Ancient Trees A recent report has emphasised the importance of protecting and preserving ancient trees.  Ancient (veteran) oaks can live in excess of a thousand years, as can Yews.  The Bristlecones of California and Nevada may live for some five thousand years ! Such trees represent a massive carbon store; the carbon dioxide from the atmosphere being locked away for a millennium or five!  Not only are such trees a significant carbon store but they also offer a home or food for many other species - fungi, epiphytes such lichens & mosses, plus larval and adult stages of insects, birds and mammals.  As such they localised centres of diversity that contribute to ecosystem stability.  Not only are these trees ‘hotspots’ for species diversity but they are also centres of mycorrhizal activity and connectivity.  Mycorrhizae represent the symbiosis between fungi and plant. Plants ‘register’ wounding. When we are hurt, our nerves register the pain through the movement of sodium and potassium ions along the nerves.  When a plant is wounded, calcium ions are known to move in response, travelling from cell to cell, and leaf to leaf.  However, it is now known (through research at the John Innes Centre in Norwich) that this is not the first response of the plant to physical injury.  When cells are wounded they release glutamate, a form of glutamic acid.  This travels along the cell was and activates channels in the cell membranes that allow the movement of the calcium ions.   A bumblebee pathogen. One of parasites of bumblebees is Crithidia bombi.  It is a protozoan (single celled animal) that reproduces in the gut of the bumble bee. When infected with this parasite the foraging behaviour of the bee is impaired, as is its ability to learn.   A colony will suffer from increased worker mortality.  Now research has shown that floral structure may influence the transmission of this parasite from bee to bee.  The length and shape of the petals seems to be a critical factor.  If the bees ‘crawls’ in a ‘tube’ of petals, then it may leave behind some faeces.  If the bee is infected with the parasite, then it will be present in the faeces.  If the flower is then listed by another bee then it runs the risk of coming in contact with and being infected with the parasite.  Plants that have flowers with shorter petals / corollas are less likely to have faeces deposited within them, and therefore less likely to pass on the parasite to the visiting bumblebees.

The vibrancy and gaudiness of sunflowers is one of the delights of summer.  The common name "sunflower" generally refers to Helianthus annuus, whose round flower heads look like the sun.  Sunflowers are cultivated as food crops for humans, cattle, and poultry, and also for the garden. They typically grow during the summer and into early autumn, with the peak growth season being mid-summer. A field of sunflowers is a welcome relief from the acres of oilseed rape. The flower of a sunflower is not a flower but hundreds of small flowers (florets) massed together the better to attract pollinators.  The structure so formed is known as a capitulum.  The inner florets are arranged in spirals that conform to fibonacci sequences.  The pattern of these florets has been described mathematically by Helmut Vogel and it allows for the most efficient ‘packing’ of the florets in the ‘flower’ head. Before the flowers open,  the plants tilt during to face the sun, gaining more light for photosynthesis. This movement is known as heliotropism  and continues for a while when the flower head opens. This may help to attract pollinators.  Frequent visitors to sunflowers are bumblebees.  Sadly, like honey bees, bumblebees face a number of problems which include parasites.  However, recent research in the United States suggests sunflowers can help certain species of bumblebee.  If sunflower pollen is included in the diet of the common eastern bumblebee then it helps reduce infection by a parasitic protozoan Crithidia bombi.  This is a parasite that lives in the gut of bumblebees. When they pass out of the gut in cysts, they can be ‘picked up’ by the next passing bumblebee (or another insect, as the parasite is not too fussy). Once established in a bee, the parasite can affect the ovaries.  If a  queen is infected then the reproductive success of the colony is affected. Giacomini et al. have found that good nutrition is vital for bumblebee health and that sunflower pollen can be a huge benefit when it is included in the diet. They noted that the majority of the bees that consumed sunflower pollen had no detectable infection a week later. The pollen* significantly reduced infection by the parasite. So sunflowers are a visual feast for us, and an edible one for bumblebees and bees.  They also provide us with seeds.  The seeds are rich in monounsaturated and polyunsaturated fats, notably linoleic acid. The seeds also contain phytosterols which may contribute toward lowering the level of blood cholesterol.  The seeds may be pressed releasing sunflower oil, and the remaining ‘cake’ can be used as a protein rich animal feed.  The Ukraine and Russia are the top producers of sunflower seed. A somewhat different use of sunflowers is phytoremediation; using plants to remove toxic organic or inorganic compounds from soil.  After the disaster at the Chernobyl nuclear reactors in 1986, an exclusion zone with a radius of 30 km centred on the nuclear power plant was created. This was later expanded to include other heavily irradiated areas.  Even now, no one lives in the exclusion zone, but scientists and others may ask for permits to allow them to enter for short periods.  Fields of sunflowers were planted to ‘harvest‘ the radioactive metals (notably caesium-137 and strontium-90) from the soil. The sunflowers accumulated these elements in their tissues.  When the sunflowers had completed their growth, they were harvested and burnt, leaving only the radioactive ash behind. This material could then be vitrified (incorporated into glass) and stored underground in a shielded container. In Brazil, a study looked at the ability of different sunflower cultivars to remove nickel, copper and lead from contaminated soil.  Though phytoremediation with sunflowers proved to be an efficient and low-cost method for the treatment of contaminated soils, the cultivars varied in their ability to take up particular metals. “Cleaning up’ with sunflowers was tried after a tsunami hit the Fukushima Daiichi nuclear power station in Japan.  However, it was not very successful.   As different cultivars vary in their capacity to hyperaccumulate, so it is important to match the cultivar to the situation. Planting sunflowers in this case did little to improve the situation. This could be in part due to the sunflowers but also be associated with the soil type and the time that the caesium has had to bind to the soil particles. Understanding the mechanisms and detail of hyper accumulation is critical if sunflowers are to be used for phytoremediation in the future. Pollen is rich in secondary plant metabolites e.g. flavonoids, terpenoids, alkaloids, amines, and chlorogenic acids [caption id="attachment_35695" align="aligncenter" width="650"] field of sunflowers[/caption]  

