Variation in botanical activity in

the British Isles 1836-1988:

how can we assess change?

Tim Rich

What do these maps tell us about the species?

Atlas of British flora, 1962

Date classes:

Dark blue 1987-1999

Light blue 1950-1986

Pale blue pre 1950.

(New Atlas, BSBI)

Neottia cordata

Lesser twayblade

Problems assessing change: Example 1

Survey 1,

50% coverage

Survey 2,

50% coverage

Random selection of the

1 in 9 squares from

BSBI monitoring

scheme Neotiia cordata

data, compare 2

surveys of STABLE

population

Survey 1,

50% coverage

47 squares

Survey 2,

50% coverage

48 squares

Two surveys combined

– apparent 36% decline?

● both surveys

O 1950-1960 (49% coverage)

+ 1987-1988 (56% coverage)

Conclusion:

No decline

And when revisited 8 ‘old’

squares, refound

immediately in 6

BSBI Monitoring Scheme (actual data)

= native 1987-2007

o = native pre-1987

x = alien• total 45 native sites in 9 squares

• by 1996 only 9 sites left (80% decline)(Biodiversity and Conservation 7: 915 (1998))

Problems assessing change: Example 2

Noccaea (Thlaspi) perfoliatum, Cotswold Pennycress

Square Date Rec. Locality

ST31 29/05/1891 AB Charlbury

ST31 03/1884 GCD Stonesfield

ST31 05/1886 GCD Stonesfield

ST31 22/04/1935 PCL Stonesfield Quarry

ST31 04/1945 JGD Stonesfield

ST31 18/04/1946 JEL Stonesfield Quarry

ST31 24/04/1948 - Stonesfield, railway

ST32 08/05/1931 KEK Fawler

ST32 16/05/1953 DMc Fawler Pits

Different

sites/habitats

Different

dates

Different

recorders

• 290 Thlaspi records traced in herbaria, literature, databases,

correspondence etc.

• A record=unique combination of locality, date, recorder, habitat

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2

4

6

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12

1830 1840 1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980

Year

Nu

mb

er

of

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rds

What is happening to Thlaspi?

• plot number of records for each year; hard to interpret

trend line

number of Thlaspi records per year (10-year running average)

• running averages also hard to interpret

•fluctuations but apparently ‘increasing’

0

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• all trendlines show Thlaspi is increasing, yet we know it is decreasing

• number of records is NOT a good measure of frequency

Number of records per decade

How can we find out what is really

happening to Cotswold Pennycress?

The problem is that there is a lot of variation in recording:

• not systematic in time or space

• a lot more recent records than historical records

• some areas have more records than others

• cannot compare like with like

So I tried to quantify the variation in recording

• took 15 years!

• results give a broad generalisation

Botanical records are made by individuals:

Eleanor Vachell 1879-1948

Number of herbarium specimens

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Year

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mb

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sp

ecim

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Number of publications each year

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46

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64

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82

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88

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94

Year

5 y

ea

r a

ve

rag

e

C. A. Stace

A. O. Chater

J. G. Dony

E. Vachell publications

0

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Year

No

. p

ub

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ati

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s

Individuals

• have very variable contributions depending on

personal circumstances

• tend to collect locally, and in botanical hotspots

• tend to publish locally but sporadically

• behave as individuals, but also contribute to organised

county and national projects

• Individuals are also organised into groups/societies etc

Botanical Societies etc

Density of botanical societies…

National: How many botanists?

Sources of data:

• Membership lists (BSL, BEC – incomplete!, BSBI)

• collectors listed in British and Irish herbaria (Kent & Allen 1984)

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Botanists to population as a whole

0

1000

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6000

1831

1851

1871

1891

1911

1931

1951

1971

1991

Census Year

National population

Botanists

proportion

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100

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Rela

tive n

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tan

ists

Interpretation of number of botanists

• Probably underestimated

Where are the

botanists?

