27,620 --> 00:22:29,360
up is a water-soluble binder.

445
00:22:29,360 --> 00:22:32,390
So when it hits the
forest floor and contexts

446
00:22:32,390 --> 00:22:35,240
and moisture falls apart, and
you can see sort of a white

447
00:22:36,560 --> 00:22:40,223
particles here on these litter surfaces.

448
00:22:41,340 --> 00:22:44,560
and this is a slide showing
you the helicopter operation.

449
00:22:44,560 --> 00:22:48,240
And these sacks are one ton
sacks that were dispersed

450
00:22:48,240 --> 00:22:51,620
over about a day and a half in

451
00:22:51,620 --> 00:22:54,713
the fall of 1999.

452
00:22:56,720 --> 00:23:01,153
So we saw really immediate
impacts on the stream.

453
00:23:02,190 --> 00:23:05,459
But one thing that
actually surprised me was

454
00:23:05,459 --> 00:23:06,870
the impacts that we saw

455
00:23:06,870 --> 00:23:08,910
on the vegetation relatively quickly.

456
00:23:08,910 --> 00:23:12,690
We saw a actually visible changes

457
00:23:12,690 --> 00:23:15,500
in ground level vegetation
shortly after the treatment

458
00:23:15,500 --> 00:23:19,343
and the canopy trees,
which, you know, are old

459
00:23:19,343 --> 00:23:24,343
the forest was cut, you
know, in the early 1900s.

460
00:23:24,400 --> 00:23:26,100
So these are, these are big trees.

461
00:23:27,160 --> 00:23:29,080
It responded relatively quickly.

462
00:23:29,080 --> 00:23:31,610
So this is the time series
we're making ongoing

463
00:23:31,610 --> 00:23:33,410
measurements every five years.

464
00:23:33,410 --> 00:23:35,360
I showed you part of this slide earlier.

465
00:23:35,360 --> 00:23:38,460
This is above ground biomass
and the watershed six

466
00:23:38,460 --> 00:23:41,190
which is our reference watershed is shown

467
00:23:41,190 --> 00:23:44,790
in blue and watershed one is shown in red.

468
00:23:44,790 --> 00:23:47,220
And then time of the treatment is

469
00:23:47,220 --> 00:23:50,930
is shown here in a sort of a green dash.

470
00:23:50,930 --> 00:23:52,430
And so you can see the measurements

471
00:23:52,430 --> 00:23:54,780
since that time has shown a large increase

472
00:23:54,780 --> 00:23:58,380
in above ground biomass, which
I find, I find it astounding.

473
00:23:58,380 --> 00:24:00,820
I showed that the
magnitude of the response

474
00:24:01,890 --> 00:24:04,510
This shows you the tree species that's,

475
00:24:04,510 --> 00:24:06,840
so the upper panel is
what I showed you before.

476
00:24:06,840 --> 00:24:09,020
We talked about sugar, maple declining

477
00:24:09,020 --> 00:24:11,550
and this is for the lower
panels for watershed one.

478
00:24:11,550 --> 00:24:13,940
And so you can see that initial decline

479
00:24:13,940 --> 00:24:15,680
the first value before the treatment

480
00:24:15,680 --> 00:24:17,770
and the initial value after the treatment.

481
00:24:17,770 --> 00:24:20,050
And since that time sugar maple has grown

482
00:24:20,050 --> 00:24:22,890
like gangbusters is doing very well.

483
00:24:22,890 --> 00:24:25,910
So it's completely turned
around the sugar maple declined

484
00:24:25,910 --> 00:24:28,833
by adding that calcium back to the system.

485
00:24:30,150 --> 00:24:33,960
Other things that have
been found in the study

486
00:24:33,960 --> 00:24:36,860
some work by Gary Holly and colleagues

487
00:24:36,860 --> 00:24:41,860
from UVM who were interested
in red spruce impacts

488
00:24:42,490 --> 00:24:46,870
looked at the changes in
winter injury at the last night

489
00:24:46,870 --> 00:24:49,990
treated watershed compared
to a reference watershed

490
00:24:49,990 --> 00:24:51,970
and observe great declines in

491
00:24:51,970 --> 00:24:55,033
in winter injury from the,
from the calcium treatment.

492
00:24:56,480 --> 00:25:00,540
So if we look at what's
going on with respect to the

493
00:25:00,540 --> 00:25:04,560
the tree species in the
most recent measurements

494
00:25:04,560 --> 00:25:06,130
we measure these every five years.

495
00:25:06,130 --> 00:25:11,130
These are six of the major
tree species from watershed six

496
00:25:12,790 --> 00:25:15,030
and this is their relative growth rate.

497
00:25:15,030 --> 00:25:18,900
So we can really see this as
sort of a tale of two species

498
00:25:18,900 --> 00:25:21,400
sugar maple continues to do poorly.

499
00:25:21,400 --> 00:25:23,361
This is not in the
Wollastonite treatment of the

500
00:25:23,361 --> 00:25:24,970
the reference watershed.

501
00:25:24,970 --> 00:25:26,880
So this, these measurements

502
00:25:26,880 --> 00:25:29,350
the trees did not experience
any added calcium.

503
00:25:29,350 --> 00:25:31,880
The sugar maple continues to do poorly

504
00:25:32,900 --> 00:25:34,410
probably the poorest growth of any

505
00:25:34,410 --> 00:25:37,520
of the species, the major
species that we monitor.

506
00:25:37,520 --> 00:25:40,420
In contrast red spruce is
growing like gangbusters

507
00:25:40,420 --> 00:25:42,110
it's right at the highest elevation.

508
00:25:42,110 --> 00:25:44,820
A lot of the early projections
were that these hinder

509
00:25:44,820 --> 00:25:47,810
for species would not do
well under changing climate

510
00:25:47,810 --> 00:25:51,380
but in deep red spruce and
balsam fir have done very well.

511
00:25:51,380 --> 00:25:53,730
The growth is, is accelerating.

512
00:25:53,730 --> 00:25:55,600
And so, and so I think that there are

513
00:25:55,600 --> 00:25:57,700
two factors that play here.

514
00:25:57,700 --> 00:26:01,500
One is we have alleviated
acid rain largely

515
00:26:01,500 --> 00:26:03,050
because of the emission controls.

516
00:26:03,050 --> 00:26:06,940
So the driver that would leach
that membrane bound calcium

517
00:26:06,940 --> 00:26:10,060
is no longer there and
second it's got in warmer.

518
00:26:10,060 --> 00:26:13,690
So the freezing injury,
the very cold temperatures

519
00:26:13,690 --> 00:26:16,523
we no longer see those at Hubbard Brook.

520
00:26:18,170 --> 00:26:20,630
So that's a good transition
into climate for me.

521
00:26:20,630 --> 00:26:24,420
But before I do that, I
wanna show you another slide

522
00:26:24,420 --> 00:26:27,060
which is intriguing and something
that we're looking into.

523
00:26:27,060 --> 00:26:31,090
We've been also measuring
the soils at Hubbard Brook

524
00:26:31,090 --> 00:26:32,860
and particularly in watershed one.

525
00:26:32,860 --> 00:26:34,946
And these are data from my
colleague, Chris Johnson

526
00:26:34,946 --> 00:26:38,140
And who's been measuring the, the soils

527
00:26:38,140 --> 00:26:39,800
including the forest floor.

528
00:26:39,800 --> 00:26:41,380
So this is forest full of carbon.

529
00:26:41,380 --> 00:26:42,910
I've got a, or he's got a bunch

530
00:26:42,910 --> 00:26:45,550
of data from a bunch of sites

531
00:26:45,550 --> 00:26:49,510
but the watershed one
data are shown in green.

532
00:26:49,510 --> 00:26:52,200
And you can see the here that
there's a marked decrease

533
00:26:52,200 --> 00:26:54,360
in the fourth floor carbon

534
00:26:54,360 --> 00:26:57,270
and we've also measured
it for watershed six.

535
00:26:57,270 --> 00:27:01,900
That's shown in the upside
down triangles that are red.

536
00:27:01,900 --> 00:27:04,810
And for years it was relatively flat

537
00:27:04,810 --> 00:27:06,170
some year-to-year variation

538
00:27:06,170 --> 00:27:10,040
but the most recent measurements
have shown large decreases

539
00:27:10,040 --> 00:27:15,030
in forest floor carbon in,
in watershed six as well.

540
00:27:15,030 --> 00:27:18,780
And so superimposed on this or
some other long-term studies

541
00:27:18,780 --> 00:27:22,840
of forest floor carbon one is from a Beech

542
00:27:22,840 --> 00:27:26,150
a forest in Western part of Germany.

543
00:27:26,150 --> 00:27:30,460
Soling and you can see that
early on, it was increasing

544
00:27:30,460 --> 00:27:33,310
but the most recent
measurement shows a decline.

545
00:27:33,310 --> 00:27:36,050
And then for us in the Czech Republic.

546
00:27:36,050 --> 00:27:38,270
So both forest in Germany

547
00:27:38,270 --> 00:27:41,424
and Czech Republic were
heavily impacted by acid rain

548
00:27:41,424 --> 00:27:46,424
which greatly reversed in the
late eighties, early nineties.

549
00:27:46,460 --> 00:27:48,760
And you can see the
the forest floor carbon

550
00:27:48,760 --> 00:27:50,610
is decreasing very markedly.

