How Trees Reclaimed a Frozen Land The British landscape we know today, its rolling hills, hedgerows and scattered woodlands, is the product of thousands of years of change. But rewind far enough and none of it existed. After the last Ice Age, Britain was a treeless, frozen expanse. What followed was one of the most remarkable transformations in the natural history of these islands: the slow, steady return of the forests. A land emerging from ice About fifteen thousand years ago, the climate began to warm and the ice sheets that had smothered much of Britain started retreating northward. The southern parts of the country may have supported a sparse arctic grassland, but trees were entirely absent.  Sea levels remained low, vast quantities of water were still locked up in ice, so Britain was physically connected to mainland Europe. A broad plain of meandering rivers linked present-day East Anglia with the Netherlands and northern Germany, across a region now submerged beneath the North Sea and often referred to as Doggerland. This land bridge allowed plants, animals, and eventually human settlers to make their way into Britain from the continent, setting in motion changes that would reshape the landscape dramatically. The pioneer trees arrive Trees gradually colonised the bare ground. The first wooded areas were likely dominated by birch — species such as Betula nana and B. pubescens that tolerate extreme cold. Although the climate was warming, conditions were still too harsh for many pollinating insects. Birch is wind-pollinated, making it an ideal pioneer species: one that can establish itself on immature or disturbed soils in challenging environments. In doing so, pioneer species modify their surroundings and 'open the door' for others to follow, a process known as succession. Over time, pine, aspen and hazel arrived and took hold, followed later by elm, oak and small-leaved lime. Forests spread across Britain, covering the land except for the highest, wettest and coldest areas. Reading the past through pollen How do we know what grew where, and when? Pollen analysis of peat bogs and other sedimentary deposits can reveal which species were present over different periods. The outer wall of a pollen grain — the exine — is extraordinarily resistant to decay, so its distinctive structure remains intact for millennia, allowing researchers to identify species long after the trees themselves have vanished. The wildwood takes shape By around six thousand years ago, forest covered most of the British countryside. This great expanse of woodland is often called the “wildwood”, a term popularised by Oliver Rackham in Trees and Woodlands in the British Landscape. The wildwood was at its most abundant during this period: a complex, tangled mosaic of trees, many of them dead or dying from the effects of wind, fire sparked by lightning, and flooding. It would have offered a rich variety of habitats and niches for plants, insects and mammals alike. Not as dense as you might think Recent research and pollen analysis published in the Journal of Ecology suggests that Europe’s post-glacial wildwoods were rich in hazel, oak and yew; species that tend to flourish in more open woodland where light reaches the ground, rather than in dense, closed-canopy forest. Hazel produces more pollen and flowers freely in sunlit conditions. Yew, while sensitive to fire, is shade-tolerant and needs some space and light to avoid being outcompeted by taller trees. Its leaves are toxic to most mammals (including humans), which protects it from grazing. The persistence of yew in ancient woodlands, along with its sensitivity to fire, points to a relatively open woodland structure; one maintained, it is thought, by the grazing activity of large herbivores. Oak, too, is a light-demanding species whose seeds germinate best on disturbed ground. Large herbivores consume huge quantities of vegetation, altering plant biomass and community composition. They also cause physical damage through trampling and bark-stripping. These processes can help create clearings and maintain open areas within the woodland. The resulting light reaching the forest floor would have encouraged a rich ground flora to flourish beneath the canopy. A living legacy Britain’s wildwood may be largely gone, but its legacy runs through the landscape. The oaks, hazels and yews that define many of our oldest woodlands are living links to those post-glacial forests. Understanding how they established themselves and how grazing, fire and climate shaped the woodland around them isn’t just a matter of historical curiosity. It offers practical insight for anyone involved in woodland conservation and restoration today. The wildwood reminds us that British forests were never static or uniform; they were dynamic, open and shaped  by many animals,  and the elements. 

Burrs or Burls? What’s in a name. What are they?  They are woody outgrowths found on stems, branches, and often on roots.  They are  typically rounded, somewhat bulbous in form.  Burrs develop as a result of rapid and uncontrolled growth,  leading to a dense and irregular wood grain beneath the external bark of the structure. The uncontrolled and abnormal growth may result from various stressors, such as :- Physical damage eg. wounds, where branches are lost in high winds, injuries as the result of boring insects, or damage from squirrels or deer. Infections caused by bacteria, viruses, or fungi may trigger burr formation  These infections can induce  hormonal changes that affect cell division. Environmental factors such as extreme weather events or pollution can influence tree physiology and growth, as can somatic mutations. In most cases, a burr does not harm a tree, indeed they may persist for decades.  If the burr formed due to injury to the tree, then it could even be considered protective.  However, If a burr develops on a branch then it may become so heavy that the branch breaks. Burrs may be seen on a variety of trees, but some species are more prone to developing them, notably oaks, maples, walnut, and birch.  Coastal redwoods are known to produce burrs of considerable size, sometimes reaching several metres in width and even encircling the trunk of the massive trees..  Although burrs may not be visually appealing from the outside, internally the complex grain pattern means makes them highly valued for woodworking.  They are used to create bowls, furniture, musical instruments and sculptures.  It is generally unwise to cut a burr from a living tree; instead they are typically harvested from fallen or dead trees. Thanks to Steve Sangster for Burr images.

