The distribution of organisms is strongly affected by abiotic factors (the non-living conditions of a habitat). When sampling with quadrats or transects, these factors are measured at each sampling point so that they can be correlated with species distribution.Common abiotic factors and how they are measured:• Light intensity: a light meter (lux meter) or light sensor
• Temperature: a thermometer or temperature probe (air, soil or water)
• Soil pH: a pH probe or meter, or soil mixed with water and universal indicator
• Soil moisture: a moisture meter, or by drying a soil sample and measuring mass lost
• Wind speed: an anemometer
• Humidity: a hygrometer (humidity sensor)
• Dissolved oxygen in water: an oxygen probe
• Water flow rate: a flow meterElectronic sensors connected to data loggers can take readings continuously over long periods, at precise intervals, and with less human error. Readings should be repeated and taken at the same time of day, because factors such as light and temperature change during the day.Worked example: a soil sample has a mass of 50.0 g. After drying in an oven until its mass stops changing, it has a mass of 38.0 g. Water content = (50.0 − 38.0) ÷ 50.0 × 100 = 24%.
• Temperature: a thermometer or temperature probe (air, soil or water)
• Soil pH: a pH probe or meter, or soil mixed with water and universal indicator
• Soil moisture: a moisture meter, or by drying a soil sample and measuring mass lost
• Wind speed: an anemometer
• Humidity: a hygrometer (humidity sensor)
• Dissolved oxygen in water: an oxygen probe
• Water flow rate: a flow meterElectronic sensors connected to data loggers can take readings continuously over long periods, at precise intervals, and with less human error. Readings should be repeated and taken at the same time of day, because factors such as light and temperature change during the day.Worked example: a soil sample has a mass of 50.0 g. After drying in an oven until its mass stops changing, it has a mass of 38.0 g. Water content = (50.0 − 38.0) ÷ 50.0 × 100 = 24%.