Blog - Woodland Web Updates
Woodland web updates- 8 : migrants and aerosols.
Migrating hoverflies. Hoverflies are important pollinators, plus they also act as important predators of crop pests such as Aphids. Some hoverflies (like the pied and yellow clubbed hoverflies) spend the summer in the U.K. but then fly to the Mediterranean or North Africa come the autumn. They begin these migrations on sunny days but simply flying towards the sun would take them on a rather long winded route. A study by a research team at Exeter University suggests that they are able to account for the sun’s movement using their circadian rhythm - an internal clock. If the circadian rhythm of the hoverfly is disrupted, then so is its flight path. Migrating cuckoos. Like many other birds, cuckoos are in decline. Some time back, the BTO set up a research unit to learn more about the decline and behaviour of cuckoos. The work of this group has revealed details of the cuckoos’ migration routes and its winter homelands. Cuckoos have two routes out of the UK : They migrate out south west via Spain and Morocco - the WEST route, or They take a south east route via Italy and the Balkans (the EAST route) but Both routes ultimately converge on the Congo Basin in Central Africa. However, the birds that take the WEST route leave some eight days later than those taken the EAST route, but were more likely to die en route. Most of the mortality of the birds occurs in the European section of the migration path. This may be a reflection of the status of their stop-over sites. Problems might include : Habitat change, droughts and wildfires Decline in food sources (e.g. large moth caterpillars). A lot more detail / information on this project can be found here. VOC’s The air around us is a mixture of different gases / particles / and aerosols. An aerosol is itself a ‘mixture’ of very small particles (solid or liquid) in air. These particles can come from a variety of sources :such as volcanoes, cars, trucks and wood fires. Examples of aerosols include mist, cigarette smoke, fires volcanoes car exhaust fumes. Some trees and plants also release volatile organic compounds (VOCs), for example Pine trees release alpha-pinene. Recent research has established that these volatile compounds / vapours are not only responsible for the characteristic scent, but are also important in the formation of aerosols found in the air in and around such woodlands and forests. Atmospheric aerosols scatter and absorb light, and also influence the formation of clouds, though these processes are not fully understood. Recent research by the University of East Finland has showed that biogenic aerosols (formed from VOCs) can reduce the amount of solar radiation that reaches the earth’ surface. They help scatter the radiation back into space. These biogenic aerosols increase the number of cloud droplets and make the clouds more reflective.
Woodlands web updates 7
The British Dragonfly Society has produced a report “State of Dragonflies, 2021”. Dragonflies display the usual characteristics of insects, three pairs of jointed legs, three clear divisions to the body, compound eyes and a pair of antennae. They also have two pairs of (transparent) wings. The hindwings are broader than the forewings so they belong to the group - Anisoptera (from the greek unequal wings). They can fly fast and manoeuvre well. Their ancestors were some of the first winged insects to evolve. The report notes that Many species have increased their distribution (since 1970), for example, the emperor dragonfly, the ruddy darter. Though some like the black darter seem to be in decline; this may be associated with a lack of heathland management and the drying of blanket bog areas. Several species have arrived in Britain from Southern Europe for the first time, with others returning after long absences. The vagrant emperor is a long distance migrant from Africa and the Middle East. It is thought that it might now be breeding more regularly in Southern Europe so that some now migrate northwards more often. Dragonflies are moving northwards across Britain and Ireland (associated with warming temperatures and climate change) Whilst the distribution of species has increased, the actual numbers of different species is not known so it is not possible to say if dragonfly numbers have increased overall. However, compared to many reports on the collapse of insect numbers, it would seem that that many dragonfly species are responding to climate warming and an increase in the number of ponds (for example, see the woodlands blog of the restoration of ghost ponds in Norfolk), lakes, gravel pits in recent years. The larval stages of dragonflies (nymphs) are spent in water. Apart from changing the distribution of various animals (and plants), climate change can have other effects. Some homeotherms ‘warm blooded’ animals (birds and mammals) are undergoing changes in their body form or ‘shape shifting’. Sara Ryder et al of Deakin University, Australia has studied several species of Australian parrot and has found that their beak size has increased since the nineteenth century: this increase in beak size is thought to be associated with better heat exchange. Other research has reported on changes to tail length in wood mice, also tail and leg size in masked shrews. The changes are generally less than 10% but they do seem to be responses to changing climatic conditions. Pampas grass (Cortaderia selloana) is a tall, clump forming grass with attractive plumes that can find a home at the coast, in town or in your garden. It was originally a species native to South America. However, it now has a much wider distribution, mainly due to its use as an ornamental plant though it was also used in South Africa to control erosion on dumps around mines. Each plume can produce tens of thousands of seeds. Consequently, it is now regarded as an invasive species in many countries. It has expanded across industrial and urban areas, squeezing out native species in coastal regions of France, Spain and Portugal, Now the IUCN (International Union for the Conservation of Nature) has introduced a system to recognise the threats posed by harmful species (such as Pampas Grass) - The Environmental Impacts Classification of Alien Taxa.
