Pulsatilla vulgaris (L.) Mill. - Plantlife

Losses to ploughing and quarrying continued into the twentieth century and by the 1960s only
29 populations remained (Wells & Barling, 1971). Losses since then have mainly been caused
by increased above-ground competition, particularly with Bromopsis erectus, as a result of
under-grazing (Walker et al., in press). Ironically this was first observed in grazing exclosures
that were erected to protect populations from over-grazing (e.g. Carter, 1967; Wells, 1971).
Of the 20 sites where Pulsatilla vulgaris has either declined or gone extinct since the 1960s,
16 have been ungrazed for over 40 years or have only received intermittent grazing, mowing
or burning (Table 9). These include small areas of grassland on earthworks or steep banks that
are now completely isolated within arable landscapes and are now partly or completely
scrubbed-over (e.g. Fleam Dyke, Fig. 12a; Honnington Camp, Fig. 12d), small exclosures
erected to exclude livestock, deer and rabbits on over-grazed sites (e.g. Aston Upthorpe
Down, Fig. 13a) and privately managed nature reserves where resources for management have
been limited (e.g. Ancaster Valley, Fig. 13).
This decline of grazing frequency and intensity on many sites has been due to the reduced
profitability of livestock farming in arable areas since the 1950s which has made it difficult to
sustain appropriate grazing management on unproductive sites (Nisbet & Shere, 2006). On
mixed farms the conversion of grassland to arable has made farmers less committed to grazing
small areas, whereas their inaccessibility has deterred potential graziers because of increased
transport and infrastructure costs. Even on livestock farms these problems have prevented the
grazing of small fragments of semi-natural grasslands perceived to be unproductive and/or
difficult to manage. In addition, there has been a decline in rabbit grazing since the spread of
myxomatosis in 1953 which is known to have caused dramatic successional changes, especially
on sites with no history of livestock grazing (Sumpton & Flowerdew, 1985).
Table 9 - Management of Pulsatilla vulgaris populations in relation to trends in abundance,
1968-2006. 1-5 represent a decline in the intensity of grazing management.
Extant
Management since 1968
1. Winter + some spring/summer/autumn
Increas
e
Stable Decline
Extinc
t
Total
grazing 3 2 - - 5
2. Winter grazing (since 1980) 2 1 - - 3
3. Irregular grazing, mowing, burning - 4 2 2 8
4. Over-grazed then under-grazed - - 2 3 5
5. Ungrazed for over 40 years - - - 7 7
6. Improved/destroyed - - - 4 4
7. Unknown - 1 - - 1
Over the last 40 years many grassland sites have also been agriculturally improved and
reseeded to increase productivity. Other threats have included the digging-up of plants for
horticulture including over 1000 from Knocking Hoe in 1948 (Hope-Simpson, 1948) and more
recently at Barton Hills (M. Gurney, pers. comm.). In addition, the last known plants were
dug-up at two former sites (Broughton Far Wood, Fleam Dyke; Marren, 1999) although other
factors were more important in causing declines. Other direct threats, including forestry,
building developments, etc. have only caused a few losses, including the dumping of rubble on
the last Leicestershire colony. More recently there has also been concern, but no direct
evidence, that atmospheric nitrogen deposition may be adversely affecting some populations
through eutrophication of infertile grassland (Crawley, 2005; Rich et al., 1993).
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