Standardised Recording. Tim Rich

Transcription

1 Standardised Recording Tim Rich

2 Dot maps have been used for 50+ years for phytogeography, ecology and conservation What do these maps tell us about the species? Atlas of British flora, 1962

3 Biological records are widely collected and used, but several major problems: Most records collected on an ad hoc basis, often in squares of different sizes Predominantly by volunteers, who vary in expertise (as do professionals) Different methods used to collect data Amount of time and effort per square/site/record varies enormously Little or no information available about how records were collected Recording is not comprehensive, so only getting a sample Results in records which are biased in space, time and taxonomy Shropshire Flora, Sinker et al. 1985

4 What can we conclude about distribution and abundance of pollinators in SE Wales from these data? No. butterfly records No. hoverfly records Source: TACP (2015). Green infrastructure action plan for pollinators in South-east Wales. Report to Monmouthshire County Council on behalf of Monmouthshire County Council and Blaenau Gwent, Caerphilly and Torfaen County Borough Councils December TACP UK Ltd.

5 Interpretation of time: Lesser Twayblade, Neottia (Listera) cordata Atlas of British flora, 1962 Open circles pre 1930 Closed circles New Atlas, 2000: Dark blue Light blue Pale blue pre 1950.

6 BSBI Monitoring Scheme Sampled systematically 1 in 9 squares Aimed to compare against Atlas of British flora data Collected recording data (time, route, who etc) Have REAL data, but first look at theory 71 squares with records Assume STABLE distribution Survey 1, Random 50% coverage Survey 2, Random 50% coverage

7 Two surveys combined into one map Survey 1, 50% coverage Survey 2, 50% coverage 2 nd survey 1 st survey only apparent 36% decline?

8 BSBI Monitoring Scheme (actual data) both surveys O (49% coverage) (56% coverage) Actual no. records : 47 records : 48 records Conclusion: No decline And when revisited 8 old squares, refound immediately in 6, and commented likely still to be present in the other 2

9 Cotswold Pennycress, Noccaea (Thlaspi) perfoliatum = native o = native pre-1987 x = alien total 45 native sites in 9 squares by 1996 only 9 sites left (80% decline) (Rich, Biodiversity and Conservation 7: 915 (1998))

10 What is happening to Thlaspi? plot number of records for each year; hard to interpret 12 trend line 10 8 Number of records Year

11 Number of records per decade Number of records Decade all trendlines show Thlaspi is increasing, yet we know it is decreasing number of records is NOT a good measure of frequency

12 Taxonomic bias e.g. Taraxacum duplidentifrons One of commonest species in north and west Walter Scott Olga Stewart John Richards Chris Haworth Andrew Dudman Tom Edmondson Mike Porter Trevor Evans Len Margetts BSBI Taraxacum handbook

13 Correlation with specialist recorders Carex hostiana x viridula

14 Records can depend on which taxa are listed on the record cards, eg apples All records for Malus agg (includes crab and domestic apple) Records for crab apple only Recording cards listing crab apple

15 Relative frequency Relative frequency Relative frequency Seasonal variation in recording All records Month Trifolium repens Month Town hall clock Adoxa moschatellina Graphs from BSBI Monitoring Scheme data, total 985,000 records Month

16 Relative frequency Autumn Lady s tresses 45 Spiranthes spiralis Month Yet rosettes present October to July December 2016, Dawlish

17 Relative frequency Relative frequency Lords and Ladies Arum maculatum Month Mistletoe Viscum album Month

18 So many sources of variation in records, varying between good and bad Recorders Organisms Methods The fewer the recorders and the more species, the worse the bias gets (e.g. birds>mammals>plants>butterflies & moths>tardigrades) Not so much a criticism of recorders, more of how we organise them

19 Quantifying sources of variation: Midhurst, West Sussex recording weekend 1992 Results 4 tetrads selected (good access, varied) 29 volunteers Pairs of botanists sent to tetrads 2.5 hours in each Different botanists paired for different tetrads on rotation Recorded all species (critical species lumped) Marked routes on map Noted habitats recorded Overall: 41 cards completed (+1 rejected) 634 plants recorded (88 other species have previously been recorded) 7254 records (12 errors) No. species recorded varied from 69 to 257 Rich, T. C. G. & Smith, P. A. (1996). Watsonia 21:

20 Records show classic Jaccard distribution, with few common species and many rarer ones 5 species recorded on every card (eg Nettle Urtica dioica) 155 recorded only once (24%) All cards contributed some unique species Cumulative number of species Note even after 100 hours recording the number of species is still going up (=Jaccard rare species)

