This is a re-post of a blog from 2023, but this time with the new film by WoodlandsTV, in which April Windle [of the British Lichen Society] examines the role of the many complex chemicals found in Lichens. Lichens are plant-like organisms that are rather unusual in that they are an amalgam of two (or occasionally three) organisms : a fungus and algae (or cyanobacterium). They are symbiotic systems, where the partners in the association work together for mutual benefit.  The fungus makes up the bulk of the lichen's form (known as the thallus), it is a complex network of fungal threads (hyphae) that surround the algal cells.  The algae (green algae or cyanobacteria) are essential to the symbiosis as they can photosynthesise, capturing carbon dioxide and providing both partners with organic carbon compounds (often in the form of sugar alcohols). Lichens produce an amazing variety of chemicals - many are secondary metabolites.  It is thought that some of these may  have medical / pharmacological properties.  Some species  of lichen are brightly coloured because of the chemicals.. The colour may vary from a golden yellow to a deep red. The pigments responsible for these colours belong to the anthraquinones.  However, these insoluble, phenolic pigments can have toxic effects. To avoid harm by these pigments, the lichen exports* the pigment from the fungal component of the symbiosis. [caption id="attachment_39795" align="aligncenter" width="675"] Moss and lichen growing together[/caption] The pigment then accumulates / crystallises on the surface of the lichen. The layer of pigment crystals reflects harmful radiation in the form of ultra-violet light and also blue light, whilst still allowing enough light to pass through for photosynthesis by the algae / cyanobacteria. Exposure to ultra-violet light can damage DNA, inducing mutations.  The pigmentl layer is effectively a ‘sunscreen’ for the lichen. * Recent work at Imperial College and RBG, Kew has identified the genes responsible for pigment production, and the transport of the pigment out of the fungal tissue. In the past, certain lichen pigments were often used to dye clothing materials.    Parmelia saxatilis, also known as grey crottle, was used to dye wool for Harris Tweed.  This lichen is often found growing on tree trunks and gives a red / brown colour to the material. For more information on the various chemicals found in Lichens, see the WoodlandsTV film below : The Chemical, Medicinal and Biofluorescent Properties of Lichen. [embed]https://youtu.be/AEc263aQ1rQ?si=00FwDTH5LljetQ0A[/embed] Curious fact : Some specimens of the lichen Rhizocarpon geographicum are thought to have lived for thousands of years.  

In 2023 the forest fires in Western Canada were so extensive that they burnt 37 million acres of forest lands, which is ten times the total area of forestry in the UK.  The carbon emissions were so great that they alone had a carbon footprint bigger than every country apart from the US, China and India.  Canada does not include emissions from wildfires in its carbon budget so the impact of its forest fires is in addition to its industrial and domestic carbon footprint. Although the total area burnt the next year - in 2024 - was smaller, the 2024 fires were particularly intense and destroyed 50% of the buildings in the city of Jasper. Forest fires affected infrastructure so badly that tourists were excluded from the whole of Jasper National Park in Alberta for many weeks.  This new intensity can also destroy trees that have been growing for hundreds of years and may have survived many other other fires.  This would have been the case for the King Arthur tree in California which had been the 9th largest Giant Redwood in the world: this huge and ancient Sequoia was destroyed in the 2020 Castle Fire. It is uncertain what is causing these intense infernos beyond climate change, to which the fires are themselves contributing. Many people believe that allowing too much dry and dead wood to build up creates the conditions for particularly hot fires which will easily jump fire breaks and natural circuit breakers, such as rivers   It may be that the First Nations [as Canadians call the native peoples who inhabited the country for thousands of years before European settlers arrived] were better at managing the land and would have reduced the fuel load in the forests, and there would have been a greater variety of tree species. Another paradox is that when the National Park authorities are most effective at putting out fires this allows a greater fuel load to build up so that there can be fewer fires but much bigger ones. To counter this, some Canadian Park managers are deliberately starting fires which they believe will be controllable - this is evident in the forests next to Lake Minnewanka. These are done in the off-season when large conflagrations are unlikely. In the past, forestry companies tried to extinguish fires by using float planes, such as the Hawaii Martin Mars dropping water.  This was put in an air museum in August 2024. The seaplane's water deposits were less well-targeted than today's helicopter drops.   Nowadays, forest blazes are usually left to run their natural course and this can take a long time.  Sometimes a fire will continue smouldering underground and it can be 18 months before a forest fire is confirmed to be finished. In cases where buildings, main roads or railway lines are threatened there will often be efforts to extinguish the fire using helicopters.  Drones are also used to survey the progress of fires. One measure which might reduce the issue is to replant burnt-out areas with  species that occur naturally and are  less flammable and better as surviving such as Eucalyptus.  However, the hotter, drier summers are creating conditions where we are in a new age of more intense forest fires and the Canadians are adjusting as fast as they can.  This means short term measures such as evacuation plans and more firefighting equipment, as well as longer term plans such as working on a better mix of trees and combating climate change more widely.

