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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - TUVOLU (Tundra biogenic volatile emissions in the 21st century)

Teaser

Summary

Biogenic volatile organic compounds (BVOCs) influence atmospheric oxidation causing climate feedback thought to be especially significant in remote areas with low anthropogenic emissions, such as the Arctic. Still, we do not understand the dynamics and impact of climatic and biotic BVOC emission drivers in arctic and alpine tundra, which are highly temperature-sensitive BVOC sources. This ERC consolidator project aims to redefine tundra BVOC emission estimates to account for rapid and dramatic climate warming accompanied by effects of vegetation change, permafrost thaw, insect outbreaks and herbivory using multidisciplinary methodology. We will quantify the relationships between leaf and canopy temperatures and BVOC emissions to improve BVOC emission model predictions of emission rates in low-statured tundra vegetation, which efficiently heats up under clear sky. We will experimentally determine the contribution of induced BVOC emissions from insect herbivory in the warming Arctic by field manipulation experiments addressing basal herbivory and insect outbreaks and by stable isotope labelling to identify sources of the induced emission. Complementary laboratory assessment will determine if permafrost thaw leads to significant BVOC emissions from thawing processes and newly available soil processes, or if released BVOCs are largely taken up by soil microbes. We will also use a global network of existing climate warming experiments in alpine tundra to assess how the BVOC emissions from tundra vegetation world-wide respond to climate change. Measurement data will help develop and parameterize BVOC emission models to produce holistic enhanced predictions for global tundra emissions. Finally, modelling will be used to estimate emission impact on tropospheric ozone concentrations and secondary organic aerosol levels, producing the first assessment of arctic BVOC-mediated feedback on regional air quality and climate.

Work performed

We have conducted field work to assess tundra shrub temperature responses at leaf level, as well as at ecosystem scale in different tundra ecosystems, and the analyses of these results is in progress. Our work on the effects of insect herbivory started by an experiment, in which we used methyl jasmonate (MeJA) to mimic insect herbivory on the dwarf birch, Betula nana, in Abisko, Northern Sweden. We showed that the MeJA-treatment strongly increased BVOC emissions and changed the profile of compounds released (Li et al. 2019, Nature Plants). Interestingly, climate warming strongly amplified this response. We have conducted three experiments to assess how the number of feeding larvae impact BVOC emissions of the mountain birch B. pubescens ssp. czerepanovii. The results are currently under analysis. With focus on permafrost thaw emissions, we have shown that thawing permafrost releases considerable amounts of BVOCs, especially ethanol and methanol, but that the emissions to the atmosphere are lower due to active microbial uptake of BVOCs during their passage through the active layer soil (WP3; KramshÃ¸j et al., 2018, Nature Communications). The microbial uptake may be an important, much overseen process, which functions efficiently for all kinds of BVOCs in all soils (WP3; Albers et al. 2018, Biogeosciences). The net amount and composition of BVOCs released to the atmosphere depends also on the water content of the soil, which determines the oxygen content (WP3; KramshÃ¸j et al., 2019, Global Change Biology).

Final results

TUVOLU will address large knowledge gaps in Arctic climate change science using an interdisciplinary approach. Achieving our objectives will require the integrated use of state-of-the-science methods in unique combinations across the disciplines of plant ecophysiology, biogeochemistry, meteorology, remote sensing, atmospheric sciences, and modelling.