Biodiversity and competing pressures in ecosystems
Ecology • Biodiversity and the effect of human interaction on ecosystems
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Key concepts
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Definition of biodiversity
Biodiversity measures how many different species of organism live in the same geographical area, including animals, plants, fungi and microorganisms . Biodiversity includes differences at the species level and contributes to genetic and ecosystem variety across habitats such as rainforests, peat bogs and coral reefs .
Why biodiversity supports ecosystem stability
High biodiversity reduces dependency of particular species on others for food, shelter and environmental maintenance, so ecosystems resist change and recover more quickly after disturbance . Low biodiversity increases vulnerability: loss of a single species can cause cascading effects, reduce resilience to disease and alter food-web dynamics .
Limiting factors that affect biodiversity
Abiotic limiting factors include temperature, water availability, light and soil nutrients; changes in any of these change species distribution and abundance . Biotic limiting factors include predation, competition, disease and the arrival of invasive species; introduction of new species or pathogens can sharply reduce native populations and local diversity .
Major human pressures that reduce biodiversity
Habitat destruction and land-use change (deforestation, quarrying, urban expansion) remove or fragment habitats, causing species loss and reduced local diversity . Intensive farming and monoculture simplify landscapes, remove hedgerows and increase pesticide and fertiliser use, causing declines in species richness and losses of pollinators and other beneficial organisms . Pollution (chemical contamination and eutrophication) causes direct mortality and oxygen depletion in water bodies, reducing aquatic biodiversity . Climate change shifts temperature and precipitation patterns, forcing species to migrate or die out, with complex effects on community composition . Extraction of peat and other resources destroys specialised habitats and releases stored carbon, harming both biodiversity and climate stability .
Competing pressures and trade-offs
Food security and economic development create pressures to expand farmland, harvest natural resources and build infrastructure, which often reduces biodiversity and habitat area . Conservation measures (protected areas, breeding programmes, habitat restoration) increase long-term biodiversity and ecosystem services but can conflict with local livelihoods and immediate economic needs in developing regions, creating ethical and practical trade-offs . Choices such as peat harvesting for horticulture provide short-term benefits to agriculture but cause long-term loss of unique habitats and increased carbon emissions, producing a direct conflict between productivity and conservation .
Evaluating solutions
Protected areas and reserves prevent habitat loss and support species recovery but may restrict land available for farming and local economic activities; effectiveness depends on enforcement and community support . Captive breeding and reintroduction increase numbers of endangered species but require long-term funding and may not restore complex habitat interactions . Sustainable land management (crop rotation, hedgerow retention, reduced pesticide use) balances production with biodiversity by maintaining habitat corridors and soil health, but may lower short-term yields without additional incentives or technology .
Key notes
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