c6.8.13 – Carbon assimilation and isoprene emission in response to rising temperature and drought in Populus nigra saplings

Fodale R, Calfapietra C, Brilli F, Barta C, Fares S, Loreto F, Centritto M

CNR – Istituto di Biologia Agroambientale e Forestale, Via Salaria km 29.300, 00016 Monterotondo Scalo (Roma), Italy
Collocazione: c6.8.13 – Tipo Comunicazione: Poster
6° Congresso SISEF *
Sessione 8: “Poster: “Biodiversità, cambiamenti climatici, monitoraggio”” *

Abstract: Isoprene (2-methyl-1,3-butadiene) is one of many biogenic volatile organic compounds (BVOCs) emitted in copious quantities by plants that substantially influence the atmospheric chemistry. The rapid oxidation of isoprene in the atmosphere contributes to the formation of carbon monoxide, ozone, organic nitrates, organic acids, and secondary aerosols. Global Change events such as drought, coupled with rising temperatures may have contrasting effects on biogeochemical carbon cycles, regarding both photosynthestic carbon assimilation and isoprene emission by forests. To improve our understanding on the acclimatory responses of isoprene emission (IE), photosynthesis (A) and respiration (R) to rising temperatures and soil water availability (FASW), one-year-old Populus nigra saplings were exposed to soil water deficit at two different temperatures (25 and 35 C°). IE and A did not acclimate to high temperatures. In well-watered non-stressed plants, high temperature doubled IE and decreased A by 30%, whereas R acclimated to high temperatures showing a not significant increase of only 15%. Moreover, plant photosynthetic activity started to decrease at FASW of ~75% and ~85% at 25°C and 35°C respectively. Drought did increase the IE to A ratio, because IE was less responsive to drought than A at the two different temperatures. Consequently, the portion of assimilated carbon lost as isoprene always increases as water stress progressed. We conclude that future warmer and drier climate will 1) significantly increase tropospheric isoprene load depending on the severity of drought, and 2) strongly reduce photosynthetic carbon assimilation.

Citazione: Fodale R, Calfapietra C, Brilli F, Barta C, Fares S, Loreto F, Centritto M (2007). Carbon assimilation and isoprene emission in response to rising temperature and drought in Populus nigra saplings . 6° Congresso Nazionale SISEF, Arezzo, 25 – 27 Set 2007, Contributo no. #c6.8.13