Abstract
Emissions of biogenic volatile organic compounds (BVOCs) have been earlier shown to be highly temperature sensitive in subarctic ecosystems. As these ecosystems experience rapidly advancing pronounced climate warming, we aimed to investigate how warming affects the BVOC emissions in the long term (up to 13 treatment years). We also aimed to assess whether the increased litterfall resulting from the vegetation changes in the warming subarctic would affect the emissions. The study was conducted in a field experiment with factorial open-top chamber warming and annual litter addition treatments on subarctic heath in Abisko, northern Sweden. After 11 and 13 treatment years, BVOCs were sampled from plant communities in the experimental plots using a push–pull enclosure technique and collection into adsorbent cartridges during the growing season and analyzed with gas chromatography–mass spectrometry. Plant species coverage in the plots was analyzed by the point intercept method. Warming by 2 °C caused a 2-fold increase in monoterpene and 5-fold increase in sesquiterpene emissions, averaged over all measurements. When the momentary effect of temperature was diminished by standardization of emissions to a fixed temperature, warming still had a significant effect suggesting that emissions were also indirectly increased. This indirect increase appeared to result from increased plant coverage and changes in vegetation composition. The litter addition treatment also caused significant increases in the emission rates of some BVOC groups, especially when combined with warming. The combined treatment had both the largest vegetation changes and the highest BVOC emissions. The increased emissions under litter addition were probably a result of a changed vegetation composition due to alleviated nutrient limitation and stimulated microbial production of BVOCs. We suggest that the changes in the subarctic vegetation composition induced by climate warming will be the major factor indirectly affecting the BVOC emission potentials and composition.
Highlights
Emissions of biogenic volatile organic compounds (BVOCs) from subarctic ecosystems have been observed to be highly responsive to temperature (Tiiva et al, 2008; Faubert et al, 2010; Holst et al, 2010; Potosnak et al, 2013; Rinnan et al, 2014)
In order to be able to better predict the consequences of climate change on the subarctic BVOC emissions, we need to know whether the plant communities and their emission rates acclimate to the increasing temperature in the long term
In Arctic and subarctic regions where NOx levels are relatively low, BVOCs mainly affect the atmospheric chemistry by reacting with the OH radicals, which can increase the lifetime of methane, an important greenhouse gas (Di Carlo et al, 2004)
Summary
Emissions of biogenic volatile organic compounds (BVOCs) from subarctic ecosystems have been observed to be highly responsive to temperature (Tiiva et al, 2008; Faubert et al, 2010; Holst et al, 2010; Potosnak et al, 2013; Rinnan et al, 2014). In order to be able to better predict the consequences of climate change on the subarctic BVOC emissions, we need to know whether the plant communities and their emission rates acclimate to the increasing temperature in the long term. BVOCs are a diverse group of compounds released from the vegetation and soil. In Arctic and subarctic regions where NOx levels are relatively low, BVOCs mainly affect the atmospheric chemistry by reacting with the OH radicals, which can increase the lifetime of methane, an important greenhouse gas (Di Carlo et al, 2004)
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