Management of the
marsh fritillary population must take account of changes in the
butterfly population, changes in factors affecting the population
and new research informing understanding the ecology of the
butterfly. An adaptable approach to management is therefore
essential. Management objectives must also be adaptable in response
to better understanding of ecological systems.
The site manager
will need to balance short-term benefit against long-term gain. For
example, in retrospect, the manager would like to have avoided the
winter poaching of the improved fields that resulted in the spread
of Juncus. Science is an essential management tool. It supports
important judgements on management. However, the site manager must
interpret scientific data very carefully. Setting of stocking
levels was critical to the management of the habitat on the NNR.
The graph below shows stocking rates and vegetation height and
demonstrates that the relationship between the two is not
straightforward (Fig. CS 4.7). At low stocking levels, stock do not
graze an entire enclosure evenly but preferentially select certain
areas. The response of the vegetation to grazing is not the same
every year, mainly because growth rates are influenced by climate
conditions. A large element of informed judgement is often
required.
Index data from 2005
and 2006 suggests that the butterfly population on the western
block is building up to a peak, possibly in 2007. There may once
again be thousands of butterflies emerging on the NNR. Given that
the population is still one of the largest in the UK. it would be
very easy to be complacent and be content with the population being
confined to the current areas of unimproved rhos pasture on the
western block. This would be nothing short of foolhardy. Who knows
what the future will bring and what it will mean for this
butterfly? The precautionary principle must be applied and every
effort made to increase the long-term viability of the population
at Rhos Llawrcwrt.
