Mites and bees. Varroa destructor also known as the Varroa mite is a small, external parasite of the honey bee : Apis mellifera. It is a mite. Mites are small members of the arachnids (8 legged arthropods).  The mite(s) attaches to the body of the bee and feeds upon its fat bodies; this weakens the bee. The mite also feeds on bee larvae. Not only that but the mite can act as a vector (‘distributor’) for five different viruses that also weaken the bees.  The varroa mite originally was to be found in Asia, and was parasitic on the Asian honeybee, Apis cerana.  Sadly, it has now spread to many countries and is responsible for significant infestations of European honeybee hives.  Over time, the mites have become increasingly resistant to chemical treatments. Now a program / study by the Universities of Exeter and Louisiana has been selectively breeding bees that identify and remove mites from their colonies [ie. showing hygienic behaviours].  They do this by removing infected larvae from the colony.  This is sometimes referred to as varroa sensitive hygiene.  Such colonies showed significant reduction in mite numbers and were more than twice as likely to survive winter as compared the ‘standard’ honey bees. The colonies also had reduced levels of three honey bee viruses The study looked at bee colonies across three American states, including California.  In the States, beekeepers move thousands of bee colonies to provide pollination services for many different fruit crops (e.g. almonds) in the Spring, thus winter survival of the colonies is vital. Historic rainfall records. was launched in March 2020 (during the 'first stay at home' / lockdown).  Members of the public were asked to help record digitally the information on pre-1960 weather sheets.  The Met Office archives had some 65000 sheets that contained the ‘scribbled records’ of thousands of weather stations/ weather recorders across the country.    Many of these sheets were the records of amateurs dating back decades, many before the foundation of the Met Office in 1854. One such 'recorder' was Lady Bayning of Norfolk, she was an early rainfall observer who took readings from 1835 to 1887.  Deciphering the idiosyncratic handwriting could not be done by character recognition software. However, the volunteers rose to the challenge and the task was completed in some 16 days. As a result, now the Met office has: Rainfall readings stretching back to 1836 Data from an increased number of rain guages  Identified the driest year on record - 1855 Identified the driest month on record February 1932 Identified the wettest month on record October 1903 Note : [The Met Office was founded by Robert Fitzroy, the captain of HMS Beagle, that carried Charles Darwin on his epic voyage around the globe. Fitzroy essentially established the science of weather forecasting] Trees on the move ? We know that trees can ‘move’.   They did so at the end of the last Ice Age (some 12,000 years ago).  As the glaciers retreated so trees started to return to the newly exposed soils as the temperature warmed.  The discovery of the remains of acorns in archaeological digs, and analyses of fossil pollen records indicates that even oaks colonised areas of the UK at the rate of nearly a kilometre a year.   Similarly, Norwegian Spruce colonised areas around the Baltic Sea and the boreal forests grew and expanded - long before humans arrived there.   Now we have warming temperatures as we have moved into the Anthropocene.  In order to survive changes conditions, plants, like us, have to move. So, like after the ice Age, plants and trees are on the move.  Scientists in California have calculated that as a result of global temperature changes, plants need to move northwards (or upwards) at the rate of 400+ metres a year.  In the eastern parts of the United States, it has been estimated that trees were shifted north and westward at a rate of 10 / 15 km per decade.  The conifers going north. Whilst oaks and birches going west.  In Scandinavia, which has experienced significant aspects of global warming, birch saplings are now found higher up mountains, gaining 500 metres in elevation within two decades.  Pines, spruces and willows are also growing at higher altitudes than previously.  Similar colonisations of  hillsides and ‘bare valleys” are seen in Alaska of alder, willow and dwarf birch. Further information here [caption id="attachment_38737" align="aligncenter" width="700"] Busy bee[/caption]

Beech and climate change. Beech trees are important (ecologically and financially) in the woodlands and forests across Europe.  Beech has a wide distribution from Southern Europe up into Scandinavia.  However, the beech has a relatively shallow root system and this makes it susceptible to drought.  In recent times, as a result of climate change, extreme weather events such as drought have become more common.  Analysis of beech tree rings (from 5000+ trees) across Europe suggest that whilst those Sweden and Norway are growing quite well those in Southern Europe are not, in fact growth may have declined by as much as 20%.   Current climate projections suggest that beech growth / productivity in southern areas may decline further, with increasing mortality. Warning signals. Many animals are able to send signals to other members of their species warning them of imminent danger, such signals can be warning sounds or ‘scents’.  The scents may be in the form of pheromones, essentially ‘airborne hormones’. Now there is growing evidence that plants may be able to act in a similar way.  