Importance of LTER Data: N Saturation Example

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Importance of LTER Data N Saturation Example
Long-term Investigations of Nitrogen Saturation
in Temperate Forest Ecosystems
In 1989, Harvard Forest group published a series
of hypotheses concerning the expected responses
of N limited forest ecosystems to chronically
elevated N deposition. The findings show that it
is indeed possible to induce nitrification and
nitrate leaching with chronic N additions,
although this took much longer in the very N-poor
hardwood stand than expected
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Stream Characteristic Changes in Hubbard Brook
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HubbardBrooktitle_typetkayear_from1997year_
to2004database1pageSize20index4
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AgainImportance of LTER Data Example
Agriculture's Impact on Global Warming and
Potentials for Greenhouse Gas Mitigation
For the past ten years scientists at the KBS LTER
site have studied fluxes of the major, naturally
occurring greenhouse gasesCO2, methane, and
nitrous oxidein a variety of cropped and natural
ecosystems. A recent report in Science showed
that different cropping strategies can have
markedly different global warming potentials.
http//www.lternet.edu/vignettes/and.html
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Long-Term Trends in Stream Data
Stream data from the HBEF reveal a number of
long-term trends (see Figure 1). Specifically,
the concentration of sulfate in streams at the
HBEF declined 20 percent between 1963-1994. The
pH of streams consequently increased from 4.8 to
5.0. Although this represents an important
improvement in water quality, streams at the HBEF
remain acidic compared to background conditions,
estimated to be above 6.0. Moreover,
acid-neutralizing capacityan important measure
of a lake or stream's susceptibility to acid
inputshas not improved significantly at the HBEF
over the past thirty years.
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4/00000054/00000002/art00008
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