Effects of snowmelt on the springtime photosynthesis of the evergreen dwarf shrubVaccinium vitis-idaea

Abstract

Background:The dwarf shrub Vaccinium vitis-idaea has been found to retain its photosynthetic capacity under snow in winter. At snowmelt, the plants are exposed to low temperatures and full light, which may lead to the inhibition of photosynthesis. Aims: To examine the changes in the photosynthesis of V. vitis-idaea at snowmelt and to determine their temporal extent. Methods: The photosynthetic capacity and the energy conversion efficiency of photosystem II (F v /F m ) were determined in a natural spring snowmelt setting in field conditions and by creating an artificial snowmelt gradient. Results: F v /F m decreased rapidly after snowmelt and remained low for several weeks in the spring. The photosynthetic capacity remained at pre-snowmelt levels at first, but started decreasing about a week after snowmelt. The depression of photosynthesis lasted for several weeks. Conclusions:The inhibition or downregulation of photosynthesis in V. vitis-idaea takes place at snowmelt, not at the onset of winter as it does in many evergreen conifers. The snow protects the plants from the harshest winter conditions and permits metabolic activity. If snow cover becomes more intermittent in the future, there may be longer periods of photoinhibition, which will affect the carbon balance of plants.

Absence of snow cover reduces understory plant cover and alters plant community composition in boreal forests

“…In addition, the bags transmit less light than natural snow cover. Plants are reported to photosynthesize below snow (Starr and Oberbauer 2003;Lundell et al 2010). We therefore hesitate to attribute the reactions found in the insulation treatment solely to the eVects of reduced frost.…”

Photosynthetic and phenological responses of dwarf shrubs to the depth and properties of snow

“…Snow also absorbs solar radiation, and the penetration of PAR usually increases with increasing snow density (Curl et al ). Many evergreen plants maintain their photosynthetic capacity through winter (Starr and Oberbauer , Lütz et al , Lundell et al , , Saarinen and Lundell ), but the rates of photosynthesis are probably limited strongly by the low intensity of PAR under deep snow. However, high rates of plant respiration under deep snow can be expected due to higher temperatures, as is suggested also by the results of Nobrega and Grogan ().…”

Cold Season Physiology of Arctic Plants

“…Arctic tundra vegetation has been shown to be photosynthetically ready during the winter-spring transition (Oberbauer et al 1996), and evidence published a decade ago provided evidence of photosynthetic activity under the snow (Lundell et al 2008;Lundell et al 2010). It has yet to be determined how these evergreens manage their water balance over the winter and acquire the water required to sustain photosynthesis during snowmelt.…”

“…As snow begins to melt in the spring, a process that may take a week or more, water percolates from the upper snow layers down to the snow-soil interface where it might be available to plant roots. During cold season photosynthesis, such as that described by Starr and Oberbauer (2003) and Lundell et al (2008Lundell et al ( , 2010, plants may be transpiring, implying that the water losses are replaced or the plants undergo water deficits.…”

“…Photosynthesis by arctic evergreens also occurs under the snow in springtime (Starr and Oberbauer 2003;Starr et al, unpublished). Recent research shows that one evergreen is photosynthetically competent over the entire winter (Lundell et al 2010). Cold season photosynthesis by evergreens may help offset winter respiratory carbon losses.…”