Several thousand years ago, Scotland was extensively forested.  As the Ice Age came to an end, so the glaciers retreated and Scots Pine, birch, rowan, aspen and juniper populated the land, forming the Caledonian* Forest.  Pollen records indicate that Scots Pine was present in southern England some 9000 years ago, it then moved into Scotland.  Scots Pine is one of the UK’s three native conifers; the other two being Yew and Juniper. As the climate warmed, Scots Pine was lost from most of England.  The pine woodland that formed in Scotland was the westernmost part of the boreal forest that extended across most of Northern Europe.  At its peak, (about seven thousand years ago), the forest covered some 1.5 million hectares in Scotland.  It was a ‘home’ to beavers, wild boar, brown bears, elk and wolves.  These have since been ‘lost’, though in recent times, the European Beaver has been re-introduced. However, with the arrival and establishment of neolithic farmers, areas of heath and woodland were burned to encourage fresh growth of heather for their cattle and goats. Some time later (about 3000 years ago), there was period of cold and wet weather, peat bogs spread and the tree line was lowered. In places, broad leaved trees replaced Scots pine.  Throughout historical times, the felling of trees for timber and fuel continued, as did the grazing of livestock.  Later came extensive sheep farming and this was followed in Victorian times by deer and grouse shooting.  All of these limited woodland regeneration.  So what was once an extensive forest was reduced to a fraction of its former size. Remnants of this once great forest can still be found and even today these woodlands offer a rich habitat that supports a diverse flora and fauna, where pine marten, capercaillie, red squirrel, Scottish crossbill and wildcat can be found.  Glenmore is a National Nature Reserve with many mature Scots Pine, Glen Tanar is another area of Caledonian* pine forest, set within the Cairngorms National Park.  The woodland floor provides a habitat for many plant species typical of the Caledonian Forest - twinflower, creeping lady's-tresses.    Rare and unusual insects are also to be found such as the bumblebee robber fly. According to a recent study by “Trees for life” many of the the remnants of the ancient pine forest are on a ‘knife edge’. Large numbers of deer have and are damaging the woodlands.  The deer eat pine saplings and damage bark. This can result in birch replacing pine. Whilst there have been efforts to exclude deer in some areas by putting fencing in place, the fenced areas were often not big enough or over time the deer were able to breach the fencing and continue to forage.  Pine trees need time to establish themselves free from the impact of grazing. Some areas of pinewood suffered from the planting (in the 1950s) on non-native conifers, such as Sitka Spruce.  As these grow they can crowd out Scots Pine.  Many others areas are small and ‘isolated’. This leads to a reduction in biodiversity, so it is more difficult for natural regeneration to occur.  It also means that resilience is lost in the face of threats like climate change.   * the roman name for the area now Scotland was Caledonia.   Scots Pine is sometimes described as an ‘honorary hardwood', as it grows slower than certain conifers and produces better quality timber. The loss of forest across the Earth is a cause for concern - see https://theconversation.com/how-forest-loss-has-changed-biodiversity-across-the-globe-over-the-last-150-years-140968    