551
00:27:50,610 --> 00:27:54,060
So is there some sort of acid
rain impact that we're seeing?

552
00:27:54,060 --> 00:27:57,180
So this is an area of, we're
not sure what the answer

553
00:27:57,180 --> 00:28:00,890
to this is, but this is
an area of ongoing work.

554
00:28:00,890 --> 00:28:03,340
So for the last half, I'd
like to transition over

555
00:28:03,340 --> 00:28:07,433
to some climate work, looking
at some of our observations.

556
00:28:09,980 --> 00:28:12,200
So we do, as I mentioned

557
00:28:12,200 --> 00:28:16,070
we do longterm measurements
and I'll show you some of our

558
00:28:16,070 --> 00:28:19,180
some of our, our interesting measurements.

559
00:28:19,180 --> 00:28:21,540
And we do experiments

560
00:28:21,540 --> 00:28:24,460
not so much watershed level experiments

561
00:28:24,460 --> 00:28:25,920
but more plot level experiments.

562
00:28:25,920 --> 00:28:28,570
And do we do modeling and we're looking at

563
00:28:28,570 --> 00:28:30,843
chronic conditions as
well as extreme events.

564
00:28:32,170 --> 00:28:34,560
So just a couple of metrics
that we've seen over time

565
00:28:34,560 --> 00:28:36,500
which probably won't be a surprise to you.

566
00:28:36,500 --> 00:28:39,660
This is a mean annual temperature.

567
00:28:39,660 --> 00:28:41,600
This is for three longterm measurements

568
00:28:41,600 --> 00:28:46,270
in New England Hanover, which
is an extremely long record.

569
00:28:46,270 --> 00:28:48,850
Well, over a hundred
years is shown in gray,

570
00:28:48,850 --> 00:28:51,340
Mount Washington which
is a little bit longer

571
00:28:51,340 --> 00:28:54,392
than Hubbard Brook is shown
in blue and Hubbard Brook

572
00:28:54,392 --> 00:28:57,300
one of our, our gauging
stations has shown a black

573
00:28:57,300 --> 00:28:58,460
and they all show the same thing.

574
00:28:58,460 --> 00:29:01,670
Although different periods
of record there's been

575
00:29:01,670 --> 00:29:03,770
as you probably are well aware, a

576
00:29:03,770 --> 00:29:07,490
a pretty significant
increase in air temperature

577
00:29:07,490 --> 00:29:09,980
but there's a lot of
year to year variability.

578
00:29:09,980 --> 00:29:12,170
But the pattern is sort
of remarkably similar

579
00:29:12,170 --> 00:29:14,920
across these three sites, which is

580
00:29:14,920 --> 00:29:16,870
which is interesting in its own, right?

581
00:29:18,030 --> 00:29:19,960
Looking across the
seasons at Hubbard Brook

582
00:29:19,960 --> 00:29:23,770
we have a number of
meteorological stations sort

583
00:29:23,770 --> 00:29:26,760
of showing data for, for these.

584
00:29:26,760 --> 00:29:29,770
So this is the slope of the annual change

585
00:29:29,770 --> 00:29:32,550
in air temperature and this is by season.

586
00:29:32,550 --> 00:29:34,300
So I've got the four seasons,

587
00:29:34,300 --> 00:29:36,520
fall, winter, spring and summer season.

588
00:29:36,520 --> 00:29:40,370
And then on the far right is
the annual and each one of

589
00:29:40,370 --> 00:29:43,080
these colored bars represents
a different gauging station.

590
00:29:43,080 --> 00:29:44,663
If it's double cross
hatched, it's significant

591
00:29:44,663 --> 00:29:48,360
that the 0.05 level, if
it's single cross hatch

592
00:29:48,360 --> 00:29:52,210
it's a significant at the a 0.1 level.

593
00:29:52,210 --> 00:29:55,900
So as I said, there are annual
increases in air temperature

594
00:29:55,900 --> 00:29:58,150
and their records are probably most strong

595
00:29:58,150 --> 00:29:59,870
for the winter period.

596
00:29:59,870 --> 00:30:02,610
So we see very clear increases

597
00:30:02,610 --> 00:30:04,800
in temperature over the winter.

598
00:30:04,800 --> 00:30:06,890
Probably the next strongest is the summer.

599
00:30:06,890 --> 00:30:09,160
Although not certainly
not as strong as the

600
00:30:10,170 --> 00:30:13,860
as we see in the winter, the
spring probably comes in next

601
00:30:13,860 --> 00:30:16,750
then fall probably the,

602
00:30:16,750 --> 00:30:20,479
the least clear trends but
showing you an increasing

603
00:30:20,479 --> 00:30:23,672
pattern, and so generally
the summer seasons are quite,

604
00:30:23,672 --> 00:30:26,940
excuse me, these shoulder
seasons are quite variable

605
00:30:26,940 --> 00:30:30,490
and that's of considerable
interest to all of us in here.

606
00:30:30,490 --> 00:30:34,510
I'll talk a little bit more
about that later in the lecture.

607
00:30:34,510 --> 00:30:37,870
If we look across the time
series here of air temperature

608
00:30:37,870 --> 00:30:41,280
this is for one of the
meteorological stations

609
00:30:41,280 --> 00:30:42,263
for Hubbard Brook.

610
00:30:43,230 --> 00:30:46,990
The annual temperature
is shown in triangles.

611
00:30:46,990 --> 00:30:49,070
You can see the long-term increase

612
00:30:49,070 --> 00:30:51,800
but a considerable year
to year variability.

613
00:30:51,800 --> 00:30:54,820
And the slope represents
the change of bent

614
00:30:54,820 --> 00:30:58,430
over the period of record,
which extends into the fifties

615
00:30:58,430 --> 00:31:01,137
and then below I've got
the winter temperature.

616
00:31:01,137 --> 00:31:04,980
And so you can see the rate
here is considerably greater

617
00:31:04,980 --> 00:31:06,500
than the annual temperature.

618
00:31:06,500 --> 00:31:09,160
And you can also see that
there's a lot more variability

619
00:31:09,160 --> 00:31:11,960
across this although
certainly a statistically

620
00:31:11,960 --> 00:31:13,033
significant trend.

621
00:31:14,960 --> 00:31:17,330
So we've seen that because of this pattern

622
00:31:17,330 --> 00:31:20,870
we've seen sort of manifestations of that.

623
00:31:20,870 --> 00:31:23,840
We back in the day we had a lot of really

624
00:31:23,840 --> 00:31:26,550
cold temperatures at Hubbard Brook.

625
00:31:26,550 --> 00:31:29,020
I know I probably sound
like your grandfather here,

626
00:31:29,020 --> 00:31:30,570
but that's indeed true.

627
00:31:30,570 --> 00:31:32,090
The record shows that.

628
00:31:32,090 --> 00:31:34,420
So these very very low
temperature classes,

629
00:31:34,420 --> 00:31:37,210
we just are not seeing them
to the degree that we saw them

630
00:31:37,210 --> 00:31:40,110
back in the fifties and
sixties, they really declined

631
00:31:40,110 --> 00:31:42,930
substantially and so you can
see this these temperature

632
00:31:42,930 --> 00:31:45,260
classes and their changes in frequency.

633
00:31:45,260 --> 00:31:48,550
The very low temperature
classes are not as abundant.

634
00:31:48,550 --> 00:31:50,280
Those observations are not as abundant

635
00:31:50,280 --> 00:31:51,730
as they were back in the day.

636
00:31:52,890 --> 00:31:55,970
We also see quite a bit
of change in precipitation

637
00:31:55,970 --> 00:31:58,610
although it's a highly variable record

638
00:31:58,610 --> 00:32:01,380
but it is a increasing record.

639
00:32:01,380 --> 00:32:03,510
This is the annual
precipitation showing you

640
00:32:03,510 --> 00:32:05,900
the time series and you
can see there's a lot

641
00:32:05,900 --> 00:32:07,300
of ups and downs, but there's a

642
00:32:07,300 --> 00:32:10,750
statistically significant upward pattern.

643
00:32:10,750 --> 00:32:13,680
And that's consistent
with other long records

644
00:32:13,680 --> 00:32:17,020
in New England, this is the
Hubbard Brook record here

645
00:32:17,020 --> 00:32:20,130
superimposed on the
record at St. Johnsbury,

646
00:32:20,130 --> 00:32:22,403
which is considerably longer and,

647
00:32:24,400 --> 00:32:26,090
so you can see a similar pattern

648
00:32:26,090 --> 00:32:28,240
although the absolute
value of the quantity

649
00:32:28,240 --> 00:32:30,500
of precipitation is quite a
bit higher at Hubbard Brook

650
00:32:30,500 --> 00:32:32,760
but a lot of year to year, very deadly

651
00:32:32,760 --> 00:32:35,873
but definitely a significant,
significant upward trend.

652
00:32:38,440 --> 00:32:40,370
So if you look at across
seasons like we did

653
00:32:40,370 --> 00:32:43,350
for temperature, it's very
different for precipitation.

654
00:32:43,350 --> 00:32:46,690
Basically we see virtually
all of our increase

655
00:32:46,690 --> 00:32:50,780
in precipitation quantity is
occurring in the summer months.

