The purpose of this study was to investigate seasonal acclimation of mitochondrial leaf respiration in three plant species at the Imnavait Creek Watershed in Toolik Lake, Alaska. The primary objectives were to determine 1) to what extent acclimation occurs, 2) how well correlated it is to temperature and 3) whether this process varies with plant species or plant community type. We examined three different plant species: the deciduous shrub Betula nana, the evergreen Ledum palustris and the sedge grass Eriophorum vaginatum. Samples were collected from three different sites, spaced 200m apart, along the same transect. Each site was characterized by a different community type: a heath vegetation site, a tussock tundra site and a wet sedge site. Measurements were made for the first five weeks of the growing season, from June 1 through July 9. Dark respiration was measured for detached leaves using a Rank Brothers Electrode (Cambridge, UK). While each species showed a change in respiration as the growing season progressed, this change was not correlated to changes in temperature. There were significant differences in the rate and degree of acclimation between species, but within species, there were no significant differences between sites. These findings suggest that temperature is not the sole or primary driver of seasonal acclimation of mitochondrial respiration, and that there may be a strong phonological component, with each plant’s acclimation being genetically pre-determined.
Images: Janeen's work in the outdoors of Alaska included extensive hiking in rugged and challenging terrain. In her e-mail communications home she noted mid way through her field work that she had attained the status of "expienced" and "avid" as a prefix to her hiking, as she advanced from needing a hand on rough terrain and over rapid streams. Photographic documentation (above right) was one of the tools included in Janeen's data collection techniques.
Janeen exploring ice caves
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Last updated: 19 January 2006, MKT.