It would seem that pollinators have ‘favourite plants’.  Research centred on the National Botanic Garden of Wales has looked in some detail at the foraging habits of bees, bumblebees, hover flies and solitary bees - our most important pollinators. Dr Abigail Lowe identified the plants that the insects were visiting by analysing the DNA from pollen grains on their bodies (a process known as DNA barcoding). It is clear that the ‘preferences’ of the insects change with the seasons and indeed the availability of particular flowers.  In Spring, nearly all the pollinators frequent buttercups, lesser celandines and dandelions (all brightly coloured yellow flowers).  Come the summer, honey bees and bumblebees tend to favour thistles, knapweeds and brambles, whilst hover flies may be seen on hogweeds and angelica plus thistles and knapweeds.  In autumn, the bumblebees can be see visiting asters (Daisy family flowers) and brambles. Full details of her work can be found here : https://botanicgarden.wales/press/plants-for-pollinators-new-dna-research-reveals-fascinating-insights-into-the-plants-used-by-bees-and-hoverflies/ There are also suggestions on how to help pollinators in your garden, such as encourage buttercups and dandelions by reducing mowing (in the Spring) plant late flowering daisy type flowers encourage some bramble (you might get some blackberries, in return) reduce the use of chemicals (especially pesticides and herbicides) hoverflies can be encouraged by damp, wet areas and rotting wood and these suggestions would also work in a woodland.   [caption id="attachment_38320" align="aligncenter" width="700"] Marmalade hover fly[/caption]

Climate change is affecting all parts of the world, from the melting of the ice caps in Antarctica, to droughts in Australia and California.  On a more local level, we may see changes in our rainfall pattern.  Certainly for many parts of the UK, it has been a very dry start to the Spring, coupled with some very cold nights. Cold and dry weather affects plant growth in significant ways.  Warmth is needed for a plant’s enzymes (catalysts) to work, speeding up reactions and allowing growth.  Similarly, if water is in short supply, growth is stunted; plants do not realise their full ‘potential’. They are smaller overall as is the number and size of flowers that they produce.  Flowers attract visitors by colour, size and scent; or combinations thereof.   Smaller and fewer flowers, in turn, have ‘knock-on effects’ for their pollinators - bees, bumble bees, hoverflies etc. The effects of drought on pollination has been recently investigated by researchers at Ulm University in Germany.  They studied the effect of drought on field mustard (aka Charlock) : Sinapsis arvensis.  This is an annual plant that is to be found in fields, waysides and field margins across Europe.  It has bright yellow flowers, with four petals.  It is visited by many different pollinators (it cannot self-pollinate).   The researchers compared the number of visits by bumblebees (Bombus terrestris) to drought-stressed plants to well-watered ones.  The data showed that as the number and size of the flowers decreased so did the number of pollinator visits.  [caption id="attachment_21589" align="aligncenter" width="600"] Bumblebees also favour the teasels[/caption] The ‘attractiveness’ of the plants / flowers to pollinators was reduced, and it is possible that the smaller flowers were more difficult for relatively large pollinators (like the bumblebees) to ‘deal with’.  If pollen movement is reduced, then fewer fruits / seeds will be set and (insect pollinated) plant populations could decline.  The effects of reduced rainfall and water stress need to be considered alongside the declining number of pollinators.  The reduction in pollen movement has lead some to speculate that it might lead to a selective pressure for self-pollination / self-fertilisation, with plants dispensing with the need for visiting insects.  Other Woodlands blogs have reported on the falling numbers of insects / pollinators. Featured image : garlic mustard.

