Impacts of soil moisture on de novo monoterpene emissions from European beech, Holm oak, Scots pine, and Norway spruce

Abstract

Abstract. Impacts of soil moisture on de novo monoterpene (MT) emissions from Holm oak, European beech, Scots pine, and Norway spruce were studied in laboratory experiments. The volumetric water content of the soil, , was used as the reference quantity to parameterize the dependency of MT emissions on soil moisture and to characterize the severity of the drought.When dropped from 0.4 m 3 × m −3 to ∼ 0.2 m 3 × m −3 slight increases of de novo MT emissions were observed but with further progressing drought the emissions decreased to almost zero. In most cases the increases of MT emissions observed under conditions of mild drought were explainable by increases of leaf temperature due to lowered transpirational cooling. When fell below certain thresholds, MT emissions decreased simultaneously with and the relationship between and MT emissions was approximately linear. The thresholds of (0.044-0.19 m 3 × m −3 ) were determined, as well as other parameters required to describe the soil moisture dependence of de novo MT emissions for application in the Model of Emissions of Gases and Aerosols from Nature, MEGAN.A factorial approach was found appropriate to describe the impacts of , temperature, and light. Temperature and influenced the emissions largely independently from each other, and, in a similar manner, light intensity and acted independently on de novo MT emissions. The use of as the reference quantity in a factorial approach was tenable in predicting constitutive de novo MT emissions when changed on a time scale of days. Empirical parameterization with as a reference was only unsuccessful when soil moisture changed rapidly

Ecosystem‐scale volatile organic compound fluxes during an extreme drought in a broadleaf temperate forest of the Missouri Ozarks (central USA)

“…In addition, several studies have reported that isoprenoid emissions continue under drought when photosynthesis has already decreased substantially and even increases in isoprenoid emissions during the first stages of the drought stress can occur (e.g. Bertin & Staudt, ; Pegoraro et al ., ,b; Fortunati et al ., ; Genard‐Zielinski et al ., ; Potosnak et al ., ; Wu et al ., ). Similarly, our measurements show that isoprenoid emissions continued to increase concurrently with a decrease in photosynthetic CO 2 fixation at the beginning of the summer (Fig.…”

Interaction of drought and ozone exposure on isoprene emission from extensively cultivated poplar

“…No significant interaction between O 3 and drought was found in leaf‐unit isoprene emission, suggesting that the stimulation due to a moderate drought did not significantly affect the negative response of isoprene to E‐O 3 and vice versa, thus confirming an uncoupling of A sat and isoprene emission under stress (Wu et al . ). When isoprene emission was up‐scaled to the plant level, however, WW plants emitted around twice isoprene in clean air relative to E‐O 3 .…”

“…; Wu et al . ). Therefore, studies on the combined effects of O 3 and drought on BVOC emissions are really needed in order to better understand how plants will react under future climatic and pollution scenarios.…”

Canopy level emissions of 2-methyl-3-buten-2-ol, monoterpenes, and sesquiterpenes from an experimental Pinus taeda plantation

“…These α-pinene fluxes values range from equivalent to six times higher than the default MEGAN estimates. These authors note that the highest values were associated with onset of drought in August, which may increase leaf temperatures due to reduced transpiration, resulting in increased terpene flux (Wu et al, 2015). Of these four studies, July rainfall was indeed the lowest (6.4 cm rainfall month − 1 vs. 9.1 to 19.6 cm rainfall month −1 for the other three studies).…”