Once upon a time, the gypsy moth lived only in the Fenlands of eastern England, where its caterpillars fed upon bog myrtle and creeping willow.   As the Fens continued to be drained and agriculture expanded, this native population died out in the early part of the C20th.  However, many years later, a colony of the European form of the moth was found in Epping Forest. This form of the moth is polyphagous, that is, its caterpillars can feed on a variety of plant leaves. They have a particular penchant for the leaves of oak and poplar.  Since its ‘introduction’, this form of the moth has spread to many parts of south-east England. The caterpillars of this moth can denude a tree of its leaves if the infestation is heavy.  Repeated attacks combined with drought can result in the death of trees. The trees do have a defence mechanism which is to increase tannin production, which makes the leaves much more bitter.  But this comes at a cost to a tree, namely an increase in metabolism and energy expenditure to make these materials. [caption id="attachment_43799" align="aligncenter" width="675"] Gypsy moth caterpillar. [Thanks to Bernell MacDonald & Pixabay][/caption] Research has indicated that oak trees have ‘solved’ the problem in a different way.  If a tree has been subject to a significant attack by these caterpillars/moths, then in the succeeding year it delays the opening of its leaves by a few days.  The effect of this is that when the caterpillars emerge, the leaves that they depend upon are still ‘sealed away’ in their buds. So, the caterpillars have little or nothing to eat.  The effect of this is to reduce the damage to the tree by over 50%! The research work was carried out over a large area in Northern Bavaria and made extensive use of radar satellites.  The satellites were able to identify which trees had been stripped bare and how they reacted in the following year.  Further details of this work can be accessed here: https://www.nature.com/articles/s41559-026-03071-9

One of the most intensely studied areas in the country is Wytham Wood, which lies just outside Oxford.  Wytham Wood belongs to Oxford University. The site includes ancient semi-natural woodland, secondary woodland, grassland and ponds. Wytham is a designated SSSI, where some 500+ plant species and 800+ butterfly and moth species have been recorded.  The records of bird populations (like that of the Great Tit) go back some sixty or more years,  initiated by the work of David Lack and others.  Recently this data has been examined in conjunction with detailed weather records over the same period. The Oxford scientists looked to see how the weather affected the growth and development of the chicks of the Great Tit.  Not only did the data cover several decades but also the records of some 80,000 great tits.  The study revealed that Great tits have adjusted to warmer Springs by breeding earlier.  Severe cold weather immediately after hatching was particularly harmful. Older chicks were significantly affected by heavy rainfall. If exposed to very hot weather and heavy rain, the young chicks can lose more than a quarter of their body mass.  This is particularly true for broods raised later in the year. Warm periods were linked to higher fledging weights. The earlier breeding enables the adult birds to take advantage of the earlier appearance of their prey -  caterpillars.  However, this earlier activity can also expose them to cold snaps that can occur in early Spring.  Newly hatched chicks struggle to maintain their body temperature in cold periods as they lack feathers.  They will also need to 'burn' more of their food energy to generate heat, rather than it being used for growth.   Bad weather not only affects their food supply (caterpillars, etc), but also whether the adults can leave the nest to search for and gather food.  The higher fledgling weights during periods of warm weather are probably associated increased insect activity (and visibly), enabling the adults to satisfy the appetites of their young.  As caterpillars have quite a high water content, this helps stave off dehydration in the young chicks. Climate change seems to be throwing more extreme weather events at us, and the seasons are becoming increasingly unpredictable. These weather events (heat, cold, intense rainfall) may well have even greater effects on our bird populations, both woodland and urban. Further details of this study can be found here.

