Bark temperature patterns in ponderosa pine stands and their possible effects on mountain pine beetle behavior

Abstract

Bark temperatures on the north and south sides of five ponderosa pines (Pinusponderosa Laws.) in each of four growing stock levels in two areas in the Black Hills of South Dakota were monitored periodically from May through August 1989. Temperatures were significantly different among growing stock levels and between sides of the tree. The magnitude of differences between the mean bark temperatures in partially cut stands and uncut controls was inversely related to stocking level. Maximum differences in mean bark temperatures among the growing stock levels occurred between 10:00 and 14:00, when differences between the lower growing stock levels and the controls reached 9 to 10°F (Fahrenheit temp. = 1.8(Celsius temp.) + 32). Diurnal differences were greatly influenced by the amount of cloud cover. Nocturnal temperatures generally differed by 1 to 2°F. North-side temperatures were cooler and less variable than south-side temperatures. Temperature relationships and mountain pine beetle (Dendroctonusponderosae Hopk.) behavior are discussed.