656
00:32:50,780 --> 00:32:54,940
So it's not what I would have anticipated

657
00:32:54,940 --> 00:32:56,940
but that's indeed what the record shows.

658
00:32:58,580 --> 00:33:02,650
So not only the, the
quantity of precipitation

659
00:33:02,650 --> 00:33:06,150
but the characteristics of
precipitation are changing.

660
00:33:06,150 --> 00:33:10,600
We're getting a lot less inputs as snow.

661
00:33:10,600 --> 00:33:14,630
And these cold temperatures
are also changing the duration

662
00:33:15,690 --> 00:33:18,860
and the amount of snow pack
that we've seen in the record.

663
00:33:18,860 --> 00:33:23,050
So these are three measures
of snow pack from snow courses

664
00:33:23,050 --> 00:33:27,270
at Hubbard Brook, the upper
panel is maximum snow depth.

665
00:33:27,270 --> 00:33:30,320
The minimum panel is snow water content

666
00:33:30,320 --> 00:33:33,800
and the lowest panel is
the ration of snow cover.

667
00:33:33,800 --> 00:33:34,633
And so you can see all

668
00:33:34,633 --> 00:33:37,300
of these measurements are, are decreasing.

669
00:33:37,300 --> 00:33:39,490
And so we just don't
have as much snow pack

670
00:33:39,490 --> 00:33:42,580
which is disappointing
to me as we did back

671
00:33:42,580 --> 00:33:44,423
in the day at Hubbard Brook.

672
00:33:45,370 --> 00:33:48,570
So I told you I would get
to the, the water cycle

673
00:33:48,570 --> 00:33:49,870
and here it is.

674
00:33:49,870 --> 00:33:51,580
So early on in the talk, we

675
00:33:51,580 --> 00:33:55,210
we talked about the
small watershed approach

676
00:33:55,210 --> 00:34:00,210
and measurements of precipitation
inputs and stream outputs.

677
00:34:00,770 --> 00:34:03,670
Precipitation inputs are shown in red.

678
00:34:03,670 --> 00:34:05,400
The stream outputs are shown in blue

679
00:34:05,400 --> 00:34:08,700
and the difference represents estimated

680
00:34:08,700 --> 00:34:11,680
of evapotranspiration and
that is shown in green.

681
00:34:11,680 --> 00:34:14,900
So these are annual
water budgets over the,

682
00:34:14,900 --> 00:34:16,340
over the period of record

683
00:34:17,820 --> 00:34:21,230
for Hubbard Brook for watershed three.

684
00:34:21,230 --> 00:34:23,610
And you can see there's a lot
of year to year variability

685
00:34:23,610 --> 00:34:26,720
but the stream flow
corresponds very strongly

686
00:34:26,720 --> 00:34:29,440
with precipitation inputs, not surprising.

687
00:34:29,440 --> 00:34:31,560
And for most of the record, the estimates

688
00:34:31,560 --> 00:34:35,090
of evapotranspiration have
been remarkably consistent.

689
00:34:35,090 --> 00:34:38,690
Although showing a long-term decrease

690
00:34:38,690 --> 00:34:41,210
There's some funky
behavior in last few years

691
00:34:41,210 --> 00:34:43,680
that we're scratching our heads on.

692
00:34:43,680 --> 00:34:47,620
You can see by my parents
that I scratch my head a lot

693
00:34:47,620 --> 00:34:49,700
but we're seeing initially it starting

694
00:34:49,700 --> 00:34:51,770
in the early two thousands, a decrease

695
00:34:51,770 --> 00:34:54,867
in this estimated ET, and then
more recently an increase.

696
00:34:54,867 --> 00:34:59,120
And we have no idea why we're
having this strange behavior

697
00:34:59,120 --> 00:35:03,653
after decades of rather
consistent response and in ET.

698
00:35:06,070 --> 00:35:08,610
So some things about the precipitation

699
00:35:08,610 --> 00:35:10,400
something known as the center volumes.

700
00:35:10,400 --> 00:35:13,280
So this is the date in
which half of the water

701
00:35:13,280 --> 00:35:17,790
leads the watershed at at
Hubbard Brook in watershed three

702
00:35:17,790 --> 00:35:21,000
that center data precipitation
of stream water, excuse me

703
00:35:21,000 --> 00:35:23,680
is going earlier and earlier and earlier.

704
00:35:23,680 --> 00:35:26,920
And that's a manifestation
of less precipitation

705
00:35:26,920 --> 00:35:31,280
as snow and Moore's rain and
less snowpack accumulation.

706
00:35:31,280 --> 00:35:33,670
So it's cumulating over a shorter period.

707
00:35:33,670 --> 00:35:38,260
So the water is moving
through more within the

708
00:35:38,260 --> 00:35:40,540
Within the early part of the season

709
00:35:42,460 --> 00:35:44,040
And then changes in frequency

710
00:35:44,040 --> 00:35:47,080
which are manifestation of the
increases in precipitation.

711
00:35:47,080 --> 00:35:50,270
So this is much like I
showed you in the frequency

712
00:35:50,270 --> 00:35:55,270
of occurrence for a temperature,
but this is for flow.

713
00:35:55,340 --> 00:35:59,510
So the left side part
are, are low flow events.

714
00:35:59,510 --> 00:36:02,800
The high values are high flow events

715
00:36:02,800 --> 00:36:05,827
and this is change in their frequency.

716
00:36:05,827 --> 00:36:08,860
So the reason why this is
on a logarithmic scale is

717
00:36:08,860 --> 00:36:13,010
because the range of flows
for streams in New England is

718
00:36:13,010 --> 00:36:17,240
is really it's goes over
several orders of magnitude.

719
00:36:17,240 --> 00:36:19,750
So in a nutshell, what
we're seeing is many

720
00:36:19,750 --> 00:36:23,310
many fewer, very, very low
flow events like we would see

721
00:36:23,310 --> 00:36:27,793
in the summer and many, many
more, very high flow events.

722
00:36:30,010 --> 00:36:32,070
So this is a measure of the peak flows

723
00:36:32,070 --> 00:36:34,700
for our hydrologic reference
watershed watershed three

724
00:36:34,700 --> 00:36:36,760
and they are increasing.

725
00:36:36,760 --> 00:36:39,140
So enroll flow is not only increasing

726
00:36:39,140 --> 00:36:41,823
but the highest flows are also increasing.

727
00:36:43,330 --> 00:36:45,970
And if we look across
these high flow events

728
00:36:45,970 --> 00:36:50,820
these are the 20th ice
flow events on record.

729
00:36:50,820 --> 00:36:53,000
I would think that they
would be a certain type

730
00:36:53,000 --> 00:36:55,160
of event that they're not there all sorts

731
00:36:55,160 --> 00:36:57,010
of different types of flow events.

732
00:36:57,010 --> 00:36:58,610
There are rain on snow events.

733
00:36:58,610 --> 00:37:00,360
There are snow melt events.

734
00:37:00,360 --> 00:37:02,010
Some of them are hurricane events.

735
00:37:02,010 --> 00:37:03,580
Some of them are convective storms.

736
00:37:03,580 --> 00:37:05,820
So it's a hodgepodge of different types

737
00:37:05,820 --> 00:37:08,950
of hydrologic events that
are producing these very

738
00:37:08,950 --> 00:37:10,733
very high flow paths.

739
00:37:12,820 --> 00:37:14,300
Okay, so I've got a couple of things

740
00:37:14,300 --> 00:37:19,200
that I would like to close
with just as teasers to you.

741
00:37:19,200 --> 00:37:20,880
And some of the things that we're thinking

742
00:37:20,880 --> 00:37:22,653
about and working on.

743
00:37:23,650 --> 00:37:27,570
So the first is what's known
as the Vernal Transition.

744
00:37:27,570 --> 00:37:29,960
And so this was identified way back then

745
00:37:29,960 --> 00:37:33,810
by Herbert Bormann as being
an important occurrence.

746
00:37:33,810 --> 00:37:37,340
And the idea here, this is
a, this is a time series

747
00:37:37,340 --> 00:37:41,600
of monthly values of April, May and June.

748
00:37:41,600 --> 00:37:43,180
And I'm showing you three things here.

749
00:37:43,180 --> 00:37:46,810
I'm showing you the shaded
area shows the accumulation

750
00:37:46,810 --> 00:37:49,110
of snow pack and loss of snowpack.

751
00:37:49,110 --> 00:37:53,830
The dashed black line shows you the

752
00:37:53,830 --> 00:37:58,250
emergence of buds from the
canopy and then the development

753
00:37:58,250 --> 00:38:01,060
of the full canopy a few weeks later.

754
00:38:01,060 --> 00:38:04,570
And then the red represents
soil temperature,

755
00:38:04,570 --> 00:38:06,370
surface soil temperature.

756
00:38:06,370 --> 00:38:11,130
So under snowpack in April,
the temperature is low

757
00:38:11,130 --> 00:38:12,900
it's cold, there's snow on the ground.

758
00:38:12,900 --> 00:38:17,900
And so it's near zero values,
but slightly above freezing

759
00:38:18,380 --> 00:38:22,510
because of microbial activity
in the, in the forest floor.

760
00:38:22,510 --> 00:38:27,330
Then as snow is snow pack
leaves, because of the occurrence

761
00:38:27,330 --> 00:38:30,870
you know, the, the emergence
of the dark forest floor

762
00:38:30,870 --> 00:38:34,400
it's very effective at
absorbing solar radiation.

