PROJECT DESCRIPTION
BACKGROUND
That humans not only destroy natural habitats, but also, perhaps with very different intentions, occasionally create some, is illustrated by the saga of the Rieselfelder Münster. It begins in 1901, when a chessboard of hectare-sized dyked and drained basins was laid out to receive sewage water from the city of Münster. As this water flowed through the basins, it was purified by microbial metabolism and percolation through the subsoil. As time passed, waterfowl and waders discovered the eutrophic waters of this biological treatment system and, given the lack of alternatives in this intensively farmed region, it became an important inland staging area for migrating birds. However, in 1975 a mechanical treatment plant was opened and the Rieselfelder were henceforth irrigated with the clean water emitted by this plant. The 233 ha site was designated SPA, but simultaneously became a tourist attraction and favourite spot for walks. That is its paradox: before 1975 the site was left to the birds on account of its overpowering stench of sewage, but now, thanks to the wastewater treatment plant which eliminated the smells, visitors (up to a thousand a day) have become a serious source of disturbance for the nesting and resting birds. Urgent action was required.
OBJECTIVES
The idea of the project was to close the former easily accessible core area to visitors. Simply banishing the inhabitants of Münster city from one of their favourite recreation spots was however impossible unless this was balanced by a compensatory measure. Therefore, the project would develop an adjoining 150 ha site, which would permit pedestrians, cyclists and birdwatchers to observe the core area and its avifauna from a respectful distance, and simultaneously bring about an expansion of the wetlands available to the birds. As a result, the Rieselfelder SPA would almost double in size and link up to two nearby nature reserves. The site to be developed, former arable land, was donated by the City of Münster; LIFE was to fund the investment in the works needed to transform it. These would include the establishment of a 22 ha lake with nesting islets, several expanses of shallow water whose levels would be allowed to fluctuate and 40 ha of humid meadows and marsh, to be grazed by a herd of Heck-cattle. To round off, visitor infrastructure (paths, observation platforms) which would be as unobtrusive as possible, was of course to be built.
RESULTS
The following measures were carried out on former arable land to close the small SPA Rieselfelder Münster totally for any disturbing leisure activities by the public. The monitoring data at the end of the project for bird species resting, moulting and breeding here confirms a very positive trend and the success of the project, but also the new bird refuge created by the project was attracting more and more birds. A management plan for the project site was elaborated first. The technical planning for the alteration of the pumping station, overhead power lines and other technical aspects of the project objectives, as well as the Wöstebach watercourse reconstruction planning, were other preparatory measures. The beneficiary bought some machinery like a dredge and a drill for excavation work, also some mowing equipment for the maintenance of the wet sites created by the project. One project coordinator was hired to manage the project implementation. The technical implementation on site was done in 5 zones: - zone 1: a 18 ha shallow lake was created by building a dyke of soil with a marl core. The water level can be controlled by a weir across the outflow of the Emsableiter ditch draining the municipal waste water treatment plant, and by a pumping station built by the project. Some finishing touches for the future lake were done: removing an old road as well as trees and bushes; building breakwaters to protect the dyke; excavating the lake bottom in a pattern of small mounds and hollows to generate shallow and deepwater areas suitable for a range of birds. In addition some improvement work was done to protect a nearby road against rising water levels. - zone 2: 13 ha have been transformed into a wet pasture by raising the ground water level and adding several aquatic habitats like shallow ponds and ditches to the site by extensive relief modification. Furthermore an old road was removed. Cattle graze this site when water levels permit; when it is flooded it is an ideal foraging area for birds. - zone 3: 22 ha have been turned into an extensively grazed wet pasture. Some relief modification has added some shallow temporary ponds and bodies of water to the site. An advanced draining system has been installed to control the water level. In addition, some infrastructure for cattle like a holding pen, a winter feeding area and a small open stable has been installed. - zone 4: a shallow impoundment was created by blocking the Aa-Ableiter, another outlet of the wastewater treatment plant. The bed of the Aa-Ableiter was renaturalised by removing the concrete slabs from its bed and enlarging the streambed. Not as much landscape design was necessary as in zone 1 because of the situation on the ground. The water control system is similar to the one in zone 1. Some parts of the adjoining grassland are grazed by cattle. Improvement work to protect nearby infrastructure was necessary. - zone 5: this 55 ha area was developed as a buffer to the zones 1-4 and is designed with a few ponds and some fruit trees, in memory of the local orchard traditions. An existing road was demolished and a parking lot has been built for the visitors to the area. The grassland has partly been leased to local farmers for extensive use, partly is being grazed by the beneficiary's own herd of Heck cattle. - Wöstebach: the restoration of the former natural meandering course of the regulated Wöstebach stream was an additional measure. The public guidance was a very important aspect, as the original SPA, a long-standing and attractive leisure area, would be totally closed: - A visitor guidance concept was drawn up and implemented for the access to the new site. It consists of 5 different circular visitor trails focusing on different topics. Visitors can observe the birds and nature from special huts and towers. Panels offer information about the site and nature and ecology in general. - Several folders informed about the project process. - A scientific symposium was organised in April 1998. Some innovative aspects: - In Zone 1 and 4 the beneficiary built a computer-controlled system which monitors water levels throughout the site and controls in- and outflow of water from the streams feeding the site (Emsableiter and Aa-Ableiter) accordingly. This is common enough in normal hydraulic engineering, but is rather unusual for a nature reserve! Via a computer in the biological station the weir can be regulated closely and in addition it has a self-regulating mechanism and warning functions when things go wrong in the flooded zone. - The pumping station, which will help regulate water levels in the new wetlands, is hampered by the masses of algae and plant matter brought down by the Emsableiter stream in spring and summer. This vegetable matter blocks the pumps and has to be cleared regularly. The project got a local engineering firm (Firma Niehues) to design and manufacture a machine to clear vegetable matter automatically, a machine able to operate at a depth of 2.5 metres of water. Such machines do not exist on the market, so Niehues had to design it from scratch and custom build it. According to the beneficiary, this machine is the first of its kind.