Two nearly adjacent subcatchments, located in the Adirondack Mountains of New York State, US, with similar atmospheric inputs of N (0.6 kmol ha-1 yr-1), but markedly different stream water solute concentrations, provided a unique opportunity to evaluate the mechanisms causing this variation.
Keywords: acer saccharum, atmospheric deposition, calcium, catchment, hydrology, land use history, nitrate, nitrogen, tree species
Source: Global Change Biology. 12: 364-381.
Although the watershed approach has long been used to study whole-ecosystem function, it has seldom been applied to study human-dominated systems, especially those dominated by urban and suburban land uses. Here we present 3 years of data on nitrogen (N) losses from one completely forested, one…
Keywords: nitrogen, nitrate, watershed, urban, mass balance, long-term ecological research
Source: Ecosystems. 7: 394-403.
In N-limited ecosystems, fertilization by N deposition may enhance plant growth and thus impact C sequestration. In many N deposition-C sequestration experiments, N is added directly to the soil, bypassing canopy processes and potentially favoring N immobilization by the soil. To understand the…
Keywords: nitrogen-15, nitrate, ammonium, nitrogen deposition, carbon sequestration, Forest elemental cycling
Source: Oecologia. 160: 589-599.
We investigated variations in resource availability (NOa-N and labile organic C [LOCJ] as determinants of potential denitrification in stream sediments in the southern Appalachian Mountains, USA. stream-water and sediments were sampled seasonally in 2 streams of contrasting NO3,-N availability,…
Keywords: dentrification, sediments, nutrient limitations, temporal variability, nitrate, dissolved organic carbon, nitrogen deposition, stream ecology
Source: J. N Am. Benthol Soc., 2001, 20(4)505-519
This study uses time series analysis to examine long-term stream water nitrate concentration records from a pair of forested catchments at the Coweeta Hydrologic Laboratory, North Carolina, USA. Monthly average concentrations were available from 1970 through 1997 for two forested catchments, one of…
Keywords: nitrate, streamwater, forest hydrology, climate change, ecological change
Source: Water Resources Research 39(7): 1-14
Presents a graphical procedure for evaluating the same sensitivity of lakes to acidification due to acid deposition. The procedure is based on empirical relationships between sulfur (and in some cases nitrogen) deposition rates and lake pH, acid-neutralizing capacity, base cation concentrations,…
Keywords: acid-neutralizing capacity, base cations, conductivity, nitrate, sulfate
Source: Research Paper NC-289. St. Paul, MN: U.S. Dept. of Agriculture, Forest Service, North Central Forest Experiment Station
Input-output budgets for dissolved inorganic nitrogen (DIN) are summarized for 24 small watersheds at 15 locations in the northeastern United States. The study watersheds are completely forested, free of recent physical disturbances, and span a geographical region bounded by West Virginia on the…
Keywords: ammonium, input-output relationships, nitrate, nitrogen saturation
Source: Water, Air, and Soil Pollution. 151: 373-396.
Five methods for estimating maximum daily and annual nitrate (NO3) and suspended sediment loads using periodic sampling of varying intensities were compared to actual loads calculated from intensive stormflow and baseflow sampling from small, forested watersheds in north central West Virginia to…
Keywords: nitrate, sampling frequency, stormflow, concentrations, suspended sediment, total maximum daily loads
Source: Environmental Monitoring and Assessment. 98: 201-223.
Competition between ponderosa pine seedlings and various grasses and forbs was studied on :I site in northern Arizona burned in 1982 by a wildfire. Two-year-old pine seedlings were planted in 3.05 x 3.05 m plots in April 1983, followed by the sowing of grass and forb seeds on the same plots in…
Keywords: competition, xylem water potential, nitrate, ammonium, Pinus ponderosa
Source: Forest Science. Vol. 33, No. 2, pp. 356-366 1987
In May 1998 an outbreak of sawflies, Periclista sp. (Hymenoptera: Symphyta), occurred in a high-elevation hardwood forest in western North Carolina. Estimated defoliation of northern red oak (Quercus rubra) and white oak (Q. alba) removed 40% of leaf area Weights of frass (insect feces) collected…
Keywords: canopy, herbivory, nutrient cycling, nitrate, sawflies
Source: Selbyana 21(1,2): 74-78. 2000.