Natural habitats have been disappearing for a long time - as a result of human activity.  The last century saw hundreds of miles of hedgerow disappear, and the same is true for ponds and wild flower meadows.  Agriculture, transport networks and cities have expanded - woodlands have become fragmented.   Now, sadly we have seemingly daily reports of our rivers and seashores being polluted with sewage.  Indeed, thousands of such incidents have been reported and many rivers and seaside resorts are now unsafe places to swim (or row?).  Clearly, the infrastructure (much of it victorian) is unable to cope with the demands placed upon it.  Surfers against sewage have collected and collated information about sewage, and on their web site there is a map of coastal areas experiencing sewage discharge. If this situation was not bad enough,  run-off from major motorways is also being discharged into our rivers and streams.  Indeed, the Environment Agency has acknowledged this as a serious issue, accounting for some 18% of ‘water quality failures’ in England.  Like sewage, it is damaging. So what does this road run-off water contain?  It seems to be a mix of particles from tyres, clutch and brake pads, motor oil, transmission fluid, coolant, gear oil, and power-steering fluid. In addition, rust or corrosion from the car / vehicle body and galvanised parts can release iron, zinc, and aluminium. Modern tyres contain natural rubber, synthetic rubber etc. so when you brake, or speed up, the tyres shed thousands of tiny rubber and plastic fragments. They form as a result of the friction between the tyre and the road; they are referred to as ‘Tyre Wear Particles’ or (TWPs)*; and are a significant source of microplastics.  Microplastic are seemingly everywhere, in the oceans, in habitats across the world and even in us.  Scientists have found even microplastics in human semen, and also follicular fluid ( the fluid that surrounds a developing egg in the ovary). During and after heavy rain, TWPs and other materials are washed off the roads, with most entering stormwater networks, which channel the run-off into rivers, streams etc. Due to their density,  the TWPs etc sink and form a sediment layer.  The BBC has reported on the ‘black gunk’ in the River Lambourn (Berkshire).  The Lambourn is a chalk stream with crystal clear water as it makes it way through Welford Park, before passing underneath the M4.  Thereafter, it turns brown and murky. This has consequences for the invertebrate animals that live in the waters of the stream or on the stream bed. It is possible to mitigate some of the effects of this run-off / stormwater. For example,  near the A38 in Devon the National Highways have built a reed bed . This filters the run-off from the busy road. There are only 210 true chalk streams worldwide, and most of them are in England.   For example, the Test and Itchen in Hampshire, the Wensum in Norfolk and the Piddle in Dorset.   They are a unique contribution to global ecosystems. The National Highways is aware of the pollution problem across the road network and is using a computer model to identify which stormwater outfalls to tackle. More than a thousand locations that are "potentially high risk" have been identified.  Under its current plans, a limited number of high-risk sites will have had a mitigation in place by the end of last year. *TWPs may be swept up into the atmosphere and transported to remote regions like the Arctic.

Like the monkey puzzle tree, the horsetails (Equisetum spp) are sometimes referred to as ‘living fossils’.  Some of their ‘relatives’ date back to the late Devonian period - about 380 million years ago.  Some were  huge and tree like, reaching a height of some 30 metres, about 98 feet.  These plants formed 'forests' and were abundant in the carboniferous period.  These ancient species persisted for some 100 million years, with some contributing to the formation of coal deposits.  Modern horsetails first appeared during the Jurassic period. Present day forms are much smaller than those of the past..  Equisetum arvense is a species that is widespread across Northern Europe and parts of America. It is a nonflowering plant, multiplying through spores. It can absorb silicon from the soil, which is unusual.  It also has the ability to take up and accumulate heavy metals such as copper, zinc, lead and cadmium.  It grows and spreads by underground rhizomes.  These rhizomes can form an extensive network, penetrating deep into the soil (sometimes to a depth of six feet).  This means the plant can be very difficult to eradicate if it appears in your garden. Techniques for removing the plant can be found on the RHS site : here.  Unchecked, Equisetum can spread extensively and smother / outcompete smaller plants. In Spring, the rhizomes produce pale, fertile shoots, topped with strobili.  Strobili are cone shaped structures that release spores. Once the spores have been released, these shoots wither and die.  Somewhat later, the non-reproductive shoots appear.  These have fine branches that appear in whorls around the ‘segmented’ stems. The whorls form at various ‘nodes’ along the stem.  These branches give the plant is characteristic form.  The name Equisetum comes from the latin Equus for horse, and setae for bristles, as the shoots have a vague resemblance to a horse’s tail.  The word arvense is also derived from the Latin where "arvum", means “ploughed”.  This references the growth of the plant in arable soil and disturbed areas.  Horsetails commonly occur in damp and open woodlands, and may also been found near the edges of streams (which may have been their original habitat). The plant has been used in herbal medicine to make a ‘tea’ or used in baths to treat skin complaints, chilblains and wounds.

