The distribution of the Oxlip Primula elatior (L.) Hill in Essex
These figures (Table 3) simply give a flavour of the changes that have occurred. They amplify the
prophetic point made by Rackham (1975) in his studies in Hayley Wood -'Although Oxlips are
reasonably long- lived they have noticeably declined since Abeywickrama's time (1948), and their
long-term future is doubtful'. Based on the 2002 survey there are probably no more than 150,000
Oxlip plants in Essex. This may be half the number that were present in any one of a number of
Oxlip woods 40 or 50 years ago. Analysis of the numbers of plants on each site reveals that 99.75%
of Oxlips occur in woodlands, 0.20% on ditches and banks, and finally a mere 0.05% in meadows.
Looking closer at the woodland figures there is a strong skew in the distribution of numbers of
plants per site. Hempstead wood alone holds approximately 20 % of the total Essex population,
and the 16 most prolific sites (including Hempstead) together hold 88% of the county's population.
These figures may be of use in considering the conservation and resource priorities for the Oxlip in
Essex.
Where have all the Oxlips gone?
It was Rackham (1975) who, in his definitive work on Hayley Wood, highlighted many of the key
factors affecting the flowering success and population size of the Oxlip. In that work he highlighted
the benefit to the Oxlip of high soil moisture and winter flooding that has the effect of suppressing
Dogs Mercury Mercurialis perennis L. that would otherwise out-compctc the Oxlips. Secondly he
quantified the increase in flowering that results from the extra light available after coppicing (a six
to nine-fold increase) and the reduced numbers of plants present in heavy and persistent shade.
And finally he highlighted that in Hayley Wood Fallow deer Dama dama L. were responsible for
consuming c.75% of inflorescences and also taking sufficient leaves to nullify the advantages of
periodic coppicing, so that the normal flush of blooms in the second year after coppicing never
occurs. The intervening years have seen more work that underlines these points, particularly in
relation to deer (Cooke 1993, 2001; Cooke & Farrell 1995; Kirby 2001; Tabor 1993, 1998, 1999)
So how important are these factors today in affecting the Oxlip population? Although detailed
measurements are available for only very few sites, there is little indication that water tables have
dropped sufficiently to affect the total population in any significant way. The numbers of other
plants indicative of high water tables and correlated with the Oxlip, such as meadowsweet, have
shown no decline, so that losses of Oxlips mainly result from other causes.
Heavy, persistent shade, however, does have an impact on both the numbers of plants and the
percentage that produce flowers. The causes of this shade are twofold: firstly is the neglect of
regular traditional management such as coppicing, often for periods as long as 60 to 80 years and
secondly the planting of exotic conifer species into ancient broad-leaved woodland sites.
We have seen (English Nature 1982) that 20% of ancient semi-natural woodland sites in the county
that contain Oxlips have been planted with conifers. Although the error in both ecological and
commercial terms of this policy has been recognised by Forest Enterprise, and is being reversed,
the damage in terms of reducing Oxlip numbers is done and may not be recoverable for many
generations, if at all. Specific figures that highlight these issues have been carried out at Hempstead
Wood (Tabor - unpublished report to Forestry Enterprise - see Table 4). When Jermyn carried out
his survey in the early 1970s, he estimated a density of 11,100 plants to the hectare. The unmanaged
coppices, untouched since that time, today contain c. 4,400 plants in the same area, and those that
have been coniferised contain c. 900. reductions of 60% and 92% respectively. Not all of these
losses are solely due to shade: deer have had a major impact on the numbers of flowering rosettes
128
Essex Naturalist (New Series) 19 (2002)