Non-methane biogenic volatile organic compound emissions from boreal peatland microcosms under warming and water table drawdown

Abstract

Boreal peatlands have significant emissions of non-methane biogenic volatile organic compounds (BVOCs). Climate warming is expected to affect these ecosystems both directly, with increasing temperature, and indirectly, through water table drawdown following increased evapotranspiration. We assessed the combined effect of warming and water table drawdown on the BVOC emissions from boreal peatland microcosms. We also assessed the treatment effects on the BVOC emissions from the peat soil after the 7-week long experiment. Emissions of isoprene, monoterpenes, sesquiterpenes, other reactive VOCs and other VOCs were sampled using a conventional chamber technique, collected on adsorbent and analyzed by GC-MS. Carbon emitted as BVOCs was less than 1% of the CO 2 uptake and up to 3% of CH 4 emission. Water table drawdown surpassed the direct warming effect and significantly decreased the emissions of all BVOC groups. Only isoprene emission was significantly increased by warming, parallel to the increased leaf number of the dominant sedge Eriophorum vaginatum. BVOC emissions from peat soil were higher under the control and warming treatments than water table drawdown, suggesting an increased activity of anaerobic microbial community. Our results suggest that boreal peatlands could have concomitant negative and positive radiative forcing effects on climate warming following the effect of water table drawdown. The observed decrease in CH 4 emission causes a negative radiative forcing while the increase in CO 2 emission and decrease in reactive BVOC emissions, which could reduce the cooling effect induced by the lower formation rate of secondary organic aerosols, both contribute to increased radiative forcing.

Volatile emissions from thawing permafrost soils are influenced by meltwater drainage conditions

“…In the warmed soils, the emissions of all individual BVOC groups, except aldehydes, as well as the sum of all groups increased with temperature, which is in strong agreement with our second hypothesis. This finding is in accordance with other studies (Asensio, Peñuelas, Llusià, Ogaya, & Filella, ; Faubert et al., ) and was well expected as temperature impacts BVOC emission through several mechanisms including microbial activity and compound volatility. The Q 10 for the total BVOC emission was 2.5, which is normal for biological processes (Niinemets, ), and in‐line with Q 10 estimates of CO 2 soil production from the same sites (Elberling & Brandt, ) but lower than the Q 10 for plant BVOC emission usually being around 3–6 (Peñuelas & Staudt, ).…”

“…The emissions were temperature‐dependent, and pH, soil water content and SOM correlated well with the BVOC emission profile. The BVOC emission rate from the warmed soils was in the same range as the emission rate measured for boreal peat incubations (Faubert et al., , ).…”

“…Faubert et al. () studied emission from drained ombrotrophic peat soils, which had previously been incubated either with a normal water table or with a 20 cm water table drawdown. Similar to our study, they found relatively higher terpenoid emissions in the drier soils exposed to water table drawdown compared to the wetter soils with normal water table.…”

The shift in plant species composition in a subarctic mountain birch forest floor due to climate change would modify the biogenic volatile organic compound emission profile

“…The carbon emitted as BVOCs was 0.2% or less of the carbon emitted or sequestrated as CO 2 . This proportion is similar to those reported by other studies that examined the relationships between BVOC and CO 2 exchanges in a heath nearby the present study site (Tiiva et al 2008), and boreal and subarctic peatlands (Tiiva et al 2007(Tiiva et al , 2009Faubert et al 2010bFaubert et al , 2011. However, Bäckstrand et al (2008) measured a higher proportion of carbon emitted as BVOCs reaching 5% of the total carbon uptake of a subarctic peatland.…”

A comparison of isoprene and monoterpene emission rates from the perennial bioenergy crops short‐rotation coppice willow and Miscanthus and the annual arable crops wheat and oilseed rape

“…Differences in the meteorological conditions between the sampling locations were observed. Emission rates of isoprene and monoterpenes are known to vary with light and temperature (Guenther et al, 1993) and water availability (Faubert et al, 2011). Isoprene emission rates are controlled by both the capacity of the leaf to emit isoprene and the prevailing environmental conditions (Geron et al, 2000b;Monson et al, 1994).…”