The last few months have been exceptional in terms of daily temperatures, and rainfall or rather the lack of it.  The effects are clear to see across the countryside - dry and parched lawns, crops stunted or failing and wild fires in many areas.  These are some of the obvious effects of the recent heatwaves, and indeed climate change.  However, there are also some more subtle effects of these high temperatures. The rising temperatures have a direct impact on the interactions between pollinators and flowers. The production of scents by flowers depends on the plant’s  metabolism.  Warming can have two effects : it can alter the amount of the scent / volatile oils produced  it can change the type of volatile oils / scent produced by the flower.   As a result, flowers may no longer emit the same chemical signals to which their pollinators are accustomed.  Bees and other pollinators may become ‘confused’ and unable to forage for nectar and pollen effectively. [caption id="attachment_43681" align="aligncenter" width="675"] Hover fly[/caption] However,  the effects of these high temperatures are not confined to the plants. Bees, bumblebees, hoverflies, butterflies and moths are also affected by increased temperatures.  They are ectothermic organisms, which means that their body temperature is largely determined by the environmental temperature that they experience. Whilst cold temperatures will result in relative inactivity, during heat waves the temperatures may well exceed their thermal limits (what they can tolerate).  Not only will the external temperature warm their bodies, but the use of their flight muscles will also generate heat.  Consequently, their ability to forage may be reduced.  The higher temperatures may also impact on their nervous system so that their sense organs may not be able to detect the scents and signals that flowers are producing.  Consequently, both plant and pollinator can no longer ‘communicate’. [caption id="attachment_43682" align="aligncenter" width="675"] marmalade hover fly[/caption] Further information : https://academic.oup.com/aob/article/137/7/2055/8541414  

Dandelions are ubiquitous.  You will see them by the roadside, growing up in pavements, in your garden.  As my lawn has turned brown with the unrelenting heat, the odd patch of green is a dandelion holding on to life. They have spread more or less world wide.  Their original range was probably through Europe and Asia, but now they are to be found on all continents with the exception of Antarctica.  Once they arrive in an area they can spread quickly. Each  dandelion stalk may produce up to 200 seeds, each with its characteristic ‘parachute’ for dispersal.  As the seeds are wind blown, they may travel considerable distances with their ‘parachutes'. A single plant may produce ten or more flower stalks, so this can amount to a lot of seeds from a single plant.  Each flower head is actually a collection of many small flowers tightly packed together. This collection of florets is termed a capitulum, which is also seen in daisies. [caption id="attachment_43347" align="aligncenter" width="650"] flower / capitulum of dandelion[/caption] Once dispersed, the seeds germinate producing a tap root which grows down into the soil, seeking water and minerals.  The seedlings can survive in hostile places, like the cracks between paving stones on the streets or your brick drive. Unlike most flowering plants, dandelions can form seeds without pollination. They reproduce by a sort of sub-sexual mechanism known apomixis*.  This has resulted in some 200+ variants or microspecies in the U.K. The species name Taraxacum officinale gg. has the gg. added to it (standing for aggregate), in recognition of the many variations / microspecies of the plant. Many of these variants have been identified by Professor John Richards over the last forty years. The common name ‘dandelion’ comes from the French ‘dent de lion’ hence lion’s tooth; this refers to the jagged / toothed edges of its leaves.  The Taraxacum part of the name is more difficult but it may derived from a mediaeval Arabic plant name. [caption id="attachment_43348" align="aligncenter" width="675"] 'toothed' leaf of dandelion[/caption] Dandelion flowers are important plants for our bees, providing an important source of nectar and pollen early in the year. Dandelions are also used as food plants by the caterpillars of some moths and butterflies and moths.  The roots of the dandelion are a food source for various soil dwelling insects; for example the grubs / larvae of cockchafers. Dandelions formed part of the herbalist’s repertoire as the leaves have a mild diuretic action; that is, they promote urine production.  They have also been described as a hepatic or liver support herb. The leaves contain vitamins   A, C and K and a number of bitter compounds (such as the sesquiterpene lactones).  The bitterness of the leaves is favoured by some chefs as part of a salad. * though sexually reproducing ancestral forms occur in Southern Europe. [caption id="attachment_43349" align="aligncenter" width="675"] seeds with their 'parachutes'[/caption]

