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Pollinator preferences

Pollinator preferences

by blogs at woodlands, 4 April, 2022, 0 comments

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]
March Fungi Focus: Bracken Map and other Little Black Dots and Smudges

March Fungi Focus: Bracken Map and other Little Black Dots and Smudges

by Jasper Sharp, 28 March, 2022, 0 comments

There are times when one does begin to wonder whether one has tumbled too far down the rabbit hole of mycological obsession. Though the Spring months might seem something like a drought period for many in search of curious fungi, they are all around us and all year round. For the hardcore few, the next few months in particular are a time of rummaging through hedgerows and peering at dried twigs, grasses and herbaceous stems in search of what effectively appear as little more than black dots. From then on, it is a just a small step away from the full-blown insanity of lichenology. This month’s focus is on the more common and recognisable of these obscure types, which all fall within the category of ascomycetes: these are the spore-shooter types that develop their spores internally, typically in tube or flask-like sacs and in batches of eight, as opposed to the basidiomycetes, where the spores grow externally on cell-like structures known as basidia, typically in groups of four, which drop off as they mature.  Patellaria atrata, growing as inconspicuous black dots on a dead fennel stem, with the spores arguable more interesting looking than the fungus itself. I’ve written quite lengthily about various groups of ascomycetes in previous posts, but despite the fact that they far outnumber the basidiomycetes in terms of prevalence and the proliferating number and variability of species – which include the colourful goblet-shaped Green and Turquoise Elfcups, the hard black woodwarts and tarcrusts, and other less noticeable things like Sycamore Tar Spots and Holly Speckle) – many consider them a no-go area due to the inedibility of the majority of them, not to mention the fact most are very difficult to even see, unless one is looking specifically for them, yet alone identify.  Few have common names, and even the Latin names change with alarming regularity as individual species find themselves reclassified or split up into numerous subspecies. The obvious exception here is that prized edible, the Morel (Morchellan esculenta, although there are a few other lookalike species), one of the few that make it into spotters guides and foragers handbooks.  The spores of Bracken Map developing within its ascus, with their characteristic crescent shape, relatively large size and multiple segments. To really get to grips with the subject would take the kind of life-long fanaticism and fastidiousness displayed by the likes of Peter Thompson, the author of Ascomycetes in Colour (2013), who has evidently spent years driving around the country in search of photographic examples of the numerous nondescript specimens that can be found on specific hosts such as dead grasses, leaves and other organic material. It took literally a lifetime of research before the husband and wife team of Martin B. and J. Pamela Ellis devoted their retirement from teaching to put pen to paper for their landmark Microfungi on Land Plants: An Identification Handbook, first published in 1985 with a revised and enlarged edition appearing in 1997. Though it’s technically been out of print for years, the book remains a must-have for serious mycologists, giving an exhaustive list with detailed illustrations of the type of species one might find on a wide array of specific hosts, and secondhand copies are accordingly pricey. There’s also been more recent scholarly books such as Bjorn Wegen’s up-to-date and even more comprehensive Handbook of Ascomycota (2017), but again, this is a specialist publication intended for an academic readership and priced beyond the range of all but the most curious of amateur naturalists. The foreword of the revised 1997 edition of Ellis and Ellis refer to microfungi as “ones which require the use of a microscope to see their variety”. Nevertheless, a microscope isn’t always necessary for the identification of a number of common types if you can ascertain their host. For example, over the next few months, if one looks closely at dead nettle stems, one might spot the tiny tangerine-coloured fruiting bodies (ascocarps) of Calloria neglecta, an ascomycetes fungus specific to them. Two very similar looking species grow on ash keys: Diaporthe samaricola, grows on the seed part; the smaller Neosetophoma samarorum only grows on the winged part. An even more extreme example of host specificity is Diaporthe samaricola, which over the winter months appears as miniscule black dots, less than half a milimeter in diameter, on the dried winged