For example, if mint leaves are damaged by a insect herbivore attack, then field mustard and soybean plants growing in the vicinity respond to the volatile chemicals released by the mint and activate their leaf defence systems (this often involves creating an unpalatable taste).  The volatile compounds released (during damage) are ‘oils’ or terpenes, like  β-Ocimene.  β-Ocimene has a sweet, woody fragrance but it is not clear how it stimulates other plants into activating the genes for their defence mechanisms.   Research is underway at the Tokyo University of Science. Lead and Birds of Prey.  Birds and Prey feed upon flesh they scavenge (like the entrails of deer, or dead pheasants) or from animals they capture.  The trouble is that often this flesh is riddled with bits of lead shot.  Lead is a poison, and is not easily eliminated from the body.  Animals injured by lead shot may suffer a slow and agonising death. Those that feed upon them also accumulate lead in their bodies, which affects their physiology and behaviour. Now Cambridge based scientists have studied the lead levels in a variety of birds of prey.  They looked at lead levels in the livers of some 3000 raptors. Birds, like eagles, are worst affected as they are long lived, breed later in life and rear relatively few young per year.  For a number of species, they have been able to estimate the % reduction in population size that the lead is responsible for. Species Estimated % loss of population White tailed eagle 14 Golden Eagle  13 Griffon Vulture 12 Red Kite & Western Marsh Harrier 3 Buzzard populations are estimated to be 1.5% smaller, which may not seem much but it equates to the loss of some 22,000 birds. Lead is still used in shotgun cartridges, many pheasants are still  killed with lead based ammunition, despite requests to hunting groups to switch to non-toxic gunshot (by 2020).  Full details of this work can be found here. Warmer autumns and butterflies. Green veined white butterflies are common in the U.K. and Europe.  Researchers in Sweden have been looking at how they might respond to warmer and longer autumn weather.  Under laboratory conditions, they exposed the chrysalises (over-wintering stages) of the butterfly to warmer autumnal conditions.  They found that the chrysalises used more energy and lost more weight under these conditions, and were less likely to survive to the adult / imago stage in the following Spring.  With global warming affecting our climate, it could be that populations of this butterfly could struggle as time passes.

LASI is the Laboratory of Apiculture and Social Insects at the University of Sussex. It is particularly noted for its research work on bees. Recently, Dr Balfour and Professor Ratnieks have published a study on the rôle of certain 'injurious weeds'.   Five of our native wildflowers fall into this category : Ragwort (Jacobaea vulgaris), Creeping or Field Thistle (Cirsium arvense), Spear or Common Thistle (Cirsium vulgar), Curly Dock (Rumex crispus), and Broadleaved or Common Dock (Rumex obtusifolius).  They compared the ragwort and the thistles with plants like red clover and wild marjoram (often encouraged / sown on field edges etc).. They found that the 'injurious weeds' were particularly 'effective' at attracting pollinators, not only did they they attract greater numbers of pollinators than clover etc, but also a greater range of pollinator species.  This was ascribed to the open nature of their flowers and their generous nectar production.  This brings into question the control of species like the ragwort, as it is clearly important to pollinators (as are some 'botanical thugs' - like brambles).  Ragwort contains chemicals that are toxic to livestock, causing liver damage; it has been blamed for the deaths of horses and other animals. At the Smithsonian, Kress and Krupnick have analysed the features of some 80,000+ species of plants to see how they might fare in the Earth's changing climate (the Anthropocene).  This may seem like a large number of different plants, but represents approximately only 30% of the known species of vascular plants.  There is not enough information of the remaining species to make a reasonable guess as to how they might react to climate change;  a reflection on how little we actually known about our 'botanical resources'.  Sadly, they conclude that more plants will lose out than win.  Particularly at risk of extinction are the Cypress family (which includes the redwoods and junipers) and  the Cycads, whereas black cherry might be a winner. As was reported previously in the woodlands blog, there is a difference between the leaves of the redwoods found at the top of the tree and those lower down.  Those at the top are small, thick, and fused to the vertical stem axis; this fusion of leaf and stem creates a relatively large volume of tissue and intercellular space that can store water. The leaves in the lower part of the crown by comparison are large, flat and horizontal to the stem axis.   Now scientists as the University of California (Davis) have further investigated the role of these leaves.  They now believe that the different leaf forms help explain how the exceptionally tall trees are able to survive in both wet and dry parts of their range in California.  In the rainy and wet North Coast, the water absorbing leaves are found on the lower branches of the trees.  In the Southern part of the redwoods range, the water collecting leaves are found at a higher level to take advantage of the fog (and rain, which occurs less often).