Woodlands and forests play a significant role in slowing climate change. They take in carbon dioxide and water, and use them in photosynthesis. The first products of photosynthesis are sugars and oxygen. The sugars are then used to make more complex organic compounds, such as starch, cellulose and lignin. These are then used in their trunks, roots and branches.  It has generally been assumed that the rising levels of carbon dioxide in the atmosphere, would result in an increased rate of photosynthesis. This would in turn lead to increased growth and greater storage of complex materials, such as lignin the main constituent of wood.  This would result in carbon being locked away for decades, even millennia. However, research on oak trees in the States has cast some doubt on this assumption.  Whilst trees may use the additional carbon dioxide available for photosynthesis, it may not ‘appear’ in the formation of new wood / growth.  This would reduce the amount of carbon stored in woodlands and forests.  Instead, some of this carbon seems to be used in leaf or fruit production, or various metabolic processes.  Some compounds are used in tree defences, nutrient uptake (an energy consuming process) and mycorrhizal relationships.  Studies showed that oak trees (in the eastern states) grew through May, June and July, but that they continued to photosynthesise into early fall (autumn).  So a considerable amount of carbon assimilation took place after growth per se had stopped.  Growth of the trees as measured by increase in biomass comes to a halt in hot and dry conditions, but photosynthesis continues albeit at a somewhat reduced rate.  This disconnect between growth and photosynthesis is even more pronounced when the weather alternates between very wet and very dry.  Knowing how much of the carbon captured in photosynthesis ultimately becomes woody biomass is critical in estimating how woodlands and forests slow global warming / climate change. Indeed, as the weather becomes more unpredictable, the projections of tree growth due to a CO2 richer and warmer world may have to be re-evaluated. Details of this study can be found here.

Eight hundred years ago Fibonacci identified a remarkable fact about the simplest of additions. When you start at 1 and just add the previous number, you get this series of numbers: 1,1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144 etc. In other words, 1 plus 0 is 1, 1 plus 1 is 2, 2 plus 1 is 3, 3 plus 2 is 5, 5 plus 3 is 8, etc. Any value in this series is a Fibonacci number and these numbers are often spotted in nature when one considers the number of petals on flowers, seeds in a sunflower or scales on a cone. Another aspect of Fibonacci numbers is that very early in the series the ratio of two sequential numbers moves towards 1.618, being the “golden ratio”. For example in the series above, 34 divided by 21 is 1.619 and 55 divided by 34 is 1.618.   A Fibonacci spiral is a curved shape made by drawing quarter circles inside squares whose sizes match the sequence - as the squares get bigger, the connected arcs form a natural, expanding spiral. In nature, the logarithmic spiral of an ammonite shell approximates this Fibonacci spiral and snail shells often exhibit a similar pattern. Many woodland trees also exhibit the ratios of the Fibonacci numbers in their leaf arrangements. This is because such patterns make the most efficient use of space or create the best way to maximise the capture of sunlight or water.  For example, in many plants the leaves are arranged so that after you have gone round the stem 3 times, you will have passed 8 leaves, after 5 turns you will have passed 13 leaves and after 8 turns you will have passed 21. The head of a sunflower often has spirals of seeds in these ratios, such as 34 in a clockwise spiral and 55 in a counterclockwise spiral. Similar Fibonacci patterns are seen in pine cones, artichokes, Romanesco broccoli and pineapples. It isn’t that the plant is *calculating* Fibonacci ratios but that there is “emergence” of these ratios - the plant follows the rule of “putting the next leaf in the biggest available space.” One human-centred result in a pattern that be very appealing.