Contact: Bridget Emmett
Email: b.emmett@ite.ac.uk
Site Location: Bangor, Gwynedd, United Kingdom
Latitude: 53.48 decimal degrees
Longitude: -4.00 decimal degrees
Mean Annual Temperature: 8.8 degrees Celsius
Mean Annual Precipitation: 1849 mm
Biome: Coniferous Forest
Experimental Manipulation: 36 kg NH4NO3, 35 kg and 70 kg NaNO3
Application Frequency: 52 times per year
Technology:
Start Date: October 15, 1990
End Date: 1996
Key Research Questions:
Key Findings:
Web Site:
Contact: Patrick Schleppi
Email: schleppi@wsl.ch
Site Location: Einsiedeln, Switzerland
Latitude: 47.05 decimal degrees
Longitude: 8.72 decimal degrees
Mean Annual Temperature: 5.3 degrees Celsius
Mean Annual Precipitation: 2350 mm
Biome: Coniferous Forest
Experimental Manipulation: 25.6 kg NH4NO3
Application frequency: 210 times per year
Technology:
Start Date: April 1, 1995
End Date: Ongoing
Key Research Questions:
Key Findings:
Web Site:
Contact: Live Semb Vestgarden
Email: live.semb.vestgarden@jordforsk.no
Site Location: Amli, Norway
Latitude: 59.90 decimal degrees
Longitude: 8.72 decimal degrees
Mean Annual Temperature: 5.2 degrees Celsius
Mean Annual Precipitation: 1100 mm
Biome: Coniferous Plantation
Experimental Manipulation: 90 NH4NO3
Application frequency: 1 per year
Technology:
Start Date: 1990
End Date: Ongoing
Key Research Questions:
Key Findings:
Web Site:
Publications:
Contact: Gus Shaver
Email: gshaver@mbl.edu
Site Location: Toolik Lake, Alaska, USA
Latitude: 68.63 decimal degrees
Longitude: -149.60 decimal degrees
Mean Annual Temperature: -9 degrees Celsius
Mean Annual Precipitation: 330 mm
Biome: Wet Sedge Meadow
Experimental Manipulation:
Application frequency:
Technology:
Start Date: July 1997
End Date: Ongoing
Key Research Questions:
Key Findings:
Web Site:
Publications:
Bear Brook Watershed Maine (BBWM)
Contact: Ivan J. Fernandez, Lindsey Rustad
Email: ivanjf@maine.edu, rustad@maine.edu
Site Location: Township 28, Maine, USA
Latitude: 44.86 decimal degrees
Longitude: -68.10 decimal degrees
Mean Annual Temperature: 7.1 degrees Celsius
Mean Annual Precipitation: 1303 mm
Biome: Mixed Forest
Experimental Manipulation: 25.2 kg (NH4)2SO4
Application frequency: 6 times per year
Technology: Aerial application of dry ammonium sulphate
Start Date: 1989
End Date: Ongoing
Key Research Questions:
Evaluate the decadal scale response of a
forested catchment to chronic additions of N and S
Key Findings:
S treatments to the West Bear
watershed. As
such, we are able to describe ecosystem processes not evident in short-term
experimental research. The treated West Bear watershed has shown evidence in
soils, soil solutions, vegetation and stream chemistry to validate our concepts
of the evolution of base cation depletion due to chronic acidification
stressors. Recent assessments of stream base cation trajectories suggest both
the reference and treatment watersheds may be approaching a new steady-state
with respect to base cation losses. Nitrogen export differences between streams
has decreased despite a continued evolution of internal ecosystem processes that
reflect continued and cumulative N enrichment. Stream SO4 export in both streams
appears to be in equilibrium with inputs, but a mechanism controlling the SO4
concentrations in West Bear is undefined. Conventional theory and models based
on adsorption mechanisms do not accurately predict stream export in the treated
watershed after two decades. We are currently studying the possibility of
mineral phases in the soil as controllers of SO4 through thermodynamic
calculations of both stream and soil solution chemistry. Extensive research has
recently been conducted on P dynamics and the LTREB data are essential to
support an understanding of P mass balance and cycling. Soil solution
measurements in 2007 demonstrated that significant P is exported in soil
solutions beyond ortho-P. In addition, the new soil solution data shows the
continuation of long-term soil solution trends in response to treatments when
added to historical soil solution data. These time series suggest good agreement
in the evolution of ecosystem biogeochemistry with streams, but poor agreement
from a mass export basis. Most recently we are developing techniques to evaluate
C, N and P enzymatic activities in soils to better define biotic mechanisms
controlling stream CNP stoichiometry and
export.
