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...

The fact that UK is an island has kept many potential pathogens and pests ‘at bay’.  However,  in recent times the growth volume of international trade has become a cause for concern.  Pests and pathogens can ‘hide’ in important plants and plant products (for example, timber that has not been debarked or suitably treated). The Great Spruce Bark Beetle is likely to have arrived here in wood that had not had its bark fully removed.  The beetle breeds under the bark of trees, creating tunnels resulting in the destruction of the cambium.  The cambium is a highly active tissue, producing new cells that will go on to form xylem and phloem tissue.  These tissues distribute nutrients and water around the tree.  With a damaged cambium, a tree is weakened and more susceptible to other pests or pathogens. In the case of the Great Spruce Bark Beetle, a bio-control measure was allowed; a natural predator of the bark beetle has been introduced (Rhizophagus grandis).  Consequently, the numbers of bark beetles have fallen.  Wherever the bark beetle goes, its predator sooner or later follows.  It is thought that its predator ‘finds’ the bark beetles due to the volatile chemicals released from the bark as a result of the beetles' burrowing activities. The U.K.’s control measures generally proceed by four steps : Try to prevents pests and pathogens arriving in the country eg. Inspection of plants etc at ports of entry If a foreign organism arrives then the authorities try to eradicate the pest / infected plants / trees, hopefully the organism does not become established If a pest or pathogen has become established then a containment policy is put in place If all of the above fail then the Forestry Commission and other bodies operate in a way that mitigates the effects of the pest or pathogen.   Phytophora ramorum is a disease of many plants that probably arrived here through the plant import trade.  It has persisted at a relatively low level for many years but from 2009 onwards it affected commercial stands of larch in South West England.  Felling of infected trees helps restrict the spread of this fungus-like pathogen; and a map is available to show where outbreaks of this disease have occurred. Clearly, these introduced species of pest / pathogen could significantly affect the make-up of our woodlands over the coming years, if diseases like acute oak decline / ash dieback are not controlled or contained.  Fortunately, the spread of disease-causing organisms and pests is monitored by both national and international organisations such as these : EU Plant Health Directive this requires nations to report new outbreaks or new pathogens, t the European Mediterranean Plant Protection Organisation is an intergovernmental organization responsible for cooperation in plant health within the Euro-Mediterranean region and  the International Plant Protection Convention, a plant health treaty signed by over 180 countries.  

