Soil, freshwater and urban ecosystems harbour extraordinary biodiversity that underpins the natural systems we depend on — yet they are among the most overlooked and most threatened habitats on Earth. Soil is home to at least 59 per cent of all described species, including more than 80 per cent of fungi and plants. Freshwater habitats, covering less than 1 per cent of the planet's surface, support a disproportionate share of global species diversity, yet freshwater fish face extinction at over 100 times the natural background rate. Urban areas — home to most of the UK population — are simultaneously losing iconic wildlife and emerging as surprising refuges for species adapting to human landscapes.
Key Takeaway
Three of the UK's most critical ecosystems — soil, freshwater and urban habitats — are deeply interconnected and under acute pressure. Seventy per cent of European soils are in poor condition. Only 16 per cent of England's surface water bodies achieve good ecological status. And just 4.3 per cent of urban land is accessible green space. Understanding these hidden ecosystems — and how they depend on each other — is essential for reversing biodiversity loss at landscape scale.
59%
Species in Soil
of all described species live underground
16%
Rivers at Good Status
England surface water bodies (WFD)
90%
UK Wetlands Lost
in the past 100 years
75%
Hedgehog Decline
in rural areas since 2000
Sources: Earth Rover Program, Environment Agency WFD data, RSPB, APHA Science
Soil is the most biodiverse habitat on Earth, yet it remains one of the least understood. At least 59 per cent of all described species live in soil — including more than 80 per cent of fungi and plant species. Soil functions as a biological structure analogous to a coral reef, with intricate networks of organisms performing the nutrient cycling, water filtration and carbon storage that sustain all terrestrial life.
Healthy soil typically contains approximately 50 per cent pore space, creating the spatial complexity needed for organisms to coexist and resources to circulate. When soil degrades through compaction, erosion or contamination, this crucial architecture collapses — impeding water infiltration, restricting root growth and triggering cascading dysfunction across the ecosystem above.
The soil microbiome — comprising bacteria, fungi, archaea, nematodes and protists — performs ecosystem functions essential to all terrestrial life. These organisms transform nutrients, suppress pathogens, modulate plant immunity and build the resilience that allows ecosystems to withstand stress. Microbial diversity is now recognised as a reliable proxy for ecosystem health itself.
Mycorrhizal fungi are particularly critical, forming symbiotic partnerships with more than 80 per cent of plant species globally. These fungi create vast underground networks that transport nutrients and water between plants, earning them the nickname "the wood wide web." Recent global mapping has revealed a troubling gap: less than 10 per cent of mycorrhizal fungal biodiversity hotspots fall within protected areas, leaving these essential networks vulnerable to agricultural intensification and development.
Soil organic carbon binds the entire system together — it is the primary energy source powering microbial communities, enhancing soil structure, improving water retention and enabling nutrient availability. Soils with elevated carbon levels demonstrate greater resistance to drought, flooding, extreme temperatures and pollution. Practices that build soil carbon — cover cropping, reduced tillage, organic matter amendments — simultaneously improve farm productivity and ecosystem resilience.
Approximately 30 per cent of all arthropods live in soil, either throughout their life cycle or during larval stages. Soil engineers — earthworms, ants, termites — fundamentally reshape their environment by mixing organic matter, creating burrows and modifying nutrient availability for other organisms. Earthworms alone can process several tonnes of soil per hectare per year, aerating the ground and incorporating organic matter into deeper horizons.
Nematodes occupy particularly important ecological roles, with their abundance and feeding diversity serving as convenient indicators of soil health. Their activities help transform organic matter into mineral and organic nutrients that support plant nutrition and crop productivity — making them essential links in the chain from soil to plate.
Soil degradation operates at timescales profoundly incompatible with human management — ecosystems require up to 1,000 years to produce just 1 centimetre of topsoil, yet degradation can occur within a few growing seasons. Up to 70 per cent of European soil ecosystems currently exist in poor condition, with the combined costs of agricultural intensification, climate change and urban sprawl reaching €97 billion per year across EU countries.
Pesticide contamination represents an escalating threat. Research published by the Natural History Museum found that overall pesticide toxicity rose substantially during the 2010s, with terrestrial arthropods experiencing a 42.9 per cent increase in toxicity between 2013 and 2019. Around 20 pesticides are responsible for over 90 per cent of toxic impacts on insects, worms and diverse wildlife. Soil organisms and aquatic fauna each experienced toxicity rises of approximately 30 per cent during the same period.