Sources:

Membership lists

1836, 1936, 1952, 1999

• most botanists in major

urban areas and cities

•Highly correlated in space

through time

• for 1999 British membership,

a constant proportion of

national population (1991

census)

Hypothesis:

The number and distribution of botanists will determine

the amount of records (information) in space and time

Compiled data on:

• Literature records

• Herbarium records

• Database records

Much of the data from these sources is inconsistent, is

incomplete, is indirect, has changed with time, etc.

Literature sources1. Simpsons Bibliographic index (1960)

2. 2. BSBI database (1960-1988)

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Literature 1:

number of pages published by botanical societies

5 year

running

average

Literature 2:

Number of publications each year (all sources and types)

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Number of publications

for each county

(corrected for area)

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(5-y

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)

Sussex

Cardiganshire

Durham

Forfar

Tipperary

Londonderry

Literature 3:

Number of county floras published each year

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6

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Flo

ras

Number of county floras

for each county

(corrected for area)

Summary of variation

in literature

01020304050

60708090

100

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lati

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lit

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pu

bli

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5 y

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nn

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)

Herbarium recordsSource: National Biological Records Centre databases

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Number of herbarium

collections (corrected

for area)Source: National Biological Records

Centre databases

Database records dated to year (excludes summary dates)

Source: National Biological Records Centre databases

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(hu

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f th

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ds)

Geographical variation in database records…

• very high variation in national database due to

incomplete inclusion of records from flora projects

However, BSBI Monitoring Scheme (Rich & Woodruff

1990) allows relationship to be explored

• 1 in 9 squares surveyed systematically in 1987 and 1988

• detailed records kept of species, location, dates, hours spent

recording, etc

• nearly 985,000 records, 9630 record cards, 1600 botanists, 21235

hours, 2660 taxa, etc.

Number of botanists

who recorded in each

square

Time spent recording in

each square

Number of records

Number of species

Relationship between number of species and time spent

recording for each square

-200

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1000

0 50 100 150 200 250 300 350

Hours spent recording

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ofs

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Overall clear links between botanical activity and

amount of information: more botanists spending more

time recording in each square results in more records

and more species…

So can we build a picture of recording activity in space

and time?

• clearly many problems with the data

• but general patterns the same

Data, where reliable, given equal weight to produce a

crude overall model of botanical activity…

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tive r

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Integrated summary of variation in time, from compilation of

literature, herbarium and database records

total recording effort

number of botanists

Integrated

geographical

variation in recording

effort ranked into 5

classes from

high recording effort

(black)

to

low recording effort

(white)

Conclusions

• first attempt to reconstruct recording history of British Isles;

the amount of recording activity has increased with time

key times

1. Druce - change from exchange club to botanical society,

2. BEC to BSBI 1948

• botanical data only reliable/representative from 1890s

• recording activity concentrated in areas where botanists live

rather than botanical hotspots

• quality and quantity of information has changed with time

• results must be taken as broad trends only, a useful tool to

help you think

• could refine models, perhaps including number of botanists

Applications 1. Correcting historical frequencies for effort:Rich, T. C. G. & Karran, A. B. (2006). Botanical Journal of the Linnean Society 152: 279-302

Thlaspi data corrected for recording effort: can see a more realistic trend!

-0.4

-0.2

0

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1

1935 1945 1955 1965 1975 1985 1995 2005 2015 2025 2053

Decade

Co

rrecte

d,

extr

ap

ola

ted

nu

mb

er

of

sit

es

Applications 2. Thlaspi predicted extinction date: 2011

For full details:

Rich, T. C. G. (2006). Floristic changes in the British Isles: geographic and temporal variation in botanical activity 1836-1988. Botanical Journal of the Linnean Society 152: 303-330.

Rich, T. C. G. & Karran, A. B. (2006). Floristic changes in the British Isles: Comparison of techniques for assessing changes in frequency of plants with time. Botanical Journal of the Linnean Society 152: 279-302.