COMPARING STEM RESPIRATION AND GROWTH OF JACK PINE PROVENANCES FROM NORTHERN AND SOUTHERN LOCATIONS

Stem respiration rates of 31-year-old jack pine (Pinus banksiana Lamb. ) trees from northern and southern provenances growing in a common gar den were compared. At 15 degrees C, the seasonal course of stem respir ation rate of northern provenances was not statistically different fro m that of southern provenances. A relationship existed between mainten ance respiration rate and stem growth rate. Because relationships betw een sapwood relative growth rate and annual growth and maintenance res piration rates were similar for northern and southern provenances, no clinal differences in stem respiration rates were observed.