PARENT SESSION
Poster Session #38: Landscape Ecology.
Thursday, August 9, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall
125
Temporal and spatial variability of air and soil temperatures within an old-growth mixed conifer.
Ma, Siyan1, Chen, Jiquan1, North, Malcolm2, Jurgensen, Martin1, 1 2
ABSTRACT- To examine air and soil temperature variability within a mixed conifer, old-growth, we established 18 microclimatic stations in the Teakettle Experimental Forest, California. Air temperature (Ta), soil surface temperature (Tsf), and soil temperature at a 15 cm depth (Ts15) were collected every 20 s and stored hourly from Aug. 1998 to Aug. 2000. Four seasons were delineated based on the two-year database, and daily mean, hourly difference (DTa, DTsf, DTs15) and their variations were calculated to detect the spatial changes of temperatures in different seasons of the year. Our results indicate that Ta is more variable than Tsf and Ts15. During the spring the largest temperature difference between the maximum and minimum temperature is 20.46°C, 15.05°C, and 13.24°C for Ta, Tsf and Ts15, respectively. The summer is the smallest variable season. The DTa, DTsf and DTs15 and their diurnal patterns appear to be season-dependent. In the spring and fall DTa, DTsf and DTs15 are ±4°C, ±3°C and ±2°C, respectively. We also found that both diurnal and seasonal temperature variation of temperatures is distinctly correlated to canopy cover, litter depth, and elevation, with correlation coefficient ranging from -0.8 to +0.8. The temperature variation is higher than in any other recorded forest ecosystem. Our current research is exploring the ecological (e.g., forest structure) and biophysical processes (e.g., energy balance) that produce this high contrast forest microclimate.
KEY WORDS: temperature, variability, old-growth, mixed conifer