While protecting dormouse habitats has become one of the big themes of British woodland conservation, it’s remarkable how little is actually known about these elusive creatures. At a recent dormouse education day led by Tom Fairfield, thirty enthusiastic conservationists fired off a barrage of questions—some of which even he struggled to answer. Why do we care about them? How many are there? Is their population stable or declining? However, “Dormouse Tom” was able to answer many other important questions about the hazel dormouse (Muscardinus avellanarius). For instance, they are widespread across southern and south-western England and in Wales (distribution map). He showed us dozens of photos of dormouse nests and demonstrated that hazel dormice aren’t restricted to hazel woodlands—they’ve been found in conifer plantations, and occasionally even on stony beaches. Tom believes the habitat protections put in place for the HS2 high-speed rail line don’t go far enough. The ecologists at Balfour Beatty only surveyed hazel woodlands along the planned route, ignoring other potential dormouse habitats. He’s learned a great deal about dormouse habits through two key methods: installing nest boxes and examining teeth marks left on discarded hazelnuts. If our roles were reversed, perhaps dormice would measure the human population by building us cosy hotels and searching for discarded apple cores. In late March and early April, dormice begin to emerge from hibernation, but they are nocturnal and difficult to spot—one of the ways they avoid predation. Tom acknowledges that some dormice are likely to be harmed during forestry operations, but there are steps foresters and builders can take to minimise the impact. His approach starts with surveys—though thorough ones can be costly. These, however, make it easier to implement core elements of a dormouse mitigation plan: avoiding key habitats, establishing buffer zones to protect woodland edges, and creating no-go areas during the breeding season (April to October). A forester from Natural Resources Wales attending the course pointed out a serious tension: if summer months are off-limits for forestry, operations must be pushed into winter, when wetter conditions and heavy machinery risk causing ruts and soil compaction. In parts of south-east England, the tiny hazel dormice are facing competition from the much larger edible dormouse (Glis glis), also known as the European fat dormouse. Introduced by the Romans and raised for food, these creatures were fattened in ceramic pots called gliraria and are still eaten today in countries like Slovenia and Croatia. Dormouse habitat protection seems set to remain a key part of British woodland conservation—partly because dormice are considered a “flagship species”: a charismatic and recognisable animal that represents deciduous woodland and helps rally public support for wider conservation efforts. Note there is a woodlands TV film about the hazel dormouse: [embed]https://youtu.be/COUh5ZluEew?si=1upUveV1FLoQRXV6[/embed]

The last century saw the destruction of many hedgerows, particularly in farming areas like East Anglia.  The logic behind this was : to increase field size and  allow ease of access of machinery, like combine harvesters that were coming available at that time.   Whilst the loss of the hedgerows and the associated wildlife is well documented, the loss of ponds during this time has not attracted the same level of attention.  Many hundreds of ponds were filled in, to give a few more metres of arable land.  The whereabouts of some of these ponds can sometimes be found on old ordnance survey maps.  Many were located on farmland and their origins may extend back centuries to when they were created as marl or clay pits, sometimes for the watering of livestock.  Some were formed in depressions (pingos) left after the last ice age. There are still  thousands of ponds across the UK but many are polluted to a greater or lesser extent, or drained.  The pollution may be associated with the the surrounding land use or agricultural runoff. Runoff may take the form of nitrates / phosphates from the use of fertilisers.  In freshwater systems, these nutrients can cause eutrophication. Other agricultural chemicals may enter ponds and water courses - insecticides, fungicides, herbicides etc. Consequently, out of the thousands of ponds, only a very small number provide a suitable habitat for pond organisms such as the medicinal leech.  Leeches are rarely found for the reasons cited above but also because, as agriculture became more mechanised and less reliant on ‘animal power’ [horses, oxen], the ponds  (or wetlands) are no longer visited by these animals, which leeches would have fed on.  Leeches used to be abundant, but their number declined when their use in blood letting was largely abandoned, and their natural habitats were drained or damaged.  The medicinal leech is one of the largest leeches found in the UK, it can grow to a length of ten centimetres, and may have stripes / patterns on its body.  Some of the ponds that are home to medicinal leeches have been designated  Sites of Special Scientific Interest.  Since historic times, the extraction of blood by leeches was deemed to be a ‘healing process’ for patients. This practice of hirundotherapy / bloodletting spread widely and the collection of leeches resulted in the over-exploitation of many populations.  The leeches were used widely in the treatment of many conditions and  diseases such as cholera, regardless of whether or not they were effective.  At one stage, leeches were in such demand that there were ‘leech farms’, and  people could earn a living as leech collectors.  Indeed, so commonplace was leech collection that Wordsworth wrote about it in his poem Resolution and Independence : “He told, that to these waters he had come To gather leeches, being old and poor: Employment hazardous and wearisome! And he had many hardships to endure: From pond to pond he roamed, from moor to moor; Housing, with God’s good help, by choice or chance; And in this way he gained an honest maintenance.” Although the use of medicinal leeches was discredited and virtually abandoned for many decades, they are medically effective in certain circumstances.  The leeches produce a saliva which  contains a number of different proteins. These help the leech to feed by keeping the blood from clotting, and actually increasing blood flow to the leech at the point of attachment.  Some of these proteins act as anticoagulants (notably hirudin),   It is also possible that the saliva contains an 'anaesthetic / antiseptic' as leech bites are generally not painful. These leeches have now found a use in microsurgery.  They are used to stimulate the circulation in tissues which experience post-operative congestion.  They are helpful in finger reattachment and reconstructive surgery of the ear, nose, lip, and eyelid. The creation of a network of new or restored freshwater ponds across the landscape will be needed if natural populations of the leech are to expand. 