Web Site: http://www.umaine.edu/DrSoils/bbwm/bbwm.html
Contact: Gary Lovett
Email: LovettG@ecostudies.org
Site Location: Ulster County, New York, USA
Latitude: 42 decimal degrees
Longitude: -74 decimal degrees
Mean Annual Temperature: 4.3 degrees Celsius
Mean Annual Precipitation: 1530 mm
Biome: Mixed Hardwood Forest
Experimental Manipulation: 50 kg NH4NO3
Application frequency: 4 times per year
Technology:
Start Date: November 1997
End Date: Ongoing
Key Research Questions:
Key Findings:
Web Site:
Contact: Fang Yunting
Email: fangyt@scbg.ac.cn
Site Location: Zhaoqing, Guangdong, China
Latitude: 23.17 decimal degrees
Longitude: 112.17 decimal degrees
Mean Annual Temperature: 21 degrees Celsius
Mean Annual Precipitation: 1927 mm
Biome: Subtropical monsoon evergreen broadleaf mixed forest, pine forest
Experimental
Manipulation: 50, 100 and 150
kg NH4NO3-N
Application frequency: 12 times per year
Technology:
Start Date: July 2003
End Date: Ongoing
Key Research Questions:
Key Findings:
Web Site:
Contact: Sherry, Schiff
Email: sschiff@sciborg.uwaterloo.ca
Site Location: Kenora, Ontario, Canada
Latitude: 49.50 decimal degrees
Longitude: -93.50 decimal degrees
Mean Annual Temperature: 2.3 degrees Celsius
Mean Annual Precipitation: 673 mm
Biome: Open Boreal Forest
Experimental Manipulation: 38 kg NaNO3
Application frequency: 38 times per year
Technology:
Start Date: May 1995
End Date: Mid-August 1996
Key Research Questions:
Key Findings:
Web Site:
Contact: Mary Beth Adams
Email: mbadams@fs.fed.us
Site Location: Parsons, West Virginia, USA
Latitude: 39.08 decimal degrees
Longitude: -79.68 decimal degrees
Mean Annual Temperature: 9.13 degrees Celsius
Mean Annual Precipitation: 1458 mm
Biome: Mixed Hardwood Forest
Experimental Manipulation: 35.4 kg (NH4)2SO4
Application frequency: 3 times per year
Technology:
Start Date: January 1989
End Date: Ongoing
Key Research Questions:
Key Findings:
Web Site:
Contact: Heather Rueth
Email: hrueth@mbl.edu
Site Location: Fraser, Colorado, USA
Latitude: 39.87 decimal degrees
Longitude: -105.87 decimal degrees
Mean Annual Temperature: 1.1 degrees Celsius
Mean Annual Precipitation: 1120 mm
Biome: Coniferous Forest
Experimental Manipulation: 25 kg NH4NO3
Application frequency: 8 times per year
Technology:
Start Date: 1996
End Date: Ongoing
Key Research Questions:
Key Findings:
Web Site:
Contact: Filip Moldan
Email: Filip.Moldan@ivl.se
Site Location: Stenungsund, Sweden
Latitude: 58.07 decimal degrees
Longitude: 12.02 decimal degrees
Mean Annual Temperature: 6.4 degrees Celsius
Mean Annual Precipitation: 1100 mm
Biome: Coniferous Forest
Experimental Manipulation: 40 kg NH4NO3
Application frequency: 25 times per year
Technology:
Start Date: April 1991
End Date: Ongoing
Key Research Questions:
Key Findings:
Web Site:
Contact: Alison Magill
Email: alison@shooter.sr.unh.edu
Site Location: Petersham, Massachusetts, USA
Latitude: 42.50 decimal degrees
Longitude: -72.17 decimal degrees
Mean Annual Temperature: 6.74 degrees Celsius
Mean Annual Precipitation: 1119 mm
Biome: Mixed Forest
Experimental Manipulation: 150 kg and 50 kg NH4NO3
Application frequency: 6 times per year
Technology:
Start Date: May 1988
End Date: Ongoing
Key Research Questions:
Key Findings:
Web Site:
Contact: Eric Davidson
Email: edavidson@whrc.org
Site Location: Howland, Maine, USA
Latitude: 45.20 decimal degrees
Longitude: -68.73 decimal degrees
Mean Annual Temperature: 7.1 degrees Celsius
Mean Annual Precipitation: 1303 mm
Biome: Coniferous Forest
Experimental Manipulation:
Application frequency:
Technology:
Start Date:
End Date:
Key Research Questions:
Key Findings:
Web Site:
Publications:
Contact: Myron Mitchell
Email: mitchell@mailbox.syr.edu
Site Location: Newcomb, New York, USA
Latitude: 43.98 decimal degrees
Longitude: -74.23 decimal degrees
Mean Annual Temperature: 4.4 degrees Celsius
