Woodland Ways – Native Trees of the British Isles

Woodland Ways – Native Trees of the British Isles:
When talking about trees, perhaps ‘native’ should mean any species that colonises a specific area naturally. Such terminology is never that easy though, as Gary Marshall explains.

Some sources define ‘native trees’ as those that have resided here since the last Ice Age glaciations retreated. Thus the first ‘native tree’ on the edge of the retreating tundra may have been the downy willow (Salix lapponum) – a shrub that can still be found in the Scottish mountains.
Tree fossils from species similar to Chile pines (Araucaria araucana) have been found in Purbeck rocks. Time has long since swept away the likes of these trees from our shores, although even garden centres now stock cultivated versions.
Over that time, seas, lakes, rivers, mountains and land masses have changed enormously. There have been Ice Ages and warmer spells.

Defining ‘native’
There are constant efforts to standardise the term ‘native’ and make it more conclusive. Many argue that it should refer only to those plants that were here when the land bridge, via Doggerland to mainland Europe, was breached by the North Sea some 6500 years ago. Different definitions apply to Scotland, Ireland and outlying isles. There are lists that include ‘archaeotypes’, which are trees that were present from specific human times.
Such lists may then include the English elm (Ulmus procera) – a tree that is thought to emanate from clones introduced in Roman times – or the sweet chestnut (Castanea sativa) whose presence is evidenced in medieval records. Trees introduced by man in any era can naturalise and spread, but these are not generally classed as native. But what if new species of airborne tree seeds were to reach us naturally now and spread? Should these be logically called non-native? 

Evidence
Tiny pollen grains are unique to each tree species and survive in bogs other soil and sediment. Pollen, submerged forests, fossilised trees, twigs and leaves have all helped to build a picture of the trees that were here in the fourth millennium BC. The Online Atlas of British and Irish Native Flora, compiled by the Biological Records Centre, lists some 80 ‘native’ species of tree and shrub. Other listings contain as few as 30 species. I don’t dispute any specific records but, since regionally ‘native species’ can change in little over one human lifespan, I suspect there is much still to learn. This is a hotly disputed and much studied subject.

Myth busting?
Any tree I mention or list as ‘native’ here is likely to be based on my knowledge, belief, research, findings and – I admit – possible established misinformation, hearsay and rural myth. You may have heard the term ‘honorary native’ applied to the sweet chestnut – a native of southern Europe – perhaps because it’s so useful, often old and handsome. Could some storm-blown sycamore (Acer pseudoplatanus) seeds have reached us naturally over the last few millennia? You won’t find many lists of natives that include this ubiquitous tree. 

List busting
So, here’s my list, with omissions but with brief observations. It excludes small natives and climbing or short-lived woody shrubs, e.g. heather, myrtle, broom, gorse, rose and bramble. Also regional sub-species are not listed. Nevertheless, I hope you find it an interesting reference. What may surprise you are the many common trees that just aren’t natives, such as sweet chestnut, horse chestnut (Aesculus hippocastanum), common lime (Tilia vulgaris), sycamore – I daren’t list it – and all conifers other than the first three trees on my list. Several trees I’ve included only occur in native stands regionally in the UK or on particular sub-soils, i.e. Scots pine (Pinus sylvestris) is native only to the remnants of the Caledonian forests in Scotland; whitebeams (Sorbus aria) you’ll mainly find on chalk or limestone and the strawberry tree (Arbutus unedo) just in a small area of County Kerry in Ireland.

Which natives that are listed here are on your doorstep? Happy hunting!