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Water, Air, and Soil Pollution

, Volume 85, Issue 3, pp 1701–1706 | Cite as

Long term effects of enhanced nitrogen deposition on a lowland dry heath in southern Britain

  • S. A. Power
  • M. R. Ashmore
  • D. A. Cousins
  • N. Ainsworth
Part VI Ecosystem Experiments — Case Studies

Abstract

Experimental additions of ammonium sulphate to a nitrogen-poor dry heathland have been carried out since 1989. There are four nitrogen treatments: a control (receiving artificial rain only), a low treatment which receives an additional 7.7 kg N ha−1 yr−1, a high treatment receiving 15.4 kg N ha−1 yr−1 and an alternating treatment which receives either the control or the high nitrogen additions, in alternate years. The estimated background deposition at the study site is 13–18 kg N ha−1 yr−1, a value similar to the critical load that has been suggested for the conversion of lowland heath to grassland. Over the past 5 years there have been significant stimulations in shoot growth, flowering, canopy density and litter production. Flowering, in particular, strongly reflects nitrogen additions in the alternating treatment.

Current models of the response of dry Calluna heathlaud to enhanced nitrogen deposition suggest that higher tissue nitrogen levels will occur and will be accompanied by heightened sensitivity to secondary stresses. This may in turn lead to canopy breakdown and replacement by grassland. The application of nitrogen at deposition rates only slightly in excess of the critical load over five years has produced small, non-significant increases in shoot nitrogen content. However, there is clear evidence of a large positive effect on shoot growth, flowering, litter production and canopy density of Calluna. The observation of these responses at the application rates used in this study supports the current proposals for critical loads of nitrogen for lowland heaths.

Key words

nitrogen heathland Calluna vulgaris critical load growth litter production 

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References

  1. Aerts, R.: 1989, Oecologia 78, 115–120.Google Scholar
  2. Allen, S. E.: 1989, Chemical analysis of ecological materials, Blackwell Scientific Publications, Oxford.Google Scholar
  3. ApSimon, H.M., Kruse, M. & Bell, J.N.B.: 1987, Atmos. Environ. 21 (9), 1939–1946.Google Scholar
  4. Berendse, F.:1990,J. Ecol. 78, 413–427.Google Scholar
  5. Bobbink, R., Boxman, D., Fremsted, E, Heil, G.W., Houdijk, A. & Roelofs, J.: 1992, Nord (Miljörapport) 41, 115–119.Google Scholar
  6. Brunsting, A.H.M. & Heil, G.W.: 1985, Oikos 44, 23–26.Google Scholar
  7. Bunce, R.G.H. (Ed.): 1989, ITE research Publication No. 3, HMSO, London.Google Scholar
  8. Caporn, S. J.M., Caroll, J., Lei, Y., Song, W., Read, D.J. & Lee, J.A.: 1995, In: Acid Rain and its Impact: The Critical Loads Debate (Ed. R.W. Battarbee), Ensis Publishing, London, 146–150.Google Scholar
  9. Gimingham, C.H.: 1972, Ecology of heathlands, Chapman & Hall, London.Google Scholar
  10. Heil, G.W. & Bruggink, M.: 1987, Oecologia 73, 105–108.Google Scholar
  11. INDITE: 1994, Jimpacts of Nitrogen on Terrestrial Ecosystems, Department of the Environment, London.Google Scholar
  12. Marrs, R.H.: 1993, Biol. Conserv. 65, 133–139.Google Scholar
  13. McCullogh, P. & Nelder, J.A.: 1983, Generalised Linear Models, Chapman & Hall, London.Google Scholar
  14. Pitcairn, C.R.E., Fowler, D. & Grace, J.: 1995, Environ. Pollut. 88 (2), 193–205.Google Scholar
  15. Prins, A.H., Berdowski, J.J.M. & Latuhihin, M.J.: 1991, Acta Bot. Neerl. 40 (4), 269–279.Google Scholar
  16. Sokal,R. &, Rohlf, F.J.: 1995, Biometry, W.H.Freeman & Company, New York.Google Scholar
  17. Uren, S. C.: 1992, PhD Thesis, University of London.Google Scholar
  18. Van der Eerden, L. J., Dueck, Th. A., Berdowski, J.M., Greven, H. & Van Dobben, H.F.: 1991, Acta Bot. Neerl. 4, 281–296.Google Scholar

Copyright information

© Kluwer Academic Publishers 1995

Authors and Affiliations

  • S. A. Power
    • 1
  • M. R. Ashmore
    • 1
  • D. A. Cousins
    • 1
  • N. Ainsworth
    • 2
  1. 1.Imperial CollegeAscotUK
  2. 2.Manchester Metropolitan UniversityManchesterUK

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