Colonization of sand and gravel quarry ponds by aquatic plants: the example of North Cave Wetlands 2001-2013

摘要

There are many ponds scattered throughout lowland England that are a legacy of industrial minerals extraction and are often valuable resources for wildlife. In East Yorkshire, for example, ponds that originated through extraction of sand/gravel, clayor spoil for construction of railway embankments have greater species richness of water plants and more species of regional conservation significance than village ponds, ancient moats or ponds of miscellaneous origin (Linton & Goulder, 1997, 2000). The initial colonization by aquatic plants of new ponds formed by the flooding of pits left by minerals extraction can be rapid. For example, clay-pit ponds in Purbeck, Dorset, acquired 5-8 species of aquatic plants within 2-4 years of abandonment (Barnes, 1983). Even more striking is that at least 67 wetland and aquatic plants colonized an experimental pond complex dug in the clay and gravel of the River Thames floodplain within seven years (Williams et al, 2008). Rapid colonization is especially well shownby events at North Cave Wetlands, a 39ha site of former sand and gravel workings in East Yorkshire that was acquired as a reserve by the Yorkshire Wildlife Trust in 2000. The lakes on this site (Fig. 1) were primarily excavated between 1983 and 1999. By2001 they had been colonized by more than twenty aquatic plants (Goulder, 2002). Of the submerged plants Lesser Pondweed1, Horned Pondweed, Spiked Water-milfoil and Stonewort were widely distributed. Emergents were represented by Celery-leaved Buttercup on muddy strands around all the lakes. Common Reed, Bulrush, Brooklime and Blue Water-speedwell were scattered around some of the lakes.