Native trees in the UK support a vast array of life because they have co-evolved with local wildlife over thousands of years
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The following native trees support the highest numbers of other species:
English Oak (Quercus robur) and Sessile Oak (Quercus petraea): The undisputed "kings" of biodiversity, supporting over 2,300 species.
They provide habitat for 1,178 invertebrates, 716 lichens, 108 fungi, and 38 bird species.
About 326 species depend solely on oak for their survival.
Scots Pine (Pinus sylvestris): As of early 2026, research identifies it as a critical keystone species supporting 1,589 species.
This includes 539 fungi, 468 lichens, 420 invertebrates, 130 mosses, 17 birds, and 15 mammals.
Losing Scots pine would threaten 215 "obligate" species that are found only on this tree.
Hawthorn (Crataegus monogyna): A vital "all-rounder" that supports more than 300 insect species.
Its dense, thorny structure provides safe nesting sites for many birds, while its spring blossom and autumn berries (haws) are essential food sources for pollinators and birds.
Silver Birch (Betula pendula): Supports over 300 insect species and a wide range of fungi.
Its light, open canopy allows enough light for ground-dwelling plants like bluebells and wood sorrel to thrive beneath it.
Willow (Salix species): Particularly the Goat Willow (Salix caprea), which is one of the most important early-spring food sources for bees.
It supports various moth species, including the sallow kitten and lunar hornet clearwing.
Hazel (Corylus avellana): Supports roughly 106 insect species and is the primary habitat for the rare hazel dormouse.
Its nuts are a staple food for squirrels, nuthatches, and jays.
While native trees like the Oak and Scots pine support the highest overall levels of biodiversity in the UK (with Oak supporting over 2,300 species), several introduced (non-native) species have naturalised and now support significant, though generally lower, numbers of plants and animals.
Based on ecological data for 2026, the introduced trees that support the most biodiversity include:
Sycamore (Acer pseudoplatanus): Introduced in the 15th or 16th century, it is now the UK's third most common tree. It supports a high biomass of aphids, which in turn provides a major food source for birds and hoverflies. While it supports fewer specialist insect species than native oaks (approx. 15 vs. 284), its large leaves and fast growth provide significant habitat structure.
Sweet Chestnut (Castanea sativa): Introduced by the Romans, it is a significant source of nectar for pollinators like bees and produces nuts that are a vital food source for small mammals and birds.
Horse Chestnut (Aesculus hippocastanum): Introduced in the 1600s, its early-season flowers are a major nectar source for bees, and its seeds (conkers) are used by some mammals.
European Larch (Larix decidua): A non-native conifer that supports various specialist birds, such as siskins and redpolls. It is also the preferred nesting material for sparrowhawks.
Sitka Spruce (Picea sitchensis): Although primarily a commercial timber species introduced in 1831, mature plantations provide critical habitat for specialist conifer-dwelling birds like crossbills, goldcrests, and the rare crested tit.
Biodiversity Comparison
Tree Type
Key Species
Approx. Species Supported
Native
English Oak
2,300+
Native
Scots Pine
1,589
Native
Silver Birch
300+
Introduced
Sycamore
Significantly fewer specialists (approx. 15 insects) but high biomass
Introduced
Sweet Chestnut
High nectar value & mammal food
While introduced species contribute to the ecosystem, recent 2026 studies emphasize that they cannot replace native species; for example, it would take 23 different alternative species to support just 41% of the biodiversity specifically associated with the native Scots pine.