Deer are eating out the bottom of our woodlands and wildlife is suffering.  Although the size of the national deer population is not known for sure it is probably at its highest for a thousand years. There may be as many as two million deer in the UK’s countryside. There are several types, such as the two native species, being the Red deer (Cervus elaphus) and the Roe deer (Capreolus capreolus) - which is the most populous of the larger deer being, perhaps, 500,000 animals. Then there are the ones the Normans introduced, the Fallow deer (Dama dama) with a population of at least 150,000. On top of that there are three species of deer which have been introduced from the Far East including the Sika deer (Cervus nippon).  The other two from China are very different - there are relatively small numbers of the Chinese Water deer (Hydropotes inermis), whereas there are probably hundreds of thousands of the small and mostly nocturnal Muntjac (Muntiacus reevesi). They are all hungry and they all love woodlands. Most people believe the deer population needs to be controlled, or even reduced in number, but the range of species makes that harder to do. If you reduce the population of one type of deer the others will expand their numbers. Culling, or shooting, is certainly helping but stalkers are usually only interested in the larger species with enough meat to make it worthwhile and this leaves the muntjac space to thrive. Here is a film we made of a Scottish deer stalker explaining her job and how her stalking helps with environmental management: [embed]https://www.youtube.com/watch?v=ISh2sN-Ljy8&ab_channel=WoodlandsTV[/embed] Megan: “99% of stalking is looking through the binoculars.” Other ways of controlling the deer population are fencing them out but that is expensive and unlikely to work in the large open areas of the British countryside such as the moors and the uplands. Another potential method of control is introducing predators such as lynx or other larger hunting species. This meets some resistance from the public and the unintended consequences are that the predators might well go after different species altogether and occasionally humans. Most work is going on with contraceptive solutions so that the birth rate is reduced and less killing or culling is needed. This is also being researched for controlling populations of wild boars and grey squirrels to keep their numbers in check. It means getting the drugs to the target species and usually to the females which is often done through their foodstuffs, using food hoppers which are designed to be only accessible to that species. Other approaches include sterilization through injections and the Deer Initiative partnership has done a lot of work on examining different methods of biological control of deer numbers: https://www.thedeerinitiative.co.uk/pdf/contraception-and-wild-deer-control.pdf It’s not easy.  Even if one of these methods works, it will require an enormous effort to cut deer populations particularly of the smaller and more evasive species such as the muntjac. What do you think should be done? Meanwhile , deer are dangerous to motor cars.  The British Deer society estimates that annually there are between 40,000 and 70,000 accidents involving deer and this leads to about 700 human injuries, and far more deer fatalities!. So, in short, an overpopulation of deer is a large and growing problem: they damage the flora in woodlands, they eat young saplings, they compete with other mammals for space, they eat farmers’ crops, they carry ticks and they cause road accidents. The challenge of controlling the deer population is very real.

Rapid onset climate change, and the spread of new pests and diseases are creating unprecedented challenges to the long-term survivability of UK woodlands.  This looming threat is becoming ever more tangible, and the need for strategies of resilience building is urgent. Promoting diversification within and amongst woodlands has been identified as one such strategy with the potential for significant, positive impact. DiversiTree is a UKRI-funded project led by the James Hutton Institute which is measuring the impact a more diverse mixture of tree species has on building resilient woodland ecosystems, as well as how woodland managers and others understand woodland diversity, and what they are CURRENTLY doing to promote resilient woodlands. The project also hopes to generate practical advice and results which managers can use to make better informed decisions regarding the species mix of their woodlands, especially with regard to conifers. A key question which often accompanies discussions of woodland diversity is