Since its formation, the earth has undergone change.  Life forms have come and gone.  There have been five major extinctions, the last being at the end of the Cretaceous Period; it killed off the dinosaurs and many other species.  This particular extinction event is thought to have been particularly rapid, due to an asteroid impact.  It caused a series of cataclysmic events and a rapid cooling of the Earth’s climate. Other changes, such as intense volcanic activity and tectonic uplift, may have pre-dated the asteroid impact but the event saw the elimination of many, many life forms. We are witnessing significant global change, that is also rapid in geological terms. Changes in the Earth’s climate and species composition usually take place over millennia, indeed over millions of years.  However, recent years have been very warm.  Global temperatures have changed noticeably. The warming that has been recorded “is exceptional relative to any period since before the last ice age, about 125,000 years ago”.  This warming has resulted in extreme and severe weather events in this country and across the world.  This year a record breaking January temperature of 19.9oC was recorded at Achfary, with storms Henk, Isha, and Jocelyn in the same month. The Earth’s warmest year on record (between 1850 to 2023) was 2023.  In early September 2023, the UK experienced a significant heatwave when daily maximum temperatures exceeded 30°C [somewhere in the UK] for seven consecutive days. [caption id="attachment_35526" align="aligncenter" width="675"] Drought![/caption] Such changes are not without effect. Phenology observations indicate that trees are producing their leaves earlier, woodland plants are coming into flower earlier. See the woodlands blog “Spring is on the move”.  A concern with these changing phenologies is that ‘mismatches’ can occur.  When trees come into leaf determines when caterpillars can feed and that, in turn, affects when birds can feed on the caterpillars and raise their young.  If these events do not occur in synchrony then the ‘functioning of the ecosystem’ is disturbed.  [caption id="attachment_25123" align="alignleft" width="300"] Leaf 'unfolding'[/caption] The agricultural and horticultural ecosystems that we have created are also affected by climate change. This year, heavy rainfall has meant that farmers in many parts of the UK have been unable to plant certain crops [such as potatoes, wheat and vegetables] during the key spring months. Some crops have rotted in the soil. In April, there was 111.4mm of rain, [the average for April is 71.9mm]; the sixth wettest April of the last 189 years.  Persistent wet weather also affects lambing, and can mean it is not possible to turn dairy cattle out onto grass / pasture, which in turn affects milk production. Monthly temperatures are more likely to be above average than below as climate change take effect.  This was true for the first three months of the year.  Warmer air holds more moisture and it can evaporate more water from the seas / oceans. A one degree (Celsius) rise in temperature adds 7% more moisture in the air.  Woodlands are affected by heavy rain as soil becomes waterlogged, which affects woodland flowers, and wet winters do no favours for animals that hibernate. The UK is not the only place to be affected by extremes of weather, be it rainfall and flooding, or high temperatures and drought.  India has recently experienced a period of extreme temperature, with temperatures approaching 50oC.  Such temperatures push human physiology to its limits.  Just as extreme rain is a problem for farmers, so is extreme heat and / or drought.  Brazil has been the main exporter of oranges for producing orange juice, but its recent crop has been substantially reduced as a result of flooding and drought; resulting in the worst harvest in decades. Spanish orange production has also been reduced due to drought. Like California, large parts of Florida ‘the Sunshine State’’ has seen its once-famous citrus industry reduced over the past two decades. Two diseases, greening and citrus canker have taken their toll, and then Hurricane Ian in September 2023, hit the citrus industry at the beginning of its growing season.  