Response of two northern temperate forest ecosystems to long term nitrogen additions

Journal Article · Fri Sep 01 04:00:00 EDT 1995 · Bulletin of the Ecological Society of America

OSTI ID:107127

Magill, A H; Aber, J D ^[1]

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1. Univ. of New Hampshire, Durham, NH (United States)

The importance of atmospheric nitrogen deposition in forest nutrient cycling has increased with increasing anthropogenic emissions to the atmosphere over the last 50+ years. Concerns of excessive NO{sub 3} leaching and greenhouse gas emissions have led to initiation of field studies using long-term, low level nitrogen additions to simulate increased N wet deposition. Results of two studies with applications rates of 0,25,50 or 150 kg N ha{sup {minus}1}yr{sup {minus}1} as HNO{sub 3} (Bear Brook Watershed Maine [BBWM]) or NH{sub 4}NO{sub 3} (Harvard Forest in Massachusetts [HF]) were compared. Control plot net mineralization rates were 85 and 70 kg ha{sup {minus}1}yr{sup {minus}1} for BBWM and HF, respectively. Net nitrification was 5 kg ha{sup {minus}1}yr{sup {minus}1} in BBWM control plots and 15 kg ha{sup {minus}1}yr{sup {minus}1} in the +50 treatment by 1991; no nitrification occured at HF. At the 50 kg N ha{sup {minus}1}yr{sup {minus}1} level, NO{sub 3} leaching losses were highest in year one (1988) at BBWM but negligible at HF even after six years of treatment. Foliar N increased with treatment at HF but not at BBWM. Although N deposition at BBWM (5 kg ha{sup {minus}1}yr{sup {minus}1}) is half of HF (8-10 kg ha{sup {minus}1}yr{sup {minus}1}) and the two stands are similar in age (40-50 yrs) BBWM appears closer to N saturation, perhaps due to differences in past land-use practices, biomass nutrient uptake or soil retention capacity.

• OSTI ID: 107127
• Report Number(s): CONF-9507129--
• Journal Information: Bulletin of the Ecological Society of America, Journal Name: Bulletin of the Ecological Society of America Journal Issue: 3 Vol. 76; ISSN BECLAG; ISSN 0012-9623
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
56 BIOLOGY AND MEDICINE
APPLIED STUDIES
BIOLOGICAL EFFECTS
COMPARATIVE EVALUATIONS
DEPOSITION
ECOLOGICAL CONCENTRATION
FORESTS
NITROGEN
NITROGEN CYCLE