Some years back, the Woodlands blog posted various articles about hedgerows,  noting the loss of many - due to the increased mechanisation of farming in the mid C20th.  Now, there is greater recognition of the importance of hedgerows, and there are initiatives to promote the maintenance and expansion of hedgerows. But what is a hedgerow? Natural England offers a definition as follows : A hedgerow is defined as any boundary line of trees or shrubs over 20m long and less than 5m wide, and where any gaps between the trees or shrub species are less that 20m wide (Bickmore, 2002). Any bank, wall, ditch or tree within 2m of the centre of the hedgerow is considered to be part of the hedgerow habitat, as is the herbaceous vegetation within 2m of the centre of the hedgerow.  This differs from the definition in the  Biodiversity Action Plan, which included references to ancient hedges / species-rich hedges.  The definition now includes all hedgerows consisting of at least one native woody species of tree or shrub (mainly), but it does exclude bramble and honeysuckle as ‘woody species’.  According to one source, there are some 550,000km of hedgerow in England, with over 400,000 km being actively managed.  Hedgerows are an important semi-natural habitat in what is otherwise a managed agricultural landscape. They are found across the country but there are more in lowland regions. Hedgerows in the south east are associated with large fields and fewer trees, the proportion of trees in hedgerows increases as one goes north and west.   The nature of hedgerows varies across the country but all are important as : They provide a habitat, shelter (micro-climate provision) and resources for many different species (from plants to insects, birds and mammals). Hedgerows are particularly important as nesting sites for birds. They support animals that have key roles within the broader ecosystem, for example pollinators and predators of pests. They offer an important source of nectar that helps support wild bees - adjacent farmland can be a poor source of nectar Hedgerows are known to support threatened (red listed) species Hedgerows capture and store carbon (above and below ground) Hedgerows offer ecosystem services eg. mitigation of water flux and availability, landscape connectivity, soil conservation / stabilisation. A number of studies indicate that increasing the number of hedgerows would help with landscape connectivity (for example, for hedgehogs) and that planting of blackthorn and hawthorn in association with later flowering species would help support a number of wild bee species.  Expanding the number of hedgerows could have some negative effects as they might offer a home to invasive species and / or pathogens; but one study has indicated that ash trees in hedgerows suffer less impact from ash dieback than trees in forests.  To date there does not appear to be any detailed research on whether increasing hedgerow coverage would have any impact on tree disease / pathogen spread. Hedgerows, like woodlands themselves, face a number of challenges due to climate change.  Warmer winters may mean that the ‘winter chill’ requirements of some shrubs / trees will not be met; this may mean flowers and fruits fail to form properly which in turn means less food for birds, small mammals etc.  Drier summers may stress some species, trees like Beech are susceptible to drought.  Extreme weather events (like Storm Arwen) can inflict damage on hedgerow trees.  If a hedgerow is next to farmland, then it may experience drift from pesticide and / or herbicide spraying  nutrient enrichment (eutrophication) due to the use of fertilisers. Hedgerows with a diverse structure, with plants, shrubs and trees of varying ages and heights provide the widest range of niches / microhabitats for wildlife.  The inclusion of dead / decaying wood offers opportunities for various fungi, saproxylic beetles, woodlice etc.  Some hedgerows are managed / reduced with a mechanical flail (see above !!!). If this is done annually, it can result in a loss of biodiversity. Trimming should be done on a 2 or 3 year cycle; and some sections of the hedge might be left for longer " see (https://www.hedgelink.org.uk/cms/cms_content/files/76_ne_hedgecutting.pdf).  Thousands of tree and hedgerow plants are being planted to create a flood defence project at Castlehill, East Hull.   The plan is to create some seven hectares of woodland and over five kilometres of new hedgerow, as part of a flood defence project (to store floodwater east of the city).  Trees such as field maple, downy birch, English oak, and black alder are being planted along with species of willow, dog rose, guelder rose and blackthorn and hawthorn to create hedgerows and scrubland.  Other species will be allowed to naturally develop in the area and the habitat is expected to reach ‘maturity in some fifteen to twenty years. There is a citizen science project that involves surveying hedgerows.  It is organised by the People’s Trust for Endangered Species [PTES].  The Great British Hedgerow Survey guidelines can be found here : https://hedgerowsurvey.ptes.org/survey-guidelines Some times hedges offer a home to other things         