the planting of non-native species within British woodlands. The DiversiTree project is taking an evidence-focussed approach to its assessment and are investigating how ecological resilience interacts with woodlands with different priorities or objectives and what this might mean for the longer-term ecological sustainability of the forests of the UK. In actuality, many native woodlands are rather species poor, and could potentially benefit from a period of managed diversification with native species, non-natives, or a mixture depending on local objectives and context. What is critical here, is understanding the ecological role ANY tree can serve in a complex landscape, and planting in a manner which enhances and strengthens a woodland’s biodiversity.   If you’d like to learn more about our work and keep updated with our progress, please follow us on Twitter @DiversiTree_UK (https://twitter.com/DiversiTree_UK?s=20) or email [email protected] with any questions.  Seumas Bates (Environmental Anthropologist, Bangor University)  

Many trees emit a scent or fragrance.  They form volatile organic compounds (VOC’s), often oils.  Pine trees, for example, release pinenes. Such VOC’s contribute to the smell that you may experience as you walk through a woodland.  The VOCs contribute to the formation of aerosols.  An aerosol is a ‘mixture’ of very small particles (solid or liquid) in air; other examples of aerosols include mist, cigarette smoke, or even car exhaust fumes!  Recent research by the University of East Finland has showed that aerosols formed from VOCs can reduce the amount of solar radiation that reaches the earth’ surface, by scattering some of the radiation back into space.  [caption id="attachment_40200" align="aligncenter" width="532"] Felling in progress[/caption] Pine trees are often grown in vast numbers and periodically felled for timber and paper making.  One by-product of paper-making (by the Kraft process) is turpentine - formed by the condensation and collection of the volatile oils in the wood). The pinenes (α and β) are major constituents of turpentine.  ‘Turps’ is used as a solvent to thin oil-based paints, for producing varnishes and as a ‘raw material’ in the chemical industry.  α-Pinene was used to make toxaphene (an insecticide, now banned).  Pinene can also treated with acetic acid to make a perfume with a pine needle smell. Recently a team of scientists at the University of Bath have found a new use for the by-products of paper production.  Using pinene from turpentine, they have been able to make a number of pharmaceutical compounds that can then be made into the painkillers - paracetamol and ibuprofen.  They have also successfully made other chemicals from the plant based turpentine, including compounds that may be used to synthesise `beta-blockers (heart tablets) and salbutamol (used for asthma).   At present, many pharmaceuticals and other chemicals are ultimately derived from crude oil.  Hopefully, this research will ultimately lead to a more sustainable and ‘green’ approach to drug / pharmaceutical manufacture. Biochar is the black residue, consisting of carbon and ashes that remain when plant biomass is subject to pyrolysis - that is, very high temperatures with very little  or no oxygen present oxygen. The material that remains is largely elemental carbon.  The benefits of converting plant biomass into biochar is that the carbon is ‘locked up’, rather than being released by decay and decomposition into the atmosphere as carbon dioxide.  Its advocates claim that when added to soil, it improves soil structure and function, as well as being a form of carbon sequestration.. [caption id="attachment_40215" align="alignleft" width="300"] cocoa fruit[/caption] Various forms of biomass (woody debris, corn stalks) have been used to produce biochar, however, a novel method makes use of ‘discarded’ cocoa bean shells.  These are heated to a temperature in excess of 600oC, with no oxygen present.  This particular form of biochar is being produced in in Hamburg. The plant, which is one of the largest in Europe, receives a supply of used cocoa shells viably a network of grey pipes from a neighbouring chocolate factory.  Apart from its use as a fertiliser, it is possible that it might be used as an ingredient to create a ‘green’ (or more environmentally friendly) form of concrete. The sequestration of carbon is vital if we are to avoid the worst effects of climate change.  Global warming has triggered an increase in heatwaves, floods, droughts, and forest fires in recent years; June temperature data confirms it was the planet's hottest on record. Cocoa fruit : courtesy of Pixabay.

