Current issue: 54(2)

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Silva Fennica 1926-1997
Acta Forestalia Fennica

Articles containing the keyword 'elevation'.

Category: Research article

article id 538, category Research article
Seppo Nevalainen. (2002). The incidence of Gremmeniella abietina in relation to topography in southern Finland. Silva Fennica vol. 36 no. 2 article id 538.
Field data of the 8th National Forest Inventory (NFI) from southern Finland and digital elevation models (DEMs) were used in this study. Damage due to Gremmeniella abietina increased slightly with an increase in absolute elevation in mineral soils. Severe damage increased almost linearly with an increase in elevation in mineral soil plots. The mean elevation in the tract area (the 7 km x 8 km area surrounding the plot) was more strongly correlated with the disease than the elevation of individual plots. The relative altitude of the plot was important: the disease was most severe in the plots situated lower than the mean elevation of the tract area, especially in the peatland plots. In this group, the damage increased linearly with an increase in absolute elevation. According to detailed DEMs in the most diseased areas, steepness of the slope was negatively correlated with the disease. The aspect of the slope had a weak influence. On mineral soils, the disease was most common in south-facing slopes. The microtopography was not as important for the disease occurrence as the relative elevation of the plot. The disease frequencies were very similarly related to the three most common types of surface features (channels, ridges and planar regions) within the 50-m scale. At the cell size of 100 metres, the disease was more common in channels than in ridges, except in mineral soil plots. Topographic variables only partly explained the regional patterns in the occurrence of this disease. The disease was frequent on upland areas, but, on the other hand, it was also common on lowland areas. The most diseased areas studied in detail differed very much from each other with respect to topography and the disease incidence.
  • Nevalainen, Finnish Forest Research Institute, Joensuu Research Centre, P.O. Box 68, FIN-80101 Joensuu, Finland ORCID ID:E-mail: (email)

Category: Article

article id 5582, category Article
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.

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, ORCID ID:E-mail:
  • Ayres, ORCID ID:E-mail:

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