Lichens losing ? Sitting on the bark of many trees and on the surfaces of fences and walls, there will be lichens.  They are there in summer, winter, spring and autumn.  Lichens come in an amazing variety of shapes, sizes and colours.  Some can grow in extreme environments such as the rocky summits of mountains. Such lichens grow slowly and may live for hundreds of years. Lichens are rather unusual in that they are an amalgam of two (or occasionally three) organisms : a fungus and algae. They are symbiotic systems, where the partners of the association work together for mutual benefit.  The fungus makes up the bulk of the lichen’s structure (known as the thallus), but the algae (green algae or cyanobacteria) are essential as they can photosynthesise and provide the organism with carbohydrates.   Lichen covered tree One of the most common algae found in lichens is a species known as Trebouxia.  It can exist in association with a fungus to form a lichen,  or as a free living organism.  If the Earth’s warming continues at the present rate, it may well be too hot for certain species of Trebouxia to survive (in their normal range). Dr M Nelson of the Field Museum (Chicago) has looked at the adaptability of Trebouxia species and suggests that it could take hundreds or thousands of years for Trebouxia species to cope with the temperature changes that we are currently experiencing.   These algae may well lose out in the evolutionary race to cope with climate change. This would, in turn, affect many different species of lichen. Lichens are important in arctic tundra ecosystems, where they together with mosses and liverworts make up the majority of the ground flora. They contribute to food chains, for example, reindeer moss is not a moss but a lichen.  Lichens are also pioneer species - they can colonise bare rock and contribute to its weathering (their exudates chemically degrade and physically disrupt the minerals).  Lichens may be used by birds as nesting material. Hedgehogs. Rural hedgehog populations are still in decline, dropping by 30 to 75%, this is in contrast to urban populations that are ‘steady’.  Though urban populations suffer mortalities on the roads, well managed urban areas, parks and wildlife-friendly gardens provide refuges for hedgehogs.  The loss of hedgerows and diminishing field margins is contributing to the decline of rural populations. Land of Plenty report The WWF-UK has produced a report entitled “Land of Plenty”, which addresses some of the problems that the UK faces now and in the coming decades. There are many reports relating to the loss of plant and animal species and the degradation of particular ecosystems (flower-rich meadows, peatlands, salt marshes etc).   Sadly, much of this  damage has been associated with the expansion of our farming / food production systems; indeed some 70% of the land is involved in agriculture.  The WWF report outlines how a move towards regenerative farming / agriculture can significantly reduce CO2 and methane emissions, reduce pollution (from fertilisers) and help with biodiversity and resilience.  Such changes would (in time) help limit farmers’ exposure to extreme weather events that affect crops / harvests.   One of the many suggestions in the report is the expansion of ‘woodland creation programmes, focussing on potential for broadleaf and native species’. The focus would be on natural regeneration in the first instance, but supported by active tree planting. Full details of the report available in PDF format here. Drought, bark Beetles and fires. Woodland recovering from a fire The Cameron Peak Fire in the Rocky Mountains of Colorado and the Creek Fire in the Sierra Nevada of California burned through forests where large number of the trees had been killed by bark beetles. Warmth favours the bark beetles.  Mountain pine beetles had killed millions of lodgepole pines.  A dead tree does not take up water, it dries out.  The drying out was ‘helped’ by the drought that the West Coast has experienced in recent years.  The fires burned with incredible ferocity.  In the case of the Creek Fire, the plume reached some 50,000 feet up into the air.  The fires were the result of Drought / climate change Bark beetle infestation Large numbers of dead, dry trees Consequently, large amounts of energy-rich dry biomass Full details of the factors behind the forest fires here. Drought is a major ‘stressor’ affecting many ecosystem across the globe.  To understand how drought affects different ecosystems, DroughtNet is working with a number of existing projects and the International Drought Experiment (IDE).  A recent experiment at the University of Florida demonstrated how drought-stressed pines did not grow as well, and when faced with an invasive species and fire - they were much likely to succumb than a healthy tree.

