Interactive effects of elevated ozone and temperature on carbon allocation of silver birch (Betula pendula) genotypes in an open-air field exposure

Abstract

In the present experiment, the single and combined effects of elevated temperature and ozone (O(3)) on four silver birch genotypes (gt12, gt14, gt15 and gt25) were studied in an open-air field exposure design. Above- and below-ground biomass accumulation, stem growth and soil respiration were measured in 2008. In addition, a (13)C-labelling experiment was conducted with gt15 trees. After the second exposure season, elevated temperature increased silver birch above- and below-ground growth and soil respiration rates. However, some of these variables showed that the temperature effect was modified by tree genotype and prevailing O(3) level. For instance, in gt14 soil respiration was increased in elevated temperature alone (T) and in elevated O(3) and elevated temperature in combination (O(3) + T) treatments, but in other genotypes O(3) either partly (gt12) or totally nullified (gt25) temperature effects on soil respiration, or acted synergistically with temperature (gt15). Before leaf abscission, all genotypes had the largest leaf biomass in T and O(3) + T treatments, whereas at the end of the season temperature effects on leaf biomass depended on the prevailing O(3) level. Temperature increase thus delayed and O(3) accelerated leaf senescence, and in combination treatment O(3) reduced the temperature effect. Photosynthetic : non-photosynthetic tissue ratios (P : nP ratios) showed that elevated temperature increased foliage biomass relative to woody mass, particularly in gt14 and gt12, whereas O(3) and O(3) + T decreased it most clearly in gt25. O(3)-caused stem growth reductions were clearest in the fastest-growing gt14 and gt25, whereas mycorrhizal root growth and sporocarp production increased under O(3) in all genotypes. A labelling experiment showed that temperature increased tree total biomass and hence (13)C fixation in the foliage and roots and also label return was highest under elevated temperature. Ozone seemed to change tree (13)C allocation, as it decreased foliar (13)C excess amount, simultaneously increasing (13)C excess obtained from the soil. The present results suggest that warming has potential to increase silver birch growth and hence carbon (C) accumulation in tree biomass, but the final magnitude of this C sink strength is partly counteracted by temperature-induced increase in soil respiration rates and simultaneous O(3) stress. Silver birch populations' response to climate change will also largely depend on their genotype composition.

From the Arctic Circle to the Canadian prairies – a case study of silver birch acclimation capacity

“…Binkley et al 2010). The length of the growing period of silver birch is genetically determined and strongly connected to the height growth (Rousi and Pusenius 2005), and it has been shown that there is large within population genetic variation in birch's acclimation to changing climate (Kasurinen et al 2012). Breeding silver birch genotypes for better growth in Canadian conditions should thus be a very profitable approach and worth further consideration.…”

High temperatures change the perspective: Integrating hormonal responses in citrus plants under co‐occurring abiotic stress conditions

“…It has been reported that stomatal regulation, efficiency in reactive oxygen species (ROS) scavenging and accumulation of key proteins are crucial plant responses to survive this stress combination (Zandalinas et al , , Balfagón et al ). Furthermore, combination of high temperatures and ozone stress had a negative effect on Betula pendula growth and leaf biomass production because allocation of carbon is partly altered by ozone stress (Kasurinen et al ). Also, it has been described that aldehyde dehydrogenase enzymes, which contribute to redox balance by producing NADPH and NADH, are key in Arabidopsis thaliana (Arabidopsis) survival under combination of wounding and heat stress (Zhao et al ).…”

Significant decrease in yield under future climate conditions: Stability and production of 138 spring barley accessions

“…For example the following two topics have received little attention: Climate change has been found to affect various crop species differently (e.g., Feng and Kobayashi, 2009;Kimball, 1986;Luo, 2011;Mills et al, 2007), however, the intraspecific variation -between and within accessions -in response to changes has received little focus (e.g., Craufurd et al, 2003;Pleijel, 2011;Weigel and Manderscheid, 2012). Also, in studies of climate change effects on crop accessions, rather few have investigated the effects of treatments, where more than one climate factor was changed (Alemayehu et al, 2014;Clausen et al, 2011;Frenck et al, 2011;Juknys et al, 2011;Kasurinen et al, 2012;Mitchell et al, 1993;Zhou et al, 2011).…”