Fig. 1 shows equipment used in an urban microclimate study in Birmingham. At six sites, students held a digital thermometer 1.5 metres above the ground for ...
Question 1 Report
Fig. 1 shows equipment used in an urban microclimate study in Birmingham. At six sites, students held a digital thermometer 1.5 metres above the ground for two minutes before recording air temperature. Sites included a tree-lined park, a narrow street between tall buildings and a large car park. Measurements were taken on the same dry afternoon. The students are testing the suggestion that surfaces and building density affect local temperature, rather than simply recording weather conditions.
(a) State the independent variable in this fieldwork enquiry. [1]
(b) State why the thermometer should be held at the same height at every site. [1]
(c) Explain two reasons why the car park may have been warmer than the park. [3]
A school ecology group used the method in Fig. 1 to compare plant cover in a shaded woodland and an open meadow. At each site they placed a 0.5 m quadrat at ten random coordinates, identified the plant species present and estimated percentage cover. The group used the same identification guide and worked in pairs. Their data will be used to test whether light availability is linked to the distribution of bracken and flowering plants in the study area.
(a) State the piece of sampling equipment shown in Fig. 1. [1]
(b) State why random coordinates should be used. [1]
(c) Explain one limitation of estimating percentage plant cover by eye. [1]
Answer Details
Urban microclimate study
- (a) The independent variable is the site type, such as land cover or building density. This is the factor deliberately compared between the park, street and car park. [1]
- (b) Holding the thermometer at the same height controls height as a variable, making temperatures from different sites comparable. [1]
- (c) The car park may be warmer because dark, hard surfaces absorb and store more solar energy than vegetated ground. It also has less tree shade, so more solar radiation reaches the surface. Finally, there is less vegetation and therefore less cooling by evapotranspiration, the transfer of water from plants to the air. [3]
Plant-cover sampling
- (a) The sampling equipment is a quadrat. [1]
- (b) Random coordinates reduce bias because students do not choose unusual, convenient or preferred patches of vegetation. [1]
- (c) Estimating cover by eye is subjective: different observers may judge the same percentage differently. This reduces consistency between results. [1]
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