Habitat & Species Recovery

Wetland wildlife has increased very noticeably following restoration. Dragonflies and damselflies have become very numerous with the improved hydrology and increased areas of open water. This has encouraged several Hobbies to remain on the fen each summer. Many more waterfowl are using the open water, and Marsh Harrier frequent the reserve each spring and summer.  Snipe have started to breed again on site, as have Bearded Tit.

Snipe Gallinago gallinago           Otter Lutra lutra                       Grass Snake Natrix natrix

picture SWT                                 picture SWT                              picture A.Excell

The river habitat has seen the return of Otters and Water Voles, the latter now breeding over the majority of the reserve. The otter-release programme into the river further downstream at Bungay must have improved their chances within the catchment, while milder winters and increased Mink trapping operations on the river will undoubtedly have helped the water vole population.

Since restoration began, 6 stonewort species Charophyte spp. (see plant/algae lists on webpage), 2 bladderwort species Utricularia vulgaris & minor and Fen Pondweed Potamogeton coloratus have been recorded in the open fen that was subjected to peat stripping management. Butterwort Pinguicula vulgaris has reappeared in a small area of Little Fen wet heath, and now also on Redgrave Fen, having last been recorded in the mid 1980s. Round-leaved Sundew Drosera Rotundifolia has now been discovered on a newly developing area of wet heath on Redgrave Fen. Areas of bog mosses Sphagnum spp. are increasing on Great Fen, Bog Pimpernel Anagallis tenella has reappeared in large patches on Redgrave and Little Fens, and the saw sedge Cladium mariscus beds are looking far less impoverished each summer.

Bee Orchid Ophrys apifera growing on Redgrave Fen in 2006

picture A.Excell

Alkaline, neutral and acid conditions exist within the open water areas in addition to fen soils. At such an early stage in the recovery of this valley fen, these assemblages of habitat-defining conditions cannot possibly hope to immediately support a finely honed, delicate juxtaposition of plant and invertebrate communities. These features of the fen, once awe-inspiring, but largely degraded over the decades, will take much longer to re-establish, as will many of the other important fen communities, but it is very exciting to report that the instigating processes are now coming together in a very positive light.

Biological Statements & Targets

1st Priority

Despite the damage caused to the fen through water abstraction and land drainage from 1959 until 1999, the communities remaining in the early 1990s earned the Fen its SAC designation and also qualified the site for EU LIFE grant aid.  Spring fed calcareous fen communities, soakways and chalky runnels (these latter features largely now absent or degraded) and the shallow flooded peat pit mires are all related to the group of communities referred to as the Caricion davillianae. Such communities are highlighted on the Habitats Directive indicating the highest priority for conservation in the European Union, and were the target of restoration management during the EU LIFE restoration project.  Prior to the 1960s these communities were in superb condition and were among the best examples of their type.  They therefore warrant first priority conservation status on the fen.  Results from the 2004 NVC Phase III resurvey indicate that early stages of many of these Target Fen Types (TFT) are becoming re-established, suggesting that they are achievable targets.  This is perhaps with the exception of M13, which appears to have limited scope for recolonisation at present.  Despite these limitations, it will remain as a TFT  priority 1 habitat.

Equal priority is also accorded at species–level, for the Fen Raft Spider, Dolomedes plantarius, a Ramsar feature and EN Species Recovery Programme (SRP) animal. The long term vision for the spider is to re-establish a self-sustaining population which does not depend on specific measures additional to normal habitat management, and that the population re-occupies its historic range on the Fen.

2nd priority

The table below highlights the communities above and their NVC type, plus the environmental conditions associated with them.  The lower section of the table comprises TFTs that have been added or reprioritised, following the results of the 2004 NVC resurvey of the fen. 

3rd priority

The remaining scrub and secondary woodland on the fen has local importance, both aesthetically and for ecological value and visual interest, and some areas represent excellent breeding habitat for important bird, mammal and invertebrate species.  It will be managed in selected areas to maintain its conservation value, in addition to routine management to prevent re-encroachment on recently restored open areas of fen. 

Management Strategy

The first priority objective is to enhance those features for which the Fen has been designated an SAC and Ramsar site, and to direct all the recently restored habitats towards favourable ecological recovery.  This will be guided through principle ‘whole reserve’ holistic management methods chosen, namely grazing, with some mechanical cutting implemented to assist recovery of the restored habitats.   The fen raft spider Dolomedes plantarius is a Ramsar species and also warrants first priority protection.