No match for nonpareil ? Many varieties of apples have been around for centuries.  For example, the nonpareil which was bred (in France) back in 1696, the Egremonet russet much admired for its flavour and appearance dates from Victorian times. The  Cox's Orange Pippin is a cultivar first grown at Colnbrook in Buckinghamshire by Richard Cox.   By end the of the C19th, the Cox’s pippin was one of the most popular apples. However, there is a concern for these heritage apples in our changing climate.  In recent years, we have experienced warmer and wetter winters.  Such winters do not offer enough chilling hours for these trees.  Many trees need a period of cold in the winter months, where the temperatures are below 6oC but above freezing.  About 1000 chilling hours are needed for apples such as the nonpareil.  However, winters are present are offering approximately 600 chilling hours. Gala apple trees (developed in New Zealand) need only 600 chilling hours but it might be that they will not respond well to the wet winters we (currently) experience.  Some feel that they do not offer the complex flavours of ‘classic apples’.   Kew Gardens has now planted a varied selection of apple trees One third are heritage apple trees One third are ‘new’ varieties needing fewer chilling hours One third are varieties from countries warmer than the UK Over the coming years, the trees will be monitored to see which ‘do best’ in terms of cropping in London’s warming temperatures. The apple-growing industry in the UK is under considerable strain, with many growers unable to afford replanting this year.  Growers ‘refresh’ their orchards regularly, replacing older trees with new ones, but now many cannot afford to do this.   The sector is struggling with  a shortage of workers - made worse since the UK's exit from the European Union  high energy costs low returns from the supermarkets that buy their produce The option to ‘buy British’ may become a much rarer option.   Further details here Recovery after forest fires. Bacteria and fungi are the first to start rebuilding from the charred remains of burnt forest and woodland.  The number and variety of microbes falls dramatically after a fire.  Then, there was a microbial succession in the burned soil, that is, the number and types of bacteria and fungi changed quite quickly, with fast growing types able to advantage of the reduced competition for resources.  The situation is not dissimilar to what happens to our gut microbiome when we have to take antibiotics.  Antibiotics ‘knock out’ many of the useful bacteria in our gut, but gradually the microbiome is re-established.   Reporting on weeds. It seems that our gardens may be home to ‘new’ or unusual species of plants.   The Royal Horticultural Society would like gardeners to report on interesting ‘weeds’ that might find as they could be rare plants or plants growing in unusual places / areas.  You are asked to take photographs of anything that you find interesting and upload the images to iNaturalist. Reporting on unusual plants is not the only thing that the RHS is interested in. There are other garden projects that one can contribute to, for example, reporting sightings of garden pests such as the berberis sawfly, cellar slug, hemerocallis gall midge, lily beetle, rosemary beetle and spittlebug.

The world is warming and many scientists are concerned that the earlier springtime flowering of many plants will disrupt the ‘normal interactions between the plants and their pollinators, be they bees, butterflies, bats. Other subtle changes have been observed.  The flower ‘morning glory - Ipomoea is a weedy, vine-like plant in the States .  Between 2003 and 2012, the size of its flowers has increased (from a diameter of 4.5 cm to 4.8 cm).  The study also revealed that flowering occurred 4 days earlier and the flowers have increased their ‘floral rewards’.  That is they devote more resources in the production of pollen and nectar to attract the bees, flies and wasps that visit the flowers.  The changes were more noticeable in northern populations of the Morning Glory. Extra Growing time ? In the late nineteenth century, an Ohio farmer (Thomas Mikesell) kept detailed records on local trees*, noting their growth, daily temperatures, rainfall, dates of frosts, snows &  thunderstorms. With the death of Thomas Mikesell  [July 18, 1917], the world lost an dedicated student of nature and a remarkable phenological record came to an end. It forms the only detailed record of plant and tree growth in North America during the late C19th / early C20th. Since that time, significant global warming has occurred. Now researchers at Ohio State University have compared  Mikesell’s observations with growth data of present day trees - from time of bud burst to peak (autumnal) leaf coloration (for seven tree species). They concluded that trees now experience a longer growing season.  Leaves stay on the trees for approximately one month longer than they did a hundred years ago.  Quite how this longer growing ‘season’ affects the trees is not known, there may be a positive through increased carbon assimilation.  On the other hand, higher temperatures may stress the trees in ways which are not yet understood.     *A Calendar Of The Leafing, Flowering And Seeding Of The Common Trees Of The Eastern United States.