It is good to have points of orientation in the woods. No matter how familiar with a particular spot you might be, these environments can change so dramatically throughout the seasons – paths and clearings become overwhelmed with brambles, branches that weren’t an obstacle in the winter become suddenly more so when covered in leaves, and woodlands are ironically much gloomier in the summer months with a thick canopy overhead than when the trees are bare – that it’s surprisingly easy to lose ones bearings.  One of the marker points in my favourite stomping ground, a chestnut coppice just outside of Canterbury, was a bracket fungus that I found growing from the top of a stump several years ago. It was a relatively easy identification for me from this sometimes daunting group – the labyrinthine arrangement of branching, elongated grooves quickly pointed me towards an Oak Mazegill, despite the fact it was growing on chestnut.  Oak Mazegill For several years, this particular specimen by the side of the path also signalled the point where I knew I’d entered into a sector of more ancient woodland, and one of those hotspot areas where there were usually lots of exciting finds nearby. Then one day it was gone – the clean cut at the base where it grew from the wood indicating that is had been consciously removed with a knife. Even now, about a year later, I can still see traces of the patch where it had endured on the top of the stump for so many seasons. The Oak Mazegill, or Daedalea quercina – the first part of its latin binomial referring to the figure of Daedalus who in Greek mythology constructed the labyrinth at Knossos housing the legendary minotaur – is a particularly prevalent fungi in my local woodlands; much more so because, as a perennial, the fruiting bodies last for years rather than rot back or drop off at the end of the season. It shares this aspect with the tough woody brackets like the Artists Conk (Ganoderma applanatum), covered in passing in a previous post on brackets, which has been known to last for decades. Oak Mazegills aren’t quite as durable, although I’ve no real idea how long a fruit body might last. Their flesh is tough, but still possible to make a clean cut through it with a sharp knife with relative ease, as if it were a piece of rubber. Oak Mazegill This species highlights the importance however of always looking at the underside when trying to identify brackets. The top is rather nondescript, a sort of buff, pale yellowish brown colour ranging to orangish brown and reaches up to 20cm across. They often grow in semicircular tiers, with the full width of the body firmly attached to the wood making them very difficult to dislodge, and sometimes have an upside-down pyramidal shape, so that if viewed in profile, the maze-like underside is very easy to see. The growth isn’t always so uniform, however, drawing attention to the fact that there can often be a fine line between the brackets and certain poroid resupinate or crust fungi, with the form they assume heavily influenced by the orientation of their substrate.  Oak Mazegills don’t always immediately form brackets when first emerging, with the specimen depicted here assuming a more resupinate form. For example, I found myself once very confused by a newly emerged Oak Bracket growing from the top of a  stump that had yet to form a cap, so that all that could be seen was a think bulbous growth covered in brain-like grooves that could look like a number of other thick poroid resupinate fungi, such as the Common Mazegill (Datronia mollis) – and it should be mentioned that the Common Mazegill, while often found in its flat resupinate form, can form caps if growing on a vertical substrate, albeit with thinner caps of a far darker colour. The not dissimilar resupinate fungus the Common Mazegill has a less pronouncedly maze-like pattern of pores Mature Oak Mazegills, I do find pretty distinctive, but the reason I’m covering them for this month is that it is during the summer months that the new fruitbodies start emerging, so if you have any problems identifying them, I’d suggest going back and monitoring their progress over the coming months, for there are a couple of species that you could confuse them with before they are fully grown. The first of these is the Birch Mazegill (Trametes betulina), but these form much more delicate annual fruitbodies which are thinner fleshed and more easily broken, with grooves on the underside that are sharper edged and look more like conventional mushroom gills (although as I described in the post linked above, these aren’t true gills) and a felty upper surface. They also grow on birch, rather than oak or chestnut, so there shouldn’t so much room for confusion here. The Blushing Bracket is less ‘chunky’ than the Oak Mazegill, despite certain similarities when viewed from above. Rather more easily confused for the Oak Mazegill, however, especially in their early stages of growth, is Daedaleopsis confragosa, the Blushing Bracket. Again, these feel a lot slighter, thinner and flatter than the chunky, coarse gilled bodies of the Oak Mazegill, although the flesh is similarly tough.  However the base is much narrower where it grows out of the wood, making it look more fan-shaped. Looking underneath, the pores are much less maze-like, and more like straight lines, which become more elongated as the cap grows radially outwards.  The underside of the Blushing Bracket reveals very different patterns than that of the Oak Mazegill The cap surface starts out a pale beige, but as it grows, it darkens through pinks, browns, russets and vinaceous purples to near black, hence the name. They also are more pronouncedly ‘zonate’, with subtle differences in texture and colour appearing from the centre and outwards. The Blushing Bracket might be confused with a number of other long-pored brackets in their early stages, but if you follow their development across the months leading into winter, it soon becomes clear what they are. Again, they favour deciduous woods, but are less likely to be found on oak and chestnut than on birch, alder and willow. Some of the literature suggests that Blushing Brackets are perennials, like the Oak Mazegills, but my experience suggests that while the new fruit bodies from any given summer may be found well into the winter, very few make it past a year. Blushing Bracket : The upper side of the Blushing Bracket darkens and reddens across the winter months Blushing Bracket : Sometimes reddening to a dramatic deep red These are but a couple of the more common hardwearing brackets with elongated pores that are found in the UK that might seem a little drab when just glimpsed in passing, but actually are quite interesting when you know what you are looking at. Like so many fungi, the exact differences are difficult to describe precisely in words, but once you get a feel for them, they can be recognised at a glimpse.  If you are a regular woodland wanderer, it’s worth paying at least passing attention to them because, as mentioned before, the new fruitbodies will have already begun appearing by now, and given that they’ll be with us for some months yet to come, it’s rather fascinating looking at how both species develop in form and colour. Additional images. Blushing Bracket Oak Mazegill Oak Mazegill Blushing Bracket   

Checking nest boxes is deeply satisfying, and a fitting reward for all the time spent during “lockdown” making and installing a dozen or more new boxes. We now have 27 in the wood - some are specialised such as those designed for Treecreepers, some for large birds like our two Tawny Owl boxes, but most are standard boxes designed for the tit family. Checking the Boxes: There’s a strong feeling of anticipation when you lift the lid of the Blue and Great Tit boxes. Sometimes the adult is there and stays steadfastly put, or sometimes off she goes, revealing what? - a beautiful clutch of eggs, a huddle of chicks (featured image).  Read more...

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]