21 Results by tetrad Tetrad K selected as relatively poor, but not significantly different from other tetrads overall Tetrad K L Q R No. cards No. records Mean distance walked (km) Mean no. habitats recorded Mean no. species recorded Total no. species recorded Mean % of tetrad list 39% 42% 44% 46% Iping Common, tetrad K, relatively species-poor heathland

22 So why does the number of species recorded vary from 69 to 257? Does number of species correlate with number of habitats? Yes, r 2 =0.22, P=0.005

23 Does number of species correlate with length of route (a measure of area covered)? Yes, r 2 =0.148, P=0.017 (no. habitats recorded and length of route recorded are also related) On average only 6% of routes were in common between pairs of cards (range 0-23%) - people pick their own routes

24 How about with recorders? Graded each from 1 (basic) to 5 (expert) and summed score for each card Yes, r 2 =0.506, P<0.001 Conclusion: biggest factor by far in variation in recording is the quality of botanist, despite survey design to minimise it

25 Recommendations to improve the quality of the basic data: 1. improve the recording ability of the botanists (training) 2. visit many different areas rather than concentrate on one area 3. aim for even coverage by recording for the same number of hours or having the same number of visits in each tetrad 4. aim to visit all habitats 5. ensure adequate seasonal coverage

26 Put into practice in demonstration project: Flora of Ashdown Forest (Rich et al 1996) 71 1-km squares in East Sussex (home of Winnie the Poo) Central core heathland, edges rivers/farmland/woodland (some 1987 data) Aim for 10 hrs by different botanists in each square Lots of training/recording meetings Kept track of recording data Free to download!

27 Looks exactly like any other flora, but the maps reflect the plants, not the botanists

28 Results - species 916 species recorded in total 734 species used in analysis (excludes critical species, hybrids etc.) 241 species on average/1-km square (mean 4 species added in 1.7 hours afterwards, so not comprehensive) Standard Jaccard distribution (194 species (21%) in 1 square, 34 (4%) in every square)

29 Habitats recorded 97% habitats recorded Habitats unrecorded generally on private land outside forest boundary Habitat recorded Not recorded

30 Recording information No. visits No. botanists

31 Seasonal recording Time (hours) Mean 11 hrs

32 ANALYSIS No correlations of species diversity with time (hours) recording (r 2 =0.201, p>0.05)

33 No correlation with no. of different botanists r 2 =-0.059, p>0.1) Small correlation of species richness with number of visits (r 2 =0.32, p=0.02), relates to random selection of different areas to record (species are often clustered)

34 No correlation with % square recorded (access not available to all land, especially at edges) r 2 =-0.19, p>0.1) Very strong correlation between species diversity and no. habitats (r 2 =0.43, p<0.001)

35 Multivariate analysis Recording data: Bit mixed, no clear pattern Environment data: Strong difference between edges and centre Species data: Strong difference between edges and centre

36 So Flora of Ashdown Forest shows standardised recording is practical Maps reflect the distributions of the plants, not the botanists Can reliably correlate distribution data against environmental variables Relative frequencies (e.g. rare, common) are reliable Survey can be repeated reliably in the future using same methods

37 Summary Recording bias arising from recorders, organisms and methods Extent of bias varies with different species and areas Extent of bias is virtually impossible to know or quantify Most recording is sampling and should be treated as such Metadata setting out how records were collected/sampled rarely given Bias posses serious limitations on way records can be used, and is largely ignored The implications We need to structure recording much more systematically preferably organised more centrally so records can be used for more things Many methods developed to correct for bias (eg Botts et al. 2012), but most fairly poor quality, giving only relative not absolute answers Much biological recording data limited by lack of meta-data describing the sampling process, and lack of reference data to allow for standardization (Bird et al. 2013).

38 Further reading Bird, T.J., et al. (2013). Statistical solutions for error and bias in global citizen science datasets. Biological Conservation Botts, E. A., Erasmus, B. F. N. & Alexander, G. J. (2012). Methods to detect species range size change from biological atlas data: A comparison using the South African Frog Atlas Project. Biological Conservation 146: Rich, T. C. G. (1997). Is ad hoc good enough? Transactions of the Suffolk Naturalists Society 14: Rich, T. C. G. (1998). Squaring the circles - bias in distribution maps. British Wildlife 9(4): Rich, T. C. G. & Smith, P. A. (1996). Botanical recording, distribution maps and species frequency. Watsonia 21: Rich, T. C. G. & Woodruff, E. R. (1992). Recording bias in botanical surveys. Watsonia 19: Rich, T. C. G., Donovan, P., Harmes, P., Knapp, A., McFarlane, M., Marrable, C., Muggeridge, N., Nicholson, R., Reader, M., Reader, P., Rich, E. & White, P. (1996). Flora of Ashdown Forest. Sussex Botanical Recording Society, East Grinstead.