Think pond. Ponds are vital habitats for all kinds of wildlife.
In Britain today, ponds are the focus of some very active conservation. They are the subject of both careful management and re-creation. While thousands of new ponds are now being made in Britain each year, the 20th century has witnessed the destruction, due to human interference such as drainage and filling in, of vast numbers of ponds.
Estimates say 75 percent of British ponds have vanished in the last hundred years. Many still existing ones are degraded by pollution. New ponds may or may not match in quality those that have been lost.
Whether ancient or new, natural or man-made (and today most new ponds are necessarily man-made), ponds are recognized as essential and particular habitats, often the only homes for rare and endangered species. Studies show that ponds are even more ecologically vital if they exist numerously in an area like a kind of mosaic.
The word "pond" in Britain refers to a water body of comparatively small scale, from as little as 25 square yards to as much as 2 hectares (about two football fields). Larger than that and it would generally be called a lake. Ponds can also be surprisingly shallow - a few inches deep - and still qualify as ponds.
Many ponds are seasonal, only having water in them for several months a year. But a large number of Britain's rarest wetland plants depend exclusively on these (paradoxically often long-lived) seasonal ponds.
A pond is not a stationary, unchanging thing. It might more accurately be called "a process." At each stage of its development, as "succession" naturally causes it to accumulate sediments and silt, it acts as a different but still useful habitat.