Mean Annual Precipitation: 1010 mm
Biome: Mixed Forest
Experimental Manipulation: 28 kg and 14 kg (NH4)2SO4
Application frequency: 1 time per year
Technology:
Start Date: 1991
End Date: 1993
Key Research Questions:
Key Findings:
Web Site:
Contact: Gary Lovett
Email: LovettG@ecostudies.org
Site Location: Millbrook, New York, USA
Latitude: 41.83 decimal degrees
Longitude: -73.75 decimal degrees
Mean Annual Temperature: 9.5 degrees Celsius
Mean Annual Precipitation: 1089 mm
Biome: Mixed Hardwood Forest
Experimental Manipulation: 100 kg NH4NO3
Application frequency: 4 times per year
Technology:
Start Date: August 1996
End Date: Ongoing
Key Research Questions:
Key Findings:
Web Site:
Contact: Per Gunderson
Email: PGU@FSL.DK
Site Location: Lemvig, Denmark
Latitude: 56.48 decimal degrees
Longitude: 8.40 decimal degrees
Mean Annual Temperature: 8.2 degrees Celsius
Mean Annual Precipitation: 888 mm
Biome: Norway Spruce Plantation
Experimental Manipulation: 35 kg NH4NO3
Application frequency: 12 times per year
Technology:
Start Date: February 1992
End Date: December 1997
Key Research Questions:
Key Findings:
Web Site:
Contact: Heather Rueth
Email: hrueth@mbl.edu
Site Location: Estes Park, Colorado, USA
Latitude: 39.87 decimal degrees
Longitude: -105.87 decimal degrees
Mean Annual Temperature: 0.8 degrees Celsius
Mean Annual Precipitation: 860 mm
Biome: Coniferous Forest
Experimental Manipulation: 25 kg NH4NO3
Application frequency: 8 times per year
Technology:
Start Date: 1996
End Date: Ongoing
Key Research Questions:
Key Findings:
Web Site:
Contact: Kurt Pregitzer
Email: ajburton@mtu.edu
Site Location: Michigan, USA
Latitude: 45.55 decimal degrees
Longitude: -84.85 decimal degrees
Mean Annual Temperature: 5.6 degrees Celsius
Mean Annual Precipitation: 872 mm
Biome: Northern Hardwood Forest
Experimental Manipulation: 30 kg NaNO3
Application frequency: 6 times per year
Technology:
Start Date: May 1994
End Date: Ongoing
Key Research Questions:
Key Findings:
Web Site:
Michigan Gradient Publications
Contact: Steve McNulty
Email: steve_mcnulty@ncsu.edu
Site Location: Mount Ascutney, Vermont, USA
Latitude: 43.43 decimal degrees
Longitude: -72.45 decimal degrees
Mean Annual Temperature: 4.69 degrees Celsius
Mean Annual Precipitation: 1000 mm
Biome: Coniferous Forest
Experimental Manipulation: 15.7 kg NH3Cl; 19.8 kg NaNO3, 25.6 kg NH4NO3, 31.4 kg (NH4)2SO4
Application frequency: 3 times per year
Technology:
Start Date: June 1988
End Date: Ongoing
Key Research Questions:
Key Findings:
Web Site:
Contact: Marife
D. Corre (NITROF) and Joseph S. Wright (long –term nutrient manipulation in tropical lowland
forest)
Email: mcorre@gwdg.de
Site Location: Smithsonian Tropical Research Institute, Panama
Latitude: Montane Forest in Fortuna -8.75 decimal degrees; Lowland Forest in Gigante -9.17 decimal degrees
Longitude:
Montane Forest in Fortuna - -82.25
decimal degrees Lowland Forest in Gigante - -79.85 decimal
degrees
Mean Annual Temperature: Montane Forest in Fortuna – 21 degrees Celsius; Lowland Forest in Gigante – 27 degrees Celsius
Mean Annual
Precipitation: Montane Forest in Fortuna - 6000 mm; Lowland Forest in Gigante 2637 mm
Biome:
Old growth tropical
montane and lowland forests
Experimental Manipulation: N addition at 125 kg ha-1 yr-1
Application
frequency: Split
in 4 applications per year
Technology:
Start
Date: Montane Forest in Fortuna - 2006; Lowland
Forest in Gigante - 1998
End Date: Ongoing
Key Research Questions:
Study 1: Changes in
internal fluxes and fates of N in forest soils
Study 2:
Effects on forest net primary production and structure (only focus on the
montane forest)
Study 3: Impact of chronic
N addition on trace gas exchange (NO, N2O, CO2, CH4)
Study 4: Effects of
increased N input on leaching losses of N, C and cations
Key Findings:
Study
1 – soil N cycling and retention:
The