UK Peatland Crisis
Approximately 80 per cent of UK peatlands are degraded, releasing stored carbon while destroying irreplaceable specialist habitats. Peat extraction for horticulture alone released 880,000 tonnes of CO₂ in 2020. Through the Nature for Climate Peatland Grant Scheme, restoration management was active on 16,120 hectares during 2024–2025 — a meaningful start, but a fraction of the total degraded area.
Soil compaction from heavy agricultural machinery is a further insidious threat — it reduces porosity, impedes water infiltration and limits root penetration. Compacted soils become drought-prone as reduced pore space limits water availability, contributing to flash flooding after heavy rainfall and reducing crop yields by 2.5–15 per cent depending on severity.
Freshwater ecosystems, covering less than 1 per cent of Earth's surface, support a disproportionate share of global species diversity — yet face extinction rates exceeding natural background rates by orders of magnitude. Nearly one third of the world's freshwater fish species currently face extinction risk, with 100 species already confirmed extinct and 11 more extinct in the wild. The modern extinction rate for freshwater fishes — 33.47 extinctions per million species-years — exceeds the natural background rate of 0.33 by more than 100-fold.
Despite this crisis, freshwater ecosystems provide extraordinary climate services. High Value Freshwater Ecosystems globally cover over 5.16 billion hectares, and restoring naturally-occurring forests within these areas could sequester between 1.07 and 3.41 gigatonnes of additional carbon annually — equivalent to halting emissions from 900 coal-fired power plants for a year.
In England, only 16 per cent of surface water bodies meet all relevant criteria for good ecological status under the Water Framework Directive. Long-term Environment Agency data covering 1990–2023 reveal some progress — ammonia concentrations declined 85 per cent and orthophosphate by 83 per cent — but nitrate concentrations increased 23 per cent over the same period, and storm overflow sewage discharges remain at staggering levels.
In 2025, 291,492 storm overflow spill events were recorded — an average of 20.5 spills per overflow. While this represented a 35 per cent reduction from 2024, the improvement likely reflects unusually dry conditions rather than infrastructure adequacy. Serious river pollution incidents surged 60 per cent in a single recent year, with rivers including the Thames and Wandle turning brown following storms. The systemic challenges are deep: Thames Water, serving approximately 15 million people, posted a loss of £1.65 billion in 2025 while pollution events increased 30 per cent.
Chalk streams are among Earth's rarest freshwater habitats, with only approximately 200 globally — and England holds about 85 per cent of them. Fed by underground chalk aquifers, these spring-fed waterways produce crystal-clear, mineral-rich water with stable cool temperatures rarely deviating from 10°C, creating ideal conditions for specialist species including brown trout and water crowfoot.
Over-abstraction is the primary threat — when excessive water is removed from aquifers, flow rates slow, silt accumulates and pollutant concentrations intensify. Reduced flow combined with climate-driven temperature increases threatens these irreplaceable ecosystems across their entire range. In November 2025, Buckinghamshire Council unanimously passed a cross-party motion protecting the county's chalk streams — signalling growing political recognition that chalk stream conservation demands urgent action.
Seven freshwater fish species now face official threat classifications in the UK, representing the first comprehensive assessment using IUCN Red List criteria. The European eel has suffered one of the most dramatic population collapses of any fish species globally, with numbers falling over 80 per cent in four decades. The vendace, Britain's rarest native freshwater fish, now survives naturally in only two Lake District lakes.
Atlantic salmon exemplify the multi-pressure crisis facing freshwater species. The 2024 Environment Agency assessment revealed that 88 per cent of England's principal salmon rivers are classified as at-risk or probably at-risk — unchanged from previous years. Salmon populations have declined from approximately 1.4 million returning adults in the 1970s–1980s to fewer than 500,000 today.
Water voles — the fastest declining mammal in the UK — have crashed by over 90 per cent in Wales since the 1980s, driven by habitat loss, pollution and predation by invasive American mink. The white-clawed crayfish, listed as globally endangered, faces extinction from habitat loss, pollution and competition from invasive signal crayfish.
River Fragmentation
Only 1 per cent of UK rivers remain completely free of artificial barriers, and just 3.3 per cent of the network allows unrestricted species movement. Small barriers alone can reduce successful fish passage by 50–80 per cent, and cumulative obstacles make some rivers more impassable than a single large dam. In 2024, over 2,900 kilometres of river connectivity were restored through barrier removal programmes.
