Birch

Betula spp.

1. Identification and origin

Birches (Betula spp.) belong to the Betulaceae family and include several tree species widely distributed in the northern hemisphere. Among the most common species are Betula pendula Roth (white birch or silver birch) and Betula pubescens Ehrh. (downy birch). The genus originates from the temperate and boreal regions of Europe, Asia and North America, being characteristic of cold forests and poor soils.

2. Economic importance

Birches have ornamental, forestry and ecological value. The wood is used in furniture, plywood, utensils and paper pulp. In urban afforestation, they are appreciated for their elegant form and decorative bark. Ecologically, they are pioneer species, colonising degraded soils and contributing to forest succession.

3. Botanical characterisation

Medium-sized deciduous trees, generally between 10 and 25 m tall. The bark is characteristic, whitish or silvery, peeling off in thin laminae. The leaves are simple, alternate, ovate to triangular, with serrate margins. The inflorescences are catkins: the male ones pendulous and the female ones shorter and erect. The fruits are small samaras with membranous wings, dispersed by the wind.

4. Edaphoclimatic requirements

Birches prefer temperate to cold climates, tolerating frosts and high thermal ranges. They develop well in fresh, light, well-drained and moderately acidic soils. They are heliophilous species, sensitive to prolonged droughts and compacted soils.

5. Main pests

• Aphids (Aphididae): honeydew and sooty mould.
• Defoliating caterpillars (Geometridae): reduction of leaf area.
• Xylophagous beetles (Scolytinae): perforations in the trunk and branches.
• Mites (Tetranychidae): chlorosis and reduction of vigour.

6. Main diseases

• Powdery mildew (Erysiphe spp.): white mycelium on the leaves.
• Cankers caused by Nectria spp.: necrosis in the trunk and branches.
• Root rots (Armillaria spp.): progressive decline and death.
• Rust (Melampsoridium betulinum): orange pustules on the underside of the leaves.

7. General crop management

Management includes choosing species adapted to the local climate, planting in well-drained soils and maintaining regular irrigation during dry periods. Pruning should be carried out in late winter to avoid excessive bleeding. In an urban context, it is important to avoid soil compaction and mechanical damage to the trunk. Pest and disease monitoring should be regular, especially in young trees.

Bibliographic references

• EPPO Global Database – Betula spp..
• CABI Invasive Species Compendium – Betula pendula, Betula pubescens.
• Atkinson, M. D. (1992). Betula pendula Roth and Betula pubescens Ehrh. Journal of Ecology, 80(4), 837–870.
• Perala, D. A., & Alm, A. A. (1990). Reproductive ecology of birch: a review. Forest Ecology and Management, 32, 1–38.
• Hynynen, J., Niemistö, P., Viherä‑Aarnio, A., et al. (2010). Silviculture of birch species in Europe. In: Spiecker, H. (Ed.), European Forest Institute Research Report.