Reports on pollinators. Research by workers at the University of Reading and the Centre for Ecology and Hydrology has shown that various ground level pollutants (nitrogen oxides and ozone) have significant effects on the pollinating activities of bees, moths, butterflies and hoverflies.  The number of flower visits by these insects declined, as did the level of pollination and seed production. The University of Göttinggen has published a study that bumblebees need a diverse pollen diet, collected over a variety of habitats.  A varied pollen diet contributes to better colony growth, more offspring (particularly young queens).  It also helps offset the effects of infestation with wax moth larvae.  Wax moth caterpillars feed on nest debris, but as they grow they switch to feeding on the food stores and even grubs / larvae, effectively destroying the nest. Recent work by an Irish postgraduate student on insect pollinators in Dublin suggests that a “less is more’ approach  might be effective when it comes to natural green areas in cities.   Emma King looked at the pollinators present in Areas of planted meadows or sown with wild flower mixes. Areas with reduced mowing that were allowed regenerate naturally. She found that though insects like bumblebees and hoverflies were more frequently recorded in planted meadows, statistically there was no significant difference in the numbers; and the community of pollinators was similar in both types of green areas.  The advantage of allowing green areas to develop naturally is that it reduces labour and material (seeds) costs.  They may take a bit longer to establish a diverse flora but they will offer resources to pollinators. Such green spaces promote habitat connectivity within the urban environment. Sunflower update Work by staff at the University of British Columbia has revealed that sunflowers (like many other flowers) helps bees to visit by invisible (to us) ultra-violet patterns - usually in the form of a ‘bulls-eye’.   They observed that sunflowers growing in drier conditions had flowers with larger UV ‘guides’.  Furthermore, it was found that a particular gene was responsible for the nature of the bulls-eye pattern, and this gene was also associated with the production of flavonol compounds.   Quite how the gene and the production of flavonols is related to the capacity of sunflowers to retain water is not known. [Full details of the work of Dr M Tedesco et al here].

Wetlands. In the past, many areas of wetlands have been drained and ‘dried out’.  Now it is recognised that this is counter-productive in terms of carbon storage / sequestration and biodiversity, so there are now measures to restore wetlands. The hope has been that restoration of wetlands will do much to restore the variety of plants and animals (and help carbon storage).  However, research by the University of Copenhagen suggests that such projects might be ‘struggling’. The study examined ten wetlands (near the River Odense) that were restored between 2001 and 2011.  The restoration involved the removal of drains and ditches, and allowed streams to meander again instead of flowing in ‘straight channels’.  The aim of the project was primarily to reduce the leaching of nitrogen and phosphorus from adjacent farmlands, and hope to see greater diversity of plants (e.g. marsh orchids, globeflower, tussock-sedge and ragged-robin).   The ‘restored’ wetlands were botanically poor (whether restored in 2001 or 2011), they had only a quarter of the plant species compared to natural wetlands.  This may be due to  the continued input of nutrients (from agriculture), which encourages species that are ‘nutrient hungry’ at the expense of others. the ‘difficulty’ of wetland species to disperse from one area to another. It may be that future restoration programs will need to include planting / seeding of additional wetland species. It has been suggested  that it could take the best part of a hundred years for the restored wetlands to resemble natural wetlands. Redwoods and relatives. Previous posts have talked about the special features of the giant redwoods (their height, age etc).  Over the last 150 years, they have ben subject to the pressures of commercial logging, clear felling and more recently high intensity fires.  Indeed, the fires have been of such an intensity that seed banks in the soil have been destroyed. Now they have been subject to genomic analysis, that is their DNA has been analysed and sequenced.  The first conifer genome to be sequenced was that of Norway Spruce, then that of loblolly pine.  These suggested that conifer genomes are large (3 to 10 times larger than the human genome), with repetitive sequences.  Coast Redwoods are hexaploid, that is, they ave six copies of each chromosome (we are diploid, that is, have only two copies of each chromosome).   The DNA of a coast redwood has  27 billion base pairs of DNA, the giant sequoia has 8 billion; by contrast we have circa 3 billion.   It is hoped that the Redwood Genome project will see the restoration of areas of coast redwood and giant sequoia that have been lost over the years. The genomic analysis will help inform and guide management strategies, ensuring genetic diversity in the newly planted tree seedlings. Such a strategy will (hopefully) enable newly planted areas to survive and thrive — in the Anthropocene. More on chromosomes Just as it has recently been shown that Coast redwoods are polyploids (i.e. have extra sets of chromosomes), so recent research in the Czech Republic has shown that the common nettle [Urtica dioica] has different ecological ‘preferences’ depending on its chromosomal status.  Nettles can be diploid (2n = 26) or tetraploid (2n = 52).  The tetraploid nettles seemingly have a broader ecological tolerance and a wide geographical distribution, whilst the diploid nettles occur in a narrower range of ecological conditions. Details of this research can be accessed here (note link opens a PDF) and Plants for a future has lots of information on nettles.    

