A life aquatic: dipping into some of Suffolk's 23,000 ponds
PUBLISHED: 10:18 17 August 2019 | UPDATED: 10:29 17 August 2019
East Anglia is renowned for many things but few people will know it can lay claim to being the farm pond capital of England and Wales.
According to Oliver Rackham's classic work The History of the Countryside, the biggest concentrations of ponds in the agricultural landscape can be found in mid and south Norfolk and north east Suffolk, as well as in a smaller area in Cheshire.
Studying Ordnance Survey maps from the 1920s, Mr Rackham found that these areas boast 30 ponds per square mile, around five times the national average. Some locations are off the scale: the ancient woodland around Wolves Wood near Hadleigh, for example, was found to have 298 ponds per square mile.
Across Suffolk, there are thought to be somewhere in the region of 23,000 ponds.
The reason ponds proliferate in these parts is down to the clay soil found there. Any dip or hole that was created to extract clay to make bricks and the like would hold water and become a pond due to clay's impermeable properties.
Traditionally, many of these ponds were well-maintained as part of a farm's cycle of work and played a valuable role providing drinking places for livestock and other services (see box). But post-war many became neglected or were drained as farms looked to maximise their land holding and watered their cattle from troughs.
And as the number of ponds in good working order has declined, so has the wildlife that relies on clean, sunny ponds: namely newts, beetles, snails, dragonflies and frogs, as well as indictor plant species such as stoneworts.
Someone who has spent a lot of the last two decades looking into the often murky world of ponds is Juliet Hawkins, a farm advisor with Suffolk Wildlife Trust who estimates she has surveyed 1,500 ponds since 2003. Her work involves visiting ponds to see what state they are in and the wildlife they maintain, advising landowners on what they can do to improve their ponds for nature and supporting those who commit to working toward bringing their ponds back to pristine.
"The problem with old, neglected ponds is that they are shaded by tree growth and silted up with leaf litter," said Ms Hawkins.
"You get this build up of sediment - once the accumulation reaches six inches or so plants just won't root into it. You'll get emergent plants but aquatic plants that like being in the water, either submerged or floating on the surface, like good clean substrate."
She added: "Historically, farmers would clean their ponds out on rotation: the sediment would be removed after harvest and spread on the fields. It was a good soil improver - light organic matter mixing with the heavy clay soil.
"Small trees that had grown around a pond would be coppiced and the wood used for firewood."
In the old rotation system, livestock would also come in and help keep the pond margins clear of emergent vegetation, like reedmace, bur-reed and rushes, which unabated will start to trap sediment and spread across the water, and sallow and brambles that seed into the margins.
Livestock would also tread in the mud around the side of ponds, a process known as poaching, creating micro-habitats with their footprints. Seeds that had laid dormant would suddenly germinate while species that require bare mud banks of ponds would benefit - house martins and swallows use the mud to build their nests while many dragonfly species like to warm up on raw clay banks.
Today, much of this work to restore and maintain ponds is carried out by diggers that scoop out sediment and clear banks.
Ms Hawkins says ideally a pond should have a gradual slop into the water, as different habitats exist at different depths. The shallow areas up to around 10cms in depth are the most fertile, as it is here where the water warms up most, creating the conditions for many different plants and an ideal place for frogspawn to develop quickly.
A gentle gradient on one side of a pond also mimics how these ponds were created - workman required a gradual slope to remove clay, a form that also provided a point where livestock were able to access the water.
One thing that has changed in the world of pond creation or restoration is that traditionally it was thought that having a perfectly smooth bottom to a pond was the ideal. However, current wisdom is that undulating topography on the bottom is the best for wildlife.
Ms Hawkins said: "You want the humps and bumps, so the detritus will fall within the troughs and plants, such as the stoneworts, will continue to grow on the clean substrates found in the raised areas where there is less build up of sediments."
Ms Hawkins' work was recognised earlier this year with the appearance of slimy-fruited stonewort in a pond in west Suffolk - in botany circles this was a major discovery, as the plant had not been seen in Great Britain since 1959. Two other very rare stoneworts were found in nearby ponds - the nationally scarce clustered stonewort and the endangered tassel stonewort.
Also known as charophytes, stoneworts thrive in clean water and provide underwater shelter and breeding opportunities for aquatic invertebrates, snails and amphibians.
"A lot of people take ponds for granted but they are incredibly rewarding to restore," continued Ms Hawkins.
"You start with a dark, shady hole and the following year, you can't believe it. There's water beetles, newts and dragonflies and they have all moved in within a year.
"Pond wildlife is very mobile - beetles and dragonflies are all winged. If you restore a pond, very quickly insects will come in. It is thought that insects colonise a pond by flying on a moonlit night and spotting the water body reflected in the moon. They probably smell it too. Amphibians can walk for miles - it's important for colonising ponds that there are hedges, woodland rides, grassland meadows around that all act as corridors for wildlife between ponds."
She added: "Landowners are thrilled how quickly things come on and are able to maintain their ponds as part of their hedging regime, flailing the edges, and when they have a digger on site, taking out a few scoops of invasive plants in the winter.
"It means they are constantly setting the clock back, as it would have been done by men with spades and handcarts in the past."