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]

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.

Bumblebees (and bees) collect nectar and pollen.  Pollen is a vital food, used in the various stages of a bumblebee’s life. In Spring, newly emerged queens feed on pollen, then it is used to feed its their sister workers. The workers, in turn, take over the feeding of the colony (the larvae and future queens). If not enough pollen is collected, then the colony will not thrive, which can have significant long term effects.  Bumblebees are already facing many threats (from habitat fragmentation, agrochemicals and disease). The collection of pollen is a demanding process, and bumblebees will forage over a wide area.  They start their pollen collecting activities earlier than many insects as they can warm themselves up by ‘shivering’, that is, rapid muscle contractions which generate heat, warming the insects up ready for flight.  Bumblebees can fly in colder conditions and at higher elevations than many other insects. However, research at North Carolina State University has shown that the North American bumblebee (Bombus impatiens) can overheat when exposed to high temperatures (circa 42oC plus).  So,  if a bee is carrying a significant load of pollen and it is a hot day, its muscles have to work harder and the bee is at risk of overheating. A bumblebee loaded with pollen may be 2oC hotter than an unladen bee; it may be reaching its ‘thermal limit’ - a temperature at which its organs are damaged.  Climate change means that many parts of the world are now experiencing extreme weather events, when temperatures can reach into the forties. [caption id="attachment_39978" align="aligncenter" width="675"] Bumblee leaving foxglove[/caption] Increasing temperatures could affect the foraging activities of bumblebees in a significant way - affecting how much pollen is collected and how much pollination takes place.  If pollen collection is reduced then colony development is affected and so population numbers will be affected.  Bumblebees are key pollinators in natural and agricultural systems, and if their numbers decline there will be ecological and agricultural consequences.  

Scotland’s west coast has a number of temperate rain woodlands / forests. They are quite rare. The remnants of oak, birch, ash, native pine and hazel woodlands are small and isolated from each other. They are noteworthy for the diversity and richness of the bryophytes (mosses and liverworts) and lichens; found in abundance on the trees, rocks and on the ground.   Sadly, such woodlands have been in decline for some time. In the past, this woodland covered large areas of the west coast of Scotland, but much has been lost over the last two thousand years.  These woodlands / forests now cover a small area, just under 5% of the land. Factors that have contributed to the decline and loss of this woodland include:- mismanagement,  overgrazing by sheep and  invasion by non-native species [such as Rhododendron ponticum]. According to recent study by Scottish Environment LINK, deer now represent a considerable threat to the woodlands.  Whilst deer are part of woodland ecosystems, when their numbers increase beyond a certain point then they become a significant problem.  Deer numbers are now at historic highs in Scotland/  Money has been made available to manage surging deer populations, for example, through the provision of deer fencing.  However, the report considers that such fencing is “both expensive and often ultimately ineffective”.  More needs to be done if deer damage is to be reduced and allow regeneration of the woodlands. Developing a community approach to deer stalking and management will be important, combined with the use of technologies such as thermal and drone surveying. A greater focus on the management of roe and sika deer, combined with the removal of Rhododendron ponticum will be needed if the woodlands are to flourish and expand. see also : https://www.thescottishfarmer.co.uk/news/23637346.soaring-deer-numbers-see-new-powers-land-managers/   [caption id="attachment_39688" align="aligncenter" width="675"] Rhododendron ponticum, these plants were growing near the River Tay.[/caption] visit https://www.instagram.com/woodlands.co.uk/?hl=en  

Plants have existed for hundreds of millions of year - as algae, mosses, liverworts, ferns but flowering plants only appeared about 140 million years ago. The exact timing of their appearance is a matter of some debate (see article) They have been a massive evolutionary success, there are perhaps 300,000 to 400,000 species world wide.  They reproduce using pollen.  This is used to fertilise the ovules and produce viable seeds.  Most plants rely on insects to transfer this pollen to the ovules, indeed over 80% of flowering plants have relied on insects for this service.  To this end, flowering plants (Angiosperms) have evolved a number of inducements to attract insects : colour, scent and nectar. When we think of pollinators, we generally tend to think of bees, bumblebees, hover flies.  But when flowering plants first evolved, fossil evidence suggests that many of these flowers were quite small so it is probably that the first pollinators were also quite small, and hence able to access these small flowers.  The first pollinators were probably small flies, midges or beetles (more than 77,000 beetle species are estimated to visit flowers).  Quite when bees (and their pollen collecting activities) evolved is not known.   A recent analysis of the "family tree" of the families of flowering plants indicates when different plant families evolved and when various forms of pollination emerged.  Insect pollination is / was clearly the most common method of pollination,  and was probably the first means of pollination.  This analysis also indicated that other means of pollination (involving small mammals, birds, bats) have evolved several times, as has wind pollination.  Wind pollination seems to have evolved more often in open habitats and at higher altitudes , whereas animal pollination is associated with closed canopy tropical forests. The pollen of insect pollinated flowers is significantly different to that of wind pollinated species.  Flowers that are insect pollinated tend to produce pollen that is heavy, 'sticky' and protein-rich.   Pollen is an important constituent of the diet of many insects.  Wind pollinated species by contrast produce large quantities of pollen, the grains being light and small.

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 of 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 hyphae that surround the algal cells.  The algae (green algae or cyanobacteria) are essential to the association as they can photosynthesise, fixing carbon dioxide and providing both partners with organic carbon compounds (often in the form of sugar alcohols). Some lichen species are brightly coloured. 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. The pigment then accumulates / crystallises on the surface of the lichen. The layer of pigment crystals reflects harmful radiation (in the form of UV light) and also blue light, whilst still allowing enough light to pass through for photosynthesis by the algae / cyanobacteria. Exposure to UV 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. [caption id="attachment_39793" align="aligncenter" width="700"] Lichen and moss growing together  (thanks to Art for photos)[/caption] Woodlands TV has produced two short videos on the biology of lichens :- https://youtu.be/XQ_ZY57MY64     https://youtu.be/0djrOgKtGlk