Large parts of the one famous citrus industry (oranges and grapefruit) have been lost and farmers are turning to the PONGAMIA tree to repurpose fallow land. [caption id="attachment_41381" align="alignleft" width="650"] Pongamia  : image thanks to Sarangib on Pixabay[/caption] This is a climate-resilient tree from India. They do not need fertiliser or pesticides.   It has been grown as a shade tree. As a member of the Fabaceae, it produces small, brown beans.  These are so bitter than not even wild hogs will eat them.  However, the beans are easily harvested by a machine that shakes the tree.  A San Francisco based company has found a way to remove the bitter tasting chemicals and use the beans in food production, as they yield a high quality protein and also an oil.  The bean (a legume) has been used to make a table oil, protein bars and a biofuel.   Orange juice production is not the only drink to be affected by changing climate.  Drought affects coffee plants and damages the quality of the soil, and excessive rainfall ‘favours’ fungal disease [e.g.coffee leaf rust and cherry rot], all of which will impact the yield and quality of the beans harvested.  Similarly, chocolate production is threatened. Cacao trees are impacted by global warming,  they can only grow and thrive within 10 degrees of the Equator, needing stable temperatures, high humidity, and ample rain.  However, temperatures are rising while rainfall has decreased. These changes lower the humidity. The trees are also under attack by a virus - cacao swollen shoot virus disease (CSSVD). Changing temperatures and rainfall patterns will influence what crops can be grown and where, it will also influence their cultivation and the working patterns associated with those crops.  Climate change is thus a factor contributing to food inflation and insecurity across the world.    

An electric or hybrid car needs a rechargeable battery to power the electric motors of the vehicle. The batteries make use of oxides of lithium nickel manganese & cobalt. The battery of such vehicles makes up a significant portion of  the cost and  environmental impact  of an electric vehicle.  Growth in this market has created issues in securing ethical battery supply chains. The future supply of nickel, cobalt and lithium is problematical, presenting challenges both in environmental and geopolitical terms.  Much of the battery production is centred on China.  Mining of a metal such as Nickel generates significant quantities of carbon dioxide, which contributes to global warming.  The demand for Nickel is forecast to double. An alternative to traditional mining techniques for metallic ores is phyto-mining. This is possible where there is a significant quantity of the metal in the soil, and there is a plant that can take up and accumulate  the metal.  The absorption and accumulation of metals like Nickel, Cadmium and Copper is perhaps more problematic as they are toxic to many plants.  Worldwide some 450 different species can absorb and accumulate ‘toxic’ metals, growing in ‘poisoned’ or toxic soils, such as former mine workings.   Some of these plants are hyper-accumulators – noted for their ability to take up a metal to many times the level in the soil. In Albania, a project is underway to use a plant to ‘mine’ nickel.  The plant is a perennial herb with yellow flowers - Odontarrhena decipiens.  It is a member of the Brassica / cabbage family and is a hyperaccumulator.  It can take up into its stems and leaves about 2% of its dry weight as nickel.  The plant is being ‘farmed’ in Albania, where there are nickel-rich soils derived in part from the mineral Olivine.     Though olivine contains too little nickel for conventional mining, it has enough for hyper-accumulators to absorb and concentrate it.  When the olivine is ground up and spread on the field, it not only replenishes the soil with nickel [that the plants absorb] but it also reacts with carbon dioxide in the atmosphere locking the CO2 away.  This project is being developed by ‘Metalplant’ . Whether phytomining using this plant will prove to be a useful way of augmenting Nickel supplies remains to be seen.  

