AbstractLarge areas of ex-industrial land remained following the decline and abandonment of heavy industries from the 1960s onwards. While most sites were developed, a few escaped significant modification and succession upon nutrient poor soils produced species-rich plant and invertebrate assemblages. One of the largest such sites is the Wigan Flashes area in North West England which now comprises part of the 1500ha Wigan Greenheart. This contains a variety of habitats including open water, extensive reed beds, grasslands scrub and woodland. It is also home to several rare species. In the last two decades, work has been undertaken to improve the conservation value of these habitats.
This thesis addresses a number of questions assessing the contribution that synanthropic sites can make to nature conservation. Within the last eighteen years, conservation work in the Wigan Greenheart area has progressed from single site-based projects to a landscape scale-approach. In the first chapter, the potential of this approach is explored by assessing to what extent the separate reedbed habitats within the area are functioning as a single unit based upon the dispersal distances and breeding area requirements of reedbed specialist species. This showed that for many vertebrates the reedbeds may function as a unit, however for the invertebrates not enough is known of the ecological requirements and dispersal capacity to determine whether the habitats function as a network.
The second study investigates the success of management interventions in a twenty-year grassland creation project. By targeting the management and steering the grassland development by the addition of Yellow Rattle, Rhinanthus minor L., the meadows have developed into recognisable plant communities, comparable to vegetation described for long established grasslands managed in a similar manner. The third study assesses the importance of secondary woodland for the fast-declining Willow Tit (Poecile montanus Conrad von Baldenstein, 1827). The connectivity provided by the network of scrub habitats and secondary woodlands is a key factor in the continued success of Willow Tit in the area. The final chapter explores the evolutionary dynamics of such disturbed sites. Utilising a morphometric approach an assessment of the marsh orchid (Dactylorrhiza spp.) populations was undertaken. This revealed extensive hybridisation between southern and northern marsh orchids (Dactylorrhiza praetermissa (Druce) Soó and Dactylorrhiza purpurella (T and T.A. Stephenson) Soó) on the ex-industrial habitats within the narrow contact zone between these two species, thus revealing the dynamic evolutionary processes at play in these habitats. Hybridization is a method by which genes are transferred from one species to another typically between closely related species. This potential source of genetic novelty may be an important source of variation and allow plants in novel habitats or changing environments to adapt to their conditions.
The thesis has provided evidence that the management of these synanthropic sites can provide nationally important conservation outcomes over a 16-year time-scale, benefiting a range of habitats, species and communities. The development of the reedbeds and the meadows demonstrates the capacity of the post-industrial landscape to support communities of conservation value.
|Date of Award||14 Nov 2019|
|Supervisor||MICHAEL POWELL (Director of Studies) & PAUL ASHTON (Supervisor)|