As society and industry have become increasingly aware of environmental damage, so there has been a growth in the search for sustainable practices, for example, switching from oil / coal based power generation to wind and solar power.  Now various industrial processes are looking to use natural and sustainable materials that cause less environmental damage, by making use of ‘green chemistry’. The leather industry (worldwide) make extensive use of chromium salts in the tanning process.  The object of the tanning process is to change animal hide into a leather that is resistant to microbial attack.  Chromium (III) sulphate is an effective and efficient tanning agent, forming compounds that interact with a protein (collagen) in the animal hide.  However, certain chromium (VI) compounds are hazardous if released into the environment.    Whilst chrome tanning is faster than vegetable tanning and produces a stretchable leather suitable for handbags and garments, research and thought are now being given to the greater use of vegetable tannins, using plant waste material.  Tannins are produced by many higher plants, indeed the bark of many trees, such as Oak, Chestnut, Acacia and Eucalyptus are rich sources of tannin. Tannins bind to the collagen in the hide so it becomes more resistant to bacterial attack. In a living tree, tannins serve to defend the tree against microbial attack and to dissuade herbivores (from insects to mammals) from eating the plant material - because of their bitter taste. Recent work has shown that waste material (bark) from Acacia nilotica (the Gum Arabic tree) and Eucalyptus globulus (Blue Gum tree) is rich in tannins and can be used commercially for tanning in the leather industry, and is a relatively eco-friendly process.  The process of reusing, recycling or composting waste materials and converting them into more useful products (materials, chemicals, fuels or sources of energy) is sometimes referred to as waste valorization. “Waste-to-energy” scenarios are becoming important as resources are depleted, and waste production and disposal  are increasingly problematic Eucalyptus image(above left) by sandid from Pixabay

The Gloucestershire Wildlife Trust has spearheaded an initiative to introduce Pine Martens to the Forest of Dean. Some 35 Pine Martens have been released into the forest, between 2019 and 2021.  They have produced litters each year, and there is now thought to a population of some 60 animals.  Pine Martens have two or three ‘kits’ (young) a year.   At one time, Pine Martens were common across the U.K. but the loss of their natural habitat (forest and woodlands) combined with hunting has reduced their presence to remote areas in the North and West. Now, they are a protected species; it is illegal to kill, disturb, sell or possess a pine marten.  Scotland’s population is estimated at 3700 adults.  In the Galloway Forest, the numbers of adults and young are being monitored with thermal imaging cameras.   Pine Martens enjoy a broad diet, ranging from small mammals, insects, eggs and wild fruits - eating that which is most abundant.  They will prey on grey squirrels, and there is the possibility that this may help red squirrels re-establish themselves in more southerly areas.  Forestry and Land (Scotland) have placed artificial pine marten dens in areas where there are red squirrels.  The boxes (with wood shavings to encourage nesting) are placed some 4 to 5 metres off the ground.  The Yorkshire Arboretum has just constructed a special enclosure and introduced a small population of red squirrels.  The enclosure is designed to keep Red Squirrels in and Grey Squirrels out. Two of the females have just produced four kits (young). The Gloucestershire Wildlife Trust is also involved in the Severn Treescapes project.  This is a scheme that involves significant tree planting to link the Wye Valley with the Wye Forest - to create a significant corridor of woodlands, hedgerows, orchards etc across the counties of Gloucestershire, Herefordshire and Worcestershire.   Woodlands TV has a video about the Pine Marten : [embed]https://youtu.be/20RS1M-U008[/embed]

We first became aware of the tree health pilot (THP) scheme in 2021 when we received a Statutory Plant Health Notice (SPHN) for trees infected by one of the specified pests. The THP scheme has been designed to help slow the spread of pests and diseases affecting trees in England. There are grants available for larch trees with Phytophthora ramorum, spruce trees affected by Ips typographus, sweet chestnut trees with Phytophthora ramorum or sweet chestnut blight, oak trees with oak processionary moth (OPM) and ash trees with ash dieback. In our case, the Larger Eight-toothed Spruce Bark Beetle [Ips typographus] had been found in the Norway spruce and we were instructed to fell, move, process and destroy all spruce trees in the defined area of the wood. Strict but clear directions were given regarding the ‘how, when and where’ for the felling and processing. An initial site visit and ongoing support from the Forestry Commission and their Plant Health Forestry Team allowed us to follow the process of applying for a THP grant with ease. We submitted the application and received confirmation that the grant application was successful, at which point it was over to the team undertaking the felling. Once complete a final inspection from the Forestry Commission took place to ensure we adhered to the agreed method statement (as specified in the SPHN) and then we were able to submit the claim. This claim was processed and received – all within approx. 3 weeks. Fast forward to 2023. One of the woods we are managing in the southeast (which lies within the Ips typographus demarcated area) has a small stand of Norway spruce (approx. 