Flora of Ashdown Forest - Botanical Society of the British Isles

20These maps show no relationship to the recording patterns, but the squares around the edge aregenerally poorly-recorded whilst those in the middle are well-recorded. This suggests that the maps aremore a function of the distribution of the plant groups used to compile them than the botanists.To test whether our species data are more closely related to the recording or environmentalvariables, we have first correlated various measures of both against the number of species recorded foreach square. The correlations presented exclude species for which there is known recording bias (e,g.Taraxacum), but very similar results are obtained if all species are included.It is well known that the number of species recorded is strongly related to the time spent recording(e.g. Rich & Woodruff 1990, 1992, Rich & Smith 19961. For our survey initially the time spentrecording was significantly correlated with the number of species recorded in each square in 1993(r~0.652, p«O.OOll and in 1993-1994 (r~0.555, p«O.OOll as expected. However, by the endof 1995 when the recording was complete and coverage was fairly uniform there was no correlation(r = 0.201, p> 0.05, not significant) suggesting that our species-richness is largely independent of effort(Figure 91.Figure 9. Relationship between number of species and time spent recording (r=0.201, p>0.05).350300• •N 250• •u sm pb e 200 :e cr i 150eo s 100•5000 5 10 15 20 25time (hours)Woodell (1975) demonstrated that independent visitors add significantly more species to squaresthan repeat visits by the same recorder, so it might be expected that more species would be recorded insquares visited by many different botanists. The relationship between number of species recorded andthe number of different botanists who visited each square is shown in Figure 10; there is no significantcorrelation (r = -0.059, p>O.l). This suggests that we have evened out this effect by getting manydifferent botanists to visit each square.As we have not had access to all land, it might be expected that the number of species would berelated to the proportion of each square investigated. The relationship is shown in Figure 11 (r= -0.19,p > 0. 1). The slightly negative relationship may be due to lower coverage around the margins of theForest where there is not open access.As many species have characteristic habitats, it might be expected that squares where morehabitats are present would have more species. There is a strong relationship between the number ofspecies and the number of habitats recorded in each square (r=0.657, p<