Contents I.History of Hubbard Brook II.Watershed Concept III.Discovery of Acid Rain IV.Long-term...

Contents

I. History of Hubbard Brook

II. Watershed Concept

III. Discovery of Acid Rain

IV. Long-term Monitoring

V. Ecosystem Recovery

I. History of Hubbard BrookI. History of Hubbard Brook

The Hubbard Brook Experimental Forest was established by the U.S.D.A. Forest Service in 1955 to study how water flows through forests (hydrology).


The Hubbard Brook Ecosystem Study was founded by in 1963 by Dr. Robert S. Pierce of the USDA Forest Service and Drs. Gene E. Likens, F. Herbert Bormann, and Noye M. Johnson, of Dartmouth College.

Dr. G.E. Likens and Dr. F.H. Bormann, 2003 Not pictured: Dr. R.S. Pierce, Dr. N.M. Johnson


Likens, Bormann, Johnson and Pierce pioneered cooperative research to study nutrient cycling, which is how elements and nutrients move through forests.

This is called biogeochemistry (the integration of biology, geology and

chemistry).

In 1967 the keystone scientific paper of the Hubbard Brook Ecosystem Study was published in the journal Science by

Drs. Bormann and Likens:

Bormann, F. H. and G. E. Likens. 1967. Nutrient cycling. Science 155(3761):424-429


This analyzes the relationship

between the amount and

timing of

inputs&

outputs

from forested watersheds.

II. Watershed conceptII. Watershed concept

Hubbard Brook Acid Rain Story: Part 1

The northern forest can be viewed as

a network of watersheds, which all have

input-output relationships.

Water: rain, snow, fog droplets

Nutrients

Wet deposition: dissolved in water

Dry deposition: dust particles, gases

Mineral weathering: chemicals from soil

II. Watershed concept

Inputs Outputs

Water: streams

Evapotranspiration

Nutrients

(water)

(gases), CO2, N

Looking at

inputs compared to outputs

gives you a sense of what’s happening chemically

inside the forest.

HBES researchers began looking at

the chemistry of rain and snow

(inputs)

compared to

the chemistry of streams.

(outputs)

II. Watershed concept

HBEF researchers measured pH (the measure of acidity and alkalinity)

From Acid Rain Revisited, pg. 5

III. Discovery of Acid RainIII. Discovery of Acid Rain


In 1963, Drs. Likens, Bormann and Johnson noticed something strange about the pH of the rain at Hubbard Brook Experimental Forest.

One rain sample had a pH of 2.85, less than that of orange juice!

These findings were published in the journal Environment in 1972: Likens, G.E., F.H. Bormann, and N.M. Johnson. 1972.

Acid Rain. Environment 14: 33-40.


Normal rain has a pH of about 5.2, but rain at HBEF had pH levels of 4.0 to 4.2 - very acidic.

Scientists had known for a while that industrial pollution

could result in rain that was acidic…

but the Hubbard Brook Experimental Forest is in the White Mountains of New Hampshire,

which is far from most pollution sources.


Where was the acid rain coming from?

This led to the question:


They realized that emissions from power plants and heavy industry in the mid-western U.S travelled to NH and

dropped with the rain and snow.

Hubbard Brook Research Foundation: Acid Rain Revisited


HBES scientists hypothesized that:

If industries reduced sulfur dioxide emissions from these plants, the pH of rain at the Hubbard Brook Experimental Forest (and the entire northeastern U.S.) would increase, or become less acidic.


Research done by HBES scientists helped inform the decision by

the U.S. Congress to cut back on sulfur emissions from power plants.

The Clean Air Act of 1970, The CAA Amendments of 1990,

AndThe Clean Air Interstate Rule of 2005

include reductions in sulfur emissions.


Long-term monitoring of precipitation and stream water chemistry was essential for

evaluating these laws.

To understand the effect of the legislation, we had to know:

• how the ecosystems behaved before the laws.

• how they behaved after the laws began to take effect.

IV. Long-term MonitoringIV. Long-term Monitoring

Long-term monitoring has shown that:

• Rain and snow pH are increasing gradually.– Precipitation is becoming less

acidic.

• Chemical and biological characteristics of the forest are responding more slowly.– Ecosystem recovery is delayed.

IV. Long-term Monitoring

• Chemical recovery– Occurs first– Defined by chemical

characteristics of streams and soils

• Biological recovery– Occurs after

chemical recovery– Most short-lived

organisms respond relatively quickly (like insects)

– Long-lived organisms may take decades to respond (like trees)

V. Ecosystem RecoveryV. Ecosystem Recovery


At the Hubbard Brook Experimental Forest and in much of the Northeast:

chemical and biological recovery thresholds have not been met,

so….acid rain is still a problem.


Acid rain has changed the chemistry of soils at the HBEF

• Made soils more acidic.

• Accelerated the leaching of base cations (such as calcium and magnesium) from soils that help to buffer acidity.

• Increased inorganic aluminum in soil, which can be toxic to organisms.

• Caused sulfur and nitrogen to accumulate in soil.


Acid rain has weakened trees’ ability to respond to stress.


It has impacted lakes

and streams.


Why has ecosystem recovery

been delayed?

More experimentation

and long-term monitoring

were needed

to find the answers.


The Hubbard Brook Acid Rain StoryPart II: The Calcium Experiment

For more information on the role of the Hubbard Brook Ecosystem Study in acid rain research,

please view the next slideshow.

For more information on acid rain, see…

Acid Rain Revisited,

a Science Links publication by

the Hubbard Brook Research

Foundation

www.hubbardbrookfoundtion.org

Contents I.History of Hubbard Brook II.Watershed Concept III.Discovery of Acid Rain IV.Long-term...

Documents

Transcript of Contents I.History of Hubbard Brook II.Watershed Concept III.Discovery of Acid Rain IV.Long-term...