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Chronic Nitrogen Amendment Experiment - LTSE

Relationships
Data Holder: 
Barker Plotkin, Audrey
Subnetworks: 
Harvard Forest Based LTSEs
Location:
Harvard Forest
United States
Latitude: 42.540000
Longitude: -72.180000
Background
Continent: 
North America
Website: 
http://harvardforest.fas.harvard.edu
Year LTSE Began: 
1988
On-going or Terminated?: 
On-going
Comments: 
The purpose of this study is to increase our understanding of ecosystem nitrogen dynamics in response to elevated nitrogen inputs. With atmospheric nitrogen deposition in the Northeastern United States currently at 10 to 20 times above historic background levels, it is possible that excessive nitrogen inputs could saturate the retention capacity of a forest ecosystem. Potential effects of nitrogen saturation include increased nitrate leaching and simultaneous base cation losses, soil acidification, altered fluxes of trace gases and forest decline. Two adjacent stands were chosen for the study: an even-aged red pine (Pinus resinosa Ait.) stand planted in 1926 and a 50-year-old mixed hardwood stand that had regenerated naturally after clearcutting in approximately 1945. The hardwood stand is dominated by black and red oak (Quercus velutina Lam.; Q. rubra L.) with significant amounts of black birch (Betula lenta L.), red maple (Acer rubrum L.) and american beech (Fagus grandifolia Ehrh.). The dominant soil types are stony- to sandy-loams formed from glacial till, and are classified as Typic Dystrochrepts of the Canton or Montauk series. Four treated plots were established within each stand: control, low N, low N plus sulfur (N+S) and high N. Each plot measures 30 x 30 meters (0.09 ha) and is divided into thirty-six 5 x 5 m subplots.
Environment
Annual Precipitation (mm): 
800-1200
Mean Annual Soil Temperature (C): 
Mesic: 8 to 15C
Is temperature regime isothermic? ie, do mean monthly temperatures deviate by <6C?: 
No
Is atmospheric deposition chemistry monitored?: 
No
Dominant plant species (latin genus and species): 
Acer rubrum (red maple), Betula lenta (black birch), Fagus grandifolia (american beech), Pinus resinosa (red pine), Quercus rubra (red oak), Quercus velutina (black oak)
Landuse: 
Forestry
Ecoregion: 
Cool Temperate
Landform (general description): 
New England Upland, elevation 220-410m asl
Slope (%): 
2-5%
Elevation (m): 
200-500
Geological material: 
granite, gneiss & schist
Experimental Design
Design (short description): 
Fertilizer additions of NH4NO3 and Na2SO4 began in 1988 as six equal applications over the growing season (May - Sept). Fertilizer is weighed, mixed with 20 liters of water (equivalent to 0.002 cm rainfall) and applied using a backpack sprayer. Na2SO4 applications were discontinued after the 1998 growing season. The hardwood and pine stands each contain four plots, with application rates as follows: Control, Low = 5gN/m^2 per year, High = 15gN/m^2 per year, N+S = 5gN/m^2 + 7.4gS/m^2 per year. Plot designations are P or H followed by C,L,H,NS for control, low, high N+S, respectively. Upon request, more detailed information is available on the exact applications rates based on fertilizer sample analysis.
Permanent plot area (square meters): 
100-1000
Number of permanent plots: 
3-10
Soil/Data Archive
Data Archive: 
Yes
Vegetative samples archived: 
Yes
Soil solid samples archived: 
Yes
Samples from multiple depths: 
Yes
Sample frequency: 
Annual
Year of first sampling for archive: 
1988
Year of last sampling for archive: 
2008
Soil Solid Data
pH and acidity: 
Yes
Organic Carbon: 
Yes
Nitrogen: 
Yes
Chemical Contaminents: 
No
Vegetation Data
Biomass above ground: 
Yes
Soil Biota Data
Microorganisms: Biomass, Densities, Taxonomy: 
Yes