More problems for bees. There is some evidence that power lines could be affecting honey bees as the lines emit an electro-magnetic field; these fields alter the bees ability to learn.  Lab experiments in which bees were exposed to electromagnetic fields similar to those under power lines showed that the bees were slower to learn to respond to a threat More likely to show aggressive behaviour Bee balls and hornets. The asian hornet is an invasive (non-native) species.  They arrived in Europe (France) in 2004.  DEFRA is trying to prevent them becoming established in the UK through the eradication of individuals and nests.  They are honeybee predators, capturing workers and feed them to their young. Back in the ‘home territory’ of the asian hornet, bees have a defence against attack.   Hundreds of worker bees quickly swarm into a balls around the hornet.   The bees then vibrate their wing muscles so quickly that they generate heat and the temperature inside the ball rises and roast the hornet alive with their body heat.  These “hot defensive bee balls” were  seen in Japanese honeybees (in 1995). The ball must form quickly before the hornet can send out pheromones to attract others of its kind. Sadly, this act of altruism by the workers comes at a cost.  Normally, workers live for several weeks but the bees that contribute to the ball die within 10 days. Unfortunately, our European honeybees do not possess such defensive strategies. Consequently, bee keepers are experimenting with various methods to deter the hornets, for example,  meshes, sticky patches and flashing lights on the hives. Warming soils ? Soils store vast amounts of carbon (in the form of humus / organic remains), more than the carbon locked up in trees.  Scientists from universities at Exeter and Stockholm have looked at data on some 9000 soil samples from around the world, and found that carbon storage declines with increasing temperature.  Coarse soils lose carbon faster than clay rich ones.

Hungry caterpillars. Many insects feed upon the leaves of the canopy in woodlands and forests.  They can vary from aphids, leaf miners, sawflies to butterfly and moth caterpillars.  Every few years there are significant ‘outbreaks’ of particular moth caterpillars, for example, gypsy moth caterpillars. These caterpillars feed on the leaves of many broadleaved trees but are 'partial' to oaks [and poplars (Populus species)] in woodland / forest situations.  When their numbers of high, they can cause significant defoliation.   A study undertaken by researchers at Cambridge has revealed that moth outbreaks can have significant effects on the surrounding ecosystem(s).  As the numbers of caterpillars are so high, they eat large amounts of leaf material.  This has a number of consequences  The amount biomass in leaf fall in the autumn is reduced The caterpillars convert the carbon-rich leaves into nitrogen-rich frass. The caterpillars are not very good at using the leaf nitrogen for their own ends.  Frass is the excrement / faecal material produced by the caterpillars.   This frass can pass into streams / waterways and end up in lakes and ponds. Once in the lakes etc, it changes the chemistry of the water and it favours the reproduction of bacteria that release carbon dioxide. This happens at the expense of the algae, which remove carbon dioxide from the atmosphere. The amount of carbon entering streams and lakes is reduced in caterpillar outbreak years. Caterpillar outbreaks significantly affect the carbon and nitrogen cycles in woodlands and associated freshwater systems. Details of the work (which focused on forest and lake systems in Canada) can be accessed here.   Air pollution and wood burning stoves. Tiny particles called PM2.5 (released from a variety of sources, such as road traffic) pollute the air.  They are harmful to our health as they can pass into the lungs and out into the blood stream.  They then circulate around the body and end up in various organs.  One source of these tiny particles is the burning of wood in wood burning stoves.  One recent study has suggested that wood burning may account for some 40000 early deaths in Europe each year!  The biggest single source of PM2.5 air pollution in the U.K is domestic wood burning, which is said to produce three times as much pollution as road traffic.  The situation is similar across Europe.  Only 8% of the population use wood burners New wood burning stoves are said to be more environmentally friendly but they still emit more tiny particle pollution than an HGV truck. The ecodesign standard developed by the EU allows wood stoves to emit 375 g of PM2.5 for every GigaJoule of energy produced.  By contrast, an HGV can only release 0.5 g per GJ.  HGV have filters and catalytic converters that capture / reduce pollution.  The burning of wood in stoves involves many factors, including air flow, fuel quality / dryness and the amount of fuel being burnt.  Full details of the European Environmental Bureau report “Where there's fire, there's smoke.  Emissions from domestic heating with wood” can be found here . Bees, weather and disease. It is well known that weather has a direct effect the foraging ability of honey bees, now it is known that weather / climate also affect the incidence of disease in hives.  A study undertaken by Newcastle University has revealed infection  / disease in hives is affected by climatic variables. For example, varroa mite infestation increased as climatic temperature increased,  but was reduced during heavy rainfall and wind.  Full details of this investigation can be accessed here.