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Decline and localized extinction of a major raised bog species across the British Isles: evidence for associated land-use intensification(Palaeoecology Laboratory (PLUS), School of Geography, University of Southampton, Highfield, Southampton SO17 1BJ, UK, Paul.Hughes{at}soton.ac.uk
(Palaeoecology Laboratory (PLUS), School of Geography, University of Southampton, Highfield, Southampton SO17 1BJ, UK
(Palaeoecology Laboratory (PLUS), School of Geography, University of Southampton, Highfield, Southampton SO17 1BJ, UK
(Palaeoecology Laboratory (PLUS), School of Geography, University of Southampton, Highfield, Southampton SO17 1BJ, UK The decline of S. austinii Sull. Ex Aust. (formerly S. imbricatum Hornsch. Ex Russ. ssp. austinii Sull. Abstract: The decline of S. austinii Sull. represents one of the most striking vegetation Russ. ssp. on the raised Ex Aust.), in most cases to local extinction, represents one of the most striking vegetation changes on the raised bogs of Britain and Northwest Europe during the last 2000 years. This study uses plant macrofossil, pollen and geochemical analyses to explore the record of human impact and land-use intensification at the S. austinii decline. There is a clear temporal association between anthropogenic woodland clearance, cereal cultivation, soil erosion and contemporary climatic change, with the decline of S. austinii. These findings suggest that S. austinii is sensitive not only to rapid climate changes but also to the aerial deposition of soil dust and/or accompanying pollutants. A modern comparison of atmospherically derived nitrogen (N) loadings with the present presence/absence of S. austinii on 16 raised bogs shows that the species is only present where the loading lies below a critical threshold for N of 10 kg/ha per yr. The palaeoecological record also shows that S. austinii has re-established itself during phases of reduced human activity but in contemporary Europe it is difficult to see this happening in the near future.
Key Words: Sphagnum austinii Sphagnum imbricatum land use soil erosion Titanium macrofossils pollen palaeoecology species decline local extinction late Holocene British Isles.
The Holocene, Vol. 18, No. 7,
1033-1043 (2008) |
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