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/  

Most months, Jasper has introduced us to a new fungus or group of fungi that have made their appearance in woodlands,  some on trees or branches or leaves, others simply emerging from the soil.  Some fungi are parasitic or biotrophic requiring a living host organism on which they feed.  Then there are those that live in and feed on dead and decaying matter in the soil; these are termed saprobic or saprophytic.  The structures that we normally see (particularly at this time of the year) are the fruiting or reproductive bodies of the fungus / fungi.  The majority of a fungus exists as a network of microscopic ‘tubes’ that permeate either the host organism, or the soil / decaying matter in which the fungus has made its ‘home’.  An individual tube is known as a hypha and collectively they form a complex network - the mycelium. The fungal mycelia present in the soil form a vast underground network.   Some of these fungi enter into beneficial associations with plants - mycorrhizal associations.  The fungal hyphae wrap themselves around (and sometimes into) the roots of plants and trees, with whom they share minerals and nutrients. Generally speaking, the fungus helps to supply the plant with mineral nutrients (like nitrates / phosphates) and in return receives carbohydrate material from the plant’s photosynthetic capacity.  These mycorrhizal systems form part of what has been termed the ‘wood wide web’.  Dr. Suzanne Simard, a forest ecologist from the University of British Columbia, coined the term to describe the complex relationships between fungi and plants in woodland and forest ecosystems. It has been suggested that (millions of years ago) fungi helped plants transition from their aquatic home to life on land, with the fungal network serving as a ‘root system’.  Fungi (and bacteria) release enzymes (biological catalysts) and these help break down the complex compounds (like lignin, cellulose and starch) present in dead plants and animals.  As a result of this decomposition, humus is formed. Humus is a colloid.  A complex mixture of materials, some in solution, some in suspension. Humus binds the inorganic mineral particles of the soil together, is a store of nutrients and helps water retention.  The fungal network in the soil sequesters enormous amounts of carbon.  The soil is one of the Earth’s main carbon ‘sinks’.   If soil is over-worked or damaged by the intensive and extensive use of chemicals in farming, then it degrades and with it the rich microbial network. Damage to the soil and its complex microbial population can impact on the growth of plants - from the simplest green plants to the largest trees. Not only are soil fungi and bacteria involved in the cycling of carbon and nitrogen, but they help maintain the fertility and structure of the soil.  Soil is the ultimate recycling system, we need to cherish the soil and its fungal and bacterial populations - it helps maintain the ecosystem services on which we all depend.  Without healthy soils, we face a very bleak future.  

Three quarters of the way through Macfarlane’s dazzling book he recounts a conversation with Robert Mulvaney – a palaeoclimatologist and ice-core expert at the British Antarctic Survey in Cambridge. After handing Macfarlane a phial containing grains of sand, Mulvaney explains that they were extracted from a kilometre deep inside a glacier and they prove that  below the ice there was once a Sahara. “They’re beautiful” says Macfarlane. “ Desert diamonds from the bottom of the world” “I can tell you are not a scientist” replies Mulvaney.  It is an unfair jibe. Scientist or not, Macfarlane serves science brilliantly well in his latest work, Underland - A Deep Time Journey. With every chapter he demonstrates his talent for explaining science and communicating the sheer wonder of the world through scientific goggles. The ambitious scope of his storytelling steps lightly from geology to linguistics to geomorphology onto folklore via nuclear physics and meteorology – all brought into focus with elegant prose and sprinklings of poetry. Like a skilled mixologist he serves up cocktails of scientific knowledge that delight and deliver more than the sum of the factual parts. Read more...