High up in the Chilterns stands Mistletoe Wood, a semi natural ancient woodland.  It is comprised of beech and oak with a smattering of other native species. My brother and I have been custodians of these four acres for nearly three years.  Today, it has a large open glade we use for social forestry.  It has a hard fought for bothy, which put the planners in a spin (they were eventually won over by our woodland management plan), a fire pit and benching.  The latter planked from the first tree we had to take down and various tree huggers, which hold tarp or shade sails depending on the English weather. We use this area to entertain, educate and encourage and it has been home to : forestry first aid,  a murder mystery and  our annual Wood Moot when local woodlanders come round, share lunch and talk all things woody, whilst trying to avoid the harvest mites.  The other three and half acres are largely left alone, we beat the bounds at least twice a week looking out for danger and excitement, a 200-year-old beech came down in Storm Henk which was a surprise. We have removed 20 trees from a massive old beech, that was toppling near the dell [where the children play], to some medium-size ash which had die back. We process and extract them using only hand tools and our trusty trolley “Dolly”.  The woodland is blessed with the most wonderful fungi including delicious trompe de mort and we do entertain foragers and learn from them. This summer we have had the first honey from our beehives.   In Mistletoe, it is more about what we don’t do than what we do!  

There are eleven thousand trees in Kew Gardens.  Each year, a few trees are lost due to natural causes, old age, disease etc.   In 2002, a drought resulted in the loss of  some 400 trees.  Such a prolonged dry spell is  likely to occur again and again as global temperatures rise, and climate change takes a hold. Modelling of future climate scenarios by Kew scientists suggests that towards the end of this century between a third and a half of Kew’s trees could be lost.  Trees like the English oak, beech, birch and holly could be vulnerable to warmer temperatures and extended dry spells.  There is a plan at Kew to replace gradually trees with species currently found in warmer areas, such the Mediterranean, Asia and Central America. Examples might include species such as the iberian alder, cherry hackberry and Montezuma’s pine.  Many of the plants in the gardens will survive, [including Kew’s ‘Old Lions’] as they were collected from in and around the Mediterranean; some of these date back to the victorian era or earlier. The ‘old lions’ of Kew are trees from the original grounds / garden that still survive. Examples include : Japanese pagoda tree (Styphnolobium japonica) Maidenhair tree (Ginkgo biloba) Oriental plane (Platanus orientalis) Caucasian elm (Zelkova carpinifolia) Black locust (Robinia pseudoacacia) The Caucasian elm dates from 1762, when an arboretum was planted.  It is thought that it might have been in a batch of plants from the Caucasus, planted in what is now the herbarium paddock.  In 1905, the height of the tree was recorded as 60 feet (18M), though they can grow to 100 feet.  A larger caucasian elm can be seen at  Tortworth. One species of oak that is common at Kew is the holly or holm oak (Quercus ilex).  This is a common, naturalised oak that was probably introduced into the country in the sixteenth century.  It is a hardy, slow growing tree and many new holm oaks were planted in 2008 to redefine the Syon Vista.  The wood of the tree is strong and, in the past, it was used in carts and farming equipment. Its acorns start off green in colour but turn a reddish brown; they are a tasty treat for pigs. The threat to Kew's trees is not unique, parks and urban spaces across the country need to plan for the future, to ensure that their trees can offer some resilience to changing weather patterns. Full details of Kew's planning here.  

Here in the Pacific Northwest of the USA (Washington State) there are some of the most incredible woodlands in the world. There are rainforest woodlands with trees over 300 feet tall such as the world's tallest Douglas Fir at 302 feet. In fact there is so much tree cover (52%) that the size of the timber industry - of this state alone - is almost seven times that of the UK. But woodlands are not just about growing trees - they can be about improving quality of life. The State parks in the US actively encourage visits and they have created tracks/trails that are easy to walk along and that have easy parking. One woodland that I visited on the Pacific coast even had signs to promote wellbeing. Maybe these are preaching to the choir in that you had to be walking on a footpath to see them but they still offered useful and encouraging information along these lines: "being outdoors lowers your chance of developing short-sightedness", "outdoor breaks relieve more stress than indoor breaks", "forest air boosts your immune system", "physical activity in green spaces boosts your self-esteem". Perhaps, too, Americans can teach the UK lessons about promoting camping in woodlands. The State Parks have plenty of places where RVs (Recreational Vehicles - camper vans) can stop for the night and they also promote "through hiking" which means doing a trek of several days and spending the nights sleeping out in a tent. The tradition goes back a long way but was given a huge boost by Theodore Roosevelt who camped out in the wilderness and learnt bushcrafting techniques: he subsequently directed this enthusiasm towards creating "National Memorials" which became some of the early US National Parks. So, can the "health crisis" which is sweeping the UK and the US be averted with the help of getting more people into woodlands? In the US there is a long way to go as there were only around 150 million recreational visits to woodlands annually. Bearing in mind that many visits will have been by the same people, this indicates that only a small minority of the US' 333 million visits a woodland in a typical year. The pandemic effect pushed up the typical number of visits to a somewhat higher level. Can Kamala Harris or Donald Trump push this up further? Indeed, will they even try to?

