Ponds, Pools and Lochans

4.2 Myths about ponds


Until quite recently, pond management for nature conservation was dominated by a series of myths about ponds. Most of these myths arose because of lack of information about the ecology of ponds. As a consequence management for wildlife was largely undertaken on the basis of what looked attractive to the human eye.

Although ponds that look attractive are often good for wildlife, some of the most valuable wildlife habitats can be visually unappealing. Dense stands of vegetation, heavily shaded ponds and ponds which dry out in the summer are often aesthetically dull, but can provide critical wildlife habitats.

Some of the more important myths about ponds are:

  • Drying out is disastrous for pond wildlife: in fact occasional or regular drying out is natural for many ponds. Although drying out inevitably excludes some animals and plants (especially fish) a remarkably large proportion of freshwater species tolerate or require periods of drought.
  • Ponds should be at least 2m deep: studies show that shallow water is normally the richest area for wildlife; deep water is not a requirement of all ponds.
  • All pond zones, from deep open water to shallow margins, should be created and maintained: to maximise wildlife diversity in a pond it was long believed that creating different water depths in the same pond was the key; in fact, to maximise diversity it is better to have a mosaic of waterbodies of different depths and degrees of permanence.
  • The bigger the pond the better: it was often thought that big ponds (because they often have more species) are automatically better habitats. In reality, small ponds may be very important habitats, and any pond from 1m2 upwards can support valuable species.
  • Ponds should not be shaded by trees: gloomy shaded ponds often seem unattractive to human eyes; yet trees bring much to ponds, and many plants and animals are associated with wooded ponds.
  • Ponds should be dredged to prevent them from becoming choked with vegetation: there is a long belief that too much vegetation is in some way undesirable, choking ponds. In fact, there is no right amount of vegetation for a pond; all stages of vegetation development form the sparse bare vegetation of new ponds, to the lush dense stands of a late succession pond are potentially valuable habitat. Perhaps the commonest pond management problem is too little vegetation, not too much.
  • Pond water-level fluctuations should be minimised: alongside myths about drying out it was often thought that water levels should be stable all the year. In fact, water level fluctuation of 0.5 m or more is normal, and the drawdown zone created by this fluctuation is one of the richest areas of any pond.
  • Livestock should be prevented from having access to ponds: the trampling of a small pond by a large herd of cattle in an intensive livestock operation is likely to be damaging. Yet ironically, gentle grazing pressure from a low density of livestock is one of the best ways of managing a pond, and should be encouraged.
  • Ponds are entirely self-contained systems, isolated islands in a sea of dry land: it has long appealed to biologists to think of ponds as isolated islands; in fact ponds are profoundly influenced by the land around them - their catchments - and constantly exchange plants and animals with neighbouring rivers, lochs, burns and wetlands.

A more detailed discussion of pond myths is given in Williams et al. (1999).

 

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Figure 17. The drawdown zone - where water fluctuates between winter and summer - is one of the richest areas of any pond and is used in many different ways by plants and animals. Where possible, maximise the width of this area and take care that it is not damaged or destroyed during management. Pond Action
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