In the eighteenth and nineteenth century, many explorers / adventurers brought ‘exotic’ plants back to the United Kingdom. These ‘exotics’ were planted in arboreta, botanic gardens, and some in gardens.  One bush that was introduced was Rhododendron ponticum. The plant is native to the eastern and western Mediterranean, and the Pontic Mountains, hence its name). It was introduced into Britain in the late eighteenth century, by Conrad Loddiges.  It was planted in Victorian hunting estates, also on heathland areas to provide shelter for game species. Its rootstock has been used for grafting of less hardy, more colourful types.  Many Rhododendron species are a delight and an adornment to our parks and gardens, indeed many hundreds of species of Rhododendron are known (many in China and the Himalayas)*.   Rhododendron ponticum has proved to be invasive.  It is a threat to key parts of our woodland ecosystems, such as Atlantic Oak Woodland.  Atlantic oak woodland is sometimes referred to as Celtic Rainforest.  It is characterised by lichen covered trees, growing amongst a rich moss and liverwort flora.  This woodland environment is damp and humid, to which streams and waterfalls contribute. These woodlands have evolved under the influence of the Gulf Stream,  which helps keeps warm and wet the area.  In some parts of the country, the woodlands have remained in their 'ancient state', since the last ice age.  However, these woodlands were more extensive but now exist as much smaller ‘pockets’ - damaged by grazing, pollution, and ‘exotics or aliens’ like R. ponticum. When this shrub ‘invades’, it 'takes over' and the woodland floor becomes a dark and barren place. A deep shade results from the thickets of the Rhododendron.  This results in the loss of much of the ground flora so that only some shade tolerant mosses and liverworts remain.  They form a ‘mat’ of dense vegetation that is a barrier to seed germination.  Even when the Rhododendron thicket is removed, the re-establishment of the original flora is compromised.  There is also evidence that as it grows this shrub produces chemicals which inhibit the growth of other species;  this is known as allelopathy. R.ponticum has spread in many areas, mainly to the West of the country. Each flower can produce several thousand seeds, so that a large bush can produce several million seeds in year. These seeds are tiny and wind dispersed; and though not all the seeds will germinate and grow, many will and colonise an area. Even when bushes have been removed from an area and the litter layer cleared, the seeds may persist in the seed bank of the soil - allowing the species to recolonise. In consequence, follow up over a five year period is really important. Recent figures suggests that some 37,000 hectares are affected in the UK.  Though the government does make a grant available for the removal of Rhododendron, progress with its removal has been slow. In Wales, there is a project called the Celtic Rainforests Project  (YouTube video link here) that focuses on invasive species and their attempted eradication in Atlantic Oak Woodlands in Wales.  With the agreement of the landowner, the project will organise surveys to identify the scale of the problem, and then contractors to carry out the work over the period of a management agreement, at no cost to the landowner [woodlands.co.uk has groups of buyers who have agreed for their various woods to be covered by such management agreements]. Clearing an area of this plant is difficult and expensive. An  effective first treatment to eliminate R. ponticum is to drill the stems, and inject herbicide directly into the plant.  This uses a lot less herbicide than spraying, and is a selective approach.  Mabberley’s Plant-book notes that the cost of eradicating the plant from Snowdonia was £30 M and that was in 1988.  Further information about the work in the welsh oak woodlands here. The plant is also a problem in Ireland. Indeed, referring to the Killarney National Park a politician has said “nothing short of calling in the army is going to put it right.” [caption id="attachment_39688" align="aligncenter" width="675"] Rhododendron ponticum growing near to the River Tay.[/caption] Forest Research has a number of publications about the management and control of R. ponticum. * Details of the genus may be found in Mabberley's Plant-Book. With thanks to Chris Colley

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.

Whilst browsing the web looking for reports, information that might interest readers of the blog, we came across a very useful site "Discover the Wild".  Discover the Wild offers a number of very useful identification sheets that can be downloaded in PDF form and are easily printed. Some of the sheets / PDFs available are :- Tree buds in winter (very useful) Garden Moths Wasps Spring in the garden (a variety of moths, butterflies, other insects and some plants) Autumn fungi Common tree leaves Seashore shells (not 'woodlandy' but might be good if you are having a day at the beach with children / grandchildren ) DISCOVER THE WILD IS DEFINITELY WORTH A VISIT. https://www.facebook.com/DiscovertheWild [email protected]    

The terms veteran tree or ancient tree are often used. But what is a veteran? A veteran tree may be defined by a combination of factors: its age its size; its condition; its history; its position. Read more...