The River Ouse Project
This interdisciplinary project integrates ecological and historical research to show how everyday human land-use might be managed to ensure biodiversity objectives. The project focuses on grassland and woodland habitats in upper inundation areas of the River Ouse in Sussex where recent theoretical work suggests that flood alleviation measures could be linked to biodiversity objectives. There are three phases to the project: ecological survey and historical research; field experiments; and grassland enhancement projects linked to flood alleviation.
The end point: grassland enhancement projects linked to flood alleviation
Many flood alleviation measures depend on managed water storage in ponds or farm reservoirs. Another strategy, however, is to allow land bordering streams to flood and drain over time, from as little as 3 days to more than 2 weeks, depending on the time of year and natural geography. Such areas are known as 'washlands'. Washlands where flooding is of short duration are ideal for flood alleviation because the site quickly becomes available to store water again, but the vegetation of washlands has to be able to withstand long periods of time without standing water as well as the brief periods of flooding. Conservation effort, then, cannot be directed just towards wetland species. Instead, in this project, we are using Meadow grassland (known as MG5 in the National Vegetation Classification) which can tolerate short duration flooding provided this is followed by relatively quick drainage of the land.
Species-rich MG5 grassland is a high priority habitat for conservation because this type of grassland has been estimated to have declined by more than 97% over the last 70 years.
The first phase: ecological survey and historical research
In the first phase of the project detailed ecological survey is being combined with historical studies to identify the best sites for woodland re-creation or grassland enhancement schemes and also the best species to use in the related grassland enhancement experiment. Documentary historical research (led by Dr Will Pilfold) is being supplemented by oral history interviews with key respondents who can recall details of land use and human impact that are not available through archive sources. The first two years of the project were funded by a Leverhulme Research Project grant.
The second phase: grassland enhancement experiments
A field experiment has been set up in the upper Ouse catchment to determine an effective method of increasing the plant biodiversity of grassland, so that good use can be made of expensive wildflower seed or plantlets on those sites identified by ecological survey and past land-use as suitable for grassland enhancement combined with flood alleviation. The site was subjected to pre-experiment treatment to reduce the grass cover and open up bare ground for colonisation by wildflower species. In September 2007, plant plugs of nine species of wildflower were planted into 4 plots and 4 other plots were sown with seed of the same wildflower species. Four control plots will enable both these options to be compared with unaided colonisation of species following the pre-experiment reduction in grass cover. The experiment is being monitored by continuing education volunteers, coordinated by Dr Margaret Pilkington. The setting-up costs of the experiment were also funded by the Leverhulme Trust.
A second field experiment was set up at Sheffield Park in October 2009 in collaboration with Kew at Wakehurst Place, the National Trust and the Weald Meadows Initiative, this time on a washland site which is subject to short-duration flooding. We know from oral history interviews with past tenants that this riverside meadow at Sheffield Park used to be full of cowslips which disappeared when fertiliser was applied in the middle of the last century. Cowslip is one of ten species of wildflower being used in the field trial which has been set up along similar lines to the 2007 field experiment. The plant plugs were grown at Wakehurst Place from Weald Meadows Initiative seed and the same origin seed was sown in the seed plots. This experiment is also being monitored by continuing education volunteers, coordinated by Dr Margaret Pilkington.
Results so far suggest that some plants such as Birdsfoot trefoil (Lotus corniculatus) and Selfheal (Prunella vulgaris) establish much better from plant-plugs whereas other species such as Yarrow (Achillea millefolium) and Oxeye daisy Leucanthemum vulgare establish really well from seed and there is no need to use plant plugs.
Also in collaboration with Kew at Wakehurst Place, permanent quadrats were set up in June 2009 in Hanging Meadow, a former washland, in the Loder Valley. Wakehurst is now cutting this flower-rich meadow for hay using a lightweight hay-cutter and mini-bailer. The hay is fed to Wakehurst's own flock of sheep which also graze the meadow in the autumn. The effect of this new management is being monitored annually by continuing education volunteers, coordinated by Dr Margaret Pilkington.
Using the results: the first washland meadow restoration begun
In collaboration with the Sussex Wildlife Trust (Sussex Wetland Landscapes Project), Kew at Wakehurst Place, Weald Meadows Initiative and local landowners we have begun restoration work on 20 hectares of washland along the upper Ouse. Wildflower seed collected by Kew and stored in the seed-bank at Wakehurst Place was used to grow 6000 plugs which were then planted into 0.5ha areas at 4 washland sites in 2011. Weald Meadows Initiative seed was also sown. Subsequently green hay from these flower-rich patches will be spread across the rest of the areas.
Ecological survey work
Ecological survey work which began in 2006 takes place each summer. Continuing education volunteers are surveying streamside woodland and grassland in the Upper Ouse to build up a picture of the existing habitats. A Geographic Information System is being used to develop an understanding of the spatial relationships between water flow within the linear stream systems and the sites surveyed; and how this in turn relates to blocks of land associated with both past and present-day farming units.
If you are interested in taking part in the ecological survey work please email Margaret Pilkington (M.C.Pilkington@sussex.ac.uk). You don't have to be an expert: just an enthusiast.
You can also read about the work on Weald Meadows by other organisations, such as Weald Meadows Initiative and The Grasslands Trust, and see information on another floodplain meadow grassland project at the Open University.