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Progress surveying Carex maritima in 2006

Progress surveying Carex maritima in 2006. David Pearman. To recap: this is the New Atlas version of the distribution map. Date Class 3: 22 dots Date Class 2: 21 dots Date Class 1: 40 dots Change Index: -1.37 ‘Considerable decline before 1930’. Still there (19) Gone (12)

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Progress surveying Carex maritima in 2006

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  1. Progress surveying Carex maritima in 2006 David Pearman

  2. To recap: this is the New Atlas version of the distribution map. Date Class 3: 22 dots Date Class 2: 21 dots Date Class 1: 40 dots Change Index: -1.37 ‘Considerable decline before 1930’

  3. Still there (19) Gone (12) Not searched for (16) This was the situation last year, looking at the post-1970 records only

  4. After much diligent searching…

  5. New squares This is what you found… Last seen 1842 Last seen 1953

  6. If we draw time-sliced maps using the date classes of the Maps Scheme… Date Class 0 1500-1929 31 dots

  7. Date Class 1 1930-1969 26 dots

  8. Date Class 2 1970-1986 41 dots

  9. Date Class 3 1987-1999 18 dots

  10. Date Class 4 2000-2009 29 dots so far…

  11. The current view: a slight decline in distribution during the 20th century, perhaps

  12. How often are new sites found? Surprisingly, perhaps, new sites (here defined as Wells Sites – 1km squares) have continued to be found at a steady pace since the mid 18th century, and the rate of discovery shows no sign of slowing. This graph ignores any losses.

  13. Is Carex maritima moving north?Probably, yes. In an analysis of 260 records, grouped by 100km northing and evenly divided into four date classes, there seems to be a clear trend towards the north. Is this climate change, development or ocean currents?

  14. If we add to the Atlas map the new records made since, and remove the introductions on dumped sand by the roadside… • Roughly half of all sites are gone. Mostly on the east coast. Why would these have gone? • Erosion? • Development/agriculture? • Accretion in dune systems? • And why are there seemingly more sites in the west? Just because they were not found before, or because the dune systems there are developing and mobile?

  15. Carex maritima in Orkney HY55. 1965. ‘In thick vegetation.’ Gone? HY75. 1981. No-one has looked. HY44. 1977. ‘Two tiny populations.’ Gone? HY64. 2003. Abundant. HY74. 2003. Abundant. HY53. 1975. Destroyed by airstrip. Gone HY22. 1883. Has anyone looked? HY42. 1972. Machair heavily grazed. HY62. 1979. No-one has looked. HY21. 2005. Some 51 plants. HY41. 1968. Introduction on roadside. Gone. HY50. 1984. Very plentiful. Unable to find since. ND29. 2005. Thousands of plants. ND49. 2005. Thousands of plants.

  16. Conclusions We should keep looking, especially in:- Orkney Sutherland Aberdeenshire Outer Hebrides

  17. Acknowledgements Thanks to the following for sending records and reports Brian & Barbara Ballinger, Pat Evans, Lynn Farrell, Ian Green, Alex Lockton, Richard Pankhurst, Walter Scott, Alan Silverside, Paul Smith & Sarah Whild

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