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examBoard: Pearson Edexcel
examType: IGCSE
lessonTitle: Biodiversity Concepts
Biodiversity is all around us! From the tiniest microorganisms to the largest whales, from desert cacti to rainforest trees, our planet is home to an amazing variety of living things. But what exactly is biodiversity and why should we care about it?
Key Definitions:
Biodiversity is crucial for several reasons:
Scientists have identified about:
Biodiversity exists at multiple levels, from the microscopic to the global. Understanding these levels helps us appreciate the complexity of life on Earth.
The variety of genes within a species. This is why not all humans, dogs, or oak trees look exactly alike. Greater genetic diversity helps species adapt to changing environments.
Example: Different varieties of potatoes have different genes for disease resistance.
The variety of different species within an area. A forest with many types of trees, birds and insects has high species diversity.
Example: A coral reef may contain thousands of different fish, coral and invertebrate species.
The variety of ecosystems in a region. This includes different habitats and the interactions between species.
Example: The UK has ecosystems ranging from moorlands to coastal wetlands.
Scientists use several methods to measure and compare biodiversity in different areas. These measurements help identify biodiversity hotspots and track changes over time.
The simplest measure of biodiversity is species richness - the total number of different species in an area. For example, a woodland with 50 plant species has higher species richness than one with 20 species.
However, species richness doesn't tell us how common or rare each species is.
Species abundance considers both the number of species and how many individuals of each species are present.
For example, two woodlands might both have 30 species, but one might be dominated by just a few common species while the other has a more even distribution.
Scientists use indices like the Simpson's Diversity Index to calculate this.
Despite its importance, biodiversity is declining at an alarming rate worldwide. Human activities are the main cause of this decline.
The main threats to biodiversity can be remembered using the acronym HIPPO:
Deforestation, urbanisation and agriculture destroy natural habitats. This is the biggest threat to biodiversity.
Example: Rainforests are being cleared for palm oil plantations.
Non-native species introduced to new areas can outcompete native species.
Example: Grey squirrels threatening red squirrels in the UK.
More people means more resources used and more habitats converted to human use.
Example: Urban expansion into natural areas.
Air, water and soil pollution harm species and ecosystems.
Example: Plastic pollution in oceans affecting marine life.
Overharvesting resources like fish, timber and wildlife.
Example: Overfishing causing fish populations to collapse.
Climate change is becoming one of the biggest threats to biodiversity worldwide. Rising temperatures and changing rainfall patterns are affecting species in several ways:
There's hope! Many strategies exist to protect and restore biodiversity. These approaches work best when combined.
Setting aside land and water for conservation:
About 15% of Earth's land and 7% of oceans are currently protected.
Laws and agreements to protect biodiversity:
Repairing damaged ecosystems:
Helping people understand and value biodiversity:
Biodiversity hotspots are regions with exceptional concentrations of endemic species (found nowhere else) that are experiencing severe habitat loss. These areas are conservation priorities.
Key facts about hotspots:
Success story: In the Atlantic Forest of Brazil, conservation efforts have reduced deforestation by 80% since the early 2000s through a combination of protected areas, sustainable agriculture and reforestation projects.
The UK has its own unique biodiversity, though it has been heavily impacted by human activities over thousands of years.
UK conservation success stories:
Biodiversity is essential for life on Earth, providing us with food, medicine, clean air and water and countless other benefits. Despite the serious threats it faces, there are many ways we can help protect it. Every action counts, from supporting conservation organisations to making sustainable choices in our daily lives.
Remember: biodiversity isn't just about saving individual species it's about preserving the complex web of life that sustains us all.
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