Growth and crown architecture of two aspen genotypes exposed to interacting ozone and carbon dioxide

Abstract

Summary• A 2-yr phytotron study was conducted to investigate the intra-and inter-specific competitive behaviour of juvenile beech ( Fagus sylvatica ) and spruce ( Picea abies ). Competitiveness was analysed by quantifying the resource budgets that occur along structures and within occupied space of relevance for competitive interaction.• Ambient and elevated CO 2 and ozone (O 3 ) regimes were applied throughout two growing seasons as stressors for provoking changes in resource budgets, growth and allocation to facilitate the competition analysis. The hypothesis tested was that the ability to sequester space at low structural cost will determine the competitive success.• Spruce was a stronger competitor than beech, as displayed by its higher aboveground biomass increments in mixed culture compared with monoculture. A crucial factor in the competitive success of spruce was its ability to enlarge crown volume at low structural costs, supporting the hypothesis.• Interspecific competition with spruce resulted in a size-independent readjustment of above-ground allocation in beech (reduced leaf : shoot biomass ratio). The efficient use of resources for above-ground space sequestration proved to be a parameter that quantitatively reflects competitiveness.

Field responses of Prunus serotina and Asclepias syriaca to ozone around southern Lake Michigan

“…However, it is more likely that roots will suffer more from ozone exposures to the canopy because of reduced export from the foliage to the roots, but roots were not examined in this study. Reduced branch elongations are consistent with the review by Matyssek et al (1998) of biomass partitioning in trees in response to ozone, and with other studies of aspen (Dickson et al, 2001) and beech (Stribley and Ashmore, 2002) showing decreased branch length caused by ozone.…”

Effects of long-term ambient ozone exposure on biomass and wood traits in poplar treated with ethylenediurea (EDU)

“…Although not significant, in fact, this decrease suggests an allometric change within the crowns and is consistent with the significant 33% decrease found after three growing seasons of exposure. Dickson et al (2001), in two trembling aspen clones planted in the ground in open-top chambers and exposed for only 98 days, found similar effects of O 3 (58e71 ppm h AOT0) on all allometric ratios but L/B, likely because they investigated current-year branches only. In our experiment, both leaf and branch biomass decreased with O 3 , but the relative weight of leaves decreased even more.…”

“…The remaining leaves and the lateral branches were then collected. Lateral branches longer than 16 cm (Dickson et al, 2001) were counted.…”

Effects of elevated CO2 and/or O3 on hormone IAA in needles of Chinese pine

“…In contrast to the beneficial effects of elevated CO 2 , O 3 is generally detrimental to tree growth and metabolism. O 3 decreases plant height, and leaf area (Noormets et al 2001;Karnosky et al 2005;Dermody et al 2006) and total biomass (Dickson et al 2001;Gaucher et al 2003;Estes et al 2004).…”