Environmental Management (0680) | Measuring and managing biodiversity

Measuring and Managing Biodiversity: Study Notes (IGCSE 0680)

Hello future Environmental Manager! This chapter is all about life on Earth—biodiversity—and how we measure and protect it. Understanding this is vital because healthy ecosystems provide everything we need, from clean air to food. Don't worry if the vocabulary seems tough; we will break down the science into simple steps!

What is Biodiversity? (Quick Recap)

Biodiversity is the variety of life in the world or in a particular habitat or ecosystem. It includes variety at three main levels:

• Species diversity (the number of different species).
• Genetic diversity (variety within a species, e.g., different breeds of dog).
• Ecosystem diversity (the variety of habitats, e.g., forest, ocean, desert).

Key Takeaway: Biodiversity is the biological richness of our planet. When we lose variety, ecosystems become weaker and less stable.

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Section 1: Measuring and Estimating Biodiversity

It's impossible to count every single organism in a large area like a forest or a field. Instead, environmental scientists use sampling techniques to get a reliable estimate.

Analogy: Imagine you want to know the variety of sweets in a huge candy store. You can't count them all, so you grab a small, representative sample bag!

1.1 Essential Sampling Techniques

We use different tools depending on whether the organisms are plants (non-mobile) or small animals (mobile).

Tools for Sampling Non-Mobile Species (Plants/Sessile Organisms)

1. Quadrats

A quadrat is simply a square frame (often 0.25 m² or 1 m² in size) used to define a specific area for study.

• How to use it: Throw the quadrat onto the ground.
• What you measure: Count the number of individuals of a specific species inside the square (abundance) or record if the species is present (frequency).

2. Transects

A transect is a line, usually a tape measure, stretched across a habitat to study how species distribution changes over a distance.

• When to use it: When you expect a gradient or change in conditions (e.g., from the edge of a forest to the middle, or moving up a sandy beach).
• How to use it: Place quadrats at regular intervals (e.g., every 5 metres) along the transect line and record the species within.

Tools for Sampling Mobile Species (Small Invertebrates)

1. Pitfall Traps

These are jars or containers sunk into the ground with the rim level with the soil surface. They are used to catch small creatures that crawl along the ground, like beetles or spiders.

• Tip: A little preservative (like salt water) or a small amount of bait can be added to prevent the animals from escaping or eating each other.

2. Pooters

A pooter is a small device used to suck small insects safely into a collecting jar. It involves two tubes: one tube for sucking (which has a safety gauze to stop you inhaling the insect!) and one tube pointed at the insect.

Think of a pooter as a delicate, scientist-approved vacuum cleaner for bugs.

1.2 Applying Sampling Techniques

How you choose *where* to place your quadrats or traps is essential for getting accurate results. We use two main methods:

1. Random Sampling

• Purpose: To ensure that your sample is unbiased and representative of the whole area.
• Method: Divide the area into a grid. Use a random number generator (or draw numbers from a hat) to select coordinates for placing your quadrat or trap.

2. Systematic Sampling

• Purpose: To investigate how the distribution of organisms changes across a specific environmental change (a gradient).
• Method: Using a regular pattern, such as placing a quadrat every 10 metres along a transect line.

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Section 2: Managing Biodiversity: Conservation Strategies

Once we know what biodiversity we have and where it's threatened, we need strategies to protect it. These strategies can be national (used within a single country) or international (global agreements).

2.1 Conservation 'In-situ' (On-Site)

This means protecting species by conserving their natural habitat. It is usually the best approach.

1. Protected Areas and Reserves

• National Parks and Wildlife Reserves: Areas of land protected by law from human development, ensuring habitats remain intact.
• World Biosphere Reserves: Designated by UNESCO, these reserves have a core protected zone, a buffer zone, and a transition zone where sustainable human use is allowed. They aim to balance conservation and sustainable development.
• Extractive Reserves: Areas where local communities are permitted to sustainably harvest certain non-timber forest products (e.g., rubber, nuts) but are legally prevented from large-scale deforestation or mining. This links conservation directly to local livelihoods.

2. Ecological Corridors

These are strips of habitat (like a hedge or patch of forest) that physically connect larger protected areas. They allow animals to migrate, find mates, and access resources safely, preventing genetic depletion (loss of genetic variety due to small, isolated populations).

2.2 Sustainable Use and Practices

Managing biodiversity often involves allowing some human activity, but ensuring it is sustainable.

1. Sustainable Harvesting of Wild Species

• This involves collecting plant or animal products (e.g., timber, medicinal herbs) at a rate that allows the population to recover quickly and maintain its size.
• Goal: To meet the needs of people today without damaging the resources for future generations.

2. Sustainable Forestry / Agroforestry

• Sustainable Forestry: Management practices that ensure forests provide resources indefinitely. This might involve selective logging, replanting harvested areas, and protecting ecologically sensitive zones.
• Agroforestry: A land-use system where trees or shrubs are grown among crops or pastureland. This helps maintain soil health, provides shade, and offers multiple sustainable products.

3. Sustainable Tourism (Ecotourism)

• Tourism that is environmentally responsible and supports the conservation of the area, often generating income that directly benefits local communities and funds conservation efforts.
• Requirement: It must be low-impact and educate visitors about the importance of biodiversity.

2.3 Conservation 'Ex-situ' (Off-Site)

This means taking species out of their natural habitat for protection, usually as a last resort.

1. Seed Banks and Gene Banks

• Seed Banks: Facilities that store seeds from a wide variety of plant species under controlled, cool, and dry conditions. They act as a genetic "insurance policy" against extinction or natural disaster.
• Did you know? The Svalbard Global Seed Vault in Norway is one of the most famous examples, housing millions of seed samples.

2. Zoos and Captive Breeding

• Zoos protect highly endangered animal species.
• Captive Breeding Programs: Animals are bred in a controlled environment with the long-term goal of increasing their numbers and eventually reintroducing them back into the wild.
• Example: The successful captive breeding and reintroduction of the California Condor.

Warning: Captive breeding is expensive and time-consuming. Animals sometimes struggle to adapt back to the wild, and releasing them requires their original habitat to be safe and restored first.

Final Review: Key Concepts

Biodiversity Management Checklist:

• Do you know how a quadrat and transect are used?
• Can you distinguish between random and systematic sampling?
• Can you give an example of in-situ (e.g., National Park) and ex-situ (e.g., Seed Bank) conservation?
• Why are strategies like ecotourism and extractive reserves important for managing biodiversity sustainably? (They involve local communities and create economic value for keeping habitats intact).