The second priority objective will be the aim to continue appropriate management of the 2nd priority habitats within the framework of the holistic management regime, limiting repeated fragmentation and ‘over-compartmentalisation’ of the reserve.

The third priority objective will be to improve the conservation value of the scrub and secondary woodland via appropriate management.  This will involve a mixture of scrub removal on rotation, some coppicing of scrub margins, and non-intervention of developing scrub and woodland stands where their ecological importance does not conflict with the internationally important fen communities.  There will also be objectives to link the non-SSSI land in SWT management to the overall fen habitat by direct practical conservation on the ground.  This will be an important process in developing the fen and peripheral land as a single unit wildlife estate.

The future

Recording & monitoring

A network of 54 dipwells and 35 vegetation plots have been installed to monitor the response of the Fen now that the borehole has stopped pumping. A full Phase 2 National Vegetation Classification (NVC) survey has been undertaken for the fen in 2004, following the last survey done prior to restoration in 1992 & 1994.  Recording and monitoring the fen hydrology and ecology will remain of paramount importance in the future, in order for us to understand more fully how the fen is recovering from years of damage.

An extract from the 2004 NVC survey summarizes the detailed findings:

In comparison with the 1992 and 1994 surveys, a number of key differences were identified, which are also discussed in later sections:

• 28 NVC communities or sub-communities were identified. The terrestrial vegetation is tall-herb fen, fen meadow, rush-pasture, woodland and scrub. In addition, several aquatic and swamp communities are identified. Some aquatic vegetation is now named and accommodated within the NVC, following a review of the classification (Rodwell et al 2000).

• Many stands are not clearly attributable to the existing classification, and are considered as intermediate between published NVC communities, or indeterminate. This continues to be a feature of the NNR and can be regarded as indicative of transitional areas responding to environmental and/or management changes.

• The central Cladium-beds north of the river have enhanced species-diversity, and grade into rush-pasture on the fen margin, often via various stands of fen-meadow.

• The introduction of scrapes into each fen has lead to their partial colonisation by a reed-swamp community, often in association with mono-specific stands of Potamogeton coloratus and Utricularia vulgaris.

• Stonewort meadows were recorded from about half of the scrapes, and species include Chara aculeolata and C. curta, both Nationally Scarce species. The NNR has now been assessed as of European importance for stonewort conservation, one of only 38 in the UK (Stewart 2004a).

• Although no direct comparison can be made with the flora recorded by the 1992 and 1994 surveys, this survey recorded 23 per cent more Principal Fen Species. These include the Juncus acutiflorus, Samolus valerandi and Baldellia ranunculoides, which are currently significant components of particular communities.

• It is notable that the moss Campylium stellatum, in particular, is now frequently recorded across the site, and other species, such as Bryum pseudotriquetrum and Campyliadelphus elodes are at least occasional records. These changes suggest a significant improvement in the general bryoflora in the fens.

• The quality of wetland communities recorded from the fens was assessed using the Rarity-Weighted Principal Fen Species Score developed by Bryan Wheeler (1988), which ranks the relative conservation value of fen vegetation. Some fen meadow and tall-herb fen stands in Great and Middle Fen are regarded as amongst the richest in the Waveney-Little Ouse headwaters.

General view over Great Fen showing a profusion of flowers

picture A.Excell

Grazing

Grazing will remain the principle fen management technique for the foreseeable future. Each year brings forward new knowledge into where, how and why grazing works on this wetland, and the annual approach to grazing will be flexible, depending on site assessments and observations from the previous year.

Mowing

The saw sedge harvest will continue each summer within the 2 main sedge areas of Middle and Little Fen, primarily for the benefit of the 2 populations of the fen raft spider in these areas. We will continue to sell the harvested sedge whenever possible, so that the material is used in supporting the thatching industry.

Tourism and the public

The reserve remains open all year round, and is well worth a visit any time of year. The fen looks at its best in summer and autumn, when it is alive with wildlife. The Education and Visitor Centre will continue to host a wide variety of organised educational activities, walks and talks, through the year, and when open to the public at weekends is a great place to stop and have something to eat and drink in wonderful surroundings!