David Wheeler
started a further revision of the management plan in 2000. Planning
guidance now focused on "Favourable Conservation Status". He had by
now realised the shortcomings of previous objectives in respect of
the butterfly population cycle. He wanted a revised objective to
take account of the variable population size over time, but it
still had to reflect the viable status of the butterfly on the
site. He now had larval web data which spanned a full cycle of the
butterfly population from the peak in 1991-1994, through the years
of very low web numbers in 1995-1997, and then the gradual rise to
the next peak in 2000. During the previous 10-year cycle, the index
fluctuated between 4 and 236. On the basis of pragmatism, I
selected a 'mid' point representing a lower limit to be exceeded
for at least half of the cycle. Factors and management
prescriptions remained unchanged from the 1995 objective. A revised
layout was adopted.
In 200 the marsh
fritillary objective was:
To maintain the
marsh fritillary population at Rhos Llawrcwrt in favourable
condition where:
Performance indicators:
Attribute - Larval web index:
Upper limit: not required
Lower limit: the larval web index will exceed
100 for 5 years in any 10-year period.
