Ponds may be small, but their impact is enormous. As geographer Lucy Clarke puts it, they ‘punch far above their weight in ecological value’. And climate change is making these little bodies of water more and more important. But more than half have disappeared in Britain, in a century.
As a result, the average distance between ponds increased by 25 metres between 1900 and 2019. That’s a long way for pond life. This is a global trend, Clarke notes. Farms are filling in ‘inefficient’ ponds to create tractor-friendly fields with better drainage; and expanding urban areas have covered ponds with roads, housing and hard surfaces. Clarke says ponds help protect against climate extremes by acting like ‘natural sponges. During heavy rain,’ she writes, ‘they slow water running across the ground and store this to reduce flood peaks. In periods of drought, they store water for plants and animals when streams run dry. They can also lock away carbon and filter pollutants, improving water quality.’
Ponds can do this surprisingly quickly. Mike Jeffries, an ecologist at Northumbria University, has analysed pond sediment from Hauxley Nature Reserve, a birdlife hotspot on the coast near Newcastle. He found carbon burial rates ‘much higher’ than in surrounding habitats such as woodland. Though small ponds occupy a tiny proportion of the UK’s land area – scarcely 0.0006%, they bury about half as much carbon as the vastly greater expanse of grassland.
Pond life
Some years ago, researchers began looking at shallow depressions in otherwise unremarkable Norfolk fields. To the untrained eye, they would have looked like a slight dip – nothing special. But to UCL’s Pond Restoration Research Group, these were ‘ghost ponds’ – former ponds filled in during the last 50 to 150 years to make way for farmland. Some were last mapped in the Victorian era. But when the team excavated three ghost ponds, all of them refilled with water almost immediately – and then something extraordinary happened. Within six months, they were suddenly alive. Plants that hadn’t seen daylight since the 19th century began to sprout. Stoneworts, a group of algae sensitive to pollution, reappeared. All three ghost ponds were colonised within six months by native plant species.
Ponds cool cities, help us in droughts, store carbon, and host unique species. As temperatures rise and biodiversity is lost, these are crucial functions. But across Britain, ponds are quietly vanishing. Poring over historic maps from the 1900s to trace old pond sites, I was struck by how many once dotted the landscape. Today, more than half have disappeared, a loss that threatens wildlife and our ability to cope with a changing climate.
Small
That may be surprising, as ponds seem small and insignificant. We talk about rivers, reservoirs and wetlands but ponds get very little mention, yet they punch far above their weight in ecological value. They store water, support biodiversity and help buffer floods and droughts. Losing them undermines both nature and our ability to adapt to climate extremes. Restoring ponds – old and new, rural and urban – is one of the simplest, most effective steps we can take. Every pond counts, from a farm hollow to a garden bowl. Together, they form networks that wildlife needs to survive and make our landscapes more resilient to climate change.
In short, ponds do far more than look good. They link habitats, boost biodiversity and strengthen climate resilience. Restoring them is a practical, low-cost solution that begins with something as basic as adding water. For wildlife, ponds are vital ecosystems and support far more than aquatic species. They provide water, food and habitat for pollinating insects, birds, bats and other mammals. Crucially, amphibians such as frogs and newts rely on networks of ponds close enough for them to move between. Lose that network or ‘pondscape’, and species vanish.
They disappear
The consequences extend beyond biodiversity. Ponds act as natural buffers against climate extremes. Ponds act like natural sponges. During heavy rain, they slow water running across the ground and store this to reduce flood peaks. In periods of drought, they store water for plants and animals when streams run dry.
They can also lock away carbon and filter pollutants, improving water quality. They link habitats, boost biodiversity and strengthen climate resilience. Restoring them is a practical, low-cost solution that begins with something as basic as adding water. But the decline in ponds can be seen worldwide, driven by changes in agriculture and the growth in urban areas.
Bringing ponds back to life
The first step is knowing where ponds are and where they’re missing. Mapping today’s ponds shows the gaps, helping us plan new ones to link habitats and build a healthy pond network. Historic maps reveal lost ponds that can potentially be restored. Many ponds survive as ‘ghosts’. Digging them out and restoring these is surprisingly effective. Seeds buried for decades can germinate once water returns, reviving plants thought extinct locally. In Norfolk, farmers and conservationists have restored dozens of ghost ponds, and within months they teem with life.
However, you don’t need a big conservation project to make a difference. Start small. A garden pond, even the size of a washing-up bowl, can attract frogs, insects and birds. Community groups can work with councils to revive neglected ponds in parks, public gardens or village greens. If you’ve got a garden, or even a wheelbarrow or large pot, you can help rebuild the pond network.
