Winter photosynthesis in red spruce (Picea rubens Sarg.): limitations, potential benefits, and risks
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Arctic, Antarctic, and Alpine Research. 32: 375-380.
Numerous cold-induced changes in physiology limit the capacity of northern conifers to photosynthesize during winter. Studies of red spruce (Picea rubens Sarg.) have shown that rates of field photosynthesis (Pfield) and laboratory measurements of photosynthetic capacity (Pmax) generally parallel seasonal ambient temperature trends; carbon exchange decreases in the fall, remains negative or close to zero for much of the winter, and increases in the spring. However, increases in Pfield, Pmax, and foliar carbohydrate concentrations can occur during winter thaws. Thaw-induced increases in photosynthesis are probably not the result of increased stomatal conductance, but may result from other changes in physiology associated with thaw-induced improvements in water relations. In addition to increased photosynthesis, red spruce also decrease in cold hardiness during thaws. The co-occurrence of thaw-induced changes in photosynthesis and cold hardiness raises questions regarding their adaptive significance, particularly in the context of potential climate change. Red spruce may face a tradeoff between potentially beneficial increases in carbon capture and potentially detrimental reductions in cold tolerance. The physiological consequence(s) of this tradeoff may depend on the number and duration of thaws, as well as ambient temperature trends following thaw. Pollution-induced reductions in cold tolerance, and the low genetic variability of red spruce, may also influence the net outcome of thaw-induced changes in physiology, acid precipitation, aluminum, calcium, cations, cold tolerance, foliage, growth, leaching, membrane-associated calcium, photosynthesis, Picea rubens, respiration.
Schaberg, P.G. 2000. Winter photosynthesis in red spruce (Picea rubens Sarg.): limitations, potential benefits, and risks. Arctic, Antarctic, and Alpine Research. 32: 375-380.