Jonathan J. Ruel, Matthew P. Ayres. (1996). Variation in temperature responses among populations of Betula papyrifera. Silva Fennica vol. 30 no. 2–3 article id 5582. https://doi.org/10.14214/sf.a9227

Keywords: Betula papyrifera; adaptation; photosynthesis; growth; temperature; climate warming; elevation

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How will global warming affect southern populations of boreal trees? In paper birch, Betula papyrifera (Betulaceae), alpine trees with an evolutionary history of relatively cool summers may be more sensitive to climate warming than valley populations. We evaluated this scenario by growing seedlings from different populations in four temperature treatments (mountain field site, valley field site, and two greenhouse rooms).

Populations from low elevations germinated earlier and had higher germination success than population from high elevations (16.8 vs. 22.0 d; 72% vs. 11%). At the valley site, seedlings from native populations grew faster than seedlings from higher elevations (mean ± SE = 0.25 ± 0.02 vs. 0.09 ± 0.04 mm · cm^-1 ·d^-1) while at the mountain site, all seedlings grew at similar rates. Seedling grown in cooler environments had higher root : shoot ratios, perhaps to compensate for temperature limitations in nutrient uptake by roots. Leaf area varied among populations but was not affected by environmental differences across the field sites. Net photosynthetic rates at valley temperatures were higher for seedlings grown in the valley than for seedling grown in the mountains or the warm greenhouse (12.0 vs. 10.3 and 5.8 μmoles · m^-2 · s^-1), perhaps due to adaptive phenotypic adjustments. Climatic warming could rapidly produce important phenotypic changes in birch trees (e.g. decreased root : shoot ratio, reduced growth in alpine populations). On a longer time-scale, warming could also result in genetic changes as natural selection favours valley genotypes in alpine sites where they are presently rare.

Ruel, E-mail: jr@mm.unknown
Ayres, E-mail: ma@mm.unknown

Category : Research article

article id 46, category Research article

Matti Rousi, Boy J.H.M. Possen, Risto Hagqvist, Barb R. Thomas. (2012). From the Arctic Circle to the Canadian prairies – a case study of silver birch acclimation capacity. Silva Fennica vol. 46 no. 3 article id 46. https://doi.org/10.14214/sf.46

Keywords: acclimation; Betula papyrifera; Betula pendula; birch adaptability; critical night length; provenance transfers

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Earlier provenance research has indicated poor success even in short distance transfers (> 2–3° latitude) of silver birch (Betula pendula Roth) southward from their origin. These results may indicate poor adaptability of silver birch to a warming climate. Some of the scenarios for a warming climate in Finland suggest effective heat sums are likely to double in the north and increase 1.5 fold in the south for the period of 2070–2099. Consequently, the outlook for silver birch appears bleak. To study the acclimation of birch to this projected change we established a provenance trial in northeastern Alberta, Canada, at the temperature area currently predicted for Central Finland (lat. 64–66°N) at the turn of this century (1400 dd). Our 10-year experiment showed that all the Finnish provenances (origins 61–67°N) have acclimated well to the warmer growth conditions experienced in Alberta at 54°N. These results suggest that silver birch has the potential to acclimate to thermal conditions predicted for Finland at the end of the 21st century. Our results also indicate that silver birch has the potential as a plantation species in Canada, where the Finnish birch grew faster in the boreal forest region of Canada than local paper birch (Betula papyrifera Marsh.) provenances.

Rousi, The Finnish Forest Research Institute, Finland E-mail: matti.rousi@metla.fi
Possen, The Finnish Forest Research Institute, Finland E-mail: bjhmp@nn.fi
Hagqvist, The Finnish Forest Research Institute, Finland E-mail: rh@nn.fi
Thomas, University of Alberta, Dept of Renewable Resources, Edmonton & Alberta-Pacific Forest Industries Inc., Boyle, Alberta, Canada E-mail: brt@nn.ca

Category : Research note

article id 659, category Research note

Anneli Viherä-Aarnio, Pirkko Velling. (1999). Growth and stem quality of mature birches in a combined species and progeny trial. Silva Fennica vol. 33 no. 3 article id 659. https://doi.org/10.14214/sf.659

Keywords: stem quality; growth; Betula pendula Roth; Betula pubescens Ehrh.; Betula papyrifera Marsh.; progeny; timber production

Abstract | View details | Full text in PDF | Author Info

The growth and stem quality of silver birch (Betula pendula), downy birch (B. pubescens) and paper birch (B. papyrifera) were compared in a 32-year-old field trial in southern Finland. The material consisted of different unselected stand origins and progenies of phenotypically selected plus trees of silver and downy birch from southern Finland and differing stand origins of paper birch from the North-West Territories, Canada. Growth, yield and a number of stem quality traits, including taper, sweep, stem defects, heights of different crown limits and length of the veneer timber part of the stem were measured or observed. The native Finnish silver and downy birches were superior to paper birch in terms of both yield and stem quality, silver birch being the best. Progenies of silver birch plus trees were better than the stand origin, indicating that the former are able to reach high quality veneer log size in a shorter time than unselected material. The cultivation of paper birch can not be considered viable in Finland.

Viherä-Aarnio, The Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: anneli.vihera-aarnio@metla.fi
Velling, The Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: pv@nn.fi

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