A Measurement of Temperature in the Forest

Abstract

Authors measured forest and non-forest temperatures and these earth temperatures in Fukuchiyama for two years. The measurements were carried out in two testing slopes in forest of Pinus densiflora and Chamaecyparis obtusa and in non-forest. Air temperatures of 1.5m high above the ground surface and earth temperatures of 2cm, 5cm, 10cm, and 20cm deep under ground surface were measured.
These results were follows:
Air temperature
1. Concerning with the maximum and minimun values of air temperature for a day, the mean and maximum values for a month had the same tendancy: In summer the maximum values were nearly same and the minimum value in forest was higher than in non-forest. In winter, both of the maxium and minimum values in forest were higher than in non-forest.
2. The difference was 2.3°C in summer, 5. 6°Cin winter and attained to 6.7°C in maximum value.
3. The di f f ererence between the maximum and minimum values was 10°C in non-forest and 8°C in forest on an average, there were little change through a year.
Earth temperature
1. In winter, there were little difference between forest and non-forest about mean values for a month, and also little difference in depth. In summer, the ground sur face temperature in non-forest was 3-5°C higher than in forest. This difference decreased with the depth, being zero at the depth of 10cm.
2. The smaller the distance from the ground surface was, the larger the standard deviation became. This inclination was more remarkable in nonforest than in forest. And also the standard deviation was larger in summer than in winter.
3. The limit of depth where the standard deviation was large was 10 cm in non-forest and 5 cm in forest.