PARENT SESSION
Oral Session #44: Disturbance ecology of forests: Animals, wind, gaps, edges. Presiding: S. Archer.
Wednesday, August 8, 2001. 8:00 AM to 11:45 AM. Hall of Ideas G.
Temperature dynamics associated with pits and mounds in managed and unmanaged hardwood forests of northern Michigan, USA.
NAUERTZ*, ELIZABETH1, ZASADA, JOHN1, CROW, THOMAS1, BUCKLEY, DAVID2, 1 2
ABSTRACT- The objectives of this study were to describe and quantify the within and between year variation in air and soil temperature associated with pit and mound microtopography in managed and unmanaged northern hardwood forests on the Ottawa National Forest in northern Michigan, USA. From 1996 - 1999, temperatures were monitored year-around in two well-defined pit and mound complexes in 2 managed and 3 unmanaged stands. Thermocouples were placed 5 cm above the surface, at the surface, and 10 cm below the surface on opposite sides of mounds and in adjacent pits. An extended 1 m to -1 m temperature profile was also monitored on nearby level ground during the same time period for comparison purposes. Pit and mound daily temperatures were more variable (particularly the maximums) overall than were temperatures on level forest floor areas. Temperatures were less variable in pits than on mounds. The most variable and extreme temperatures occurred on south-facing mounds. All pits and mounds tend to exhibit the same annual variation in temperature regime, with the most variability occurring prior to full leaf development in late spring. Each complex has a unique pattern of temporal variation depending upon orientation of the mound, slope characteristics, litter fall, and snowmelt. The management regime may affect the distribution and characteristics of pits and mounds by the target tree size, spatial distribution of overstory and understory plants, harvest methods, and site treatments.
KEY WORDS: pits and mounds, temperature, northern michigan