Carbon exchange measurements at the whole ecosystem level have revealed that net carbon uptake by coniferous forests is downregulated or even completely supressed during the winter season. This is followed by a rapid onset of photosynthesis in spring during which the evergreen boreal forests take up about one third of their annual carbon gain. Maintenance of green needles during winter and retaining the capacity for rapid onset of the downregulated photosynthetic machinery is therefore important for the carbon budget and success of the evergreen boreal forests. There is already evidence of increased physiological activity of northern hemisphere vegetation resulting from an earlier start of the growing season as a consequence of global warming. However, our current understanding of seasonal patterns of carbon sequestration and photosynthesis in these forests and their interaction with the environment is rather poor. We hypothesize that the seasonal changes in photosynthesis are accomplished by well regulated changes in just a few chloroplastic key proteins involved in light harvesting and photoprotective processes as a response to changing environmental conditions. By this process, most of the components of the photosynthetic machinery can be retained during winter, thus allowing for rapid recovery in spring just by reconversion of the involved key proteins. We will elucidate such key proteins and place them in the context of ecophysiological function and track changes in response to environmental conditions. We will also use marker transcripts (mRNA) to elucidate signaling pathways and understand regulatory mechanisms. We hope to develop our process based understanding of this phenomenon to a level sufficient to allow a mechanistic description of the autumn and spring transition processes. Incorporating such mechanisms into models of current and future ecosystem gas exchange would allow for reliable predictions of how forests may respond to future climate change.
Fields of science
Call for proposal
See other projects for this call