Successive agri-environment schemes have tended to place a relatively low emphasis on farmland ponds, but have we been ignoring one of the most important farmland habitats? In recent years, the UCL Pond Restoration Research Group has been studying the decline of ponds and in turn, how they can be best managed to benefit wildlife in UK farmland.
Before the Second World War parts of the UK were pond heaven! Cheshire, Lancashire, Norfolk, Suffolk and many other areas were pock-marked with ponds, often with 4-5 present in just one field. Ponds were used for watering livestock, cooling farm machinery and even as a supply of organic matter to the fields. Moreover, they were an important part of local culture, much loved by local people.
But after the 1950s all was to change. With agricultural intensification, many ponds were lost to in-filling with hedges, hedge banks and tree stumps pushed into ponds, many which were successfully ploughed over – “Ghost Ponds”. A count of in-filled ponds in Norfolk reveals the loss of over 8,000 ponds between the 1950s and the present day. But this is only part of the story of pond degradation. After the 1960s/70s, the management of ponds started to peter out and as a result thorn, willow and alder crowded over the remaining ponds. The result today is whole landscapes of heavily overgrown ponds that our studies show to be generally very species poor.
But all is not lost. The inspiration for the next part of this story comes from Norfolk Farmer, Richard Waddingham, the recent and much deserved winner of the Wildfowl & Wetlands Trust “Marsh Award” for wetland conservation. Richard has some 40 ponds on his 243 hectare farm and every year he manages 3-4 ponds, halting terrestrialisation. This periodic re-setting of pond succession has resulted in a dynamic mosaic of ponds, varying in shading and hugely rich in species – a stark contrast to the surrounding landscape. Richard’s ponds always astound visitors, be they farmers, conservationists or locals, and his approach has inspired the creation of the Norfolk Ponds Project (NPP) – the central aim of which is to increase the portion of high quality “open-canopy” ponds in the landscape. With some 23,000 ponds still present in Norfolk, this represents a big challenge.
Our UCL pond research has been directly focused on Richard’s ideas and is informing the work of the NPP. We have been examining the response of ponds to restoration involving major scrub and sediment removal and to say that the responses are remarkable is a massive understatement. A series of pond landscape comparisons show huge gains of species after pond restoration, including aquatic plants, dragonflies, invertebrates, amphibians and fish. Remarkably, many species that are very rare in the surrounding landscape quickly return to restored ponds, and in the case of water plants we can show that a long-lived seedbank is the key. We have also been resurrecting Ghost Ponds by careful re-excavation and can show that, even when buried underneath arable fields for 150 years, seeds are still alive and allow the rapid re-colonisation of ponds by underwater plant beds. Farmland ponds are incredibly resilient habitats.
More recently, we have been looking at the wider advantages of restoring and subsequently managing ponds, to reduce terrestrialisation. The studies show that farmland birds and pollinators benefit in major ways. Mass-hatches of emerging insects (especially mayflies), combined with dense beds of marginal plants, make managed open-canopy ponds rich sites for insect and plant food. Our studies show the number of bird species and bird visits to be much higher in open-canopy ponds compared to overgrown ponds. Additionally, declining species such as Swallow, House martin, Swift, Linnet, Goldfinch, Bullfinch and Brambling are all major beneficiaries of pond management. It does not end there; managed ponds are excellent sites for pollinators and in late summer, the ponds are buzzing with bees and hoverflies. There is more work to be done, but thus far every species group we have examined would benefit from a mosaic approach to pond management, as demonstrated by Richard Waddingham.
A major positive of pond restoration is that it is cheap, with just £500-£1,000 needed to re-excavate a Ghost Pond, or for restoration of an overgrown pond. Further pond restoration and creation also leads to minimal loss of farmland; the footprint of ponds is small, but the effect is large.
So here is an idea and maybe also a plea. Given all the measurable benefits to biodiversity, let’s bring farmland ponds to the fore in agri-environment schemes post-Brexit. If we can restore existing overgrown ponds, resurrect Ghost Ponds where possible, and dig new ponds on a big enough scale, the gains for farmland wildlife will be huge.
Dr. Carl Sayer
Reader in the Department of Geography, University College London