Biotope monitoring: temperature, humidity, rainfall
The biotope is the non-living place where a community lives: its soil, water, light and weather. We monitor it with simple instruments.
- Temperature is measured with a thermometer in °C. Keep it in the shade, about 1.5 m above the ground, and read it at the same time each day. Ground and soil temperature are different from air temperature.
- Humidity is how much water vapour is in the air. A hygrometer shows relative humidity in %. Warm air at noon is usually drier than cool air in the morning.
- Rainfall is collected in a rain gauge (a straight-sided container in an open place). It is read in millimetres. 1 mm of rain means 1 litre of water on every square metre.
Write each reading in a table: date, time, place, value. Compare days and places, for example sun against shade.
Species lists and indicator species
A species list is a written list of every kind of organism found in the study area. Use a field guide or a phone app to name them, and photograph the ones you cannot name. Never pick rare plants.
An indicator species tells you about the conditions of a place, because it can live only in certain conditions.
- Lichens on tree bark: many kinds die in polluted air, so many lichens mean cleaner air.
- Stinging nettle: grows where the soil is rich in nitrogen, for example near manure or fertiliser.
- Mayfly larvae in a stream: need clean, oxygen-rich water.
A long species list with many different species shows rich biodiversity.
Frequency, abundance, dominance indices
We cannot count every plant in a big field. So we use quadrats: square frames, usually 1 m × 1 m, placed at random places. We count the plants inside each quadrat, then calculate three indices.
- Frequency (%) = (quadrats where the species occurs ÷ total quadrats) × 100. It says how widely the species is spread.
- Abundance = number of individuals ÷ number of quadrats (average per quadrat). It says how many there are. Some books divide only by the quadrats where it occurs; always say which you used.
- Dominance (%) = (individuals of the species ÷ individuals of all species) × 100. It says how big a share the species has. The species with the highest dominance is the dominant species.
Example in the 3D: clover is in 5 of 5 quadrats (frequency 100%); 25 plants ÷ 5 = abundance 5 per quadrat; 25 of 32 plants = dominance 78%. Use more quadrats for better results.
Safety rules and first aid
Before you go: tell an adult where you are going and when you return. Go in pairs or groups. Check the weather. Wear long sleeves, closed shoes or boots, and gloves. Take drinking water, a hat and a charged phone. Carry a first-aid kit.
In the field: do not touch or taste unknown plants, berries or mushrooms. Watch for ticks, thorns, stinging insects and slippery banks. Stay away from deep water. Wash your hands before eating.
Basic first aid (it does not replace a doctor):
- Small cut: wash with clean water, press with a clean cloth, cover with a bandage.
- Insect sting: remove the sting if you can see it, put something cold on it. If the face swells or breathing is hard, call the emergency number at once (112 in many countries).
- Sprain: rest, cold pack, wrap gently, raise the limb.
- Heat or sunburn: move to shade, sip water, cool the skin.
Try it: survey a patch
In the 3D, tap each species and write its three indices before you read them. At school or home, make a 1 m square frame from sticks, throw it over your shoulder to choose a random spot, and count the plants in 5 spots. Calculate frequency, abundance and dominance for the two most common plants.
Key formulas and definitions
- Frequency (%) = (quadrats with the species ÷ total quadrats) × 100
- Abundance = individuals of the species ÷ number of quadrats
- Dominance (%) = (individuals of the species ÷ individuals of all species) × 100
- Density = individuals ÷ area sampled (for example per m²)
- 1 mm of rain = 1 litre of water on 1 m²
Worked examples
1. A species is found in 3 of 5 quadrats. Find its frequency.
Frequency = 3 ÷ 5 × 100 = 60%.
2. Six daisies are counted in 5 quadrats. Find the abundance.
Abundance = 6 ÷ 5 = 1.2 plants per quadrat.
3. In a survey 25 of the 32 plants counted are clover. Find the dominance of clover.
Dominance = 25 ÷ 32 × 100 ≈ 78%.
4. A rain gauge shows 12 mm. How many litres of rain fell on a plot of 50 m²?
1 mm = 1 litre per m². So 12 mm = 12 litres per m². For 50 m²: 12 × 50 = 600 litres.
5. Air temperature readings in the shade are 14 °C, 22 °C, 24 °C and 18 °C. Find the mean.
Sum = 14 + 22 + 24 + 18 = 78. Mean = 78 ÷ 4 = 19.5 °C.
6. Ten quadrats of 1 m² contain 84 plants of one species. Find the density.
Area = 10 × 1 = 10 m². Density = 84 ÷ 10 = 8.4 plants per m².
7. Many lichens grow on the oak trunks near a village road, but none on trunks next to a busy highway. What does this suggest?
Lichens are indicator species for clean air. Many lichens near the village suggest cleaner air; none near the highway suggest air pollution there.
Common mistakes
- Mixing up frequency and abundance. Frequency is about how many quadrats; abundance is about how many individuals.
- Placing the quadrats only where plants look nice. Choose positions at random to avoid bias.
- Putting the thermometer in the sun and calling it air temperature. Keep it in the shade.
- Going out alone or without a first-aid kit "just for a short time".