763
00:38:34,400 --> 00:38:36,770
So you see a very short period of time.

764
00:38:36,770 --> 00:38:41,110
There's this huge increase
in surface soil temperature.

765
00:38:41,110 --> 00:38:45,050
And that continues through
this period until the

766
00:38:45,050 --> 00:38:48,890
canopy floor develops,
and then it levels off.

767
00:38:48,890 --> 00:38:51,990
And so this time period between the loss

768
00:38:51,990 --> 00:38:55,210
of snowpack and the
emergence of the canopy

769
00:38:55,210 --> 00:38:56,880
we call the Vernal Transition.

770
00:38:56,880 --> 00:39:00,270
So there's a period of very sharp change.

771
00:39:00,270 --> 00:39:02,270
It's a phenological event

772
00:39:02,270 --> 00:39:04,780
and temperatures change very quickly

773
00:39:04,780 --> 00:39:06,360
and a lot goes on within the forest.

774
00:39:06,360 --> 00:39:08,426
So we think it's, it's an important

775
00:39:08,426 --> 00:39:10,110
it's an important occurrence.

776
00:39:10,110 --> 00:39:12,060
And we thought that for a long time

777
00:39:12,060 --> 00:39:14,130
but we've been looking at
the time series of this

778
00:39:14,130 --> 00:39:17,230
and we see, as I told you,
before that the snow pack is

779
00:39:18,520 --> 00:39:21,520
occurring earlier, earlier, earlier

780
00:39:21,520 --> 00:39:23,570
and so as the canopy development.

781
00:39:23,570 --> 00:39:27,090
So these periods of
these are, are shifting.

782
00:39:27,090 --> 00:39:31,170
And if we look at the, the
difference over time, the

783
00:39:32,270 --> 00:39:35,900
open squares represents the last day

784
00:39:35,900 --> 00:39:38,030
of snow pack and the
record at Hubbard Brook.

785
00:39:38,030 --> 00:39:39,730
And see, you can see this is

786
00:39:39,730 --> 00:39:41,900
although there's a lot of
year to year variability.

787
00:39:41,900 --> 00:39:44,770
The overall trend is it's
marching earlier, earlier,

788
00:39:44,770 --> 00:39:47,520
earlier, as we discussed a few minutes ago

789
00:39:47,520 --> 00:39:49,540
and this is the full development

790
00:39:49,540 --> 00:39:51,540
of the canopy shown in the dark circles.

791
00:39:51,540 --> 00:39:53,207
And you can see that's
also getting earlier

792
00:39:53,207 --> 00:39:56,079
and earlier and earlier,
but it's not keeping paths.

793
00:39:56,079 --> 00:39:58,680
Hey, excuse me for the snow pack.

794
00:39:58,680 --> 00:40:00,200
So this

795
00:40:00,200 --> 00:40:02,800
Vernal Transition period

796
00:40:02,800 --> 00:40:06,550
is not in sync between
the loss of snow pack

797
00:40:06,550 --> 00:40:09,600
and the emergence, full
emergence or the canopy.

798
00:40:09,600 --> 00:40:11,420
So it's getting, it's getting a larger

799
00:40:11,420 --> 00:40:13,200
and larger discrepancy
and we're interested

800
00:40:13,200 --> 00:40:15,050
in what are the implications of this.

801
00:40:16,820 --> 00:40:18,910
The other thing I wanna
touch on briefly at the end

802
00:40:18,910 --> 00:40:21,880
is this crazy behavior for nitrate.

803
00:40:21,880 --> 00:40:26,020
A lot of Biogen chemists
are focused on nitrate

804
00:40:26,020 --> 00:40:28,150
Maybe you could even argue
a little bit too much

805
00:40:28,150 --> 00:40:29,980
or nitrogen a little bit too much.

806
00:40:29,980 --> 00:40:32,670
I showed you this earlier,
but this is a blowup

807
00:40:32,670 --> 00:40:35,150
of the nitrate flux record.

808
00:40:35,150 --> 00:40:37,530
So again, precipitation
is shown in sort of the

809
00:40:37,530 --> 00:40:42,010
yellowish color and the
stream is shown in, in red.

810
00:40:42,010 --> 00:40:44,100
And you can see that in
general, there's been

811
00:40:44,100 --> 00:40:47,750
a longterm decrease in
nitrate, but there is this sort

812
00:40:47,750 --> 00:40:51,048
of strange behavior where
there were large increases

813
00:40:51,048 --> 00:40:55,050
particularly ramping up from
the sixties to the eighties

814
00:40:55,050 --> 00:40:57,597
back in the day, that was
thought to be due to acid rain.

815
00:40:57,597 --> 00:40:59,550
And it was considered
to be a phenomenon known

816
00:40:59,550 --> 00:41:02,260
as nitrogen saturation, but then starting

817
00:41:02,260 --> 00:41:04,350
in the late seventies, that's reversed.

818
00:41:04,350 --> 00:41:08,150
And you can see these
little blips over time.

819
00:41:08,150 --> 00:41:11,300
And so we're not sure what
these are, but we have

820
00:41:11,300 --> 00:41:15,120
some ideas what may be causing
this episodic behavior.

821
00:41:15,120 --> 00:41:16,780
And we're also interested in what is

822
00:41:16,780 --> 00:41:19,370
driving this long-term decline.

823
00:41:19,370 --> 00:41:24,250
It's undoubtedly linked to
inputs of atmospheric nitrogen

824
00:41:24,250 --> 00:41:27,650
deposition, but the pattern
is not coincidence with it.

825
00:41:27,650 --> 00:41:30,230
The decrease in deposition really

826
00:41:30,230 --> 00:41:33,790
didn't start until the
late 1990s and is grown

827
00:41:35,400 --> 00:41:37,240
prominently since that time.

828
00:41:37,240 --> 00:41:40,504
It really started back
in the, in the seventies

829
00:41:40,504 --> 00:41:43,360
and it's continued over
a much longer period.

830
00:41:43,360 --> 00:41:45,403
So we're interested in why, what is that?

831
00:41:45,403 --> 00:41:46,920
What is driving that?

832
00:41:46,920 --> 00:41:49,130
And it's consistent with
other patterns that we see

833
00:41:49,130 --> 00:41:51,660
with that we've been measuring dating back

834
00:41:51,660 --> 00:41:53,570
to Jerry Melillo in 1970.

835
00:41:53,570 --> 00:41:56,300
So made some of them
first microbial assays.

836
00:41:56,300 --> 00:41:58,720
We have measurements of
nitrogen mineralization

837
00:41:58,720 --> 00:42:00,980
and nitrification and
a continuing today with

838
00:42:00,980 --> 00:42:02,660
Peter Groffman's measurements.

839
00:42:02,660 --> 00:42:04,930
And you can see that there
are long-term decreases

840
00:42:04,930 --> 00:42:07,080
in these microbial assays

841
00:42:07,080 --> 00:42:09,710
within the soil at, at Hubbard Brook.

842
00:42:09,710 --> 00:42:12,290
So there's a decrease in the cycling

843
00:42:12,290 --> 00:42:15,300
of nitrogen that's been
going on for a long time.

844
00:42:15,300 --> 00:42:17,150
These are some soil data.

845
00:42:17,150 --> 00:42:19,770
The upper panel represents
the pool of nitrogen

846
00:42:19,770 --> 00:42:22,580
within the forest floor,
and that is not changing

847
00:42:22,580 --> 00:42:26,430
but the carbon to nitrogen
ratio shown below is changing.

848
00:42:26,430 --> 00:42:28,760
So the carbon to nitrogen ratio is showing

849
00:42:28,760 --> 00:42:31,053
a longterm increase.

850
00:42:32,390 --> 00:42:36,250
We also have other assays,
these are gas flux assays

851
00:42:36,250 --> 00:42:39,760
the upper panel shows
carbon dioxide fluxes

852
00:42:39,760 --> 00:42:41,930
from soil that does not show any change

853
00:42:41,930 --> 00:42:43,530
although a lot of variability

854
00:42:43,530 --> 00:42:46,550
but the nitrous oxide
fluxes are showing very

855
00:42:46,550 --> 00:42:51,310
strong statistically significant decreases

856
00:42:51,310 --> 00:42:55,030
where initially they were
a source to the atmosphere

857
00:42:55,030 --> 00:42:57,673
and now they're transitioning
to, to be a sink.

858
00:42:58,904 --> 00:43:00,150
So what's driving this?

859
00:43:00,150 --> 00:43:01,860
When we don't, we really don't know.

860
00:43:01,860 --> 00:43:03,803
As I mentioned, initially,
we thought it was a

861
00:43:03,803 --> 00:43:07,820
there have been a manifestation
of increases in acid rain.

862
00:43:07,820 --> 00:43:09,480
But back in the seventies

863
00:43:09,480 --> 00:43:12,270
there was also a significant
drought in New England.

864
00:43:12,270 --> 00:43:16,090
And that could have been a
factor for this large increase.

865
00:43:16,090 --> 00:43:19,310
And there were also some
insects eruptions that occurred

866
00:43:19,310 --> 00:43:21,890
at this time, which may
have been responsible.

867
00:43:21,890 --> 00:43:25,070
Those are the slides just showing
you this prominent drought

868
00:43:25,070 --> 00:43:25,913
in New England.