0.5 hectare). Some of the trees are damaged, stressed or dead, and at risk of providing the right conditions for the eight-toothed spruce bark beetle. Advice from the Forestry Commission is: How does felling healthy spruce help the situation? This reduces the opportunity for colonisation [of the beetle] and may sometimes be required as a precaution to ensure that trees that could be potentially infested are removed. Removing spruce as a host from the demarcated area entirely will limit the possibility of populations of Ips typographus establishing and prevent spread to other areas. Predicted climate change means that what is currently healthy spruce may not remain so over future years, hence early felling could reduce the risk of these areas becoming future outbreak sites. We decided to investigate whether the THP scheme could support the proactive felling and extraction of the Norway spruce. We submitted an Expression of Interest for the THP scheme, the Forestry Commission undertook a site visit and were able to confirm there was no Ips found in the wood, and we were eligible to apply for the grant. We concurrently applied for a felling licence to clear fell the compartment of Norway spruce. It is worth noting, if an SPHN is served then normally there are no restocking conditions applied however restocking and maintenance grants are available to support restoring woodland In this case there are restocking conditions in line with the felling licence – an opportunity to plant and enable native broadleaves to thrive – that can also be grant-aided. An application for the THP scheme was submitted and we subsequently received a grant offer which was accepted. What next? A pre-felling survey was required in order to determine pest freedom for Ips typographus, and the authorisation for harvesting operations remains valid for 3 months. [caption id="attachment_40238" align="aligncenter" width="675"] Galleries formed by the beetles[/caption] An inspection for Ips typographus will need to take place before any felled timber can be taken off site – the advice is to fell and move the timber quickly rather than leaving stacks in the wood. The felling commences this week and should only take 5 days, and we plan to restock with native broadleaves over the winter. The Forestry Commission has produced a very useful guide Ips typographus: Guidance on the movement restrictions of spruce trees - Forestry Commission (blog.gov.uk) but throughout the whole process the Forestry Commission and Plant Health team have been really supportive and quick to answer queries about Ips, the THP grant scheme and the forestry operations. My advice if you have a stand of Spruce – is to speak to your Forestry Commission Woodland Officer about getting involved with the Tree Health Pilot scheme or visit their website to find out more: Tree health pilot scheme - GOV.UK (www.gov.uk) Last week we hosted a number of people from the Forestry Commission, the Plant Health Forestry team, Forest Research, and DEFRA. They are continually evolving the scheme to understand how best to provide this vital funding to woodland owners to enable and encourage management of spruce and Ips. We were pleased to say they have, however,  not found it in the wood!

Across the world there may be three trillion trees. A mature tree may have 200,000 leaves, so there are a lot of leaves in the world - not counting those on herbaceous plants, grasses and shrubs.  The broad structure of a leaf is outlined here in woodlands.co.uk Tree ID. The leaf is the site of photosynthesis, providing food for the tree, and oxygen for us.  As the leaf is rich in nutrients, it is a source of nutrition for many organisms - other than the tree.  Oak trees are said to support over 2000 species, ranging from mammals, birds, beetles, spiders, fungi - through leaf-based food chains.  Leaves also support many micro-organisms through the detrital food chain (the decomposition of leaves in the litter layer and the soil). We do not eat many tree leaves, though some do make their way into our diet.  For example, the evergreen shrub Camellia sinensis is widely grown in many parts of the world for the production of tea.  The young leaves can be picked in spring and dried to make tea.  Leaves of other plants are used in various herbal infusions or for flavouring such as bay, sage, oregano, thyme etc. The fact that leaves are attractive to so many herbivores means that trees (and other plants) take measures to protect themselves. Some measures are physical - such as spines, thorns, prickles etc.   But when is a thorn a thorn, rather than a spine or a prickle?  These terms are used casually and interchangeably.  Botanically speaking, they are all ‘spinose structures’ that is hard, rigid extensions or modifications of leaves, roots, or stems - all of which have sharp, stiff ends and all have the same role - to deter animals from eating the plant that bears them.  Plants that bear sharp structures that deter herbivory are termed spinescent.  There are differences between these various ‘structures’. thorns are derived from shoots (they may be branched or not, may or may not have leaves). The thorns of Hawthorn (Crataegus monogyna) can bear leaves. spines are derived from leaves (they may be formed from all of the leaf or just part of it and like thorns they have vascular tissue*) prickles are derived from the epidermis (the outer layer of cells of a stem, root or a leaf).   Prickles may be found almost anywhere on a plant and they do not have vascular tissue inside.  Wild lemon and lime trees (Genus: Citrus) have spines, which protect young plants and indeed the fruits. The defences on roses are often described as thorns, but they are prickles, as they do not have vascular tissue (xylem and phloem) inside them. Sometimes, the leaf epidermis forms smaller, ‘simpler’ physical barriers called trichomes.  These are outgrowths of epidermal tissue but generally consist of only a few cells which form a defence against small insects.  