Britain’s ponds are disappearing fast, but every new or restored pond helps reverse that trend. Restoring old ponds and creating new ones, even in gardens and parks, is one of the simplest, most effective steps we can take to protect wildlife and adapt to climate extremes.
Ponds are a common habitat
All-too often, ponds are missed out of conservation strategies which are instead fixated on larger lakes and rivers. This is a serious omission – ponds are the most common and widespread habitat for all plants and animals across the continents and islands of Earth, from Antarctica to the tropics. Perched on the surface of Alpine glaciers or waiting out desert droughts to refill with the rains, deep in equatorial forest or amid the city sprawl. They could well be found on Mars.
The past 20 years have seen a blossoming of research into ponds, led in the UK by the Freshwater Habitats Trust and, internationally, the European Pond Conservation Network. These organisations bring together researchers and practitioners to help conserve pond biodiversity. Their work has revealed that ponds are biodiversity hotspots in the landscape, disproportionately rich in species when compared to rivers, streams and lakes and home to many rare specialists, such as fairy and tadpole shrimps.
Ponds benefit humans by slowing down water run-off that can cause flooding and mopping up excess nutrients – a great example of what are now recognised as ‘small water bodies’ that enrich and enliven a landscape. But, globally, ponds may also be important in influencing atmospheric carbon by storing and releasing it, given the intensity of geochemical processes and the sheer number of ponds around the world. However, just how fast ponds can bury carbon is poorly understood.
A carbon sink in your own backyard
Measuring the rate at which ponds can store carbon is tricky, primarily because the age of many ponds is unknown. To get precise measurements of carbon burial rates we exploited an unusual opportunity using some small, lowland pools whose age is known to the exact day. The ponds were dug out in 1994, at Hauxley Nature Reserve in north-east England. Their original purpose was to follow the colonisation of plants and invertebrates.
Two decades later they had accumulated a layer of sediment, dark and rich in organic debris, distinctly different to the underlying clay. We used sediment cores and dug out all of the sediment from some ponds, to measure the organic carbon that had accumulated. The amount of carbon in the cores was scaled up to the amount dug up from other ponds to reflect the total volume of sediment.
The ponds’ burial rates for organic carbon ranged from 79 to 247g per square metre per year, with a mean of 142g. These rates are high – much higher than the rates of 2-5g attributed to surrounding habitats such as woodland or grassland. Small ponds occupy a tiny proportion of the UK’s land area – scarcely 0.0006% – compared to grassland at 36% or 2.3% for ancient woodland. But the rate of carbon burial we found would result in ponds burying half as much as the vastly greater expanse of grassland.
Carbon cycle
However, the role ponds play in the carbon cycle is complicated. Some ponds may be significant sources of greenhouse gases, such as permafrost thaw ponds in the Arctic which release even more carbon as tundras. Our ponds can switch back and forth from being a net sink to a net source of carbon as they dry out or re-flood. Nevertheless, our ponds have accumulated plenty of carbon over their 20 years and provided a home to a wealth of animals and plants.
Many lost ponds leave behind a ‘ghostly’ mark in the landscape – visible as damp depressions, areas of poor crop cover, or changes in soil colour. Colleagues and I have recently discovered that these buried ‘ghost ponds”’are not completely lost, but can be resurrected from historic seeds lying dormant underneath intensively cultivated agricultural fields.
These ghosts are an abundant yet overlooked conservation resource. Resurrecting them would of course mean more ponds, which in turn links up aquatic landscapes as plants and animals jump from pond to pond and species are able to thrive in larger populations. But the main advantage of a ghost pond, compared to a new pond, is the historic seed bank buried below the surface. This provides a source of local native species, speeding up the process of colonisation, and potentially restoring lost populations or even locally extinct species to the resurrected pond.
Ponds against climate change
The ponds included in our study are constructed water bodies, and as such, have many opportunities for management with the goal of increasing greenhouse gas uptake from the atmosphere. So far, we have concluded that ponds deeper than three metres are more likely to act as nitrous oxide sinks, and those with overall better water quality have less carbon emissions.
We plan to compile construction and management recommendations when all three greenhouse gas analyses are complete. With this information, landowners may be able to add carbon offsets to their land while additionally providing water storage and resources for their farmland.
Interesting? Then also read:
Carbon storage in the soil
Bamboo, a material with endless possibilities
Blue carbon: an excellent way to store carbon dioxide