PONDS AND THE DCV

Why dig Ponds

Nearly all ponds the DCV work on are man made. Some might be of mediaeval origin used to store drinking water but most have occurred in the last 100 years due to extraction of minerals, aggregates or clays. More recently from the 1970's onwards ponds have been made with wildlife in mind. Ponds were once very common in the countryside but are disappearing at an alarming rate due to neglect and improvements in farm mechanization. Urban ponds have also disappeared due to neglect and being filled with rubbish and also due to the dangers they hold for children.

Ponds are very dynamic and can very quickly grow over and become damp scrub. They have a natural succession of plant life from weed and other aquatic plants through marsh plants to young scrub and trees. This happens when the silt builds up with decaying matter using up the oxygen in the water resulting in anaerobic conditions known by volunteers as black smelly mud. These conditions kill off most animal and aquatic plants.

This is where the DCV comes in to dig out the black smelly mud, winch out trees and roots, and cut back the vegetation to allow more light in.

Many conservation bodies and councils now like to create new ponds for wildlife and in Dorset this is mainly on wet heath to benefit amphibians and dragonflies.

How to dig out Ponds

Old ponds may require more work than digging out a new one. Firstly, many overhanging trees will have to be cut to allow more light in, then any trees growing in the pond will have to be cut and the stumps winched out. Next the DCV tracks will have to be laid for volunteers to walk on and wheelbarrow access. Use spades with a tread on them to dig out the silt or mud, this puts less pressure on  the sole of your foot especially if one is wearing wellington boots. Use a shovel to move loose soil or watery mud, this is more efficient. The spoil will have to be taken away and dumped, scattered or sometimes used to build up the banks to make a deeper pond.

If the pond is not too old there may be some animal life in the spoil and this should be left on the bank to allow them to escape back into the pond. The depth of the bottom of the pond should be established and the volunteers told not to dig into this as it may be a clay or other water proof lining. There should be deeper areas in the middle where the water won't freeze in winter or get too hot in summer, and shallow areas with graduated banks for plants to root in and wildlife to get in and out.

Some ponds may require just a little maintenance. Weeds, sedges and grasses may need taking out using cromes (muck rakes) and rubbish can be taken out using a grappling hook on a rope.

Most traditional ponds have a stream or water course topping it up. This should be investigated for blockages or diversions. The water exit should also be checked and may need some kind of sluice installed to control the height of the water

The DCV have in recent years dug out new ponds at the Bourne Valley nature reserve in Poole for the Borough Council. This is a heathland reserve with the Bourne stream running through it. This is an ideal environment for us to create new ponds on the wet boggy heath for amphibians and dragonflies and a pond can be dug out quickly in a day.

Safety

Volunteers, just like all other workers, need to work in safe conditions. They should be made aware of the dangers of tools, safe work practices and any hidden dangers on site such as deep water, soft mud and rubbish in the silt. There may also be a danger from insect bites and sap from broken plant stems or roots. All volunteers should be aware of each other, working too close can be dangerous. We should also be on the look out for dangers to other volunteers, i.e. getting too close to deep water or getting stuck in the mud. We all need to work as a team.

Wildlife

 The plant and animal life of the pond is dependent on what type of habitat the pond is situated in. On acid heaths, mires and bogs for instance the open water pond may be too acid to support a great variety of plant and life. There may be shallow wet areas with carpets of Sphagnum moss and plants such as Bog Asphodel, Sundews and Heathers. Less acid ponds and bogs will have some of the following plants and animals:

• Common Reed
• Water Mint
• Yellow Flag Iris
• Arrow Head
• Water Crowsfoot
• Water Speedwell
• Water Parsnip
• Nymph of Mayfly, Stonefly, Dragonfly
• Freshwater Shrimp
• Snails
• Water boatman
• Frogs and Newts

Ponds should normally be maintained at regular intervals to remove overhanging trees, persistent plants and young trees in the water also any rubbish thrown in. Dredging to remove some of the black smelly mud will improve oxygen levels.

Some of the smaller dragonfly ponds on heathland may be left for nature to fill in and a natural succession of plants and animals to take over, whilst new ponds can be dug nearby to start the cycle off again.

Don Simcock