Last year was not a good year for bumblebees, according to the Bumblebee Conservation Trust.  The trust has been collecting data on bumblebee numbers since 2008, through the BeeWalk.  The BeeWalk project began as as a small scale initiative at Weybourne, Norfolk.  This involved counting the bumblebees seen on a monthly walk along a set route from March to October.  The BeeWalk was opened up first to members of the BCT and then to the wider public - a citizen science project.   Today, it is the Trust’s longest running (and largest) project.  For each site in the BeeWalk scheme, the bumblebee species seen are recorded, and whether the bee is a queen, worker or male.  Also recorded is information about the site (habitat type, land use, temperature and other relevant information).  The fact that the BeeWalk has been running for some years and is now widespread (across England, Wales and Scotland) means that it is possible to monitor how bumblebee populations are changing and correlate with any changes in climate and land use. In March last year, bumblebee numbers were relatively OK, having emerged from winter dormancy into warm and sunny conditions. Queen bumblebees need stable weather to establish their colonies.  In April the weather turned wet and cold but numbers remained stable.  But in June, the weather was particularly ‘unseasonable’ and worker bees of many  species were noticeably absent from many counts.  The effect was especially true of those species that normally reach peak numbers in early summer.  White tailed and red tailed bees were down by 60% and 74% respectively. In contrast, the garden bumblebee (Bombus hortorum) showed a smaller decline of just 12%. In July and August, the weather improved as did numbers but across the country overall bumblebee numbers (for all species) were down by 22%.  The red tailed bumblebee has declined year on year since 2015, but last year was the worst.  On a more positive note, some of the rarer species (the shrill carder & brown banded carder) have shown year on year increase. The decline highlights the sensitivity of pollinators to changing weather patterns, and emphasises the need for conservation efforts through: Protecting natural environments Restoring wild flower meadows The use of sustainable land management practices eg avoidance of insecticides (such as the neonicotinoids) Improving habitat connectivity to support bumblebee  movement and survival

Back in the Nineteenth Century, John Bennet Lawes, a Victorian entrepreneur founded a research station at Rothamsted Manor.  It was to investigate the impact of organic and inorganic fertilisers on crop yield.  Lawes had a factory making some of the first artificial fertilisers.  The manor was to become the Rothamsted Experimental Station, now known as Rothamsted Research.  It has two of the longest running experiments - the Broad balk experiment and the Park Grass experiment - started in 1856. The Park Grass area was started by Lawes and Gilbert.  Its original purpose was to investigate ways of improving the yield of hay through the use of inorganic fertilisers or organic manures. Different strips of land received varying amounts of fertiliser to none.  It soon became clear that the different treatments had a dramatic effect on the species composition of what had been a uniform sward.  There are 35-45 plant species on the unfertilised plots but only 2 or 3 species on some of the fertilised plots. Fertilisers create conditions that allow fast growing grasses to dominate the vegetation.  More recently the plots have received attention (by Dr Balfour et al, Sussex University) for the number of pollinators that they support.  It was found that High levels of common fertilisers on grassland halves the pollinator numbers. Increasing the amount / availability of NPK (nitrogen phosphorus and potassium) on grassland reduces flower numbers five fold. Bee number were most affected.  There were 9 times more bees in untreated plants compared to plots with the most fertiliser input.   The number of bees, hoverflies, butterflies, wasps and flies on each experiment strip was counted. Whilst all pollinator types were present on untreated plots or with low fertiliser levels, only flies and beetles were present on high fertiliser plots. Interestingly, plots with lime added which changed the soil pH had more pollinators (50%) and flower species than those not treated with lime. as fertiliser use increases so there is a decrease in pollinator numbers.   Though these observations are for a specific area of managed grassland, they can be considered in a broader context.  Many grasslands and meadows, which offered homes to pollinators, have been lost in recent times,.  Over a similar period of time, farmlands across the country have extended (eg. hedgerow removal, ploughing meadows) and have been making significant use of fertiliser to improve crop yield, but the wider effects of these changes on insect populations and biodiversity in general has not received enough attention. The ‘excessive’ use of fertilisers can lead to soil eutrophication, air pollution, freshwater eutrophication and a loss of biodiversity.  It can favour botanical thugs )like nettles and invasive species.  We do know that there have been dramatic falls in insect numbers in recent years in what has been termed the ‘insect armageddon or the ‘insect apocalypse’.  Whilst there are many factors at play affecting insect numbers (such as the intensive use of pesticides), the maintenance or the reintroduction of natural areas [with low nutrient soil and native wild flowers] within farmland would at least offer sanctuary to many insects / pollinators that are vital for our crops.  Any reduction in the use of fertilisers would help reduce the CO2 emissions resulting from the Haber–Bosch process, used to produce ammonia and ammonium nitrate. Interesting fact : the institute employed Ronald Fisher in the 1920s to analyse data collected from many experiments.  His work and that of other statisticians means that many consider Rothamsted the birthplace of modern statistical theory (e.g. analysis of variance) and practice.  