The UK has also lost 90 per cent of its wetlands in the past 100 years. Wetlands now cover just 3 per cent of the country yet remain home to one in ten UK species. The RSPB's Species Coastal and Wetlands programme, funded by £2.5 million from the Species Survival Fund, is restoring reedbeds, lagoons and wet grazing meadows across 13 sites from the Solent to the Norfolk Broads — targeting the government's legally binding target to halt species abundance decline by 2030.
Urban areas across Great Britain allocate just 4.3 per cent of their territory to accessible green space and 1.2 per cent to blue space — a combined total of 5.5 per cent. Yet cities are complex habitats supporting both wildlife winners and losers, and they offer unprecedented opportunities for nature recovery through strategic green infrastructure.
London illustrates the urban paradox vividly. Hedgehogs have seen populations halved through road traffic, fenced gardens and habitat loss. British hedgehogs have declined by up to 75 per cent in rural areas since 2000 and are now classified as near threatened. House sparrows and starlings — once ubiquitous urban sights — have suffered dramatic declines. Swifts find fewer nesting sites. European eels struggle to navigate polluted waterways.
Yet urban foxes exemplify remarkable adaptation. They began colonising towns in the 1930s, and today an estimated 90 per cent of urban areas across England and Wales contain foxes. Peregrine falcons have taken to nesting on tall buildings, treating them as substitute cliff faces. And Sheffield researchers have documented over 120 tree species growing in private gardens — including species native to China and Africa — demonstrating that urban gardens can harbour extraordinary phylogenetic diversity.
Green roofs, wildlife corridors, pocket parks and sustainable drainage systems offer multifunctional solutions addressing biodiversity loss, flooding, urban heat and air quality simultaneously. Green roofs absorb rainfall and reduce peak stormwater flows, cool buildings through insulation and evapotranspiration, and provide essential habitat for pollinators.
London's Urban Greening Factor assigns scores to different vegetation types in new developments. Tree canopy receives the highest factor (1.0), with semi-natural planting matching this value, while sealed hardstanding scores zero. The system incentivises high-value green infrastructure — from living walls to sustainable drainage — by embedding ecological quality into planning decisions. Birmingham's Naturally Birmingham initiative and its Green Infrastructure Master Plan for East Birmingham provide a further blueprint for biophilic city design at landscape scale.
In England, 92 per cent of households have access to a garden or outdoor space — yet only 34 per cent actively encourage wildlife through feeding areas or planting. This represents enormous untapped potential. Creating diverse habitats within even modest gardens — wildflower patches, mini ponds, log piles, hedgehog highways (CD-sized gaps in fences) — can transform private land into a coherent urban habitat network.
Citizen science amplifies the impact. The BTO's Garden BirdWatch, Big Butterfly Count and hedgehog surveys generate invaluable data tracking wildlife trends at scales beyond official monitoring capacity. In 2024, bumblebee numbers declined by 22.5 per cent across Great Britain — the worst year since records began — while flying insect numbers fell 63 per cent since 2021. These citizen-gathered datasets provide the evidence base for targeted conservation action.
Soil, freshwater and urban ecosystems function as interconnected components of a single landscape system — processes in one domain produce cascading effects in others.
Degraded soils with reduced pore space and compaction limit water infiltration, increasing surface runoff that carries eroded particles, nutrients and contaminants into rivers and lakes. Conversely, healthy soils with adequate organic matter and biological activity filter water moving through the ground, removing pollutants and moderating discharge rates to prevent flash flooding. When the soil microbiome is disrupted by pesticides or compaction, nitrogen and phosphorus cycling breaks down — increasing nutrient mobility into freshwater systems, driving eutrophication and dead zones.
Urban development replaces permeable soil with impervious surfaces, increasing runoff volumes that overwhelm drainage and trigger sewage overflows into rivers. Green infrastructure — green roofs, sustainable drainage, restored wetlands and riparian buffers — mimics natural processes, reducing runoff while enhancing water quality and providing wildlife habitat. River corridors provide ecological connectivity through otherwise fragmented urban landscapes, enabling aquatic and semi-aquatic species to disperse between isolated habitat patches.
Understanding these connections transforms conservation from a compartmentalised exercise into landscape-scale action. Restoring soil health upstream improves river water quality downstream. Removing river barriers reconnects fish populations while creating diverse habitats that support urban birdlife. Urban garden networks collectively provide habitat area that may exceed designated public green space. No single ecosystem can be saved in isolation.
