Measuring and managing biodiversity Revision Notes

Estimating biodiversity involves measuring the variety and abundance of species in a habitat. Sampling techniques are essential because it is impractical to count every organism in an area. Common tools include pitfall traps, pooters, quadrats, and transects.

Pitfall traps are containers buried flush with the soil surface to capture ground-dwelling invertebrates like beetles and spiders. They provide quantitative data on species presence and relative abundance over time. For example, setting 10 pitfall traps in a woodland for 48 hours can estimate insect diversity.

Pooters are small suction devices used to collect tiny insects by drawing them into a container without damage. They are useful for sampling insects on leaves or flowers where direct capture is difficult. For instance, a pooter can collect aphids from a plant for identification and counting.

• Pitfall traps capture ground insects passively over time.
• Pooters actively collect small insects without harm.

Sampling locations can be chosen randomly or systematically. Random sampling selects points without a pattern, reducing bias but possibly missing some habitat features. Systematic sampling uses regular intervals, such as every 5 metres along a transect line, ensuring even coverage but risking bias if the pattern coincides with habitat variation.

Quadrats are square frames (e.g., 1m x 1m) placed at sampling points to count plants or slow-moving animals within. Random quadrat placement avoids bias, while systematic placement along transects helps study changes across gradients.

Transects are lines marked across a habitat where observations or samples are taken at set intervals. For example, a 50-metre transect with quadrats every 5 metres can show how species composition changes from a forest edge to an open field.

• Random sampling reduces selection bias but may miss patterns.
• Systematic sampling ensures coverage but can coincide with habitat features.
• Quadrats estimate species density and frequency in small areas.
• Transects study spatial changes in biodiversity.

Conservation aims to maintain biodiversity and genetic resources for ecosystem health and human benefit. Sustainable harvesting involves collecting wild species at rates that do not reduce populations, such as regulated fishing quotas.

Sustainable forestry and agroforestry integrate tree cultivation with agriculture, maintaining habitat diversity and soil health. For example, shade-grown coffee farms support more species than monocultures.

Protected areas include national parks, wildlife reserves, extractive reserves, and biosphere reserves. National parks protect ecosystems with minimal human interference, while extractive reserves allow sustainable resource use by local communities. Biosphere reserves combine conservation with sustainable development and research zones.

• Sustainable harvesting prevents overexploitation of wild species.
• Sustainable forestry balances timber production with ecosystem health.
• National parks and reserves protect habitats and species.
• Extractive reserves support sustainable local resource use.
• Biosphere reserves integrate conservation and human activity.

Seed banks store seeds under controlled conditions to preserve plant genetic diversity, safeguarding against extinction and supporting future restoration.

Zoos and captive breeding programs maintain populations of endangered species, enabling reintroduction into the wild. For example, captive breeding of the California condor has helped increase its numbers.

Sustainable tourism and ecotourism promote environmental education and economic benefits while minimising ecological impact. Well-managed ecotourism can fund conservation and support local communities, as seen in Costa Rica's protected areas.

• Seed banks conserve plant genetic diversity for future use.
• Zoos and captive breeding aid endangered species recovery.
• Sustainable tourism balances human activity with conservation goals.

Formulating clear aims and hypotheses is essential for focused investigations. For example, hypothesising that insect diversity is higher in shaded areas than open fields guides sampling design.

Designing questionnaires requires clear, unbiased questions to collect reliable data on human impacts or perceptions related to biodiversity.

Simple experiments should include controls to isolate variables. For instance, comparing plant growth inside and outside a protected area controls for environmental factors affecting biodiversity indirectly.

• Aims and hypotheses focus investigations.
• Questionnaires must avoid bias for valid data.
• Controls in experiments isolate variables for accurate conclusions.

Analysing biodiversity data involves calculating averages, percentages, and ratios. For example, percentage cover of a plant species in quadrats is calculated as (number of quadrats with species / total quadrats) × 100.

Interpreting tables, charts, and graphs helps identify trends, such as species abundance changes along a transect.

Understanding map scales allows accurate measurement of habitat areas and distances, important for planning conservation zones.

• Calculate percentages: (part/whole) × 100.
• Use averages to summarise data sets.
• Interpret graphical data to identify patterns.
• Apply map scales to measure real-world distances.