Trees and shrubs that grow in temperate regions, where the seasons alternate (warm / cold, dry /wet) create annual rings.  The rings formed in a deciduous tree (like beech, oak, lime) are generally quite noticeable when the tree is felled.  They may be counted to give an indication of the age of the tree.  Annual rings are formed because there is a difference in the creation of ‘wood’ / xylem tissue when growth is fast in the Spring and slow as Autumn progresses.  The thickness of the rings from year to year reflects the changing climate and environment that the tree experiences during its life. Xylem tissue is one component of a tree’s vascular tissue.  The xylem tissue conducts water and minerals around the plant, whereas phloem tissue transports sugars and other organic molecules.  Lying between these two tissues is the cambium.  This is a layer of dividing cells, which becomes active in the Spring forming new cells some of which will form new phloem tissue and others develop into xylem tissue. The cells that will form the xylem tissue undergo a series of dramatic changes.   The walls of the cells that will form the long tubes of the xylem are made of cellulose to begin with, but then they are strengthened with lignin.  Lignin is the ‘stuff of wood’.  It is a complex material - made from polyphenols and other substances such as pectins and hemicelluloses.  It is a waterproofing material that is highly resistance to decay.  It lines the tubes of the xylem so that water can be transported from the roots, up the trunk / stem to the leaves etc.  The xylem vessels that form in the Spring [early wood] have a greater diameter than those formed later in the year [late wood].  It is this size difference in the vessels that results in the visible ‘rings’ when a tree is felled. Careful study of tree rings can reveal information about climate, sometimes extending back through the centuries   using species such as the long lived Bristlecones. It has given rise to the discipline of dendrochronology [link opens / downloads a PDF].  This information can then be ‘combined’ with tree ring data from intact remains in cold, dry (and often high altitude) environments and material from archaeological sites.   Apart from measuring the ‘width’ of the annual rings by creating thin section of the wood that can be examined under microscope, it is also possible to use staining techniques to reveal which xylem tissue has a higher / lower, lignin / cellulose content.  By using a double staining technique with the dyes Safranin and Astra Blue, it is possible to identify which xylem vessels are rich in lignin, and which have more cellulose.  Tree rings which stain largely blue are formed from cells which have not lignified properly.  Lignin stains red.  A recent study of blue rings in Pine trees and Juniper shrubs suggests that blue rings are indicators of cold summers. These two species are typical of the upper tree line in Northern Norway. Furthermore, blue rings have the potential to weaken the pine trees, leaving them more susceptible to mechanical damage and / or disease.  This study has identified blue rings associated with the cold summers of 1877 and 1902, which might have been caused by the eruptions of volcanoes as far away as Ecuador and Martinique. Note : The xylem tissue in conifers is different to that of broad leaved deciduous trees.  It is made up of shorter structures called tracheids, which pass water from one to the next via pits - ‘pores’ in their lignified walls. For more information on Blue rings in Black Pine, click here  

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.