The UK government's Environmental Improvement Plan 2025 establishes goals for air, water, soil and biodiversity recovery — including creating or restoring 250,000 hectares of wildlife-rich habitat by 2030 and cutting fine particulate matter exposure by 30 per cent.
Biodiversity Net Gain requires all development in England to deliver at least 10 per cent net habitat improvement. Early evidence is encouraging: BNG is projected to prevent 6,000 to 10,000 hectares of habitat loss annually — roughly the size of Nottingham. Forty-eight Local Nature Recovery Strategies are being prepared across England, mapping priorities for nature recovery and identifying proposals for habitat creation.
The Water Special Measures Act has brought swifter penalties against polluters, while the government secured £104 billion in private investment commitment over five years to upgrade water infrastructure. A record £10.5 billion is being invested in flood defences, including nature-based solutions such as woodland planting and wetland restoration. New Sustainable Farming Incentive actions specifically target soil health through no-till farming and multi-species cover crops, with £43.7 million committed to farming innovation research since April 2024.
Whether these frameworks deliver depends on implementation, resourcing and enforcement. The UK's most recent assessment found it far off track on 19 of 23 Kunming-Montreal targets. Policy commitments exist. Delivery at the scale the crisis demands does not — yet.
At least 59 per cent of all described species live in soil, including more than 80 per cent of fungi and plant species. This makes soil the most biodiverse habitat on Earth — exceeding tropical rainforests, coral reefs and ocean systems. Yet soil biodiversity remains among the least monitored and least protected of all ecosystems globally.
Only 16 per cent of England's surface water bodies achieve good ecological status under the Water Framework Directive. The main causes are agricultural nutrient runoff, storm overflow sewage discharges (291,492 spill events in 2025), over-abstraction, legacy pollution from heavy metals and abandoned mines, and barriers to fish migration. While some pollutants have declined — ammonia down 85 per cent since 1990 — nitrogen levels have increased 23 per cent over the same period.
Chalk streams are globally rare spring-fed rivers emerging from underground chalk aquifers. Only about 200 exist worldwide, and England holds approximately 85 per cent of them. Their crystal-clear, mineral-rich water at stable cool temperatures supports extraordinary species diversity including brown trout and water crowfoot. They are threatened primarily by over-abstraction, agricultural runoff and sewage discharges.
Mycorrhizal fungi form symbiotic partnerships with more than 80 per cent of plant species, creating vast underground networks that transport nutrients and water between plants. Often called the "wood wide web," these networks are essential for plant nutrition, carbon cycling and ecosystem resilience. Less than 10 per cent of mycorrhizal biodiversity hotspots currently fall within protected areas, leaving them vulnerable to agricultural intensification.
Urban areas support biodiversity through green infrastructure (green roofs, wildlife corridors, pocket parks, sustainable drainage systems), strategic planning (London's Urban Greening Factor, Local Nature Recovery Strategies, Biodiversity Net Gain), and private gardens — 92 per cent of English households have garden access. Creating diverse habitats including wildflower patches, ponds, log piles and hedgehog highways transforms gardens into connected wildlife networks.
The UK has lost 90 per cent of its wetlands in the past 100 years. Wetlands now cover just 3 per cent of the country, yet remain home to one in ten UK species. The RSPB's Species Coastal and Wetlands programme is actively restoring reedbeds, lagoons and wet grazing meadows across 13 sites in Southeast England, funded by £2.5 million from the Species Survival Fund.
Healthy soils filter water as it moves through the ground, removing pollutants and moderating flow to prevent flooding. Degraded soils with reduced pore space increase surface runoff carrying nutrients, pesticides and eroded particles into rivers. When soil microbiomes are disrupted, nitrogen and phosphorus cycling breaks down, increasing nutrient loads that drive eutrophication in freshwater systems. Restoring soil health upstream directly improves river water quality downstream.
Soil, freshwater and urban ecosystems are deeply interconnected — and all three are under acute pressure. Seventy per cent of European soils are degraded. Only 16 per cent of English rivers achieve good ecological status. Freshwater species face extinction at over 100 times natural rates. Urban areas allocate just 5.5 per cent of their territory to green and blue space. Yet the evidence also shows that recovery is possible where genuine effort is applied — from river barrier removal unlocking 2,900 kilometres of connectivity in a single year, to Biodiversity Net Gain preventing thousands of hectares of habitat loss annually, to the quiet revolution happening in the 34 per cent of British gardens where households choose to make space for nature.
Further reading: Why biodiversity matters · Ecosystem services explained · The UK biodiversity crisis · Biodiversity Net Gain