Interactive effects of elevated ozone and springtime frost on growth and physiology of birch (Betula pendula) in field conditions

Abstract

We studied the impact of ozone enrichment and late frost, singly and interactively, on four birch (Betula pendula Roth) families selected from a naturally regenerated birch stand in southeastern Finland. Seedlings were exposed to 1.59 ambient ozone over one and a half growing seasons using free-air ozone enrichment system. Simulated springtime frost was implemented at the beginning of the second study year, 4 weeks after the bud burst. Plants were measured for timing of bud burst, visible ozone injuries, chlorophyll fluorescence, net photosynthesis and concentrations of photosynthetic pigments, as well as for growth and carbon allocation. Frost treatment caused a rapid 60% decline in net photosynthesis. The recovery of net photosynthesis from acute frost treatment was not complete during the subsequent 3 weeks, which led to significant growth reductions, decreased shoot/root ratio and accumulation of excess nitrogen in the leaves. Photosynthetic responses to ozone were very variable and family-specific. Concentrations of photosynthetic pigments were sensitive to both stress factors, while the maximum quantum yield of PSII was unaffected. Ozone exacerbated the effect of frost only on diameter increment. However, ozone and frost affected different seedling characters, e.g., ozone reduced pigments and frost collapsed net photosynthesis, and these effect combined appear to damage birch seedlings more than a single stress situation.

Intrapopulation Genotypic Variation of Foliar Secondary Chemistry during Leaf Senescence and Litter Decomposition in Silver Birch (Betula pendula)

“…Due to its ecological and economic importance in the northern areas, the intra- and interpopulation genotypic variation of B. pendula traits have been a subject of intensive research. The studies have covered tree growth ( Prittinen et al, 2003 ; Silfver et al, 2009 ; Mikola et al, 2014 ) and physiology ( Silfver et al, 2008 ; Possen et al, 2014 ) as well as herbivore susceptibility ( Rousi et al, 1991 , 1997 ; Pusenius et al, 2002 ; Sinkkonen et al, 2012 ) and decomposition of leaf litter ( Silfver et al, 2007 , 2015 ). Foliar secondary metabolites ( Keinänen and Julkunen-Tiitto, 1998 ; Laitinen et al, 2000 ), their genotypic variation and role in herbivore and stress responses ( Mutikainen et al, 2000 ; Yamaji et al, 2003 ) are equally well known for B. pendula .…”

European aspen and hybrid aspen under changing environment – Leaf traits, growth and litter decomposition

“…The delayed formation of terminal buds suggests this to be at least partly mediated by an N-related prolongation of the vegetative period. These results suggest that high N inputs, such as doses used in nursery fertilization, may predispose aspen to damage by both autumn and spring frosts, which in turn can adversely affect subsequent growth (Silfver et al 2008). However, the negative effect of high N supply on frost hardening was evident mainly at the beginning of the frost hardening period, implying that if the hardening period is long enough, N supply does not notably affect frost hardiness later in the autumn / winter.…”

Temporal Changes in Ozone Concentrations and Their Impact on Vegetation

“…Later research focused particularly on the interactive effects of elevated [O 3 ] and spring frost events [160,161]. While ozone (1.3 × ambient) exacerbated the effect of frost (applied after bud burst) only on diameter increment of Silver birch (Betula pendula), interactive effects on a number of physiological variables, including photochemical quantum yield of photosystem II, photochemical quenching of absorbed light energy and chlorophyll and carotenoid contents, were observed [149].…”