869
00:43:27,030 --> 00:43:30,710
The event in the late eighties

870
00:43:30,710 --> 00:43:33,297
we think may have been
a soil freezing event.

871
00:43:33,297 --> 00:43:36,990
And that has spawned a
number of research projects

872
00:43:36,990 --> 00:43:41,460
looking at the role of
snow pack development in

873
00:43:41,460 --> 00:43:44,680
in winter below ground processes.

874
00:43:44,680 --> 00:43:46,440
So we've done a series of experiments

875
00:43:46,440 --> 00:43:49,950
such as illustrated here,
where we shoveled snow

876
00:43:49,950 --> 00:43:51,320
I've not done a lot of shoveling

877
00:43:51,320 --> 00:43:54,390
but some of my graduate
students and technicians have

878
00:43:54,390 --> 00:43:58,200
where we expose the soil and
that facilitates a freezing.

879
00:43:58,200 --> 00:44:00,600
So you can see these comparisons

880
00:44:00,600 --> 00:44:03,580
of a soil temperature
between the control plot

881
00:44:03,580 --> 00:44:08,470
in which is above freezing and the

882
00:44:08,470 --> 00:44:13,000
shoveled plot in red which
induces soil freezing and that

883
00:44:13,000 --> 00:44:16,630
results in mortality
reduces nutrient uptake

884
00:44:16,630 --> 00:44:20,600
by plants and can cause a
Hulsman leeches of nitrate.

885
00:44:20,600 --> 00:44:23,097
So it demonstrated that
snow eventually but

886
00:44:23,097 --> 00:44:25,210
but it's not clear that that translates

887
00:44:25,210 --> 00:44:27,430
to the watershed level.

888
00:44:27,430 --> 00:44:29,453
That's still an open question for us.

889
00:44:30,507 --> 00:44:32,320
The one that we know very clearly that

890
00:44:32,320 --> 00:44:36,920
was the '98 Ice Storm,
which I mentioned previously

891
00:44:36,920 --> 00:44:40,609
this was a big event and
so we run the widespread

892
00:44:40,609 --> 00:44:44,120
in Northern new Orleans
and Southern Canada

893
00:44:44,120 --> 00:44:48,030
caused a lot damage,
a number of fatalities

894
00:44:48,030 --> 00:44:51,210
we've done measurements, detail
measurements, characterizing

895
00:44:51,210 --> 00:44:55,150
that and we've also recently
completed some experimental

896
00:44:55,150 --> 00:44:58,420
work that we've done
experimental treatments

897
00:44:59,330 --> 00:45:02,300
different levels of icing
events and looking at the

898
00:45:02,300 --> 00:45:06,013
at the response of the
appliance to those treatments.

899
00:45:07,090 --> 00:45:12,090
So I just want to close
with just this one idea

900
00:45:12,140 --> 00:45:14,860
which is sort of the overarching idea

901
00:45:14,860 --> 00:45:17,070
for a project that we just had funded

902
00:45:17,070 --> 00:45:19,410
from the national science foundation data.

903
00:45:19,410 --> 00:45:22,130
And Hubbard Brook this the lead on that?

904
00:45:22,130 --> 00:45:24,380
This is really to try to understand what's

905
00:45:24,380 --> 00:45:29,380
driving this long term
pattern of nitrogen retention.

906
00:45:30,280 --> 00:45:33,720
And so we call this phenomena
Forest Oligiotrophication

907
00:45:33,720 --> 00:45:38,407
So the, the system is becoming
less and less nutrient rich

908
00:45:39,360 --> 00:45:41,747
or more and more nutrient poor.

909
00:45:41,747 --> 00:45:43,570
And we think it's partially driven by

910
00:45:43,570 --> 00:45:45,620
changes ad flows in carbon

911
00:45:45,620 --> 00:45:49,310
So we hypothesized that there
could be increased uptake

912
00:45:49,310 --> 00:45:50,950
of carbon by plants,

913
00:45:50,950 --> 00:45:52,420
which then drive

914
00:45:53,590 --> 00:45:56,550
carbon flows, below ground,

915
00:45:56,550 --> 00:46:00,080
and that could facilitate
immobilization of

916
00:46:00,080 --> 00:46:04,010
of nitrogen and decreases in
mineralization and decrease

917
00:46:04,010 --> 00:46:07,790
available nitrogen which we
think will likely feed back

918
00:46:07,790 --> 00:46:12,330
to the, to the trees and cause
an increase in reabsorption

919
00:46:12,330 --> 00:46:16,000
of nitrogen which then
will have a cascade of

920
00:46:16,000 --> 00:46:18,960
decreases nitrogen and
litter fall and then

921
00:46:20,066 --> 00:46:22,790
an ongoing Oligiotrophication of that

922
00:46:22,790 --> 00:46:26,430
So this, we wanna sort of pass
this idea and make a series

923
00:46:26,430 --> 00:46:28,170
of measurements but we're also interested

924
00:46:28,170 --> 00:46:30,089
in mode of the drivers.

925
00:46:30,089 --> 00:46:31,850
And we have a couple
ideas of what it could be.

926
00:46:31,850 --> 00:46:36,770
It could be a fertilization
effect of episodic CO2.

927
00:46:36,770 --> 00:46:39,150
It could be a lengthening of
the growing season we know

928
00:46:39,150 --> 00:46:42,100
from nitrogen so there's
greater growing season

929
00:46:42,100 --> 00:46:43,620
is getting longer and longer.

930
00:46:43,620 --> 00:46:46,850
So there's greater inputs of carbon

931
00:46:46,850 --> 00:46:48,310
over that longer growing season

932
00:46:48,310 --> 00:46:52,520
we also think it could be doing
a terrific period for that.

933
00:46:52,520 --> 00:46:57,260
The changes in the
Phosphorus cycles of soils.

934
00:46:57,260 --> 00:46:59,820
We know that it, it it's

935
00:46:59,820 --> 00:47:03,750
it's changing the dynamics of, of nitrogen

936
00:47:03,750 --> 00:47:07,830
but is it translating to
the whole watershed process?

937
00:47:07,830 --> 00:47:09,990
And it could also be a manifestation

938
00:47:09,990 --> 00:47:11,310
of recovering from acid rain.

939
00:47:11,310 --> 00:47:14,040
So the trees are less stressed.

940
00:47:14,040 --> 00:47:17,227
There could be some changes
in carbon and airflow

941
00:47:17,227 --> 00:47:21,660
and changes in microbial
activity that could be driving.

942
00:47:21,660 --> 00:47:25,030
So we think that there is,
we have a lot of reference

943
00:47:25,030 --> 00:47:29,320
that there's changes in the
internal supply of nitrogen

944
00:47:29,320 --> 00:47:33,090
and that's manifested through
decreases in stream nitrate.

945
00:47:33,090 --> 00:47:37,500
So we think that this may be
driven by climate effects.

946
00:47:37,500 --> 00:47:40,570
It could be due to, as I mentioned

947
00:47:40,570 --> 00:47:43,070
CO2 uptake could be a lengthy
new, the growing season.

948
00:47:43,070 --> 00:47:46,280
It could be some changes in
the processing of nitrogen

949
00:47:47,383 --> 00:47:49,900
in soil, and there could be a linkage

950
00:47:49,900 --> 00:47:52,050
to recovery from, from acid rate.

951
00:47:52,050 --> 00:47:55,711
So this is something that
we're just starting to work on.

952
00:47:55,711 --> 00:47:59,580
And we're, we're excited
about this project.

953
00:47:59,580 --> 00:48:01,980
So to close, I know I've covered a lot

954
00:48:01,980 --> 00:48:03,760
of material and I appreciate your patience

955
00:48:03,760 --> 00:48:07,450
but maybe just to summarize
a chart to show you

956
00:48:07,450 --> 00:48:10,840
that we have these longterm
measurements and experiments.

957
00:48:10,840 --> 00:48:12,090
And I think they provided a lot

958
00:48:12,090 --> 00:48:14,830
of insight into ecosystem function.

959
00:48:14,830 --> 00:48:16,510
And they're very important in terms

960
00:48:16,510 --> 00:48:19,670
of generating hypotheses
and for testing models

961
00:48:20,644 --> 00:48:25,570
of our understanding of
ecosystem, pattern and process.

962
00:48:25,570 --> 00:48:30,300
So clearly we have received
the inputs of, of acid rain.

963
00:48:30,300 --> 00:48:32,760
We've seen changes in
precipitation chemistry

964
00:48:32,760 --> 00:48:37,440
and string chemistry, and
we seen the effects of that.

965
00:48:37,440 --> 00:48:40,120
And those effects that,
that manifested in changes

966
00:48:40,120 --> 00:48:44,440
in soil changes in stream
chemistry and impacting the health

967
00:48:44,440 --> 00:48:48,530
of two prominent tree species,
sugar maple and red spruce

968
00:48:48,530 --> 00:48:50,700
so that the clients and
acid inputs we'd have

969
00:48:50,700 --> 00:48:54,850
seen really remarkable
recovery yet in red spruce

970
00:48:54,850 --> 00:48:58,130
but not sugar maple, because
that's a soil mediated

971
00:48:58,130 --> 00:49:01,802
because of a very slow
weathering rates from soil.