seeds, or keys (‘samara’) of ash trees. However, they will only appear on the seed part of the ash keys. Another fungus, Neosetophoma samarorum, produces eruptions of even smaller dots on the winged parts of the keys. The two will often appear side by side. They have no adverse affect on the health of the tree in question, although there is another ascomycetes that does have a notoriously detrimental effect on its host - Hymenoscyphus fraxineus, responsible for Ash Dieback and detailed in a previous post. Its small, white nail-shaped fruitbodies can be found on the blackened twigs and petioles at the foot of the infected tree around June. Bracken Map (Rhopographus filicinus) is another commonplace and instantly recognisable species that is host specific. It can easily be spotted at this time of year in most places where you find dead bracken, just prior to a new season’s growth sprouting up to replace the last, but actually one can find it all year round. The reason for its name is self-evident, as it grows in elongated spreading black blotches that eventually merge to form irregular shapes like countries on a map. Dead bracken stems throughout the year can be seen hosting the tell-tale ascocarps of the Bracken Map. These blotches are the ascocarps, the fruitbodies from which the spores are released. The are described as pyrenomycetous, meaning that like the tarcusts or woodwarts or commonly-spotted Cramp Balls (Daldinia concentria, aka King Alfred’s Cakes), they are hard, brittle, and often carbonaceous, optimised to continue releasing spores over a relatively long period of time during the late-winter and spring months when the weather is relatively dry and temperatures start increasing, and yet there’s little greenery about to shelter them from the dry wind and lengthening hours of sunlight or get in the way of spore dispersal. Each of these fruit bodies contains numerous tiny ‘perithecia’; flask shaped pits in which the asci sacks and the spores that develop within them are housed and are kept from dessication. The spores are released from holes known as ‘ostioles’ in the top of the perithecia that cover the black surface of the Bracken Map. If one looks really closely, one can see that the ostioles in the case of the Bracken Map are elongated along the length of the bracken stems. The ostioles from which the spores are released can just about me made out when the ascocarp is looked at extremely closely. The shape of the ostioles are a key feature in identifying other pyrenomycetous fungi, as detailed in my 2020 post on Woodwarts, Blackheads and Tarcrusts. It’s just as well, because there are many other types of such fungi that are not quite as distinctive-looking as the Bracken Map, and often much much smaller. I’ve been scrutinising various hedgerows recently, and noting that despite their superficial similarities, the seemingly identical black dots that appear on, for example, elder or hawthorn, are often very different species from those that appear on the woody dead stems of clematis or hogweed or other plants. Fortunately, for those with a microscope, these kind of ascomycetes do have very distinctive spores that often serve as much better means of identification, in consultation with the literature cited above, than the actual ascocarp fruitbodies. As mentioned, basidiomycetes produce their spores externally on basidia, growing like apples from trees almost, and so they are typically asymmetrical and one can note the vestiges of a kind of stem by which they were attached to the basidia. The ascospores of ascomycetes tend to be much more symmetrical, often much larger and in some cases much more complex, consisting of multiple cells in different arrangements.  These tiny specks on a dried hogweed stem could be anything, but the complex multi-celled spores compare with a species called Pleospora phaeocomoides. The spores of the Bracken Map are a great example of this – they are 27-35x7-8 microns in size, making them about three to four times the size of a typical mushroom-shaped basidiomycetes type like a Brittlegill – and to put this in perspective, they are just a smidgen smaller than the 40-micron threshold considered visible to the naked eye, or about the size of a small grain of salt. They are crescent shaped with 4-8 segments, and look rather like croissants under the microscope. I’ve detailed a scant few of these types of fungi prevalent over the next few months that can at least be recognised without recourse to a microscope. There are, however, at least 10,000 ascomycetes species found in the British Isles alone, so this is clearly a subject few will want to engage with too thoroughly. There are a couple of other more readily identifiable species that might catch the attention of the woodland walker, however, but I’ll leave these for next month... Bracken Map
Fire and forests.