long-term N addition to the lowland forest has increased gross N mineralization
rates and significantly increased N availability such that NO3-
pool (and thus, gross nitrification) became quantifiable. The 15N
natural abundance and 15N-enrichment factor, which reflect the
long-term behavior of soil N cycling of an ecosystem, tended to increase in the
long-term N fertilized plots, signifying that long-term N addition to the
lowland forest increased soil N cycling rates and consequently N losses.
Microbial biomass slightly decreased under long-term N addition, and the
microbial C:N ratio indicated a shift to a more bacterial dominated population.
These results showed that long-term N addition to a tropical forest can result
to changes in microbial biomass and microbial community structure. The baseline
measurements (prior to treatment) of the gross rates of soil N cycling in the
montane forest showed comparable rates as the lowland forest, which were higher
than other N-limited montane forests. Abiotic immobilization of NH4+
decreased under long-term N addition in the lowland forest. Both the lowland and
montane forest soils showed high abiotic NO3-
immobilization.
Study
2 – net primary production and
structure in a montane forest:
During
the first year N addition to the montane forest, we observed a significant
increase in diameter growth in trees with 10-30 cm diameter (0.7 ±
0.1 mm for the control plots and 1.1 ±
0.1 mm for the N plots from mid-February to mid-November 2006). There were also
differences in species response. We
did not detect N addition response from Oreomunnea mexicana. Vochysia
guatemalensis tended to show higher (although not statistically significant)
growth rates in the N than the control plots for trees with 30-50 cm diameter.
In contrast, Eschweilera panamensis revealed a strongly positive reaction
to N addition, particularly for trees with 10-30 cm diameter. The most
responsive category of litterfall was the leaf litter; total and leaf litterfall
significantly increased in the N plots after the third N application during the
first year.
Study
3 – trace gases emissions:
The
total emissions from the montane forest (0.77 ± 0.12 kg NO-N ha-1
and 0.61 ± 0.12 kg N2O-N ha-1 from mid-February to
November 2006) were higher than other N-limited montane forests. These emissions
significantly increased during the first-year N addition (6.93 ± 2.1 kg NO-N ha-1
and 3.59 ± 1.23 kg N2O-N ha-1 within the same period).
Although study 2 revealed that trees responded to N addition (signifying N
limitation), relatively high N oxide emissions also concurrently occurred. Our
results revealed that N oxide losses do not follow the notion that all sinks for
N have to be filled up first before losses occur. As shown in study 1, gross
rates of N cycling in this montane forest were comparable with the lowland
forest. Background emissions (control plots) from the lowland forest were (1.97
± 0.65 kg NO-N ha-1 and 1.06 ± 0.10 N2O-N ha-1)
higher than the montane forest. These increased further with long-term (9 years)
N addition (19.07 ± 4.34 kg NO-N ha-1 and 5.66 ± 1.69 kg N2O-N
ha-1). CO2 fluxes were lower from the montane than the
lowland forest. There was no difference in the CH4 uptake between the
montane and lowland forests. In both forest sites, N fertilization did not
affect CO2 and CH4 fluxes.
Study 4 – leaching losses:
After
nine years of N addition in the lowland forest, NO3-
leaching losses significantly increased. Soil acidification and decrease in base
saturation were also observed. For the montane forest, there was no N addition
effects observed on leaching losses during the first two N applications in the
first-year N addition. It is then apparent that effects of elevated N input on N
losses were manifested earlier on soil N oxide emissions rather than on leaching
losses from our montane forest.
