Why biodiversity matters, how pollution, eutrophication, land use, deforestation and peat burning reduce it, global warming, and the percentages and graphs used to measure the change.
What you will learn
- Explain why high biodiversity makes ecosystems stable
- Describe the effects of pollution, deforestation and peat destruction
- Explain eutrophication step by step (Edexcel)
- Calculate percentage changes and areas from survey and land-use data
- Read carbon dioxide data from a graph and use indicator species
Biodiversity under pressure
Biodiversity is the variety of all the species in an ecosystem or on Earth.
High biodiversity makes an ecosystem more stable, because species rely less on any one other species.
A growing human population uses more land and resources and makes more waste:
- Water: sewage, fertiliser and toxic chemicals.
- Air: smoke and acidic gases.
- Land: landfill and toxic chemicals; building, quarrying and farming.
- Deforestation (for cattle, rice and biofuel crops) and burning peat release carbon dioxide and destroy habitats.
Carbon dioxide and methane add to global warming, which shifts where species can live and changes migration.
Biology only, Higher: environmental change alters the distribution of species (where they are found). The changes that matter are in temperature, the availability of water and the composition of the atmospheric gases. They can be seasonal (a pond that dries every summer), geographic (cooler higher up a mountain) or caused by human activity (polluted air, drained wetland, a warming climate). To judge whether a change caused a shift, look for the change and the shift happening together over many years, and for other factors that could explain it.
Protecting biodiversity: breeding programmes, protecting rare habitats, hedgerows and field margins, less deforestation, recycling, peat-free compost.
Some species only survive in clean conditions (lichens in clean air, mayfly nymphs in clean water): these are indicator species, whose presence or absence shows how polluted a place is. Counting them is a cheap way to monitor pollution.
The rest of this lesson and its 15 practice questions are locked.
In this lesson
- Biodiversity under pressure
- Eutrophication (Edexcel)
- Measuring the change
- Try it: A population in decline
15 practice questions, marked as you go; about 20 minutes in all.
Key terms
Biodiversity, Stable, Deforestation, Burning peat, Global warming, Environmental change, Distribution, Indicator species, Eutrophication, Bacteria
In this unit: Ecology
Communities and adaptations, sampling with quadrats, transects and capture-recapture, food chains and the carbon, water and nitrogen cycles, decay, parasitism and mutualism, eutrophication, biodiversity and human impact, biomass transfer and food security.
- Communities, interdependence and adaptations
- Sampling with quadrats, transects and capture-recapture
- Food chains, cycles and decay
- Biodiversity and human impact
- Trophic levels, pyramids and efficiency
- Food security and farming
- Biological control and bioaccumulation
- Fish farming, introduced species and the cycles in depth