We purchased Knox Wood in August 2023, part of Boltonmuir Wood, an old woodland site on fairly boggy ground in East Lothian. Our five acres are split 50% almost pure birch (Silver and Downy) regenerating [about 20 years old] and 50% mature Scots Pine that is well thinned over mixed natural regeneration.  All of the site has previously been used for commercial forestry so there is plenty of natural regeneration from Sitka Spruce, Douglas Fir, Western Hemlock, Silver Fir and Larch. Some oak, rowan, hawthorn and beech regeneration is also present. Roe deer use the site but are not having much impact on the trees, just ticks to be aware of.   Plenty of mosses, ferns and bracken that indicate acidic soil conditions. Our plan is to improve the site for biodiversity and use some birch for green wood working.  So far we have been taking out non-native conifer regen, leaving a few that are suitable for bird nesting and to provide a bit of evergreen shelter. A few Rhododendrons to eliminate as well, easy enough using the lever and mulch technique. We will create some standing deadwood and add to the fairly good level of deadwood from previous birch thinning that is now well rotten.  We will add a few native species, such as Aspen and maybe more Willows for weaving.   Also hoping to grow some edible fungi on site, there are wild mushrooms and I am sure plenty of people already roam around there collecting them.  As Alien Spoons, I teach green wood working so will thin out the birch for spoon carving, shrink pots, bowls and other treen.  Maybe make some besoms and other products with it as well.    [caption id="attachment_41045" align="aligncenter" width="675"] Birch regenerating[/caption]  

A besom is a bunch of twigs tied to a handle to make a broom. In fiction and children’s stories, a witch is often depicted as flying on such a broom. However, a witch’s broom* can also refer an abnormal growth of twigs in a tree. A number of trees and shrubs (evergreen or deciduous) can develop these ‘abnormal growths’, but in the UK they are more likely to be seen on Birch.  When high up in the canopy, they may be mistaken for a bird’s nest or a ball of mistletoe.  Mistletoe is a different organism, a partial parasite, growing on the tree, whereas a witch’s broom is part and parcel of the tree itself. Normally, the buds of a tree develop in a predetermined sequence that is governed / controlled by plant hormones.  On a twig or stem, the apical bud is dominant and the lateral buds are ‘held back’.  This is under the control of the growth regulator - auxin (indole acetic acid).  Auxin slows or inhibits the growth of the lateral buds so that the apical bud is favoured.  If auxin production is impaired the regulated development of the twigs is upset so that many buds open and develop, and a multitude of closely packed twigs is formed.   Many things can interfere with auxin production, for example, physical damage to a tree, which may allow the entry of micro-organisms - for example, infection with the fungus Taphrina betulina. This fungus can affect dwarf birch, silver birch and downy birch.  Different species of Taphrina can infect hornbeam and cherry resulting in witches brooms on these trees.  Sometimes, a witch’s broom can form as a result of a mutation occurring in a growing region (meristem).  Such brooms are more often seen in certain conifers, sometimes cuttings of these are propagated to make attractive dwarf or colourful new cultivars (for example Picea abies 'Clanbrassiliana Stricta’). * or hexenbesen in German. Thanks to Torquil and Helen for images.

They grow in dense overlapping tiers on dead stumps and branches, the felty topside of these semi-circular shelves primarily an orange to tawny brown colour demarcated to form zones of different colours, including a rather striking blue in places, and tending towards white at the edges. The Crimped Gill, or Plicatura crispa (also Plicaturopsis crispa), does indeed from such descriptions, sound remarkably similar to the Turkey Tails described in last month’s post. In these winter months when bracket fungi are plentiful in our woodlands, there are a good number of fungi that might be confused with Turkey Tails, in fact, from the False Turkey Tails and Hairy Curtain Crusts described last month, through the Tripe Fungus covered in a Fungi Focus from last February and other lookalike species such as the Smokey Bracket (Bjerkandera adusta).  Read more...

Checking through my emails, I came across a link sent by a friend to one of the winter talks in the program offered by the Botanical Society of Scotland - specifically “The Scottish Uplands: how to revive a degraded landscape” by Dr Helen Armstrong.  The talk was live-streamed but was also recorded and is available here.   Dr Armstrong spent 24 years at the Nature Conservancy Council, the Macaulay Land Use Research Institute, Scottish Natural Heritage and Forest Research carrying out research and advisory work. The following is an attempt to summarise some of the key features of her informative and enlightening talk. Read more...

Bark is the term that is often applied to the outer covering of tree stems and other woody plants. It serves to protect a tree from  Water loss Insect attack Infection by bacteria and fungi Physical damage (by fire, animals, rock fall) The nature of bark is immensely variable.  In some trees, the bark is extremely rough, corrugated and thick.  In others it is is thinner and appears to peel off in strips.   Redwoods are noted for having an extremely thick bark (see featured image above). Their bark is very fibrous and can be up to three feet thick. Read more...

 Some years back, the blog talked about a 5000 year old ‘mummy’ - called Otzi.   Otzi was a Neolithic man, and was found frozen, high in the mountains between Austria and Italy.   Careful examination of his body, clothing and possessions gives us some insights into his daily life and diet.  Otzi and, we presume, his contemporaries made good use of the plants and natural materials around them. Thus,  His bow was made from Yew  Ash provided his dagger handle  Woven grass and bast for his cloak (bast is made from the fibres of the linden tree) goats hide for his leggings and jerkin,  bear skin for his cap deer skin for shoes  arrows from a wayfaring tree and dogwood Read more...