972
00:49:01,802 --> 00:49:04,770
The exchangeable calcium
has not come back.

973
00:49:04,770 --> 00:49:07,400
And so sugar Maples remains.

974
00:49:07,400 --> 00:49:08,963
It continues to be challenged.

975
00:49:10,150 --> 00:49:13,090
So superimpose on these
air pollution impacts.

976
00:49:13,090 --> 00:49:16,220
We've seen changing patterns
of, of climate increases

977
00:49:16,220 --> 00:49:19,573
in air temperature and
precipitation stream discharge.

978
00:49:20,810 --> 00:49:23,330
We've seen decreases in
precipitation occurring

979
00:49:23,330 --> 00:49:26,720
as snow and decreases
in snowpack accumulation

980
00:49:26,720 --> 00:49:30,660
which seems to affect soil
processing during winter.

981
00:49:30,660 --> 00:49:33,050
And these are consistent
with regional observations

982
00:49:33,050 --> 00:49:35,140
and future climate projections.

983
00:49:35,140 --> 00:49:38,900
And so one of our ongoing
hypothesis is climate

984
00:49:38,900 --> 00:49:42,620
change has really driven
the, the nitrogen cycle

985
00:49:42,620 --> 00:49:44,040
the changes in the nitrogen cycle

986
00:49:44,040 --> 00:49:46,100
but that's something we're investigating.

987
00:49:46,100 --> 00:49:48,230
So I appreciate your patience.

988
00:49:48,230 --> 00:49:50,020
And if we have time for questions

989
00:49:50,020 --> 00:49:52,753
I'm happy to try to answer your questions.

990
00:49:54,210 --> 00:49:55,580
- Thank you, that was a great talk.

991
00:49:55,580 --> 00:49:57,610
And we do have a couple of
questions rolling in already.

992
00:49:57,610 --> 00:49:59,270
So we'll definitely be keeping you busy

993
00:49:59,270 --> 00:50:01,030
for a little bit longer here.

994
00:50:01,030 --> 00:50:02,090
- No problem.

995
00:50:02,090 --> 00:50:05,140
- First is we had a question from

996
00:50:06,990 --> 00:50:08,320
Neil Camon.

997
00:50:08,320 --> 00:50:10,260
- [Neil] My question has to
do with the water loading.

998
00:50:10,260 --> 00:50:11,830
So you've been documenting changes

999
00:50:11,830 --> 00:50:13,450
in water loading to the watershed

1000
00:50:13,450 --> 00:50:16,100
and changes in stream
flow as a result of that?

1001
00:50:16,100 --> 00:50:17,080
- Yes,

1002
00:50:17,080 --> 00:50:18,630
- [Neil] One of the
things that we've noticed

1003
00:50:18,630 --> 00:50:21,010
So our researchers in Lake
Champlain have attempted

1004
00:50:21,010 --> 00:50:23,670
to do the same thing at the
whole Lake watershed scale

1005
00:50:23,670 --> 00:50:26,070
looking at all the major river basins

1006
00:50:26,070 --> 00:50:27,630
and we're documenting same kind

1007
00:50:27,630 --> 00:50:29,370
of changes in precipitation.

1008
00:50:29,370 --> 00:50:33,640
And frankly the same kinds
of changes in event types

1009
00:50:33,640 --> 00:50:35,270
both on the low end and the high end

1010
00:50:35,270 --> 00:50:39,300
but what we're not seeing is a real change

1011
00:50:39,300 --> 00:50:42,640
in water loading of any kind,
which is real interesting.

1012
00:50:42,640 --> 00:50:45,090
You would expect that
some point or another

1013
00:50:45,090 --> 00:50:46,440
you would see those that

1014
00:50:46,440 --> 00:50:48,400
that congruence just like
your research showed.

1015
00:50:48,400 --> 00:50:51,470
So I'm wondering if you
have any thoughts as to the

1016
00:50:51,470 --> 00:50:54,380
maybe the scale or difference
between something the size

1017
00:50:54,380 --> 00:50:56,410
of Hubbard Brook relative
to something the size

1018
00:50:56,410 --> 00:51:00,520
of Lake Champlain and
whether there's, you know

1019
00:51:00,520 --> 00:51:02,910
some kind of big watershed
attenuation factor

1020
00:51:02,910 --> 00:51:04,763
that we should try and account for.

1021
00:51:06,160 --> 00:51:08,310
- Yeah, I would, you know, I
would have to think a little

1022
00:51:08,310 --> 00:51:10,030
bit about this, but I would, you know

1023
00:51:10,030 --> 00:51:12,100
I guess my first guess
might be some something

1024
00:51:12,100 --> 00:51:14,820
that is resulting in
some change in storage.

1025
00:51:14,820 --> 00:51:16,850
So at Hubbard Brook, we see a change

1026
00:51:16,850 --> 00:51:19,570
in storage through
changes in snowpack, but

1027
00:51:19,570 --> 00:51:23,010
because we try to account
for the water year in June

1028
00:51:23,010 --> 00:51:27,080
we try to minimize the storage
impact, but there are some

1029
00:51:27,080 --> 00:51:29,550
some of the variation that
I showed you is differences

1030
00:51:29,550 --> 00:51:31,240
in storage, sort of moisture,

1031
00:51:31,240 --> 00:51:33,370
but if you see a long-term trend

1032
00:51:33,370 --> 00:51:36,621
you wouldn't think that
that storage would change.

1033
00:51:36,621 --> 00:51:40,560
So something has to be going
on if it is indeed storage

1034
00:51:40,560 --> 00:51:43,350
or if there is another loss mechanisms.

1035
00:51:43,350 --> 00:51:47,470
So the watersheds at Hubbard
Brook are pretty watertight

1036
00:51:47,470 --> 00:51:49,460
there is certainly deep seepage, but

1037
00:51:50,933 --> 00:51:52,820
but we think it's minimal

1038
00:51:52,820 --> 00:51:55,853
from the measurements that, that we have.

1039
00:51:56,780 --> 00:51:59,260
But in your case probably
those large basins,

1040
00:51:59,260 --> 00:52:02,550
probably do have that, but yeah.

1041
00:52:02,550 --> 00:52:03,460
So I don't know.

1042
00:52:03,460 --> 00:52:05,140
And you don't, you don't see any change

1043
00:52:05,140 --> 00:52:07,390
in terms of Lake stage
or anything like that.

1044
00:52:08,701 --> 00:52:12,180
- [Neil] The Lake stage
certainly varies with waterflow

1045
00:52:12,180 --> 00:52:14,960
kind of on a day to day, week to week

1046
00:52:14,960 --> 00:52:17,460
and season to season basis,
I'm not sure actually

1047
00:52:17,460 --> 00:52:19,400
that we've looked at that specifically.

1048
00:52:19,400 --> 00:52:20,400
- Yeah, yeah.

1049
00:52:20,400 --> 00:52:22,540
Yeah, I don't know, I
have to think about that.

1050
00:52:22,540 --> 00:52:23,585
- Anyway, it's interesting.

1051
00:52:23,585 --> 00:52:25,740
I focused right in on that
when you were presenting it.

1052
00:52:25,740 --> 00:52:26,760
Thank you so much.

1053
00:52:26,760 --> 00:52:27,773
- Okay, very good.

1054
00:52:28,850 --> 00:52:29,970
- Thanks Neil.

1055
00:52:29,970 --> 00:52:31,810
We had a couple come in from the chat.

1056
00:52:31,810 --> 00:52:33,840
There was one for

1057
00:52:33,840 --> 00:52:36,250
from David brand says
peak flows are increasing.

1058
00:52:36,250 --> 00:52:39,300
Should we be revisiting our
best management practices?

1059
00:52:39,300 --> 00:52:41,960
Should we Forest the
tenders, be focusing more on

1060
00:52:41,960 --> 00:52:45,890
optimal conservation practices
to protect water quality

1061
00:52:45,890 --> 00:52:48,280
and to enhance flood resilience?

1062
00:52:48,280 --> 00:52:50,840
- Yeah, I think that's a
great, it's a great point.

1063
00:52:50,840 --> 00:52:52,693
So locally here,

1064
00:52:54,280 --> 00:52:56,930
I'm dealing with harmful algal blooms.

1065
00:52:56,930 --> 00:52:59,930
I'm not sure to what
extent that's a problem

1066
00:52:59,930 --> 00:53:02,640
throughout New England but
it's a prominent problem

1067
00:53:02,640 --> 00:53:03,610
in upstate New York.

1068
00:53:03,610 --> 00:53:06,300
And we think that that's partially driven

1069
00:53:06,300 --> 00:53:08,270
by these very large events

1070
00:53:08,270 --> 00:53:12,620
which are increasing erosion
and increasing nutrient supply.

1071
00:53:12,620 --> 00:53:14,770
And then of course with water increases

1072
00:53:14,770 --> 00:53:18,030
in water temperature,
it becomes problematic.

1073
00:53:18,030 --> 00:53:20,760
So yes, we, we are locally.

1074
00:53:20,760 --> 00:53:24,740
We were doing a lot of
remediation projects and looking

1075
00:53:24,740 --> 00:53:29,740
at best practices to try to
improve infiltration and to

1076
00:53:31,570 --> 00:53:36,570
and to eliminate these very,
very high damaging flow events.