Web Site: http://www.nitrof.forst.uni-goettingen.de
Publications:
Contact: Myron Mitchell
Email: mitchell@mailbox.syr.edu
Site Location: Warrensburg, New York, USA
Latitude: 43.55 decimal degrees
Longitude: -73.80 decimal degrees
Mean Annual Temperature: 8 degrees Celsius
Mean Annual Precipitation: 1000 mm
Biome: Red Pine Plantation
Experimental Manipulation: 28 kg and 14 kg (NH4)2SO4
Application frequency: 1 time per year
Technology:
Start Date: 1991
End Date: 1993
Key Research Questions:
Key Findings:
Web Site:
Contact: Myron Mitchell
Email: mitchell@mailbox.syr.edu
Site Location: Pancake Hall Creek, New York, USA
Latitude: 43.83 decimal degrees
Longitude: -74.85 decimal degrees
Mean Annual Temperature: 4.4 degrees Celsius
Mean Annual Precipitation: 1024 mm
Biome: Mixed Forest
Experimental Manipulation: 28 kg and 14 kg (NH4)2SO4
Application frequency: 1 time per year
Technology:
Start Date: 1991
End Date: 1993
Key Research Questions:
Key Findings:
Web Site:
Contact: Tryggve Persson
Email: Tryggve.Persson@eom.slu.se
Site Location: Halmsted, Sweden
Latitude: 56.55 decimal degrees
Longitude: 13.22 decimal degrees
Mean Annual Temperature: 7.5 degrees Celsius
Mean Annual Precipitation: 1145 mm
Biome: Coniferous Forest
Experimental Manipulation: 100 kg (NH4)2SO4
Application frequency: 3 times per year
Technology:
Start Date: June 1988
End Date: August 2001
Key Research Questions:
Key Findings:
Web Site:
Publications:
Contact: Marife Corre
Email: mcorre@gwdg.de
Site Location: Solling, Lower Saxony, Germany
Latitude: 51.52 decimal degrees
Longitude: 9.76 decimal degrees
Mean Annual Temperature: 7.3 degrees Celsius
Mean Annual Precipitation: 1100 mm
Biome: Mixed Forest
Experimental Manipulation: 140 kg (NH4)2SO4
Application frequency: 1 time per year
Technology:
Start Date: 1983
End Date: 1993
Key Research Questions:
Key Findings:
Web Site:
Contact: Wim Wessel
Email: wwessel@science.uva.nl
Site Location: Garderen, Spueld, The Netherlands
Latitude: 52.22 decimal degrees
Longitude: 5.65 decimal degrees
Mean Annual Temperature: 9.25 degrees Celsius
Mean Annual Precipitation: 800 mm
Biome: Coniferous Plantation
Experimental Manipulation: -32.5 kg (NH4)2SO4
Application frequency: continuous
Technology:
Start Date: May 1989
End Date: May 1995
Key Research Questions:
Key Findings:
Web Site:
Contact: Rich Phillips
Email:
Site Location: Ithaca, New York, USA
Latitude: 42.45 decimal degrees
Longitude: -76.41 decimal degrees
Mean Annual Temperature:
Mean Annual Precipitation:
Biome:
Experimental Manipulation:
Application frequency:
Technology:
Start Date:
End Date:
Key Research Questions:
Key Findings:
Web Site:
Publications:
Contact: Myron Mitchell
Email: mitchell@mailbox.syr.edu
Site Location: Woods Lake, New York, USA
Latitude: 43.88 decimal degrees
Longitude: -74.95 decimal degrees
Mean Annual Temperature: 4.4 degrees Celsius
Mean Annual Precipitation: 1407 mm
Biome: Mixed Forest
Experimental Manipulation: (NH4)2SO4
Application frequency: 1 time per year
Technology:
Start Date: 1991
End Date: 1993
Key Research Questions:
Key Findings:
Web Site:
Contact: Win Wessel
Email: wwessel@science.uva.nl
Site Location: Ysselsteyn, The Netherlands
Latitude: 51.50 decimal degrees
Longitude: 5.92 decimal degrees
Mean Annual Temperature: 9.8 degrees Celsius
Mean Annual Precipitation: 793 mm
Biome: Coniferous Plantation
Experimental Manipulation: -45.2 kg (NH4)2SO4
Application frequency: continuous
Technology:
Start Date: May 1989
End Date: Ongoing
Key Research Questions:
Key Findings:
Web Site: