Global & UK Ecosystems
A Living Planet, Mapped
From space, Earth’s land surface looks like a patchwork of greens, browns and yellows. Each colour reflects a biome — a continent-sized ecosystem shaped above all by climate. Tropical rainforests cluster around the equator. Hot deserts sit at 30° latitude where the Hadley cell descends. Temperate grasslands and deciduous forests fill the mid-latitudes. Boreal coniferous forests (the taiga) form a giant belt across northern Canada, Scandinavia and Russia. Tundra fringes the Arctic. The pattern is not random — it is the global circulation made visible.
What Climate & Local Factors Do
Two climate variables decide which biome forms where. Temperature controls how long a growing season is and which plants can survive winter; rainfall controls how lush vegetation can grow before water runs short. Plot any spot on Earth on a graph of mean temperature versus rainfall and you can predict its biome to within one band. Soil and altitude add finer detail. Tropical soils are deep but nutrient-poor (because heavy rain leaches them); temperate soils are deep and fertile; boreal soils are thin and acidic. Every 100 m of altitude is roughly equivalent to moving 100 km polewards — which is why mountainsides reproduce the global pattern in miniature, with rainforest below cloud forest below alpine meadow.
Climate (temperature and rainfall) sets the global pattern of biomes. Hot wet near the equator = rainforest. Hot dry at 30° = desert. Cool wet at 50–60° = boreal forest. Cold dry near the poles = tundra.
The Biosphere as a Resource
The biosphere is the global sum of all ecosystems — everywhere life exists. People depend on it for four main things. Food — over 7,000 plant species are eaten and 75% of global food comes from just 12 of them. Medicine — a quarter of modern drugs (including aspirin from willow and the cancer drug Taxol from Pacific yew) are biosphere-derived. Building materials — timber, bamboo, thatch, and indirectly limestone (from ancient sea creatures). Fuel — firewood still cooks the meals of 2.4 billion people; modern bioenergy adds 6% of UK electricity. The biosphere is also exploited commercially for energy (oil from former forests), water (irrigation extraction) and minerals (open-cast mining), each of which can damage the very ecosystems we depend on.
Plants take CO2 out of the atmosphere through photosynthesis and release oxygen; they also pump water back into the air through transpiration. Tropical forests alone store an estimated 250 gigatonnes of carbon — roughly half of all the carbon humans have burned from fossil fuels since 1850. Soils store an additional 2,500 gigatonnes. Damage to ecosystems doesn’t just lose biodiversity; it releases stored carbon and reduces the planet’s ability to recycle gases. The biosphere is therefore a regulator as much as a resource.
UK Terrestrial Ecosystems
The UK is small but ecologically varied. Moorlands (about 12% of UK land area) cover upland Britain — peaty soils, heather, grouse and pipits dominate; the North York Moors and the Pennines are classic examples. Heathlands are lower-altitude open habitats on poor sandy soils — the New Forest and Dorset heaths support reptiles such as the smooth snake and Dartford warbler. Woodlands are mainly deciduous (oak, ash, beech) in the south and coniferous (Scots pine in the Caledonian forest) in northern Scotland. Wetlands — reed beds, fens, bogs — cover the Norfolk Broads, the Somerset Levels and Caerlaverock; they are migratory bird hotspots. Each ecosystem evolved with farming over millennia, so most is ‘semi-natural’ rather than truly wild.
UK Marine Ecosystems
UK seas are productive because cool Atlantic water mixes with shallow continental shelves. Cod, herring, mackerel and shellfish support a fishing industry worth around £1 billion at the dockside. Salt marshes on coasts like Morecambe Bay buffer storms and store carbon. Kelp forests off western Scotland host octopus, lobster and seal. But human pressure is severe: industrial trawling has cut North Sea cod stocks to a fraction of 1970s levels; sewage discharges have made many beaches unsafe; offshore oil and gas extraction has degraded seabed habitats. The 2009 Marine and Coastal Access Act created Marine Protected Areas to slow the damage; today, around 38% of UK seas have some level of protection on paper, though enforcement varies.
The Caledonian Forest in the Scottish Highlands is the UK’s only fragment of true boreal woodland — a relict of the post-Ice Age forest that once covered most of Scotland. The chalk grasslands of the South Downs (Sussex, Hampshire) are some of the richest grasslands in Europe, with up to 40 plant species per square metre. The Flow Country in northern Scotland is the world’s largest blanket bog, storing 400 million tonnes of carbon — designated a UNESCO World Heritage Site in 2024. Each is irreplaceable.
UK terrestrial ecosystems include moorland (Pennines), heathland (New Forest), woodland (Caledonian Forest, Sussex Weald) and wetland (Norfolk Broads). Marine ecosystems support a £1 billion fishing industry but face pressure from trawling, pollution and oil and gas extraction.