1077
00:53:37,530 --> 00:53:39,560
One interesting observation

1078
00:53:39,560 --> 00:53:41,210
which is a little bit

1079
00:53:42,650 --> 00:53:46,280
challenging that I didn't
focus on this in the lecture

1080
00:53:46,280 --> 00:53:50,750
is that, you know we're seeing
these increases in flow,

1081
00:53:50,750 --> 00:53:55,510
but we are not seeing that the forest

1082
00:53:55,510 --> 00:53:58,400
is really doing a great job at attenuating

1083
00:53:58,400 --> 00:54:01,780
these very high flow
events, so you might expect

1084
00:54:01,780 --> 00:54:05,570
that with increases in temperature
that you might anticipate

1085
00:54:05,570 --> 00:54:08,430
an increase in evaporative losses

1086
00:54:09,394 --> 00:54:12,330
but we are not really seeing that.

1087
00:54:12,330 --> 00:54:16,752
So I think we have to
think about, you know

1088
00:54:16,752 --> 00:54:20,870
flow paths of water and
thinking about riparian zones

1089
00:54:20,870 --> 00:54:22,690
and thinking about wetlands

1090
00:54:24,140 --> 00:54:26,840
in terms of attenuating

1091
00:54:27,880 --> 00:54:32,470
water trying to increase
storage and promote infiltration

1092
00:54:32,470 --> 00:54:34,480
because we're, I don't think
we're going to get a lot

1093
00:54:34,480 --> 00:54:37,130
of benefit from additional
evapotranspiration

1094
00:54:37,990 --> 00:54:41,410
at least not over the short-term
from these large events.

1095
00:54:41,410 --> 00:54:42,980
It's not clear why that is, maybe

1096
00:54:42,980 --> 00:54:45,750
the events are so intense
that the trees can't

1097
00:54:45,750 --> 00:54:50,103
really process that water
as rapidly as we would like.

1098
00:54:51,000 --> 00:54:53,750
But, so I think we have
to really think carefully

1099
00:54:53,750 --> 00:54:55,983
about best practices and,

1100
00:54:56,820 --> 00:54:58,823
but that is really a critical concern.

1101
00:55:02,210 --> 00:55:06,890
- Thanks, there is a comment
and a question about fire.

1102
00:55:06,890 --> 00:55:09,860
One pointing out that longer
Vernal Transitions correspond

1103
00:55:09,860 --> 00:55:12,860
to a longer wildland
prescribed fire burn window

1104
00:55:12,860 --> 00:55:15,390
is the potential upside,
I think for management.

1105
00:55:15,390 --> 00:55:19,280
And then a question about
any pre or post colonization

1106
00:55:19,280 --> 00:55:23,043
fire history at Hubbard Brook
that you all have or track?

1107
00:55:24,307 --> 00:55:28,740
- Well, we always call the
forests at Hubbard Brook asbestos

1108
00:55:28,740 --> 00:55:31,360
forest, cause they're
really are are quite wet

1109
00:55:31,360 --> 00:55:32,770
and quite resistant to fire.

1110
00:55:32,770 --> 00:55:34,750
We have had some

1111
00:55:34,750 --> 00:55:36,640
episodes of

1112
00:55:36,640 --> 00:55:37,603
fire.

1113
00:55:39,470 --> 00:55:42,320
And so that, you know, that
is an interesting question.

1114
00:55:42,320 --> 00:55:45,620
There was a relatively large
fire, I think it was in 2017

1115
00:55:47,630 --> 00:55:50,660
in the lower Appalachians that really

1116
00:55:51,940 --> 00:55:53,960
created a lot of problems.

1117
00:55:53,960 --> 00:55:57,700
So usually we don't worry a lot about fire

1118
00:55:57,700 --> 00:56:02,150
but I think that given the,
the longer growing season, they

1119
00:56:03,030 --> 00:56:04,677
the loss of snow pack earlier

1120
00:56:04,677 --> 00:56:09,480
and earlier potential
increases in drought stress.

1121
00:56:09,480 --> 00:56:13,830
I would not be surprised if
a fire was not more prominent

1122
00:56:13,830 --> 00:56:17,140
in the future, as strange
as that, if that seems

1123
00:56:17,140 --> 00:56:19,310
and we do that, we have done, you know

1124
00:56:19,310 --> 00:56:23,180
where there've been fires
in the, in the region

1125
00:56:23,180 --> 00:56:27,000
we've gone out regionally and
done some, some measurements

1126
00:56:27,000 --> 00:56:30,893
but not really focusing at all
at the experimental forest.

1127
00:56:32,500 --> 00:56:33,450
- Great, thank you.

1128
00:56:34,650 --> 00:56:36,800
From Jerry Carlson, he's asking,

1129
00:56:36,800 --> 00:56:40,460
Do you have coincidental time
measures of soil organism

1130
00:56:40,460 --> 00:56:43,330
abundance and complexity, and
could they play a large role

1131
00:56:43,330 --> 00:56:45,770
in the variations that you have found?

1132
00:56:45,770 --> 00:56:48,420
- Yeah, that's well out
of my area of expertise

1133
00:56:48,420 --> 00:56:51,780
but we do have a lot of
interesting information

1134
00:56:51,780 --> 00:56:53,623
on invertebrates,

1135
00:56:56,072 --> 00:56:57,103
and birds.

1136
00:56:58,330 --> 00:57:03,330
And there are large changes
and we try to integrate the

1137
00:57:04,550 --> 00:57:07,430
the food chain work
with the Biogeochemical

1138
00:57:07,430 --> 00:57:08,580
and the vegetation work.

1139
00:57:08,580 --> 00:57:09,810
We need to do a better job at it

1140
00:57:09,810 --> 00:57:11,070
but we are doing more of that

1141
00:57:11,070 --> 00:57:15,150
but there have been large
declines in insect populations

1142
00:57:15,150 --> 00:57:18,560
up at the forest, and there've
been some fairly large shifts

1143
00:57:18,560 --> 00:57:20,850
in bird species as well.

1144
00:57:20,850 --> 00:57:23,030
So yes, we are tracking that.

1145
00:57:23,030 --> 00:57:25,520
I can't really speak to that
with any great authority.

1146
00:57:25,520 --> 00:57:28,000
So I'm just going to leave it at that

1147
00:57:28,000 --> 00:57:30,018
not embarrass myself in front of you all.

1148
00:57:30,018 --> 00:57:32,153
(Jim laughs)

1149
00:57:32,153 --> 00:57:35,660
- Thanks and good to know
that that's something

1150
00:57:35,660 --> 00:57:38,200
that's out there and being looked at

1151
00:57:38,200 --> 00:57:40,648
as this larger part of the study.

1152
00:57:40,648 --> 00:57:43,480
Sarah Nelson shares great talk is always

1153
00:57:43,480 --> 00:57:46,330
for the investigation of
climate on potential forest

1154
00:57:46,330 --> 00:57:47,900
electrification.

1155
00:57:47,900 --> 00:57:50,680
You slide mentioned an
elevational gradient.

1156
00:57:50,680 --> 00:57:52,110
Are you collecting climate data

1157
00:57:52,110 --> 00:57:55,293
on an elevation gradient at Hubbard Brook?

1158
00:57:56,780 --> 00:57:59,360
- Yes, yeah, well, Sarah,
good to hear from you.

1159
00:57:59,360 --> 00:58:00,510
Hope you're doing well.

1160
00:58:01,540 --> 00:58:04,550
We, so we, as I mentioned early on taught

1161
00:58:04,550 --> 00:58:06,450
we use a variety of approaches.

1162
00:58:06,450 --> 00:58:08,280
And so at Hubbard Brook

1163
00:58:09,420 --> 00:58:11,100
there's quite an elevational gradient.

1164
00:58:11,100 --> 00:58:13,920
And so there's about a two
degree difference between

1165
00:58:15,683 --> 00:58:19,690
the lower part of the Valley
and the, the highest elevation.

1166
00:58:19,690 --> 00:58:21,660
And so we've set in a series

1167
00:58:21,660 --> 00:58:25,593
of plots that we've been
doing measurements of,

1168
00:58:27,540 --> 00:58:30,500
you know sort of physical
measurements, as well as

1169
00:58:30,500 --> 00:58:34,000
soil measurements associated
plant measurements.

1170
00:58:34,000 --> 00:58:38,110
So we're trying to take
advantage of this gradient as

1171
00:58:38,110 --> 00:58:40,540
you know, a speciAL
gradient that we could then

1172
00:58:40,540 --> 00:58:42,220
infer temporal patterns.

1173
00:58:42,220 --> 00:58:45,590
So the amount of snowpack
accumulation is much greater

1174
00:58:45,590 --> 00:58:50,590
up at higher elevations than
it is at lower elevations.

1175
00:58:50,760 --> 00:58:53,240
And so we've had these plots

1176
00:58:53,240 --> 00:58:55,470
in place and we are taking advantage

1177
00:58:55,470 --> 00:58:58,170
of those in the, in the current study.

1178
00:58:58,170 --> 00:59:01,853
Another interesting
thing that we're doing is

1179
00:59:01,853 --> 00:59:03,740
and maybe some of you know, this

1180
00:59:03,740 --> 00:59:06,530
but when the

1181
00:59:06,530 --> 00:59:08,880
leaf litter inputs

1182
00:59:08,880 --> 00:59:12,310
generally the nitrogen content
of that leaf litter changes

1183
00:59:12,310 --> 00:59:15,870
over the period of, of
leaf loss from the canopy.