Fire and forests.

by blogs at woodlands, 25 March, 2022, 0 comments

There is evidence that trees lost to fires and drought are not returning to fire damaged areas.  Fire has been ‘part and parcel’ of  the dynamics of some forest ecosystems.  The fires take out smaller trees, giving space and light to others.  Fire (or the smoke associated with it) can even help the seeds of some species to disperse and/or germinate (eg. serotiny in certain Pines). Different chemicals from smoke such as karrikinolide and glyceronitrile are known to play key roles in smoke-stimulated germination of certain species, such as heather. However, climate change is affecting forests (and woodlands) across the globe. Fires are becoming more frequent (associated with increasing drought) and trees are struggling to return / regenerate after intense or repeated fires.  An analysis of a number of sites in the Rocky Mountains suggests that in some areas fire, moisture stress and increasing temperatures result in a loss of resilience so that forested areas are being replaced with shrubs, grassland and flowers.  "Fire refugia" are areas that somehow avoid significant or frequent damage; they burn less often and/or less intensely than the surrounding landscape.  Such areas are important in the recovery of the ecosystem after a fire - allowing re-population of the area with a variety of species.  [caption id="attachment_35352" align="aligncenter" width="650"] Woodland recovering from a fire[/caption] Consequently, studies have been directed towards understanding the physical and biological nature of such refugia.  The work has focused on mature, conifer dominated forests in the States (The Klamath-Siskiyou region)  and the fires that have occurred over a period of some 30 years.  It was found that refugia were associated with physical features of the habitat such as rocky outcrops, depressions in the landscape.  It was also noted that the density of the smoke that the fires generated was a factor in tree survival (perhaps dense smoke offered a degree of shade?).   The area studied has a complex and diverse geology,  with varied habitats that support considerable biodiversity.   Fire has always been a key factor in the maintenance of the varied landscape but with the climate becoming hotter and drier, there is concern that an increasing frequency of fires will ‘eat away’ at the forest’s ability to regenerate - with the loss of refugia and incineration of seed banks in the soil. Severe fire can reset the path of succession - so that forest can be reduced to bare soil. Complex and established communities of fungi, microbes, plants and animals are lost, reduced down to bare soil. Intense heat will damage the structure of the soil, reducing its organic content and its complex community of microbes. In extreme cases, this can lead to the erosion of the soil.  
Changing forests and woodlands.

Changing forests and woodlands.

