Enhancement of nitrogen deposition to forest trees exposed to SO2

McLeod, Andrew; Holland, Mike; Shaw, Peter J.; Sutherland, P. M.; Darrall, N. M.; Skeffington, R. A.

doi:10.1038/347277a0

Cited by 62 publications

(12 citation statements)

References 17 publications

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“…The different responses of spruce and pine to ' NHj^ rain' in this experiment are consistent with the difference in N status observed between species in the Liphook Experiment (McLeod et al, 1990). When spruce and pine in the high SO^ treatments were exposed to NH^ co-deposited with SOg the concentration of N increased in needles of spruce but not in pine.…”

Section: Species Differencessupporting

confidence: 84%

Foliar uptake and release of inorganic nitrogen compounds in Pinus sylvestris L. and Picea abies (L.) Karst.

Wilson

1992

New Phytologist

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SUMM.'^RVFoliar uptake and release of inorganic nitrogen compounds were studied by immersing current-year shoots of Scots pine {Pinus syhestris L.) and Norway spruce [Picea ahies (L.) Karst] in either NH^"-or NOg'-rain solutions at different N concentrations. The effects of N form, N concentration and tree species on ion influx and efflux were investigated.Spruce shoots absorbed NH^"^ from the external solution. Uptake apparently occurred by diffusion rather than by H"' or base cation exchange as commonly accepted, and increased iinearly with NH^"^ concentration in the external solution. In contrast, pine shoots released NH^* to the external solution. The different reactions of spruce and pine may refiect species differences in physical and chemical properties or differences in tissue N concentration. If the latter is the case, a tree's N status may determine whether the canopy acts as a source or sink for NH,', influencing deposition rates to the needle surface. The results show that where NHj* concentration on the needle surface exceeds 4 mg t"', foliar uptake may make a significant contribution to N status. In the absence of N'H^^-base cation exchange, atmospheric inputs of NH^"^ to the canopy appear unlikely to be directly responsible for the nutrient deficiencies typical of Dutch forest decline.Neither spruce or pine shoots were able to utilize NO^" in the external solution and generally released NO3". Adverse effects resulting from foliar accumulation of wet-deposited NO3" appear unlikely. However, higher NO3" concentrations and longer residence times than simulated in this experiment may result in foliar uptake of NOj" in the field.

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Section: Species Differencessupporting

confidence: 84%

Foliar uptake and release of inorganic nitrogen compounds in Pinus sylvestris L. and Picea abies (L.) Karst.

Wilson

1992

New Phytologist

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“…The deposition velocities of the two species are relatively fast and show a synergistic interaction for dry deposition. This particularly applies where a wet surface is present, when the amounts deposited can be very high (Draaijers et al, 1989;Van Hove et al, 19896;McLeod et al, 1990), although estimates for ammonia deposition to both wet and dry moorland have shown high rates of deposition in both instances (Sutton et al, 1992). McLeod et al (1990) conclude that SOj may enhance ammonia deposition to all ecosystem surfaces, e.g.…”

Section: Depositionmentioning

confidence: 99%

The deposition of atmospheric ammonia and its effects on plants

1993

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SUMMARY Across Europe, total nitrogen deposition is increasing and, of this total, atmospheric ammonia can contribute up to 50–80%. Average deposition of ammonia in the UK is likely to be around 15–20 kg ha−1 yr−1, while in The Netherlands, which has some of the highest rates of deposition, this value is likely to be between 40 and 50 kg ha−1 yr−1. It is argued that because of the processes of assimilation and nitrification this ammonia is an acidifying pollutant. Ammonia taken up by plants is most likely to be directly assimilated and this uptake can have a strong effect on the nutrient imbalances of the plant. With root uptake in particular, anions are taken up in preference to cations. However, simple soil/plant nutrient measurements are unlikely to be a definitive means of monitoring ammonia pollution. This is because the processes of ammonia metabolism and acidification affect soil ion activity, mycorrhizas, plant uptake, and foliar leaching. These effects interact with acidity per se, and are compounded by the strong correlative co‐deposition of ammonia with sulphur. Evidence for uptake of gaseous and wet deposited ammonia by leaves is presented. The exact mechanism of ammonia toxicity is still not really clear, but could be due to physiological perturbation, rather than to the direct toxicity of the ion. Assimilation of ammonia by leaves releases protons which can cause cellular acidosis, and has important implications for acid‐base regulation in cells. This regulation depends on intrinsic features of the plant's metabolism, that is in turn dependent on the ecology of root versus leaf nitrogen nutrition under normal conditions. Certain species are more acidic in a leaf physiological sense and tend to be prone to damage by pollutants. Likewise, acidic habitats are particularly prone to damage through both eutrophication and the different capacities of plants both to utilize and to buffer against this nitrogen enrichment. The current evidence from The Netherlands suggests that the part this plays in perturbing the ecosystem should not be underestimated.

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“…The predictive capacity of regional acid deposition models thus depends on detailed knowledge of NH, sources and sinks, but these remain poorly characterized in remote areas. Natural ecosystems are generally believed to be net sinks for NH, because uptake by growing plants is well documented ( 1 4 ) and NH, volatilized from agricultural sources has been implicated in the decline of European forests (7)(8)(9) and heathlands (4). However, several studies (1 0-13) have suggested that growing vegetation will emit NH, when exposed to air with concentrations below some "compensation point" related to the partial pressure of NH, in the substomatal cavities.…”

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confidence: 99%

Natural Vegetation as a Source or Sink for Atmospheric Ammonia: A Case Study

Langford

Fehsenfeld

1992

Science

146

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Measurements of gaseous ammonia above a montane-subalpine forest in the Colorado mountains show that the role of the forest as a source or sink depends on the atmospheric concentrations. The canopy appeared to be an ammonia source when exposed to air containing low concentrations, but a sink when exposed to air enriched by nearby agricultural sources. The forest-averaged compensation point was 0.8 part per billion by volume at 20 degrees C. The net burden of ammonia and other nitrogen species of anthropogenic origin at this site was much less than at forest sites in the eastern United States and Europe and may provide a valuable resource for this nitrogen-limited ecosystem.

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Enhancement of nitrogen deposition to forest trees exposed to SO2

Cited by 62 publications

References 17 publications

Foliar uptake and release of inorganic nitrogen compounds in Pinus sylvestris L. and Picea abies (L.) Karst.

Foliar uptake and release of inorganic nitrogen compounds in Pinus sylvestris L. and Picea abies (L.) Karst.

The deposition of atmospheric ammonia and its effects on plants

Natural Vegetation as a Source or Sink for Atmospheric Ammonia: A Case Study

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