1184
00:59:15,870 --> 00:59:20,870
So we've been capturing
cohorts of, of litter at time,

1185
00:59:20,990 --> 00:59:23,860
through the leaf fall season

1186
00:59:23,860 --> 00:59:27,270
and where we're collecting
that. and we will do a series

1187
00:59:27,270 --> 00:59:29,450
of litter bags that will
have different levels

1188
00:59:29,450 --> 00:59:30,930
of nitrogen to try to look

1189
00:59:30,930 --> 00:59:35,930
at this resorption phenomenon
and try to try to track

1190
00:59:36,400 --> 00:59:39,530
try to track that down and
understand that better.

1191
00:59:39,530 --> 00:59:41,570
So where we're trying to take advantage

1192
00:59:41,570 --> 00:59:44,150
of different aspects, spatial

1193
00:59:44,150 --> 00:59:45,830
and temporal aspects of the forest

1194
00:59:45,830 --> 00:59:48,710
and try to understand,
you know, what's going on.

1195
00:59:48,710 --> 00:59:51,500
So it's, I didn't emphasize in the talk

1196
00:59:51,500 --> 00:59:54,050
but it's an important
approach to do quick to do

1197
00:59:54,050 --> 00:59:56,690
great in studies as well
and taking advantage

1198
00:59:56,690 --> 00:59:58,173
of the spacial variations.

1199
01:00:01,256 --> 01:00:02,363
- Great, thank you.

1200
01:00:03,870 --> 01:00:07,240
Breck Bowden added or asked,
what is your explanation

1201
01:00:07,240 --> 01:00:10,020
for the strong decrease in
nitrogen oxide over time

1202
01:00:10,020 --> 01:00:14,280
decreasing nitrification
decreasing denitrification or both

1203
01:00:15,820 --> 01:00:18,110
- Brac, you should be able to
answer that question better

1204
01:00:18,110 --> 01:00:20,900
than me, you know, much
more about those processes

1205
01:00:20,900 --> 01:00:23,250
than I do, but I mean,
they're coincidence with

1206
01:00:24,460 --> 01:00:27,460
with certainly decreases in nitrification

1207
01:00:27,460 --> 01:00:32,460
I showed you those sort of
longterm data we don't have as

1208
01:00:32,756 --> 01:00:35,980
you know, like if we don't
have really good assays about

1209
01:00:37,740 --> 01:00:41,690
about denitrification, but the soils

1210
01:00:41,690 --> 01:00:44,350
our soil moisture is increasing.

1211
01:00:44,350 --> 01:00:46,670
I actually, because I
was worried about time

1212
01:00:46,670 --> 01:00:49,140
I pulled out a slide of soil moisture.

1213
01:00:49,140 --> 01:00:51,750
We have long-term
measurements in soil moisture

1214
01:00:51,750 --> 01:00:54,330
and soil moisture is increased
bigly during the summer

1215
01:00:54,330 --> 01:00:56,370
months because that's when
all the rain is coming in.

1216
01:00:56,370 --> 01:00:57,863
So it,

1217
01:00:58,706 --> 01:01:01,200
you know it's not really
clear to me what's going on.

1218
01:01:01,200 --> 01:01:03,170
That's something that
we're hoping to look into

1219
01:01:03,170 --> 01:01:04,683
into this current study.

1220
01:01:05,880 --> 01:01:09,670
- I wanted to ask if you
wanted to pontificate

1221
01:01:09,670 --> 01:01:14,150
or just extrapolate and think
about, is there any monitoring

1222
01:01:14,150 --> 01:01:16,710
that we are not currently
doing that we need to be doing

1223
01:01:16,710 --> 01:01:19,475
at the larger landscape
scale to compliment

1224
01:01:19,475 --> 01:01:22,740
or confirm the information
you're seeing at Hubbard Brook?

1225
01:01:22,740 --> 01:01:24,480
Like if there's one thing
that we were going to focus

1226
01:01:24,480 --> 01:01:27,553
on at a landscape scale,
what might we consider?

1227
01:01:29,110 --> 01:01:31,100
- Yeah, that's a really good question.

1228
01:01:31,100 --> 01:01:34,620
And I worry a lot about
monitoring because, you know

1229
01:01:34,620 --> 01:01:36,050
as you know, probably much better

1230
01:01:36,050 --> 01:01:38,070
than I monitoring is really under siege.

1231
01:01:38,070 --> 01:01:41,620
We're losing more and more
monitoring stations all the time

1232
01:01:41,620 --> 01:01:43,530
really fundamental measurements, you know

1233
01:01:43,530 --> 01:01:45,723
stream flow measurements,
things like that.

1234
01:01:46,590 --> 01:01:48,500
And that's really critically important

1235
01:01:48,500 --> 01:01:51,403
in terms of understanding these processes.

1236
01:01:53,961 --> 01:01:56,670
You know, I'm involved
in, I am heavily involved

1237
01:01:56,670 --> 01:02:00,590
in the NADP, National
Atmospheric Deposition Program

1238
01:02:00,590 --> 01:02:04,350
and there's a bit of a crisis
within that organization

1239
01:02:04,350 --> 01:02:07,610
because so many States have
pulled out their support

1240
01:02:07,610 --> 01:02:11,840
for atmospheric deposition
monitoring just at a point when

1241
01:02:11,840 --> 01:02:15,530
where we're implementing
changes or they're in the case

1242
01:02:15,530 --> 01:02:18,420
of the Trump administration,
rollbacks and rules.

1243
01:02:18,420 --> 01:02:21,760
So are we really
characterizing the response

1244
01:02:21,760 --> 01:02:23,880
and the effectiveness of
these management actions?

1245
01:02:23,880 --> 01:02:26,790
So that's one example, but
there are lots of examples.

1246
01:02:26,790 --> 01:02:30,960
There've been closures of a
lot of USGS gauging stations

1247
01:02:30,960 --> 01:02:33,160
which is really in my mind, a tragedy

1248
01:02:33,160 --> 01:02:36,340
we need the women with these
increases in extreme events.

1249
01:02:36,340 --> 01:02:38,340
We need those data more

1250
01:02:38,340 --> 01:02:40,610
than ever to make intelligent decisions.

1251
01:02:40,610 --> 01:02:44,200
So I think it's a, it's a wide spread

1252
01:02:44,200 --> 01:02:47,110
it's a widespread problem, and
it's hard to point a finger

1253
01:02:47,110 --> 01:02:49,833
on any one, but there's lots of examples.

1254
01:02:50,698 --> 01:02:52,640
And so I think we just
have to make the case

1255
01:02:52,640 --> 01:02:55,830
that it's critically
important and it's really

1256
01:02:55,830 --> 01:02:58,660
giving us measures of what
our environment is doing

1257
01:02:58,660 --> 01:03:00,493
and how we need to respond to them.

1258
01:03:02,960 --> 01:03:03,793
- Thanks.

1259
01:03:03,793 --> 01:03:07,690
And one last question we'll
sneak in here at the end,

1260
01:03:07,690 --> 01:03:10,780
from Dan McKinley, how much
of a role can steep headwaters

1261
01:03:10,780 --> 01:03:13,370
like Hubbard Brook play
in flood attenuation

1262
01:03:13,370 --> 01:03:15,363
and how can it be improved?

1263
01:03:16,860 --> 01:03:17,930
- Yeah, that's a good question.

1264
01:03:17,930 --> 01:03:20,120
You know, I don't, I don't really know.

1265
01:03:20,120 --> 01:03:24,823
It's so different than the
larger, a larger landscape.

1266
01:03:28,290 --> 01:03:30,040
you know, I don't really
know what we can do

1267
01:03:30,040 --> 01:03:35,000
in terms of informing
attenuation other than informing

1268
01:03:35,000 --> 01:03:37,883
the drivers, the magnitude of the change.

1269
01:03:38,980 --> 01:03:41,110
And so what, what is
coming down the plaque

1270
01:03:41,110 --> 01:03:45,020
I think we have to think
further down slope to think

1271
01:03:45,020 --> 01:03:49,757
about effective attenuation
or mitigation options

1272
01:03:51,820 --> 01:03:54,610
because certainly the rain is increasing.

1273
01:03:54,610 --> 01:03:57,440
It's becoming more intense
and it's just going

1274
01:03:57,440 --> 01:04:02,440
down these high elevation
sites and heading into the

1275
01:04:02,634 --> 01:04:06,040
into the larger tributaries

1276
01:04:06,040 --> 01:04:08,250
and causing and causing problems.

1277
01:04:08,250 --> 01:04:11,610
So I think probably lower elevation areas

1278
01:04:12,930 --> 01:04:14,540
where there's more developed land

1279
01:04:14,540 --> 01:04:17,360
provide opportunities for smart management

1280
01:04:17,360 --> 01:04:19,720
but I think we certainly
know that it's a problem

1281
01:04:19,720 --> 01:04:21,600
and we can try to characterize the problem

1282
01:04:21,600 --> 01:04:25,003
but I'm afraid in terms
of offering solutions.

1283
01:04:26,280 --> 01:04:27,720
it doesn't look like

1284
01:04:27,720 --> 01:04:32,000
at least from what I can, you
know, what I can see anyway