Woodland web updates 6.
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.
Woodland web updates (5)
Humidity and bumblebees Recent research at the University of Bristol has shown that bumblebees are sensitive to the humidity of the air that surrounds flowers. Being able to detect this sensory information affects the bees’ behaviour. Just as bees learn to recognise patterns, colour and the scent of particular flowers so they can distinguish humidity patterns. How effective these humidity patterns are will depend on the immediate micro-environment of a flower - which may be affected by climate change. Full details of this work can be accessed here : Willows and waste water Read more...
Woodland web updates 4
Beavers Two decades after were first returned to the UK, in Scotland, and 400 years after the species was hunted to extinction in Britain, counties across England and Wales will also become home to new beaver families. Beavers were hunted to extinction in the UK some 4000 years ago. A number have been reintroduced in Scotland and the South West, but this year should seen more re-introduction in Wales, the Isle of Wight, Derbyshire and Nottinghamshire. It is hoped the beavers’ activities will help restore/create wetland habitats, boosting biodiversity and reducing flood risks. Further details of these reintroductions can be found here. Peatlands As the woodlands blog has reported, peatlands are often under threat, for example, by fire. The Wildlife Trusts has called on the Government to do more to protect and restore our carbon rich habitats. The peatlands of the UK are estimated to store 3.2 billion tonnes of sequestered carbon - more than UK woodlands. Greening cities. London is to introduce a green space system in the coming months - termed the Urban Greening Factor (UGF). The Green Space Factor is an innovation of the City of Berlin in 1994, The plan calls for the various boroughs to implement urban greening practices. Ideas behind the plan have also come from the Swedish city of Malmö. Here, the Western Harbour (20-minutes from Malmö’s centre), was essentially 175 acres of contaminated soil and deserted docklands, subsequent to decline of the city’s shipbuilding industry. But now, it has been redeveloped with new apartment blocks - each of which is complemented by a green space area. There are parks, social courtyards and meeting spaces which offers beds planted with a native herbs and wildflowers. There are also stormwater drains and ponds that offer opportunities for wildlife. The impact of the road network. Our road network is extensive. There are nearly 700,000 km of road across the UK, which cover some 0.8% of the land. Roads permeate nearly every part of the country. Roadless areas are in short supply; they are mainly upland regions (peat bogs, moors, heathland and grasslands). Pollution from roads can take many forms Light pollution, Noise pollution, Heavy metals, Nitrogen oxides Particulates (PM2.5 & PM10) Whilst high levels of pollution are localised and associated with the busiest roads, a recent study (by researchers at Exeter University and the CEH) suggest that low levels of pollution from road networks are pervasive, and may extend over 70% of the land area of the UK. As the woodlands blog has reported, hedges can help block pollution to some degree and this has been substantiated by work done by Dr Tijana Blanusa et al at the Royal Horticultural Society. They investigated the effectiveness of hedges in ‘soaking up’ pollution, comparing different types of shrubs/trees - such as hawthorn and western red cedar. They found that on roads with heavy traffic that a species of Cotoneaster (franchetti) was 20% more effective than other species; though shrubs with ‘hairy’ leaves were generally effective in ‘trapping’ particulates.
Woodland web updates (3).
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...
Woodlands web updates (2)
Holly and ivy have seasonal connotations, and due to climate change they are probably looking quite lush and vigorous at present. Studies have shown that in recent times, holly has spread further north in Europe than ever before - ‘pushing forward’ by some eighty miles since the 1960’s. Ivy too is on the move, growing vigourously. However with both plants, their growth can come as a threat to other woodland species, smothering some (Ivy can grow to great heights using its tiny adventitious roots) or when growing horizontally it can affect the herb layer. https://www.theguardian.com/science/2020/dec/16/plantwatch-holly-ivy-and-how-warmer-weather-boosts-christmas-plants Read more...
woodlands web updates (1)
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...