Cambridge IGCSE Environmental Management Fieldwork 2: Environmental measurements and equipment

Environmental measurements turn a place into evidence. The equipment must measure the variable at a suitable range and resolution, while the sampling technique must suit the organisms, habitat and question. A sophisticated instrument does not rescue a poorly chosen site or inconsistent method.

This Eclat skills note organises the measurement and sampling techniques in Cambridge IGCSE Environmental Management 0680 section 5.4. It supports written assessment of investigation skills and does not imply a separately timetabled practical examination.

Choosing a measurement

Begin with the variable, not the instrument. Soil moisture, water pH, air temperature, stream velocity and species abundance require different methods. For each measurement, specify:

• the instrument or technique;
• the unit or counting rule;
• the range and resolution required;
• calibration or a standard check where relevant;
• a consistent position, depth, time or duration;
• repeats and independent locations;
• contextual observations that could explain variation.

Resolution is the smallest change displayed or distinguished. Accuracy is closeness to the accepted value, while precision is the closeness of repeated values to one another. A meter can give tightly clustered readings that are all wrong if it is poorly calibrated.

Check zero readings, batteries, clean probes and appropriate calibration before field use. Rinse probes between water samples when the method requires it and avoid contaminating the site. Let a sensor stabilise for the same time at every location. Record raw values before rounding so later analysis is not based on avoidable information loss.

Quadrats and transects

A quadrat defines a known area for plants or slow-moving organisms. Presence, frequency, abundance or percentage cover can be recorded using a consistent rule. Quadrat size should suit the scale and distribution of the organisms. A very small quadrat may miss sparse species; a very large one can be slow and reduce the number of independent samples.

A transect is a line or belt along which observations are made. It is useful where a variable changes across an environmental gradient, such as distance from a path, shore or pollution source. A line transect records organisms touching the line, while quadrats placed along a belt provide area-based observations. Cambridge requires the broad technique, so use any extra detail only when it helps the method shown.

Pitfall traps, pooters and sweep nets

A pitfall trap samples ground-active invertebrates. A container is sunk so its rim is level with the soil surface, protected from rain and larger animals, checked frequently and removed after use. Catch depends on both abundance and activity, so a faster-moving species may appear more common than it is.