PARENT SESSION
Contributed Oral Session 134: Forest Ecology: Reproduction and Recruitment
Thursday, August 11, 1:30 PM - 5:00 PM, Meeting Room 516 D, Level 5, Palais des congrès de Montréal

Estimating Net Primary Productivity of Jack Pine in Relation to Stand Age and Climatic Gradient along BFTCS.

Bhatti, Jagtar¹, Varem-Sanders, Theirry¹, Banfield, Ed¹, ¹ Northern Forestry Centre, Edmonton, Alberta, Canada

ABSTRACT- The ability to measure net primary productivity (NPP) over a period of years using relatively inexpensive methods can be a tremendous asset when assessing the forest response to climate change. This project investigates and evaluates methods of estimating historical jack pine productivity using biomass stocks and tree ring width measurements along stand age and climatic gradient. Jack pine NPP was calculated for stands along age sequence along Boreal Forest Transect Case Study (BFTCS) similar in soil and fertility characteristics. Biomass functions were modified using local Dbh-height functions to determine stand level functions with Dbh as the sole predictor. Above ground net primary productivity was estimated from the change the biomass with measured litter production rate on these sites. Tree biomass carbon and rate of litter production decreased from Candle Lake (Central Saskatchewan) at the southern limit of the boreal forest where the climate is warm and dry up to Thompson (Northern Manitoba) where the climate is wetter and colder. Both at the southern boreal sites and northern boreal sites, the tree productivity was highly sensitivity to climate variability. The younger jack pine stands are considerably more productive than older ones. Although the individual tree productivity is higher in the harvested site than in the fire origin site, the stand productivity is very similar in both, due largely to differences in stem density. The NPP of jack pine was higher for 30 years old both harvest and fire origin stand (1.8 to 2.4 t C/ha/yr) and was almost 100% lower for the older stands (1.4 t C/ha/yr).

Key words: Boreal Forest, NPP, Tree Productivity, Cliamte change