Succession and Conservation management - Wicken Fen - case study
The way in which conservation management on nature reserves such as Malham Tarn NNR has changed
dramatically over time. Initially a lot of reserves were virtual no-go areas for people unless they had special
permission to visit the place. Management was often based on the idea that we should just let nature get on
with things and see what happened. Neither of these approaches was satisfactory.
Can you suggest reasons why not?
More recently conservation management became based on a rather better understanding of what would
happen if things were left to themselves and this required a thorough understanding of the successional
processes within the habitats that people were trying to conserve. Management then became focused on
trying to halt succession at an appropriate stage to maximize the conservation value of the habitat being
conserved. In many cases (Tarn Moss and Fen areas are good examples) allowing succession through to
climax woodland would not be the best way of managing the conservation value of the sites.
Recently the recognition of inevitable changes to our wildlife due to climate change has led to a re-appraisal
of how we manage nature reserves. There is a feeling that we have to accept that the balance of species on
those reserves will change – we may lose some species of concern but others will move in. To allow those
changes to take place needs greater connectivity between reserves to allow the movement of species and
perhaps also a return to a more naturalistic method of allowing natural processes to determine the
outcomes of these changes. The Wicken Fen reserve in East Anglia provides a nice case study of how these
thoughts are developing.
Wicken Fen (on the outskirts of Cambridge) is a National trust
property as is Malham Tarn and similarly has been designated as
a:
 National Nature Reserve
 Site of Special Scientific Interest under the Wildlife and
Countryside Act 1981.
 Special Area of Conservation under the EU Habitats
Directive.
 Wetland protected under the international Ramsar
Convention.
The vision statement for the site envisages an extension and rewilding of a wider reserve area:
Conservation Management at Wicken Fen
The conservation management processes at Wicken Fen are varied, continue
throughout the year and fall into two main categories. The first is intensive and arrests or halts the natural
succession process at a desired point. The second is extensive. This process is much more flexible, does not
prevent succession and in effect has no end point.
Intensive Conservation Management
This form of management is the one commonly used in conservation in the UK. In essence it follows the
traditional methods of land management dating back to the early days of human cultivation. The basic
principles are to cut or otherwise "harvest" the vegetation growth and remove that biomass from the area.
Formerly, as early as the 15th Century, this process was undertaken at Wicken and the surrounding area in
the form of Sedge Harvesting. At that time all the work was carried out by hand and required entire families
to gather in the harvest produce. This remained the case until the early-20th Century when low key
mechanisation became available. However, it wasn't until the 1960's-70's that this equipment became
readily obtainable by conservationists. Latterly, in order to achieve the maximum amount of management in
the given period Wicken has adopted a more mechanised process, albeit using the same basic principles as
were used by the "harvesters" 600 years ago. Modern day management has several formats at Wicken Fen.
Like our predecessors we continue the sedge harvest. This is still a labour intensive activity that is
undertaken during the mid-summer period. Following on from the sedge the litter or marsh hay is cut. This is
a more mechanised process whereby the vegetation is treated in the same way as hay. This process
continues until the end of September when efforts are switched to the fringes of the many droves at Wicken
Fen. Although the communities are different the vegetation is treated in much the same way as the litter in
that it is cut and cleared using machines. There are of course many other aspects to the management of the
Fen. Some are connected to the management of our water courses: brinking and slubbing. These are a
means of halting the aquatic succession at an earlier stage than the terrestrial fen habitats, giving a greater
diversity to the wildlife found at Wicken Fen
Extensive Conservation Management
Although this process is quite common in many countries around the world and has been used on large
areas in the UK uplands, it is fairly unique to lowland Britain. Whilst 'intensive' management follows the
basic principles of traditional 'agriculture', 'extensive' management attempts promote the same basic
principle of natural/semi natural processes to drive landscape development. It is a far more hands off
approach, requires patience and relies on topography and hydrology to drive landscapes development,
whilst the grazing of large herbivores and natural regeneration/colonisation influences the vegetation (and
thus the habitats). The exciting aspect of 'extensive' or "naturalistic" management is that the landscape is far
more dynamic, being in a constant state of flux. As water levels fluctuate over time so the communities
change. As grazing levels of large herbivores change, either through population changes or migration, so the
influences on the vegetation change. These changes cause subtle differences in the landscape. The sort of
scenario that could be expected is as follows; several seasons of dry weather will concentrate the herbivores
in the areas where water can be found and grazing is lush. This concentration will reduce the growth of
vegetation in these areas whilst at the same time significantly reducing grazing pressure in the dryer areas.
Most aquatic or marginal plants will be suppressed in the wet areas with reed beds giving way to wet
grassland. In the dryer areas where grazing is reduced, taller vegetation will ensue, eventually leading to
woodland. As the weather follows its cyclical path and seasons become wetter, the reverse will happen.
Water will be more readily available across a wider area thus reducing the pressure on the wetter areas.
These will experience a prolonged period of water-logging and herbivores will range more widely. The wet
grassland areas will once again give way to reed bed. The drier areas that had been abandoned by
herbivores will once again be put under grazing pressure. This will break up the established tall vegetation
and the area will become more open.
Because the former type of management is based on traditional methods its results can be predicted fairly
accurately. We therefore know how the habitats will develop. This certainty becomes less clear with the
latter form of management. Extensive management is still in its infancy at Wicken Fen and because it is
based on natural or semi-natural events, the direction of development can only be assumed. The effects are
constantly being monitored and the results will help us and our successors ensure that the landscape and
habitat development continues to produce the diversity for which the "ancient" fen has become renowned.