by blogs at woodlands, 18 March, 2022, 2 comments

For millions of years, forests and woodlands have been changing - as a result of natural regeneration, storms, fires and climate change.  However, with the expansion of human populations, woodlands and forests have been cut down to make way for towns, cities and the infra-structure of ‘modern’ life.  Sadly forests, and woodlands such as those in the path of HS2,  are still disappearing. ‘Untouched’ rain / tropical forest is being cut down to make way for cash crops; plus vast wooded areas have been destroyed by fire in Australia, Sweden and on the West Coast of the United States in recent years. Clearfell of any forested area for timber or agriculture involves the removal of all trees / vegetation and is sometimes followed by burning of the remaining debris. Clearfell can also have unintended consequences (beyond the loss of entire animal communities.  An Australian study has shown that it lowers soil nutrient levels - notably nitrate and phosphate.  Furthermore, the use of heavy machinery in clearfelling can compact the soil and its consequent exposure to the elements can lead to erosion (rain runoff).   When an area is subject to intense fire, there is a drop in the organic carbon content of the soil and structural damage to the soil; it can take many years for such fire-damaged soil to ‘recover’. Forests and woodlands support the vast majority of land-based species. However,  the species that we see today on a woodland walk may be different to those our ancestors might have seen five hundred or a thousand years ago.  Certain species only survive in relatively undisturbed (and ancient) forests / woodlands.  There are species that can ‘deal’ with disturbance and are adaptable, indeed opportunitistic,  such as red deer and fox.  The same can be said for certain plants species, which can become invasive.   Changes in species make-up and biodiversity do not always immediately follow loss of forest or woodland.  Generally speaking, the longer the life span of a species then the longer for the effects of forest loss to become apparent.  It may be that the effects ‘span’ generations, raptors / birds of prey may manage to raise their young in the immediate period following loss of forest or woodland. But their offspring may struggle to survive in a depleted environment. It might be that with limited resources an animal might simply not reproduce for years, if ever again.  Consequently, the impact of forest destruction / loss that species depletion might not be apparent for many years. The loss of forests and woodlands has lead to many local, national and inter-national initiatives to offset these losses: for example, New Zealand’s ‘One Billion Trees” project and the Nature Conservancy’s “plant a billion trees’ campaign.  Broadly speaking, reforestation involves the planting of native trees in an area, whereas planting with new (non-native) species is afforestation. Recent research suggests that whilst non-native plants often grow faster than native species, they also have less dense tissues (think: oak versus larch) and decompose more readily, which can contribute to more rapid cycling of carbon.  This will not help to mitigate climate change. It is also important to consider which trees might prosper and offer resilience in the light of climate change. Our climate is changing and will be different in the future, with summer temperatures being higher.  We have already seen more extreme weather events (leading to flooding and wild fires).  Forestry England has a number of tools to help plan which tree species will be suited to a site, now and in future.   There is ESC4 which offers a means to help forest managers and planners select tree species that are ecologically suited to particular sites; and there is also the climate matching tool.  As Forestry England says this is “so that we can see which places in the world currently experience the climate we are projected to have in future. We can compare these different places to help us plan which tree species will be suited to a site, now and in future”.  One strategy is to create woodlands that are more diverse, as it thought that diversity helps woods more resilient to climate change. This can be through encouraging a range of different, but carefully selected trees to grow, and being aware of the provenance of seeds or saplings.
Spring is on the move.

Spring is on the move.

by blogs at woodlands, 8 March, 2022, 0 comments

In recent decades, signs of Spring have occurred earlier and earlier, indeed the early flowering of crocuses and daffodils in our gardens is one such sign. Now a detailed analysis of such ‘signs’ has been undertaken by using the information held in Nature’s Calendar.  This is an enormous database * of records of seasonal changes; it has records of some 400+ species of plants, from trees, to shrubs and herbs. Nature’s Calendar includes records from organisations like the Royal Meteorological Society, plus those of scientists, naturalists and gardeners. Recording when things happen (such as when horse chestnut and ash trees come into leaf, or when the first swifts or bumblebees are seen) is known as phenology. These timings vary from year to year.  Phenology is not a new discipline. One of the first phenologists was Robert Marsham, who recorded ‘indications of spring’ starting back in 1736. He catalogued some 27 different natural events on his family’s estate in Norfolk.  In 1875,  the Royal Meteorological Society set up a national recorder network.  Nature’s Calendar includes thousands of these historical observations and enables scientists to look for trends and see if they correlate with changes in temperature, rainfall, weather phenomena. The research team from Cambridge University looked at FFDs - first flowering dates and temperature records. They found a difference in flowering dates from the 1750s and the most recent years of almost a month.  Professor Ulf Büntgen has said that rising global temperature has brought Spring forward by several weeks.   This raises concerns. For example, if a plant grows and comes into flower earlier in the year what happens to insects that are dependent upon it? For example, some bees collect from only one species of plant.  Or to put it another way, suppose the plant flowers earlier but its pollinating agent (an insect such as a hover fly) is not about, has not emerged from its over-wintering stage? What if there is a ‘late’ frost?   * Nature’s Calendar : The Woodland Trust joined forces with the Centre for Ecology & Hydrology to collate phenology records into Nature’s Calendar; this has some 3.5 million records- some going back to eighteenth century.  
Home to roost  : an owl box.

