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.

Many plants have a distinctive scent, think of sweet peas, jasmine or honeysuckle, or stand next to a pine tree on a warm, summer’s day.  The scent is due to the release of volatile organic compounds (VOC’s, often oils), produced by specific tissues or glands.  Often it is the nectaries within flowers that produce the scent, apart from their ‘job’ of producing the sugary nectar.  The nectaries may be found on almost any structure within a flower - petals, sepals, stamens, ovary*. The location of nectaries varies from species to species.  There are other structures that can produce scent, for example, trichomes, and osmophores. Osmophores are clusters of cells specialising in scent production.  Any part of a plant can release scent, for example, the leaves of eucalyptus, lavender or myrtle. The scent of a plant may include a variety of VOC’s, indeed there may be dozens of different organic compounds contributing to a particular scent.  Many of these compounds are terpenoids (isoprenoids).  They contribute to the scent of eucalyptus oil, lavender oil and the flavours of cinnamon and ginger. Scent may have a number of functions.  It may be released to attract specific pollinators - moths, butterflies, bees, hoverflies etc. (who have learned to recognise the scent).  The production of VOCs can be modulated, for example,  scent production may be turned off when a flower is pollinated.  A scent may also unfortunately be a signal to herbivorous insects to ‘come and feed’. So, scent have positive or negative effects. A scent may be produced to deter herbivory by certain insects.  Sometimes, plants have a different approach. For example,  when pollen beetles feed on oil seed rape, the rapeseed releases VOCs which attract the attention of other insects.  Specifically, those that will lay their eggs in the larvae of the pollen beetles. These insects are usually from the same family as bees, wasps and ants - the Hymenoptera (insects with membranous wings and a ‘narrow waist’).   The pollen beetle larvae are then ‘eaten’ from the inside by the developing parasitoid larva.  The release of VOC’s is affected by a number of factors temperature, light, circadian rhythms, physical damage and drought.  As the temperature increases so the amount of VOCs released increases (usually). This may be experienced in coniferous woodland.  Conifers give off a variety of volatile oils (i.e. biogenic VOC’s) that contribute to a unique aroma and the formation of aerosols found in the air in and around such woodlands and forests; it is most noticeable in warm weather.  [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]. In snapdragons, the most scent is emitted at noon which tends to coincide with pollinator activity, in contrast tobacco plants scent release is in the evening / night when hawkmoth are active.  Drought reduces the ability of plants (like rosemary and thyme) to produce / release VOC’s, this in turn, has been observed to affect which pollinators visit their flowers.  Nectaries located within the flowers of a plant are sometimes referred to as nuptial nectaries, whereas those found in other parts are termed extra-nuptial.  

Last year Tawny Owls nested successfully in one of two boxes sited close together in the quietest part of our wood. They are traditionalists by habit, and will continue to use the same nesting site year after year unless they are disturbed.   The pair will re-bond during autumn around their nest site, and eggs will be laid early to late March. We were expecting to see them use one of the boxes again this spring, and our trail camera frequently showed them inspecting the box. We captured the shots below in October, and were confident they would nest there again this year. It’s during these early stages of nesting that Tawny Owls are most sensitive to disturbance, and inevitably the owls were given a lot of competition by the squirrels for their rights to the box.   Also, regrettably, on a couple of occasions we disturbed the female owl which prompted her to leave the box in daylight.  Read more...

Climate change means that we are likely to experience more extreme weather events from intense and prolonged rainfall to severe drought and heat.  The plants and trees of woodlands may experience periods of flooding, during which their roots may be deprived of oxygen (as the soil is waterlogged) and consequently - die.  Similarly trees and other plants may be subject to drought - resulting in the stunting of growth or even death.  It had been thought that most trees had roots that penetrated deep into the soil (in search of water and minerals) but the aftermath of the Great Storm of 1987 revealed that this was not the case for many types of tree.  The root systems of many trees are, in fact, relatively shallow - the root plate may only reach down some five to six feet. Read more...

Pine trees are found across the world, there are over one hundred different species.  Many are native to the coniferous forests  (Taiga) of the Northern Hemisphere.  Their evergreen needles (leaves) offer shade in summer, and the trees may offer a degree of shelter from the winds of autumn and winter.  Gardeners and foresters 'like' Pines as they generally tolerate nutrient poor and somewhat dry soils.   In the period after WW2,  considerable areas of ‘low grade’ land were pressed into service (in the U.K.).   Areas around Thetford and Kielder were used, as were some sandy coastal sites (for example,  Holkham in Norfolk) and many large tracts of land in Scotland.  Pines are central to the business of agroforestry in places like the U.K,  New Zealand and Brazil, providing a source of lumber.    Read more...