Temporary ponds and scrapes

Despite their tendency to change between wet and dry, temporary ponds support a vast array of wildlife.

Drying out prevents fish from establishing, providing a predator-free environment for tadpoles and many aquatic invertebrates to thrive.

What

Temporary pools and scrapes hold water for periods of the year, but dry out in most years. Prior to extensive land drainage, it is likely that temporary ponds were a much more common part of the landscape, particularly in semi-natural habitats such as grassland.

How

Clean water is a vital part of a healthy pond – many of the species that rely on ponds cannot survive in very nutrient-rich or polluted water. Often, temporary ponds only have a small volume of water, making them extremely vulnerable to pollution and to changes in drainage.

Temporary ponds in existing semi-natural habitats such as grassland and heathland should always be protected from any land management practices. It is essential that temporary ponds are not deepened to hold water all year round. This removes many of the key features that support specialist wildlife.

Many temporary ponds are often overlooked or viewed as simply waterlogged areas or muddy hollows, particularly when dried out and grass dominated, but it is important that these seasonal pools are not drained or filled.

Although many temporary ponds can have great longevity, some will naturally fill in overtime as sediment is deposited with inflowing water. However, temporary ponds are often best left unmanaged, even when they begin to become silted up or over-vegetated. In this instance, it may be better to prepare for the future by creating a new temporary pond nearby, allowing the existing temporary ponds to dry out naturally.  Establishing a mix of existing and newly created ponds, will produce a range of conditions suitable for a wider range of wildlife.

To create a new temporary pond or scrape, try excavating a shallow depression in nearby areas with a similar underlying soil type. Ensure that the margins have a shallow gradient to maximise the bare muddy margins exposed as water levels recede, and resist the temptation to dig a deeper pond which would hold water for much of the year. Where there is room, consider creating a network of different scrapes around the farm to different depths. There will be no need to plant up the scrape, which will be naturally colonised by both terrestrial and aquatic species as it settles.

Buffering temporary ponds in arable areas can help to reduce the impact of farm inputs and pollution. Ideally, the buffer around an arable temporary pond should be at least 12m.

The best place to site ponds is in permanent pasture, however a wide buffer strip planted up with a mixture of robust grasses will mimic this habitat, providing the grassy margins that benefit amphibians. Link ponds to other key habitats by appropriate terrestrial habitat, such as buffer strips, rough grassland and hedgerows, allowing animals to move between different water bodies, forage and migrate to hibernation areas.