Home to roost : an owl box.

by Liz, 2 March, 2022, 1 comments

In late winter, it’s good to put up new nest boxes and clear out existing ones, in time for the breeding season.  In Ellekers Wood, as part of our management plan, we've been making lots of new boxes for birds and bats. Bats are currently having problems finding food to eat, plus many of their natural roosting places have disappeared. Building a bat box offers them :- somewhere safe to roost,   a place to raise their pups and  Sleeping quarters during the day.  Our biggest boxes are the two tawny owl ‘chimney boxes’.  Tawny (or brown) owls (Strix aluco) ‘own’ the classic owl hoot. They will nest in large gardens with trees, but woodlands are good for them. Their diet ranges from worms to rabbits.  Tawny owls like a north east facing entrance,  with a clear route.  Our boxes are made from 1" thick, rough sawn larch planks. We followed the RSPB design. Each box is approximately 800mm long (measurements / specifications available here).  Fortunately,  Dan has a head for heights and he has installed the boxes in mature oak trees at a height of approximately 6 metres.  The tawny owl typically makes its nest in a tree hole where it can protect its eggs and young against potential predators. They will occupy / nest in smaller cavities than barn owls and the design of the box reflects this. As tawny owl chicks start to explore their surroundings before fledging, it is important that the boxes are placed with easy access to nearby branches, so that they can climb over.  As with many species of birds, tawny owls are sensitive to disturbance when incubating their eggs, and should not be approached as they can be aggressive.  It is important that consideration is given to the siting of any box [embed]http://youtu.be/RfXIHXCyTNk[/embed]   Full details of RSPB nest boxes for various birds can be found here : https://www.rspb.org.uk/birds-and-wildlife/advice/how-you-can-help-birds/nestboxes/nestboxes-for-owls-and-kestrels/  
The lost trees of Dartmoor

The lost trees of Dartmoor

by blogs at woodlands, 25 February, 2022, 2 comments

Certain upland areas of the UK , such as Dartmoor, have experienced long term grazing.  This has lead to soil compaction, which in turn means that water run-off is greater. Instead of percolating into the soil, rain water runs over the surface and into rivers. This can lead to flooding during extreme weather events.   Dartmoor (National Park) is a large upland area, which historically was dominated by oak woodland.  Oak woodland now covers a very small area.   The region is now dominated by blanket bog, heathland and acid grassland.  The number of grazing animals (sheep, cattle and ponies - deer) increased significantly between the 1950s and 2000, resulting in soil compaction. Researchers at the University of Plymouth have investigated areas of upland pasture on Dartmoor, and the potential for the establishment of native oak saplings. Working with test sites, they were able to show that significant improvements in soil properties could be observed with 15 years of sapling establishment.   The most effective location (in terms of flood prevention) for sapling / tree planting was on steep hillside on the edge of upland areas.   Their initial work on the planting of woodland has since been expanded to determine the factors that affect the establishment of the tree (oak) saplings.  Their most recent paper notes that the presence of livestock meant that fewer oak saplings survived and those that did were smaller.  However, the effects of cattle and ponies was not always negative in that their trampling could reduce the growth of bracken - allowing more light to reach young tree saplings. [caption id="attachment_34391" align="aligncenter" width="650"] A southern upload moorland - Exmoor[/caption] The research team formulated a number of recommendations relating to the creation / establishment of woodlands in such upland pastures. Livestock should be excluded in areas where there are seedlings and young saplings (1 - 3 years). This exclusion should last for some 12 years. Larger oak (4 - 7 yrs) saplings can be planted into areas of dense vegetation, as this protects the saplings from livestock. Livestock could be allowed to graze in the vicinity of mature oak trees as this would reduce dense, competitive vegetation, allowing seedlings to grow / develop.  Strategic planting and management should be considered  / encouraged for upland slopes where drainage is poor - to allow for soil recovery and development of ecosystem services (flood mitigation). Whilst natural tree colonisation is a low-cost and environmentally sensitive mechanism to promote woodland expansion (working towards government targets on climate mitigation, carbon sequestration etc.), it is likely that the expansion of oak woodland into upland pasture systems will require strategic planting and informed livestock management. [caption id="attachment_37920" align="aligncenter" width="650"] Exmoor Ponies.[/caption] Full details of their paper can be found here : https://besjournals.onlinelibrary.wiley.com/doi/10.1002/2688-8319.12126  (Thanks to Art for images of exmoor and ponies).
pollution over city

