18 Notes - Reporting on Local Change / The Maps SchemeThe resulting indices would, as far as I can see,be independent of differences in recording level.They could be subjected to further processing asindicated below:• By making the same calculations forselected groups, rather than individual taxa,the Relative Percentage Change could becalculated for the assemblage of speciesfound in a particular habitat, or for anyother grouping.• The Relative Percentage Changes could beconverted to any other scale desired.• The results could be subjected to statisticalprocedures to see how far changes werelikely to be due to chance factors ratherthan be real.Indices of this kind would be valuable inhelping decide, in combination with other data,which taxa or groups of taxa to worry aboutmost.I looked at the possibility of carrying out thesuggested analyses myself, but the data entryrequired would be an impossibly long task forme. The authors of the report, however, couldpresumably do it very quickly from whateverspreadsheet or database they used, since allnecessary information should be enteredalready.ReferencesBRAITHWAITE, M.E., ELLIS, R.W. & PRESTON, C.D.2006. Change in the British flora 1987-2004 (AReport on the BSBI Local Change survey). BotanicalSociety of the British Isles, London.PRESTON, C.D., PEARMAN, D.A. & DINES, T.D. 2002.New Atlas of the British & Irish Flora. OxfordUniversity Press, Oxford.The Maps SchemeQUENTIN GROOM, Louis Pelserssquare 1, 3080 Tervuren, Belgium. qgroom@reticule.co.ukOne ofthe benefits of maintaining an up-ta-datedatabase of biological records is that one canrapidly detect changes in the abundance of ataxon. This is certainly true for the BSBI MapsScheme (known the Atlas Updating Project).The Maps Scheme database holds data in fourdifferent date classes, before 1970; 1970-1986;1987-1999 and 2000 onwards. The data from2000 onwards is far from complete; it has onlyabout 30% of the data compared with 1987-1999. Despite this incompleteness, it is sufficientto detect taxa that are increasing. I used abasic change index to compare the relativechange in the number ofhectads that each taxonwas recorded in. The method I used highlightstaxa whose distribution is small, but is increasingfast. For the results presented here, Icompare distribution in the date classes 1987-1999 and 2000 onwards.The analysis is complicated by changes inrecording practices and changes in the taxonomy.Critical taxa, hybrids and subspecies wereall stripped out of the results, because of theinconsistency of recording. Likewise, whollyplanted taxa were removed and others wereremoved because the numbers of hectads theyhave been recorded in is so small (~10). Somerare natives were removed because there havebeen particular efforts to re-record these. Theremaining top 40 taxa can be seen in table 1.Note that there is some bias in the resultstowards taxa from the south of England,because there is a bias in the submission ofpost-1999 data towards this region. I expect therest of us will catch up.I'll largely let the results speak for themselves.However, I should point out another usefulfunction of the Maps Scheme. It helps validaterecords and highlight errors. For example, itwas surprising that Symphytum asperum cameso high on the list of spreading species.S. xuplandicum is often mistaken forS. asperum, so this apparent increase is nowunder investigation by the Symphytum referee(Clare O'Reilly). The Maps Scheme databasehas help correct numerous other errors insubmitted data.In the future, the Map Scheme database willrequire proper study; meanwhile, it is possible,with a simple analysis, to alert us to changes inBritain's flora. Anyone wanting more details ofthese apparently spreading taxa should first lookon the Maps Scheme website (www.bsbiatlas.org. uk). You are also welcome to contact me fordetails. Please continue to contribute recordsand many thanks to those who have alreadycontributed.
Notes - The Maps Scheme 19Table 1. The top 40 species in the Maps Scheme database with the highest proportional increase in thenumber ofhectads they have been found in. The columns state the number ofhectads each species hasbeen recorded in for each date class. Consider that the geographic coverage for the date class '2000 onwards'is only about 30% ofthat for the previous date classes.TaxonConyza bilbaoanaVerbena bonariensisBidens /erulifoliaPersicaria capitataCardamine corymbosaChenopodium quinoaSenecio inaequidensSymphytum asperumScilla lilio-hyacinthusEryngium planumPolypogon viridisYucca recurvifoliaConyza bonariensisBerberis julianaePolygonum maritimumEchium pininanaCortaderia richardiiPoa injirmaCordyline australisHydrocotyle ranunculoidesPhysalis peruvianaEuphoria oblongataSymphytum bulbosumSmyrnium per/oliatumConyza sumatrensisCyperus eragrostisChionodoxa luciliaeSagittaria latifoliaAmbrosia artemisiifoliaCrassula tillaeaAllium subhirsutumIris orientalisLonicera pileataEchinochloa crus-galliPontederia cordataSonchus palustrisGeranium purpureumSisyrinchium striatumCortaderia selloanaPhacelia tanacetifolia1970-1986o4oooo34161735238o47o10o1551154253221512812613201987-19997104152414271310968141113112525683951271812171916615179096313561235353457561931752000 on43391541602443191311801612141125236134442315101314549111262662123401522221353410997
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