Pesticides problems. The effect of pesticides on bees and bumble bees is now well documented.  However, the combined effect of different pesticides is less well known.  If pesticide A is known to kill 10% of the bees in an area that has been treated, and pesticide B kills another 10% then it might be reasonable to assume that 20% of the bees would be killed - IF the effects are additive.  However, evidence is beginning to indicate that the effects of the pesticides is more than the sum of the parts - the pesticides work together / synergistically. Pesticide formulations that are sold to farmers are often ready mixed ‘cocktails’ so exposure to more than one pesticide is often the norm,  so it is important that these co-operative effects are understood and known. Honey bees have been affected by not only pesticides but also varroa.  Varroa is a mite, which lives and feeds on honeybees and their larvae.  Fortunately, bees have complex hygienic behaviours, for example, removing dead larvae or pupae.   Research indicates that honey bees are modifying this behaviour to deal with varroa mites. Helping pollinators Researchers at the University of Freiburg have recently published work establishing the importance of semi-natural habitat regions next to orchards and other agricultural landscapes for pollinators.  Such areas (ditches, banks, overgrown fences etc) help ensure that flowers (and therefore nectar and pollen) are available over a significant period of time.  This is important for pollinators such as hover flies, solitary bees, bumblebees etc. as nectar / pollen provided by crops is only available for a short and limited period.  Such areas are also important for overwintering, nesting sites, providing food for larval stages etc).  Their work focused on orchards near Lake Constance in Southern Germany. Soil remediation with lupins. There are many sites around the world where the soil is contaminated with metals (such as arsenic) as a result of past mining / industrial activities.  Such arsenic contaminated soil might be ‘revived’ by using the natural mechanisms that some plants have evolved to deal with certain contaminants.   The white lupin (Lupinus alba) is an arsenic-tolerant plant that might be a candidate for phytoremediation of soil.  The tolerance of the white lupin to arsenic is thought to be due to the release of chemicals by the roots into the soil.  Staff at the University de Montréal placed nylon pouches close to the roots to capture the molecule released.  The chemicals were then analysed to see which could bind to the arsenic (phytochelatins).  Phytochelatins are known to be used within plants to deal with metals but here they seem to be used externally.  Quite how they work is yet to be determined.

Silwood Park is part of Imperial College, a postgraduate campus, located some 25 miles west of central London, near Ascot. It is a centre for research and teaching in ecology and allied disciplines. The campus includes areas of wet woodlands, acid grasslands, traditional orchards and parkland. The veteran and ancient trees support an significant number of rare species of insects, lichens and fungi that depend on decaying wood. Silwood is the heart of the wildlife corridors for the surrounding area.  Read more...

Much of England experienced a series of ‘tropical nights’ last summer, when night time temperatures were 20oC or above.  These tropical nights were associated with the heat wave that affected most of south east England.  Central London experienced its longest stretch of extreme daytime temperatures since the 1960’s -  temperatures of 30+oC were recorded on six consecutive days.  A number of experts have said that such heatwaves and associated tropical nights are likely to become more common as a consequence of climate change.   We were not alone in experiencing high temperatures by day and night, much of western Europe  sweltered in the heat this August. The problem was most marked in urban areas and large cities.  Some three-quarters of the population of Europe now live in urban areas. Extreme heat affects our health causing general discomfort, malaise, respiratory problems, headaches, heat stroke, heat cramps and heat-related mortality.  Read more...

Primroses were said to be the favourite flower of Benjamin Disraeli, indeed he wrote of them that he liked primroses so much better for their being wild “they seem an offering from the fauns and dryads of the woods”.  On his death, Queen Victoria sent a wreath of primroses to his funeral with a note ‘his favourite flower’ (though it is not clear whether this referenced Disraeli or her late husband - Albert). Primroses are generally regarded as the harbingers of Spring, indeed the name Primrose comes from the latin for first rose - Prima Rosa. In different parts of the country, the primrose sometimes has other names such ‘Easter Rose’, ‘Lent Rose’ and ‘Early Rose’.  Its scientific name is Primula vulgaris. Read more...

Big Garden Birdwatch.  Once again the RSPB’s Big Garden Birdwatch is about to swing into action.  This year , it will take place from the 29th to the 31st of this month.  To take part, you just need to count the birds that you see in one hour.   Details and guidance are available here : https://www.rspb.org.uk/get-involved/activities/birdwatch/everything-you-need-to-know-about-big-garden-birdwatch/  Butterflies (and moths).   If you are interested in adding to your knowledge of wildlife, then the Butterfly Conservation people not only offer guidance on identifying moths Read more...

The woodlands blog has reported on the anthropocene - how human activity is creating a geological era characterised by human impact on the Earth.  Now a report finds that human-made (artificial) material will this year surpass the sum total of all living material (biomass) on earth. https://www.nature.com/articles/s41586-020-3010-5 A Swedish study has shown that crop yield can be enhanced  by ensuring that woodland and grassland areas are present in the vicinity of crop fields.    If the landscape is more diverse in terms of plants and habitats, then the number of pollinators (bees snd bumblebees) is greater.   Read more...