Much has been written about the explosion of the UK deer population in recent times, and the damage to woodlands through their browsing activities.  However, the grey squirrelis associated with tree damage.  The grey squirrel is not just the 'cheeky chap' who steals the bird food in the garden, it is a serious pest.    The grey squirrel is a non-native species.  It was introduced in the 19th century.  The squirrels have spread across the country and have displaced the native red squirrel from many areas (either through competition or disease).  The grey squirrel's bark stripping activity now poses a threat to the sustainable management of woodlands. Gnawing of the bark means that they can get to the sweet, sap filled tissue (phloem) just beneath the bark. This tissue is responsible for the movement of sugars and other organic molecules around the plant (known as translocation). If the gnawing extends around the stem then the tree is ‘ringed’ [i.e a complete circle of bark and underlying tissue is removed]  then the tree us likely to die.  The squirrels tend to take bark from the main stem (and branches). The bark stripping may : Lead to the loss of particular tree species (for example, beech) Lead to the loss of insect / spider and fungal species associated with the loss of tree species, i.e. a loss of biodiversity allow fungal infection of the tree Reduce carbon capture Reduce the economic value of timber Act as a disincentive to creating new woodland for timber In order to reduce squirrel damage, it is important to Start inspecting for damage in late February as damage typically occurs in early Spring.  Examine the base of trees for damage. Look for ‘tester patches’ made by squirrels (to which they may well return later). Check young, broadleaf trees as they are particularly favoured by the squirrels.  Oak and beech are quite vulnerable to damage (see image of damaged beech trunk below). Recent research* at Bangor University has investigated the microbiome of the squirrel in relation to its bark stripping activity.  The microbiome of the gut refers to the various micro-organisms found with the intestines.  Analysis of bacterial DNA found in the colon of great (and red) squirrels revealed that grey squirrels had 'oxalobacter' bacteria in their colons.  These bacteria are able to 'release / access' calcium from the tree bark to the squirrels.  Calcium is an important nutrient in terms of bone building and is also involved in muscle contraction. had  a more diverse bacterial population in the colon. These findings may help explain why the grey squirrel 'outcompetes' the red squirrel.  Their more diverse gut microbiome may mean that they can access a greater range of resources. For example, grey squirrels can digest acorns, which red squirrels cannot;  this is possibly associated with tannin content of acorns. In order to reduce damage in a woodland, the number of grey squirrels may need to be managed.  This can be done though trapping or shooting.  Trapping is a legally acceptable and effective way of controlling grey squirrels in most situations. Grey squirrels can be trapped throughout the year though March to September is a good time as food is less abundant. Through autumn, berries, nuts and seeds [natural foods] are available so trapping is less successful.  Details of the various types of traps and their use / placement may be found at: https://greysquirrelcontrol.co.uk/trapping-method.php https://www.britishredsquirrel.org/wp-content/uploads/2016/07/Grey-Squirrel-Best-Practice.pdf https://basc.org.uk/pest-and-predator-control/grey-squirrel-control-with-live-capture-traps/ https://www.britishredsquirrel.org/wp-content/uploads/2016/09/Trapping-Protocol.pdf  https://bpca.org.uk/a-z-of-pest-advice/squirrel-control-how-to-get-rid-of-squirrels-bpca-a-z-of-pests-/188983 To go down the ‘shoot to kill’ route then there are a number of rules and regulations to observe.  Details may be found in the link below : http://www.britishredsquirrel.org/grey-squirrels/grey-control/ It is hoped that eventually a form of oral contraception will be developed, which will offer a non-lethal and humane means of population control. Full details of this research work may be found here