Differential impacts of long-term (CO2) and O3 exposure on growth of northern conifer and deciduous tree species

Abstract

The long-term effects of elevated CO 2 and CO 2 +O 3 concentrations on the growth allocation in northern provenances of Norway spruce [Picea abies (L.) Karst.], Scots pine [Pinus sylvestris (L.)] and pubescent birch clones (Betula pubescens Ehrh.) were examined in open-top chambers after a 4-year-long experiment. The total biomass responses of the tree seedlings to increased CO 2 and CO 2 +O 3 concentrations were not statistically significant and varied between the provenances and species. The seedlings of northern origin were the least sensitive in their response to treatments. The total biomass of the Norway spruce seedlings slightly decreased in response to CO 2 in three provenances. Scots pine from the local provenance had a slight biomass increase after elevated CO 2 +O 3 treatment. The slowergrowing birch clone seemed to benefit from elevated CO 2 , whereas in the faster-growing clone, reductions in biomass accumulation were seen. The combined CO 2 +O 3 treatment reduced the positive effects of elevated CO 2 , especially in the slower-growing birches. Observations of significant effects were limited to a few parameters. Carbon dioxide treatment decreased needle dry weight of Norway spruce in one northern provenance. The needle and wood dry weight increased (CO 2 + O 3 ) in local Scots pine. Significant birch response was limited to increased fine root density (O 3 + CO 2 ) in the inland clone. The diverse effects of elevated CO 2 and CO 2 +O 3 on seedling growth and biomass provide evidence that exposure of northern trees to the enhanced variable CO 2 and O 3 concentrations of the future will have varied effects on the growth of these species. The direction and magnitude of those effects will differ depending on species and origins.

Conifer stem growth at the altitudinal treeline in response to four years of CO2 enrichment

“…The treeline ecotone is considered in many respects a harsh environment (Körner, 1998), such that the lack of responsiveness to CO 2 by Pinus , the more classic of the two treeline genera in our study and which is arguably not carbon limited according to a global comparison of treeline Pinus (Hoch & Körner, 2003), would fit this interpretation. Vanhatalo et al (2003) also found less responsiveness in the northern (more harsh environment) of two provenances of 10‐year‐old P. sylvestris in their 4‐year OTC study in Finland. In the only other long term in situ test of elevated CO 2 concentrations in harsh high mountain conditions (a Carex sward at 2500 m a.s.l.…”

“…Studies in which conifers showed a clear ring width or biomass response to elevated CO 2 treatment, like we observe after four years in L. decidua, include a 4-year OTC experiment of P. taeda seedlings growing under nonlimiting nutrient conditions (Telewski et al, 1999), as well as a 4-year study starting with 13-year-old P. taeda growing on old fields (Hamilton et al, 2002), a 3-year OTC study starting with 3-year-old P. sylvestris (Ceulemans et al, 2002) and a 4-year phytotron study starting with 1-year-old P. sylvestris (Ziche & Overdieck, 2004), both growing in unamended but fertile soils, and a 4-year model ecosystem study starting with 2-to 3year-old Picea abies grown in natural forest soils of low and high fertility (Spinnler et al, 2002). In contrast, conifer studies showing no significant response to CO 2 enrichment, like we observe in P. uncinata, include a 4-year OTC study starting with 2-year-old Pseudotsuga menziesii under low nutrients (Olszyk et al, 2005), a 3-year model ecosystem study of 4-year-old P. abies under low and high nutrients (Hättenschwiler et al, 1996), a 4-year OTC study of varying provenances of P. sylvestris and P. abies seedlings under nonlimiting nutrient conditions (Vanhatalo et al, 2003) and two phytotron studies on Larix species, L. sibirica and L. kampferi seedlings, under low and high fertility (Yazaki et al, 2001(Yazaki et al, , 2004. Four further studies where no overall significant growth response to elevated CO 2 is reported (although singular year effects or marginal effects were observed) include a 3-year OTC study of tissue cultured P. radiata seedlings under low and high nutrients where a significant effect was observed under high nutrients in the first year only (Atwell et al, 2003), a 6-year OTC study of P. ponderosa seedlings under varying N levels where an increase in biomass was also observed in the first year only (Johnson et al, 2006), a 3-year OTC study of 15-year-old P. sylvestris under low nutrients where although no significant effect was reported due to large variance, a doubling of radial growth was observed (Kilpeläinen et al, 2003), and a 3-year whole tree chamber study of 41-year-old P. abies where significantly wider rings were only observed in the second year of a 3-year experiment under low nutrient treatment (Kostiainen et al, 2004).…”

Regional potential yields of short rotation willow plantations on agricultural land in Northern Europe

“…In addition, the predicted rise in the temperature and CO 2 levels can lead to significant growth stimulation on properly fertilised plantations, although the magnitude of this increment will depend strongly on various and confounding factors (Weih 2004): i.e. the performance of the varieties used (Vanhatalo et al 2003) and possible pest diseases. In addition, significant yield improvements can be expected in the next years, beyond the scope of the projections presented.…”

Assessment of the Risk of Amazon Dieback

“…7. For commercial forestry this would mean that slow-growing trees may respond li le to elevated CO 2 (e.g., Vanhatalo et al 2003), while fast-growing trees would possibly do so more strongly (Calfapietra et al 2003;Liberloo et al 2005;Wi ig et al 2005). T he previous analysis was made on the basis of no land use change and in response to climate-induced changes in rainfall through a dynamic (LPJmL) vegetation model.…”