Abstract
Primary important temperatures in forest ecosystems are associated with the air, topsoil,
and streamflow. However, previous studies mostly examined these factors individually. Limited
studies investigating these temperatures in the same plot can be found especially in a forest environment.
We recorded temperatures of the air, topsoil layers and streamflow in a riparian area of
Harpen Creek of the Fushan Experimental Forest from 2005, and we accumulated more than 5 yr
of continuous records. The analytical results showed that the average yearly temperatures for air,
streamflow, and 5-, 30-, and 50-cm soil layers during the monitoring period were 17.7, 17.6, 17.9,
18.0, and 18.1℃, respectively. The highest average monthly temperature for air and streamflow
occurred in July, while those for the soil layers occurred in August. The minimum monthly average
temperatures for all monitoring items occurred in January. Air, streamflow, and topsoil layers had
nearly the same monthly average temperature of about 16.5℃ in the month of April for the Harpen
Creek drainage basin. When the air temperature was < 15.5℃, the streamflow had the highest temperature
among all monitored items, and the second highest was the 30-cm soil layer. Yearly temperature
fluctuations for all monitoring items were significant, and the descending rank of ranges
of yearly temperature changes was air, 5-cm soil layer, 30-cm soil layer, 50-cm soil layer, and
streamflow. Air temperature had the maximum magnitude of changes within a day for all months,
and the second was the temperature of the 5-cm topsoil layer. However, the maximum magnitude
of daily changes was < 0.5℃ for soil layers deeper than 30 cm, and this indicated that there was
only a small and insignificant diurnal change in temperatures of deeper soil layers. The magnitude
of changes of streamflow temperature within a day was less than that for the 5-cm soil layer except
for the period from September to December. In addition, the linear regression relationships for air
temperature versus streamflow temperature and air temperature versus temperatures of the monitored
topsoil layers were also established in this report. Hopefully those investigations will provide
knowledge of the riparian ecosystem of Harpen Creek.