contents i.ecosystem changes ii.chemical recovery iii.biological recovery iv.future changes
TRANSCRIPT
Contents
I. Ecosystem Changes
II. Chemical Recovery
III. Biological Recovery
IV. Future Changes
Ecosystems are dynamic• They are constantly
responding to a changing environment.
• Examples of natural disturbances:- hurricanes/wind storms- fire- ice storms- drought- insect damage
Damage from the ice storm of 1998
I. Ecosystem ChangesI. Ecosystem Changes
they go through a process of
recovery.
When ecosystems are relieved
from a stress such as acid rain,
I. Ecosystem Changes
Photo by Joseph Mehling
Hubbard Brook Acid Rain Story: Part III
Chemical recovery
of an ecosystem must happen before
biological recovery
can take place.
II. Chemical RecoveryII. Chemical Recovery
If emissions reductions are sufficient, then:
• Sulfate concentrations in soil and stream water decrease
• Nitrate concentrations in soil and stream water decrease
• Inorganic aluminum concentrations in soil and stream water decrease
• pH of soil and stream water increases (less acidic)
• acid-neutralizing capacity increases (soil is more “buffered”)
• base cations (nutrients) increase
II. Chemical Recovery
Chemical Recovery
leads to
Biological Recovery
Biological recovery usually occurs in stages...
III. Biological RecoveryIII. Biological Recovery
Hubbard Brook Acid Rain Story: Part III
Stream macroinvertebrates
may recover within three years…
III. Biological Recovery
Lake zooplankton
may take a decade or more to reestablish.
III. Biological Recovery
Fish populations
should recover in
five to ten years
III. Biological Recovery
Trees probably take decades.
III. Biological Recovery
Ecosystem Recovery from Acid Rain
Clean Air LegislationPassed
Emissions and Deposition Reduced Chemical Recovery Biological Recovery
From Acid Rain Revisited, pg. 16-17
To what extent must emissions be reduced to allow ecosystems in the
Northeast to fully recover?
To answer this question, HBES scientists used a computer model called PnET-BGC
to estimate the relationship between emissions, deposition and chemical
recovery at the HBEF.
IV. Future ChangesIV. Future Changes
Hubbard Brook Acid Rain Story: Part III
Results of the model suggest that
deeper reductions in emissions beyond
those mandated in the 1990 Clean Air Act
Amendments
are necessary to achieve ecosystem
recovery. Photo by Joseph Mehling
IV. Future Changes
In specific, results from the model suggest that
an 80% reduction in electric utility emissions of sulfur dioxide beyond
the requirements of the CAAA
would cause headwater streams like those found at the HBEF to become biologically
favorable to organisms again within the next 20-25 years.
IV. Future changes
The only way to determine the effects of legislation on ecosystem recovery is to
continue long-term monitoring of deposition, surface waters and ecosystems.
The Hubbard Brook Experimental Forest is one of 26 sites in the U.S. that monitor ecological
processes over long periods of time as part of the Long-Term Ecological (LTER) Network. The
HBEF has been an National Science Foundation-funded LTER site since 1988.
IV. Future Changes
With continued funding, HBES researchers will continue to monitor ecosystems in the
Northeast.
Their findings help us to understand our relationship with the natural environment.
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For more detailed information on ecosystem recovery:
Acid Rain Revisited,
a Science Links publication of the Hubbard Brook Research Foundation
www.hubbardbrookfoundation.org