We can communicate in many ways, other animals may  message each by vocalising or gesturing.  Some release air-borne chemicals (pheromones) to attract a mate.  Plants also communicate by chemical signals that they release into the environment. The most obvious example is the release of scents to attract pollinators.   These floral scents are usually oils, made from volatile organic compounds (VOCs).  VOCs are carbon based compounds, such as the terpenes. They usually have a strong and pleasant odour.  They form partt of the scent of many plants, for example, honeysuckle, roses, jasmine, lilac, and mock orange.  Different plants produce different scents.  These different chemical signatures help pollinators identify particular species, and locate the nectar on offer. The VOCs produced by ripe fruit help attract animals that assist in seed dispersal. [caption id="attachment_43370" align="aligncenter" width="675"] Buff tailed bumblebee visiting a foxglove[/caption] VOCs are also produced by leaves when plants are under attack.  These may deter the attacking organism directly, e.g. caterpillars, or they may attract an organism that predates upon the herbivore. When pollen beetles feed on oil seed rape, the plants release VOCs which attract the attention of insects (a type of wasp). The wasps lay their eggs in the larvae of the pollen beetles. The pollen beetle larvae are then ‘eaten alive’, by the developing wasp larvae.  Sometimes, VOCs are produced by stressed or attacked plants,  these VOCs ‘warn’ nearby plants of the same species. These plants can then activate their defences before they are attacked. This helps ensure the survival of some of the population. Recently, it has been suggested that mycorrhizal systems act as a physical and chemical ‘means of communication’ between the trees in a woodland, in what has been termed the ‘wood wide web’. The term was coined by Dr. Suzanne Simard, a forest ecologist at the University of British Columbia to describe the complex relationships between fungi and plants in woodland ecosystems.  Interestingly, VOCs can influence air quality and atmospheric processes.  In a woodland,  the scent of pine or other conifers may permeate the air.  Pines release volatile compounds, such as alpha-pinene.  Recent research has established that these volatile compounds / vapours are not only responsible for the characteristic scent, but also contribute to the formation of aerosols in the atmosphere* both in and around such woodlands and forests.  In the presence of sunlight, VOCs can interact with the gas nitric oxide to form ground level ozone, which contributes to smog formation. Forests can be a significant source of VOC emissions. The production of VOCs is affected by environmental  conditions.  VOCs release generally goes up with an increase in temperature, as the plants metabolism increase.  An increase in temperature also helps in the evaporation / volatilisation of plant oils and scents. Water availability and light intensity also affect VOC release.  * An aerosol is a ‘mixture’ of very small particles (solid or liquid) in air; other examples of aerosols include mist, cigarette smoke, or car exhaust fumes Addendum : Heavier and far rarer VOCs are the sesquiterpenes, larger molecules that trees in the Amazon release when exposed to drought.  These reactive molecules help form tiny particles that seed clouds and scatter sunlight. These emissions could change the weather and climate over the whole region.  For full details see : https://www.earth.com/news/amazon-trees-emitted-never-before-seen-chemicals-during-drought/  

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.

At this time of year, certain flavourings come to the fore.  Cloves, nutmeg and cinnamon are a bit more prominent than at other times of year.  Though widely used in many cultures and cuisines, they are perhaps more associated with the winter months and Christmas.  Nutmeg comes from a dark leaved, evergreen tree Myristica fragrans.   The tree is indigenous to the Maluku Islands of Indonesia (specifically the Banda Islands), but is now widely grown in Indonesia, Malaysia, Grenada in the Caribbean and Kerala in India. The tree is dioecious, that is to say, there are male and female trees.  Male trees are unproductive in terms of nutmeg harvest, so grafting of cuttings from female trees is often used to produce new plants.  The trees take some twenty years to reach ‘peak production’. The fruit of the tree yields the Nutmeg, and the covering of the seed (the aril) is the source of Mace.  The fruits are gathered up and dried in the sun (for some 6 to 8 weeks).  As the structure dries,  the husk (seed coat) and seed separate.  The seed coat or shell is then broken and the seed picked out; it is separated from the reddish aril, which is the source of mace.  The grinding of the seed yields nutmeg.  Nutmeg has a distinctive, somewhat pungent fragrance and contributes a warm, slightly sweet taste to food.  It is used to flavour mulled wine, punches and cider, added to pumpkin pie and can be used to ‘spice up’ baking, from gingerbread to muffins or chocolate and fruit cakes. Nutmeg oil, which can be produced by a process of steam distillation, is rich in terpenes (like pinene and limonene).  It, too, can be used as a food flavouring or in products like toothpaste !  Mace, from the covering of the seed, has a more delicate flavour (than nutmeg) and may give a saffron-like colour to dishes - which may range from meat recipes to Christmas pudding. Cinnamon is used extensively in many cuisines and even in scented candles.  It is one of the most commonly used spices in Sweden.  Indeed, such is the ‘importance’ of their cinnamon buns - kanelbullar - that the Swedes now have an official Cinnamon Bun Day - on October 4th!  [caption id="attachment_39202" align="aligncenter" width="650"] Cinnamon 'buns'[/caption] Together with other spices such as turmeric, saffron, sumac, and cardamom, cinnamon is widely used in Portuguese, Turkish and Persian Cooking.  The properties of cinnamon come from the chemicals - cinnamaldehyde and eugenol. The cinnamaldehyde is largely responsible for the flavour and aroma of cinnamon,   whilst the eugenol has a pleasant, spicy, clove-like scent.  Cinnamon comes from the inner bark of trees of the genus Cinnamomum,  the trees belong the Laurel family.  They are four main species associated with cinnamon production “ Cinnamomum verum  Cinnamomum burmannii Cinnamomum cassia  Cinnamomum loureiroi C. verum has its origins in Sri Lanka and is sometimes referred to as ‘true cinnamon’, with the material derived from other sources sometimes referred to as “cassia’.  The material derived from the different Cinnamomum species has different physical properties.  Ceylon cinnamon gives a thin inner bark of a light brown colour, with a crumbly texture.  It has a subtle and aromatic flavour. , whereas, Cassia has a stronger, spicy flavour (and is much used in baking).   Most of the world’s production of cinnamon cassia now comes from Indonesia and China.  Cinnamon and cassia are often used interchangeably.  The trees are evergreen, with oval shaped leaves and a thick bark.  When a tree is two years old, it is coppiced.  That is, it is cut back to ground level so that in the following year a number of shoots are produced, which are allowed to grow on for future harvesting.  When cut, the stems have the outer bark is scraped off so that the inner bark can be removed.  It is this material that is rich in the spice.  As it dries, it curls up into rolls or ‘quills’.  Like many spices and metals, cinnamon was extensively traded across the ancient world.  It was utilized as a perfume in rubbing oils and was also used as a fragrance in the mummification / preservation of dead bodies in ancient Egypt.  Nero was said to have burned enormous quantities of the spice / incense at the funeral of his wife (Poppaea).  In recent times, cinnamon rich materials have been investigated for medical uses, specially in relation to type 2 diabetes and blood sugar control. Thanks to Pixabay for images (Emmie_Norfolk and aga2rk)