CO2 and light effects on deciduous trees: growth, foliar chemistry, and insect performance

Abstract

This study examined the effects of CO and light availability on sapling growth and foliar chemistry, and consequences for insect performance. Quaking aspen (Populus tremuloides Michx.), paper birch (Betula papyrifera Marsh.), and sugar maple (Acer saccharum Marsh.) were grown in controlled environment greenhouses under ambient or elevated CO (38.7 and 69.6 Pa), and low or high light availability (375 and 855 μmol m s). Because CO and light are both required for carbon assimilation, the levels of these two resources are expected to have strong interactive effects on tree growth and secondary metabolism. Results from this study support that prediction, indicating that the relative effect of rising atmospheric CO concentrations on the growth and secondary metabolism of deciduous trees may be dependent on light environment. Trees in ambient CO-low light environments had substantial levels of phytochemicals despite low growth rates; the concept of basal secondary metabolism is proposed to explain allocation to secondary metabolites under growth-limiting conditions. Differences between CO and light effects on the responses of growth and secondary metabolite levels suggest that relative allocation is not dependent solely on the amount of carbon assimilated. The relative growth rates and indices of feeding efficiency for gypsy moth (Lymantria dispar L.) larvae fed foliage from the experimental treatments showed no significant interactive effects of light and CO, although some main effects and many host species interactions were significant. Gypsy moth performance was negatively correlated with CO- and light-induced increases in the phenolic glycoside content of aspen foliage. Insects were not strongly affected, however, by treatment differences in the nutritional and secondary chemical components of birch and maple.

Effects of simulated and insect herbivory on nitrogen and protein precipitable phenolic concentrations of two legumes

“…These results do not support some hypotheses which predict that more resources are spent on defenses in high-intensity herbivory conditions (Janzen 1974;Coley et al 1985). Similarly, McDonald et al (1999) found that increased CO 2 availability increases polyphenolic concentrations in certain trees. Starch, a product of photosynthesis (Sharkey 1985), is also positively correlated with accumulation of certain tannins, including CT (Lawler et al 1997;McDonald et al 1999).…”

“…Protein-binding affinity affects ruminant nutrition since it prevents microbial degradation in the rumen (Silanikove et al 2001;Min and Hart 2003;Pawelek et al 2008). PTC PB declined following 100% defoliation in this study as well as in that reported by Cooper et al (2014) corresponding to the physiologically costly requirements of making protein-binding compounds (Coley et al 1985;Keinänen et al 1999), since polyphenolic production is reliant on photosynthesis to fix carbon (Bryant et al 1983;McDonald et al 1999). These results do not support some hypotheses which predict that more resources are spent on defenses in high-intensity herbivory conditions (Janzen 1974;Coley et al 1985).…”

“…Similarly, McDonald et al (1999) found that increased CO 2 availability increases polyphenolic concentrations in certain trees. Starch, a product of photosynthesis (Sharkey 1985), is also positively correlated with accumulation of certain tannins, including CT (Lawler et al 1997;McDonald et al 1999). Even in nutrient-rich conditions, CT are much lower in low light (thus low photosynthetic activity) conditions for Eucalyptus spp., possibly mirroring conditions with little to no leaves (Lawler et al 1997), although severe defoliation increases polyphenolic response in some species (Bryant et al 1993).…”

Ecophysiological Responses of Northern Birch Forests to the Changing Atmospheric CO2 and O3 Concentrations

“…With some exceptions, Koike et al (2006) and Wang et al (2009) found a greater amount of tannin in leaves and an increased C/N ratio with CO 2 enrichment; also, herbivorous insects fed with leaves from a high CO 2 environment did less well. Other studies have also found changes in foliar chemical composition due to CO 2 enrichment (Ji et al, 2011;Mattson et al, 2005;Kuokkanen et al, 2003;McDonald et al, 1999). Because herbivory is an important component in C balance of trees, interactions between insect-herbivore and trees should also be taken into account in considering the effect on trees of atmospheric changes (Fig.…”

“…In a high CO 2 environment, the leaf N concentration ordinarily decreases (Zhang et al, 2008;Cao et al, 2007;Mattson et al, 2005;Juurola, 2003;Kuokkanen et al, 2003;McDonald et al, 1999;Tjoelker et al, 1998;Kubiske and Pregitzer, 1996). The reduction in leaf N is partly explained by dilution of leaf N with more assimilates from photosynthesis under elevated CO 2 , consistent with increased starch accumulation (Zhang et al, 2008;Mattson et al, 2005;Rey and Jarvis, 1998;Tjoelker et al, 1998), which is believed to be a factor in the down-regulation of photosynthesis (Peterson et al, 1999;Rey and Jarvis, 1998).…”