Some 90% of the world's plants, including many food crops, rely on animals for pollination (as opposed to wind or even rarer water pollination). The contribution of honey bees and bumblebees to these pollination services is vital but they are at risk due to: the effects of disease,  climate change  effects of pesticides and  habitat loss / destruction. Whilst it is sometimes possible to help hives / colonies of the ‘domesticated’ honeybee suffering from parasites / disease, ‘helping’ wild populations is a much more difficult proposition. Read more...

Declining bee populations in Europe have caused alarm in recent years and the decline has been attributed to a multitude of factors / causes, for example :- Climate change Pesticides - especially neonicotinoids Varroa mites Viruses Now Russia is reporting mass bee deaths and major declines in their bee populations in recent months.  Read more...

Bumblebees and honeybees seem to be assailed from all sides - pesticides, parasites and viruses, habitat fragmentation, climate change all come into play.     Now a study of honeybees in the North West (of the UK) suggests that there is a clear link between their immediate landscape and the quality of their diet. Bees collect pollen and nectar for their food    Nectar is converted into honey in the hive, whilst the pollen is converted into beebread / 'bee pollen' .  Read more...

It might not be much to look at, but Laetiporus sulphureus sure tastes good on a plate. A relatively common adornment to many a tree in Summer and early Autumn, the legendary Chicken of the Woods is one of the tastiest edible mushrooms found in the UK, and also one of the most highly prized: as the name suggests, it has the taste and texture of chicken, and its firm flesh makes an ideal substitute in stews, stroganoffs, curries, pilaffs and other meat dishes. Easily overlooked by those not in the know, it is instantly recognisable to the gourmet fungi forager, and bares little resemblance to other poultry-named fungi like the Turkey Tail (Trametes versicolor) or the Hen of the Woods (Grifola frondosa), the Japanese delicacy known as maitake. It is a bracket fungus that grows in large clusters of undulating fan-shaped shelves, the colour ranging from bright yellow to orange on its topside (hence the alternate common name Sulphur Shelf), with its yellowish underside pitted with pores from which it releases its spores and a firm white fleshy interior. Read more...

It is that time of year, when many of our plants are looking a bit past their prime. The flowers on many have turned to seed heads, much of the new growth of Spring is now yellowed or dried, and the assorted flora of meadow, woodland and garden alike are succumbing to fungal pathogens such as powdery mildew. Another dramatic manifestation of the changing seasons around this time is the appearance of Tar Spots; peppering the leaves of sycamores and maples. Caused by the fungus Rhytisma acerinum, these brown-black blotches with yellow borders will be equally familiar to urban-dwellers, as they are commonly to be seen on that most ubiquitous of city trees, the London plane (Platanus acerifolia). Read more...

The woodlands blog has previously posted about hygienic behaviour that is seen in some bee colonies, this involves the removal of dead bee larvae and pupae. These could act as breeding grounds for mites and other insects that make “their home” in a hive. Mites, such as the varroa mite, are small spider-like creatures that attach to bees and ‘suck their blood’ and in so doing inoculate the bees with various viruses such as acute bee paralysis virus, deformed wing virus, and slow paralysis virus etc.   Mites are endemic to both wild and domestic bee colonies, as are insects such as wax moth larvae.  Wax moth larvae can burrow into the combs of a hive / colony destroying the cells where the larvae etc. are developing and growing, and where honey is stored. Read more...