The loss of animal species, and the effects on fruit and seed dispersal.

by blogs at woodlands, 23 February, 2022, 0 comments

Sadly, the world is losing species, both plant and animal, at a significant rate.  Indeed, some claim that we are now experiencing the sixth mass extinction.  In contrast to previous extinctions (the Permian extinction is thought to be due to an asteroid impact), the present loss of species is largely associated with a mix of direct and indirect human activities. These include :- destruction and fragmentation of habitats,  Exploitation fishing stocks and hunting (think dodo),  chemical pollution,  invasive / introduced species, and  human-caused global warming The loss of animal species has knock-on effects in terms of food chains and biodiversity. Plants are also affected as many rely on animals for the dispersal of their fruits and seeds.  In times of global warming, it is essential that plants can reach new areas that are suitable for their growth.  If not, they are stuck in areas where they may not be able to survive in the changed / changing conditions.  This could mean that plant species are lost, together with the ‘ecosystem services’ that they provide (be it food, timber, carbon storage, flood mitigation etc).  Seed dispersal is also important in terms of recovery from ecological disasters, like wildfires.  Natural forest regrowth usually happens through seed dispersal. If an ecosystem is rich in species, it is generally more resilient to environmental change.  The relationship between fruit / seed dispersal and animals has been significantly affected by the creation of roads, motorways, farms, and the development of cities - essentially habitat fragmentation.  Animal dispersal is often associated with fleshy fruits.  Whilst this is particularly true / obvious for many tropical fruits, it is also the case for many plants in temperate regions.  Berries, hips and haws are dispersed by animal means, with birds being particularly important agents. Several pines produce large seeds and attract corvids such as nutcrackers and jays. The birds, sometimes called scatter hoarders, collect seeds and bury them in areas away from the parent trees but in habitats suitable for the next generation of trees  Mammals also play significant roles.  In Africa, elephants are important  seed  dispersers  for  numerous  species; they  have an extra-ordinary sense of smell and will search out ripe, fleshy fruits. Some seeds have been shown to be distributed 60+ kilometres from a parent plant. Not only this, but the journey through the gut of the elephant seemingly increases the chance of germination, and being deposited in the dung reduces the chance of the seed being eaten by beetles.  Some monkeys in South and Central America eat as many as fifty different types of fruit in a day. carrying some off in their stomachs and dropping others to the ground. In Britain, as part of their diet, foxes will eat various wild fruits, like blackberries; squirrels eat nuts; and mice / voles eat grass and other seeds.  Even invertebrates, like ants, disperse seeds. This may be through the activity of harvester ants, which, like squirrels and other ‘gatherers’,  forage the ground of the wood or forest (collectively) gathering large quantities of seeds and  then transport them back to their nests / colonies.  As they transport the seeds, some get dropped or lost on the way.  Others may be ‘cached’ in or near the nest for later consumption but then are ‘forgotten’ or ignored. Some fruits contain seeds covered with a sticky substance as is the case of Mistletoe. When birds feed on the fruits, the seeds often stick to the beaks of birds.  Then, they may wipe the sticky seed off on a branch;  or it may be eaten and pass out in the bird’s droppings. The ‘glue’ (viscin) around the seed helps fasten the seed in place. Even humans carry seeds far away for plants, for example, by taking an apple on a picnic and throwing the core with its seeds into the bushes. Or seeds may transported in the mud sticking to boots and shoes, or indeed on tractors, cars or other machinery. The loss / extinction of animal species from any given habitat will sooner or later effect the plants.  We are only beginning to fully appreciate the interdependence of life.    The loss of any species - plant or animal - will undoubtedly have unintended and unforeseen consequences which can only be to the detriment of all life on earth.  

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