Journal ArticleDOI
Predicting the Effects of Atmospheric Nitrogen Deposition in Conifer Stands: Evidence from the NITREX Ecosystem-Scale Experiments
Bridget A. Emmett,D. Boxman,Michael Bredemeier,Per Gundersen,O.J. Kjønaas,Filip Moldan,Patrick Schleppi,Albert Tietema,Richard F. Wright +8 more
TLDR
The NITREX project as mentioned in this paper investigated the effect of atmospheric nitrogen (N) deposition in coniferous forests and found that the status and dynamics of the forest floor are key components in determining the response of forests to altered N inputs.Abstract:
The NITREX project, which encompasses seven ecosystem-scale experiments in coniferous forests at the plot or catchment level in northwestern Europe, investigates the effect of atmospheric nitrogen (N) deposition in coniferous forests. The common factor in all of the experiments is the experimentally controlled change in N input over a period of 4–5 years. Results indicate that the status and dynamics of the forest floor are key components in determining the response of forests to altered N inputs. An empirical relationship between the carbon–nitrogen (C/N) ratio of the forest floor and retention of incoming N provides a simply measured tool through which the likely timing and consequences of changes in atmospheric N deposition for fresh waters may be predicted. In the terrestrial ecosystem, a 50% increase in tree growth is observed following the experimental reduction of N and sulfur inputs in a highly N-saturated site, illustrating the damaging effects of acidifying pollutants to tree health in some locations. Few biotic responses to the experimental treatments were observed in other NITREX sites, but the rapid response of water quality to changes in N deposition, and the link to acidification in sensitive areas, highlight the need for N-emission controls, irrespective of the long-term effects on tree health. The observed changes in ecosystem function in response to the experimental treatments have been considered within the framework of the current critical-load approach and thus contribute to the formulation of environmental policy.read more
Citations
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Journal ArticleDOI
N : P ratios in terrestrial plants: variation and functional significance
TL;DR: This review examines how variation in the relative availability of N and P, as reflected by N : P ratios of plant biomass, influences vegetation composition and functioning.
Journal ArticleDOI
Nitrogen deposition makes a minor contribution to carbon sequestration in temperate forests
Knute J. Nadelhoffer,Bridget A. Emmett,Per Gundersen,O. Janne Kjønaas,C.J. Koopmans,Patrick Schleppi,Albert Tietema,Richard F. Wright +7 more
TL;DR: In this paper, the authors used evidence from 15 N-tracer studies in nine forests to show that elevated nitrogen deposition is unlikely to be a major contributor to the putative CO2 sink in forested northern temperature regions.
Is Nitrogen Deposition Altering the Nitrogen Status of Northeastern Forests
John D. Aber,Christine L. Goodale,Scott V. Ollinger,Melinda D. Smith,A. Magill,Mary E. Martin,Richard A. Hallett,John L. Stoddard,N. Participants +8 more
TL;DR: In this article, the authors present a new synthesis of existing data sets for the northeastern United States, intended to answer a single question: Is N deposition altering the N status of forest ecosystems in this region?
Journal ArticleDOI
Is Nitrogen Deposition Altering the Nitrogen Status of Northeastern Forests
John D. Aber,Christine L. Goodale,Scott V. Ollinger,Marie-Louise Smith,Alison H. Magill,Mary E. Martin,Richard A. Hallett,John L. Stoddard +7 more
TL;DR: In this article, the authors present a new synthesis of existing data sets for the northeastern United States, intended to answer a single question: Is N deposition altering the N status of forest ecosystems in this region?
Journal ArticleDOI
Sources of nutrient pollution to coastal waters in the United States: Implications for achieving coastal water quality goals
TL;DR: In the U.S., human activity has increased the flux of nitrogen (N) and phosphorus (P) from land to the oceans by 2-fold and 3-fold, respectively, with the increase varying by region as mentioned in this paper.
References
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Book ChapterDOI
Critical Loads for Sulphur and Nitrogen
TL;DR: A group of Nordic experts have tried to draw conclusions on critical loads for sulphur and nitrogen as discussed by the authors, defined as the highest load that will not cause chemical changes leading to long-term harmful effects on most sensitive ecological systems.
Journal ArticleDOI
Use of Calcium/Aluminum Ratios as Indicators of Stress in Forest Ecosystems
TL;DR: In this paper, the Ca/Al molar ratio of the soil solution provided a valuable measurement endpoint or ecological indicator for identification of approximate thresholds beyond which the risk of forest damage from Al stress and nutrient imbalances increases.
Journal ArticleDOI
A Comparative Analysis of Potential Nitrification and Nitrate Mobility in Forest Ecosystems
TL;DR: In this article, the authors investigated the controls of potential nitrogen mineralization, nitrate production, and nitrate mo- bilization in a wide range of forest ecosystems through a combination of field and laboratory experiments.
Book
Acid Deposition and the Acidification of Soils and Waters
J. O. Reuss,D. W. Johnson +1 more
TL;DR: In this paper, the authors focus on those systems in which acid deposition is most widespread and deleterious and analyzes the effects on the soil-plant system and on the composition of the solution that is released to surface waters and groundwaters.