Equally, a thick,  waxy cuticle on a leaf may be something of a deterrent to smaller insects. Leaves sometimes form ‘teeth’ on the leaf margins and leaf apices.  A classic example of this is seen in Holly.  Holly leaves that develop at ground level are wavy, with large triangular ‘teeth’, bearing spines.   As the tree grows and holly can reach up to 80 feet,  the leaves become less spiny. The spines offer protection against grazing animals at the lower levels but are no longer needed when the trees reach a certain height. While physical defences such as spines, prickles and trichomes can deter various herbivores,  chemical defences may also be deployed.  Chemical defences can take different ‘forms’, such as  [caption id="attachment_28705" align="alignright" width="300"] Oozing latex - Euphorbia[/caption] tannins and phenolics. These create an bitter taste, they are complex polyphenols built from several phenolic molecules. Tannins are common in leaf tissues - particularly in the cells on the top surface of a leaf.  Scale leaves of buds are often particularly rich in tannins, reducing  the palatability or "tastiness" of the tissue thereby offering protection from herbivores.  Alkaloids are again usually bitter tasting compounds -, many of them derived from amino acids. Glycosides, as the name suggests, contain a sugar that is joined to another chemical, such as cyanide (as seen in bitter almonds (amygdalin). Another possibility is that leaves may emit chemicals (aka VOC’ volatile organic compounds, scents, aromas) that deter insect visitors, or if a leaf is under attack by a insect pest then a leaf may release a VOC to ‘warn’ nearby plants of the attack so that they produce chemicals that make the leaves distasteful. How long a leaf lives is incredibly variable, it may be eaten within days of its formation, it may last till autumn or it may last for years.  Many trees of temperate climes are deciduous, that is they shed their leaves come the shorter days of autumn.  The advantage of this is that the tree offers less resistance to the winds of winter, so is less likely to suffer physical damage (also true of snowfall).  The tree enters a state of dormancy until spring.  If in spring the tree produces flowers before the leaves (like Blackthorn) this  can facilitate wind dispersal of the pollen.  However, losing leaves each year means that their nutrients are either lost or have to be moved out and stored somewhere else.  Having longer lasting leaves means that nutrients are retained, which is a distinct advantage in a nutrient poor, harsh environment.  The longest lived leaves are found in a plant of the Namib Desert : Welwitschia.  This plant has two leaves throughout its life of some two thousand years.  The leaves may reach a length of 4 metres, the ends die or get worn away but the base generates new tissue.   Welwitschia is a type of Gymnosperm. Image (with thanks) by Nhelia from Pixabay  

An obvious answer to this question would be - caterpillars.  But when did butterflies first appear?  There are now some 160,000 species of moths and butterflies -worldwide.  Seemingly, they appeared some 100 million years ago  - in North America.  They evolved from nocturnal moths in the period when flowering plants were undergoing a major expansion (in the Cretaceous period).  Butterflies may have become diurnal to avoid predation by bats, or it may have been to take advantage of nectar production and availability [using the proboscis]. The butterflies and their caterpillars were able exploit the diverse range of food resources that these ‘new’ plants offered.  Butterflies moved out from North America to South America and then on to other parts of the world, though they probably did not arrive in Europe until some 17 million years ago. The evolutionary expansion of the butterflies has been investigated by researchers at the University of Florida; they analysed the genetic makeup of many species (from 90 countries).  They were able to build up a picture of the relationships between the various groups of butterflies and also determined their evolutionary point of origin.  They also catalogued the plants eaten by the caterpillars and it was found that some two thirds of butterfly caterpillars feed on plants from the legume family (the Fabaceae - peas and beans).  It is probable that the first butterfly caterpillars also fed on these plants. Research at the Georgetown University in Washington DC suggests that larger species of butterfly are ‘coping’ better with higher temperatures, associated with global warming.  Bigger wings seem to offer a greater range of movement and the opportunity to find new and suitable habitats.  Smaller butterflies are not faring so well.  The study involved an analysis of the range of some 90 North American species between 1970 and 2010, during which period the monthly minimum temperature increased by 1.5oF. Others have analysed the butterfly collections at the Natural History Museum, using digital technology.   The Natural History Museum’s British and Irish butterfly (and moth) collection is probably the oldest, largest, and most diverse of its kind in the world; some of the specimens date back over a hundred years The measurements of the various specimens were paired with the temperature that the species would have experienced in its caterpillar stage. It was found that for several species that the adult butterfly size increased as the temperature increased (during late larval stage). So, it may be that we will see a gradual increase in butterfly size as temperatures increase with global warming. Join the Big Butterfly Count ? Between Friday 14th July and Sunday 6th August , the big butterfly count will take place.   For full details visit : https://bigbutterflycount.butterfly-conservation.org/about Thanks to Angus for images.