How to restore ‘forgotten’ farm ponds for wildlife
© Carl Sayer As many as two-thirds of farmland ponds in England and Wales have been lost though drainage and in-filling, while those that remain are often shaded and tree-covered and do very little to support wildlife.
Putting that right is straightforward, says Professor Carl Sayer of the Pond Restoration Research Group at UCL, who stresses that pond restoration and management is one of the best things that can be done for nature recovery.
“In a good state, farm ponds really pack a punch,” he says. “They are biodiversity hotspots and critically important for invertebrates, plants, amphibians and fish.”
See also: How a coastal group’s audit is focusing biodiversity effort
When cleared of trees and scrub and opened to sunlight, their recovery can be rapid, he stresses. “Letting daylight and oxygen in means they become species-rich in a very short time and the local landscape is transformed.
“Keeping them like this then only takes a bit of management every three to five years.”
Restoring ponds
Most pond restoration involves scrub and sediment removal, advises his colleague Dr Helen Greaves, although the first step is to choose an appropriate pond for the work.
“Don’t opt for a pond that is fed by streams, ditches or field drains, or one that receives road run-off or other pollution,” she says. “Use your local knowledge and consider the wider landscape.”
When not to restore a pond
Seek expert advice before restoring any of the following ponds:
- In a semi-natural habitat
- On the pond priority map
- With abundant wetland plants
- Contains rare or protected species
- In a nature reserve or site of special scientific interest
- Part of a scheduled monument
- Included as a listed structure
With many neglected sites, the aim is to clear them so that they are no longer completely shaded and to remove enough sediment to return it as close to the original pond profile as possible.
“There’s no prescribed solution. Letting the sun in brings back plants that used to be supported; mud and sediment removal helps to expose long-buried but still viable seeds, bringing back older species.”
Work timing
The best time to do any restoration work is from September to November, when water levels are generally low and there will be minimal impact on the breeding seasons of birds and amphibians, advises Helen.
“Remove trees and scrub from at least 50% of the pond margin and be prepared to make a major impact on mud removal – it can look brutal when it’s first done.”
Only soft mud should be removed and some sediment should be left in the pond bottom, to supply the water plants, she adds.
“Don’t dig out the marl layer or bankside material, as that can cause damage. Any removed sediment can be put on a nearby arable field.”
Signs of success
The first sign of success is that the water starts to clear – which usually takes place after six months. Left to colonise naturally, plants will start to come up, with stoneworts being good indicators of a revival.
“They thrive in clear, unpolluted water, which is why we look for them.”
After a year or two, insect life will be abundant and bird numbers will increase.
“It takes a few years for amphibian populations to build up, but their presence is a very obvious sign that things are much better.”
Multifunctional ponds
Once restored, wildlife ponds should be kept for that purpose alone, recommends Helen.
There are enough ponds in the landscape to cater for other uses, such as angling or wildfowling, without expecting them to fulfil more than one purpose, she notes.
What about ghost ponds?
Ghost ponds – old pond sites that have been deliberately filled in – can be brought back to life very quickly.
“It’s one of the most successful forms of ecological restoration,” notes Carl. “All of the science shows that it works.”
Often appearing as damp patches or depressions in fields, it may be necessary to refer to old farm maps to determine their exact location and size. Once found, they can be restored with the following steps:
- Dig a trench through the suspected centre of the ghost pond to find the original pond sediment
- Dig a second trench at right angles to the first
- Work outwards from the two trenches to excavate the pond, keeping it a similar size and shape to the original
- Dig down through the historic pond sediment (but don’t remove it all)
- Any field drains at pond locations should be removed or broken
- The pond’s buffer and its margin should be left to colonise naturally
- Leave ponds to fill naturally with water through the winter
“Damaging activities, such as feeding to attract ducks, disturbs them too much and reduces their ability to support wildlife. Ponds used by dogs aren’t suitable either.”
The same is true of ponds used for natural flood management or pollution interception, she adds.
Funding for ponds
Pond restoration hasn’t been given the priority that it deserves by agri-environment schemes, believes Carl, who is hopeful that there may be a Sustainable Farming Incentive action included when future developments are unveiled.
“Compared to rivers, ponds get the least amount of attention and yet they can be restored and delivering for the environment in a very short space of time,” he explains.
The Countryside Stewardship options WN5 and WN6 are available for those in Mid Tier, although haven’t been adopted widely, while the District Level Licensing Scheme, which protects great crested newts, means that £700/pond may be available.
Top tips for restoring ponds for wildlife
- Ponds should be surrounded by natural vegetation – a 10m buffer of rough grassland is ideal
- Ponds with in-flows, field drains or other pollution source are not suitable for restoration – clean water is essential for wildlife
- Carry out any work from September to November – avoid the January to August breeding season for amphibians and birds
- Remove scrub and trees from at least 50% of the pond margin
- Only soft mud should be removed, not clay or bankside material, and enough to expose the seed bank
- Remove mud from two-thirds of the pond area – stop when you start seeing clay on the digger bucket
- Let nature naturally colonise your pond after any works – excavated surfaces should be left rough
- Restoration of a farm pond takes just one to two days with a chainsaw operator and digger working together
- Avoid non-native invasive species from getting established – make sure pond workers and equipment don’t bring them on-site
- Keep wildlife ponds for wildlife – don’t try and combine with other uses such as angling or natural flood management
- Ghost ponds offer an option for the most successful form of ecological recovery
- Pond variety is critical for wildlife, too – some shaded ponds are required, as are those that dry out in the summer
Pond restoration guide
The Guide to Restoring, Creating and Managing Ponds for Wildlife is available free of charge and can be downloaded from www.norfolkponds.org.
Initiated by Natural England, it was written by the Freshwater Habitats Trust and the Pond Restoration Research Group at UCL, with funding provided by UCL.
The 47-page colour guide covers all aspects of bringing ponds to life – from restoring existing ponds to creating new ones.