In the southern parts of Britain, beech is a dominant woodland/forest tree, further north, oak is prominent.  Beech trees are often large with smooth, silvery grey bark.  They can grow to a height of 150 feet, with a stout trunk (perhaps 10 feet in diameter) and an impressive canopy. The leaves, certainly on younger trees, may persist throughout winter in a brown and withered state — a phenomenon known as marcescence.  The root system of the beech is shallow but extensive.  The large roots spread out in all directions, and establish mycorrhizal connections, often with fungi such as Russula and Laccaria.  The mycorrhizae help the trees by supplying mineral nutrients (like phosphate) and water.  In return, the trees provide various organic nutrients to the fungus. Despite these associations, beech trees are susceptible to drought.  After the drought of the summer of 1976, many beech trees died. It is not surprising that people are concerned about the ‘health’ of beech trees in light of climate change — higher temperatures, extreme weather,  specifically periods of drought.  It was thought that climate change would reduce growth of trees like beech through the increasing frequency and intensity of summer droughts. Recently, a study conducted by researchers at the University of Liverpool looked at tree growth data (annual growth ring and masting data) accumulated over more than forty  years and found that growth was indeed reduced (by some 28%).   However, the reason was that the trees were investing more energy into reproduction than into growth.  Beech trees are known for their mast years - see previous blog on masting. In a mast year, a tree will produce enormous quantities of seeds (beech nuts✝︎). However, it seems that the changing climate is causing a ‘breakdown’ in the masting process, and whilst the trees now reproduce more more frequently.  Total seed production and seed viability is reduced.   It may be that the diminished reproductive capacity of beech trees as a result of climate change will affect their ability to regenerate woodlands and forests in the UK and indeed across Europe in the coming years.   [caption id="attachment_41997" align="aligncenter" width="675"] Marcescence[/caption] ✝︎ Masting means that so many seeds that even the most voracious squirrels cannot consume all of them * After the summer of 1976, drought damaged trees were still dying some 15 years later.

At first, you might not notice them, but ants in a woodland are important. Their presence indicates healthy woodland, and the Forestry Commission recognises them as a ‘keystone species’ in the woodland / forest ecosystem and encourages woodland owners to treat them sympathetically.  Ants, like bees and wasps, belong to a group of insects known as the Hymenoptera .  These are insects with membranous wings and narrow ‘waists’. Like bees, ants are ‘social insects’  and within their nests, there is a division of labour (workers, soldiers, queens).    There are four main species of true wood ant - Formica rufa, F. aquilonia, F. lugubris and F. pratensis. Ants are important for a number of reasons, for example :- They help disperse seeds.  They manage pests by preying on herbivorous insects that damage leaves They contribute to nutrient recycling, t Their nests provide a habitat for a whole range of invertebrates that live specifically in wood ant nests. For example, the woodlouse  (Platyarthrus hoffmannseggii), which has ‘lost’ its eyes and colour and is completely adapted to living in the dark recesses of the ants’ nests. They are a source of food for various predators including woodpeckers. Through the building of nests, they affect the soil profile, the drainage and permeability of the top soil, and help with the distribution of various nutrients.  A wood ant colony nest can persist for many years and survives so long as there is a queen / s present.   During the winter months, only queens and a limited number of the workers live on deep inside the nest. Once the temperature begins to rise in the Spring, then workers will begin to emerge and start to forage – and the queen(s) will begin to start laying eggs again.   Fertilised eggs will give rise to female ants, and unfertilized eggs give rise to males.   The males and queens have wings, and are bigger than the workers. The life expectancy of a worker is about 60 days.   Ants such as the southern wood ant [Formica rufa]. build large, ‘thatched’ nests, (see the film link below) which may contain many thousands of workers and queens (up to a quarter of a million). An ant nest is instantly recognisable, it looks like a roughly shaped dome, made from an untidy heap of leaves and twigs – with ant trails leading to and from. The heart of the nest is deep underground, whilst on the surface is the dome shaped ‘thatch’. The thatch consists of a variety materials in the thatch – small twigs, moss, heather, pine needles.   These materials are positioned so that they  not only intercept the sun’s rays to help warm the nest  but also are laid in such a way that water / rain runs away from the nest, reducing the risk of flooding.  Some ant species build their nests in /on gravel or sandy / stony soils - which reduces the risk of water logging. Like many insects, ants make use of pheromones (volatile chemicals). For example, to lay paths to the nest. The study of ant trails and ant behaviour has inspired computer programs / simulations to the “travelling salesman problem”, that is finding the shortest route round a large number of fixed locations (think of the Amazon’s driver’s day!  Woodlands TV has produced another film that focuses on woodland ants.  The film, presented by Giles Pitman, can be seen either on this website or on YouTube https://youtu.be/9wtvwlL2Wzg. Interesting fact : Ants can spray formic acid from their abdomen – when threatened. This smells like vinegar and is thought to be a deterrent to birds or other predators.