Farm Ponds
Supported by the Department of Environment, Food and Agriculture through the Agri-Environment Scheme
All farms used to have ponds and the Manx Gaelic name for a pond, ‘dub’, is still in common use on Manx farms. They were needed for livestock to drink from, amongst other purposes, but now with clean piped water they are relics of the past, sometimes filled in and often fenced out and overgrown. Flora and fauna of traditional ponds was really specialised, with many species needing bare muddy areas every spring to complete their life-cycle. Once a pond no-longer has animals grazing out the willow scrub and rough weedy plants their specialised biodiversity declines. As well as rare species ponds are a magnet to wider diversity as well.
Dub at Gat-e-Wing, one of MWT's Nature Reserves
The Prehistoric Past
At the end of the last Ice-age as glaciers melted they left behind vast amounts of silt rock and gravel that are now our soils. Lodged within this material were often large ice boulders which, when these melted, left behind big holes, sometimes a football pitch in size, that would fill with water. In the subarctic conditions the main plant that colonised these areas was chara, a plant that when it dies in calcium rich water is covered in chalky silt. Eventually the pond fills up with this silt and becomes dry land. Thousands of years later and this chalky silt was found to be a perfect additive to Manx soils and was dug up by Victorian farmers and spread on fields. This left behind a landscape on the Northern Plain unusually rich in ponds.
The Lhaggagh dub
Drawdown
The most valuable part of a pond for rare wildlife is between the winter water-level and the summer water-level. This is the ‘drawdown’ zone. In areas where cows, sheep or horses are present in winter, this area will become muddy; cows in particular love to wade into to ponds. As the water-level drops plants like pennyroyal and golden dock germinate and rapidly grow. Shallow ponds on sandy soils have some of the best drawdown zones, with many pools drying-up completely.
Drawdown wildflowers are often able to survive for decades as dormant seeds awaiting the right conditions to occur again. This is why restoring old ponds can be very successful, even after 100 years.
Pennyroyal the traditional Manx name for pennyroyal is lurgeydish which is a Manx Gaelic corruption of the northern English name 'lurk in a ditch'.
Perfect ponds
Creating new farm ponds, and restoring old ones, need a few ground rules to be successful:
- Never create a pond on species-rich wetland
- Use natural groundwater- A lined pond is not of value to most rare species.
- Give livestock access to the pond in autumn and winter. Only cattle will create perfect muddy conditions, but sheep and horses can be valuable summer grazers.
- Deep ponds have little value for most wildlife. Shallow pools with very gently sloping sides are best. Seasonal pools are great, but for dragonflies and frogs water needs to be present all summer.
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