Editing Birch (section)

==Ecology==
[[File:Frosty Birches - panoramio.jpg|thumb|left|upright|Frosty birches in [[Kangasala]], Finland in February 2013]]
[[File:Hankasalmi stream.jpg|thumb|Birch trees by a river in [[Hankasalmi]], Finland]]
[[File:Stand of birch trees.jpg|thumb|A stand of birch trees]]
[[File:Sügise märgid.jpg|thumb|A birch tree in autumn]]
Birches often form even-aged stands on light, well-drained, particularly [[soil ph|acidic soils]]. They are regarded as [[pioneer species]], rapidly colonizing open ground especially in [[secondary succession]]al sequences following a disturbance or fire. Birches are early tree species to become established in [[primary succession]]s, and can become a threat to heathland if the [[seedling]]s and saplings are not suppressed by grazing or periodic burning. Birches are generally lowland species, but some species, such as ''[[Betula nana]]'', have a [[montane]] distribution. In the [[British Isles]], there is some difference between the environments of ''Betula pendula'' and ''Betula pubescens'', and some hybridization, though both are "opportunists in steady-state woodland systems". [[Mycorrhizal fungi]], including sheathing (ecto)mycorrhizas, are found in some cases to be beneficial to tree growth.<ref>''Birches''. (A Symposium, Royal Botanic Garden, Edinburgh 24–26 September 1982. [[Proceedings of the Royal Society of Edinburgh]], 85B, 1–11, 1984.</ref>

A large number of lepidopteran insects feed on birch foliage.