Water relations of black spruce trees on a peatland during wet and dry years

Published in Wetlands 22(2): 225-233

Low water tables typically found in peatlands during dry summer periods or in the vicinity of drainage ditches may lead to moisture deficiency in porous surface peats. Episodes of drought stress might compromise the growth benefits brought about by lower ground-water levels. We examined the water relations of black spruce (Picea mariana) trees on a natural peatland during relatively wet (1990) and relatively dry (1991) summers. Seasonal patterns of pre-dawn and mid-day shoot water potentials and stomatal conductance were not related to peat water content or to water-table depth. There was no evidence of water stress or osmotic adjustment in sampled trees during wet and dry growing seasons. Our soil moisture data showed that although water-table levels were as low as —66 cm in 1991, water availability in the root zone remained high. Even with the absence of mid-day water stress during the summer of 1991, a 50% reduction in stomatal conductance as compared with the previous year was found. We suggest that signals from the bulk of the roots located in dry peat top layer contributed to the regulation of stomatal conductance.

Forests

Scientific Article

Forestry Research, Forests, Silviculture

PEPIN, Steve, André P. PLAMONDON and Abderraouf BRITEL

2002

Available at the Direction de la rechercher forestière

Picea mariana, black spruce, shoot water relation parameters, stomatal conductance, forested bog, osmotic adjustment, soil moisture, silviculture and yield of natural forests - softwood stands, sylviculture et rendement des forêts naturelles - peuplements résineux, sylviculture des forêts naturelles résineuses