Plant eco-physiological responses to multiple environmental and climate changes
The current global changes of temperature, precipitation, atmospheric CO2 and UV-B radiation impact in concert ecosystems and processes in an unpredictable way. Therefore multifactor experimentation is needed to unravel the variability in strength of these drivers, whether the factors act additively...
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| Format: | Book |
| Language: | English |
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2009
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| Online Access: | https://orbit.dtu.dk/en/publications/aa61a4ff-99fa-44d2-adeb-a233504da219 https://backend.orbit.dtu.dk/ws/files/3553933/2009_78.pdf |
| Summary: | The current global changes of temperature, precipitation, atmospheric CO2 and UV-B radiation impact in concert ecosystems and processes in an unpredictable way. Therefore multifactor experimentation is needed to unravel the variability in strength of these drivers, whether the factors act additively or synergistically and to establish cause-effect relations between ecosystem processes. This thesis deals with heath plant responses to global change factors (the CLIMAITE project). In a Danish temperate heath ecosystem elevated CO2, experimental summer drought, and passive nighttime warming was applied in all combinations (based on the scenario for Denmark anno 2075) and the responses after one year of treatment were investigated through a growing season in Hairgrass (Deschampsia flexousa) and Heather (Calluna vulgaris). In a high arctic heath ecosystem situated in NE-Greenland UV-B exclusion experiments were conducted on Salix arctica and Vaccinium uliginosum during six years. Responses of photosynthesis performance were characterized on the leaf scale by means of leaf gas-exchange (A/Ci curves), chlorophyll-a fluorescence, leaf nitrogen, carbon and δ13C and secondary compounds. The main findings were 1) The different growth strategies of the evergreen Calluna versus the opportunistic bi-phasic Deschampsia affects the photosynthesis response to drought and autumn warming (Paper I); 2) Elevated CO2 and warming synergistically increase photosynthesis in spring and autumn (Paper II and III); 3) Summer drought decreased photosynthesis in both species, but where Calluna maintained photosynthetic metabolism then major proportion of grass leaves wilted down (Paper I); 4) Elevated CO2 did not decrease stomatal conductance, but the treatments affected soil water content positively, pointing to the complex water relations when plants of contrasting growth strategy co-occur (Paper III and IV); 5) Water availability affected the magnitude of photosynthesis to a higher degree than warming and elevated CO2 (Paper II and III); 6) ... |
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