Biogenic volatile organic compounds (BVOCs) emitted from terrestrial vegetation are highly reactive non-methane hydrocarbons which participate in oxidative reactions in the atmosphere prolonging the lifetime of methane and contribute to the formation of secondary organic aerosols. The BVOC emissions from the arctic region are assumed to be low, but data from the region is lacking. BVOC emissions are furthermore expected to change drastically due to the rapidly proceeding climate change in the Arctic, which can provide a feedback to climate warming of unknown direction and magnitude. BVOC measurements in this thesis were performed using a dynamic enclosure system and collection of BVOCs into adsorbent cartridges analyzed by gas chromatography-mass spectrometry following thermal desorption. Also modifications in leaf anatomy in response to the studied effects of climate change were assessed by the use of light microscopy and scanning electron microscopy.
This thesis reports the first estimates of high arctic BVOC emissions, which suggest that arctic environments can be a considerable source of BVOCs to the atmosphere. The BVOC emissions differed qualitatively and quantitatively for the studied common arctic plant species, illustrating the great importance of vegetation composition for determining ecosystem BVOC emissions. Additionally, this thesis assesses the BVOC emission responses in common arctic plant species to effects of climate change: warming, shading and snow addition.
Against expectations, only a few effects of long-term warming and shading on BVOC emissions were found. The snow addition effects on BVOC emissions, presented in this thesis, reflect responses after one year of treatment and more effects are expected to become apparent after a longer treatment period. The results demonstrate that leaf anatomy responds rapidly to changes in the environment and that the responses are highly species-specific. The results in this thesis further suggest that anatomical modifications caused by long-term experimental climate change treatment may partly explain the low number of observed treatment effects on BVOC emissions. Furthermore, the anatomy of arctic plants seems to respond differently to warming than species at lower latitudes.
The results in this thesis demonstrate the complexity of the effects of climate change on BVOC emissions and leaf anatomy of arctic plant species. The presented results add to the understanding of present and future arctic BVOC emissions, necessary to adjust the estimates of global BVOC emissions, which are for example used in climate models.