Nitrogen input/output relationships in Tennessee forests. Final report

Technical Report · Thu May 01 04:00:00 EDT 1986

OSTI ID:5493291

Kelly, J M; Meagher, J F

Nitrogen is one of the most important limiting nutrients for biological productivity, and in response to this limitation, natural forest ecosystems tend to accumulate and cycle large amounts of nitrogen. Atmospheric sources, based on a 28-month study, are estimated to introduce a total of 11.6, 11.3, and 13.2 kg ha/sup -1/ yr/sup -1/ of nitrogen to the Cross Creek, Camp Branch, and Walker Branch Watershed study sites, respectively. These inputs interact with the forest canopy resulting in average nitrogen inputs to the forest floor of 13.4, 11.6 kg ha/sup -1/ yr/sup -1/, respectively. Summing wetfall, dryfall, gaseous NO and NO/sub 2/, and estimated HNO/sub 3/ vapor indicates a contribution of 28, 38, 5, and 29 percent of total atmospheric input at Cross Creek; 26, 39, 6, and 29 percent at Camp Branch; and 22, 31, 18, and 29 percent at Walker Branch. Summing throughfall and stemflow indicates a contribution of 89 and 11 percent, respectively, to forest floor inputs at Cross Creek; 93 and 7 percent at Camp Branch; and 96 and 4 percent at Walker Branch. Comparison of atmospheric inputs to nitrogen losses via streamflow indicates 66 to 79 percent of input is retained, leading to losses via streamflow of 3.9, 2.4 and 4.4 kg ha/sup -1/ yr/sup -1/ at Cross Creek, Camp Branch, and Walker Branch, respectively. The data collected suggests that dry deposition of gaseous NO and NO/sub 2/ are small contributors to nitrogen input at Camp Branch and Cross Creek (<6 percent), but do contribute substantially (18 percent) at Walker Branch. These differences are attributed to the fact that Walker Branch is located in an urbanized area and as such is subject to local impacts. Estimates of nitrogen input obtained in this study indicate that atmospheric pollutants contribute an amount equivalent to approximately 10 percent of the available nitrogen pool and 30 percent ofthe annual foliar nitrogen requirement at the study sites.

• Research Organization: Tennessee Valley Authority, Muscle Shoals, AL (USA). Div. of Air and Water Resources
• OSTI ID: 5493291
• Report Number(s): EPRI-EA-4577; ON: TI86920348
• Country of Publication: United States
• Language: English

Related Subjects

500200* -- Environment
Atmospheric-- Chemicals Monitoring &amp; Transport-- (-1989)
510200 -- Environment
Terrestrial-- Chemicals Monitoring &amp; Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ACID RAIN
ATMOSPHERIC PRECIPITATIONS
CHALCOGENIDES
DATA
DEPOSITION
ECOSYSTEMS
EXPERIMENTAL DATA
FORESTS
INFORMATION
MATERIAL BALANCE
NITROGEN COMPOUNDS
NITROGEN CYCLE
NITROGEN OXIDES
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
RAIN
TERRESTRIAL ECOSYSTEMS