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great tit

Food for thought?

by blogs at woodlands, 16 January, 2022, 0 comments

It is estimated that each year UK households spend some 250 million pounds on bird food.  This amounts to some 150,000 tonnes of suet pellets, fats balls, peanuts, sunflower seeds etc - on offer (in feeders of varying complexity*) in urban and sub-urban gardens.  These offerings are a marked contrast to the occasional kitchen scraps that were placed on home-made bird feeding tables some 50 years ago.  The question has recently been raised as to whether this is a good thing.  In 2019, research by the British Trust for Ornithology indicated that this provision of food can affect bird communities in the United Kingdom.   For example, species that rarely visited gardens in the past, have become common visitors. Now, researchers at Manchester Metropolitan University have suggested that these extensive offerings of food might be affecting the ecological balance between different species. Blue tits and great tits are regular feeders in gardens, and they appear to benefit from this provision.  Blue tits tend to be be quite dominant in terms of their interactions with other birds - whether quarrelling over food or nest sites.  Consequently, species like willow tits and marsh tits tend to ‘lose out’ in such altercations.  Certainly, willow tits miss out to blue tits in the competition for nesting sites.  Another species affected is the pied flycatcher.  This is a summer visitor, spending the winter in West Africa.  It, too, is in competition with great tits for nesting sites.  The provision of food for resident bird populations may tip the balance against summer migrants, like the flycatcher. The change in feeding patterns of some birds may of course be associated with the expansion of farming over the decades and the consequent loss of natural foods such as fruits, seeds, nuts and berries - from  hedgerow flowers and shrubs.  This may contribute to birds visiting gardens more often.  It may be that our desire to help garden wildlife needs more thought as to the type of ‘help’ that is offered.  This could involve allowing our roadside verges and gardens to be ‘wilder’, with less frequent moving of lawns / grassy areas, more ground cover, planting native trees (like crab apples, hawthorn), less weeding, allowing seeds and fruits  (eg. rose hips) to form, which would encourage insects / spiders Consequently more natural resources would be available to birds and only in harsh times would supplementary materials be needed.   NB : it is essential that feeders are regularly cleaned so that disease is kept to a minimum [e.g. Trichomonosis  caused by the protozoan parasite Trichomonas gallinae] . Remember later this month (28 - 30th January), there is the Big Garden Birdwatch, organised by the RSPB. For further information, click on the image below:-   A footnote : As a species, we have not always been kind to birds.  A recent paper from Tel Aviv University details how humans have been responsible for the extinction of hundreds of birds species (over the last 50,000 years).  They have listed some 469 species of birds that have been lost, though the true number is probably considerably higher.   Many of these extinctions occurred in a short time frame and  were due to either : The hunting of birds (and their eggs) for food or The killing of birds by animals (rats etc) that human expansion brought to islands / countries. Many of the extinct species shared a number of features : Most lived on islands Many were large or very large birds (e.g. the dodo on Mauritius - that provided humans with significant quantise of high quality protein. (A similar fate befell certain large lizards and turtles). Many of the birds were flightless and could not escape their hunters.  
Promoting wildlife in gardens

Promoting wildlife in gardens

by blogs at woodlands, 7 January, 2022, 0 comments

Reports in the papers and electronic media have made us aware that many forms of wildlife are under threat.  This threat is wide ranging - from the destruction of tropical rain forests, coral reefs, the loss of species-rich meadows, the insect apocalypse - indeed where does this loss of plant and animal species end? One small positive observation amidst the doom and gloom is the findings of The Biodiversity in Urban Gardens project [BUGS] at the University of Sheffield.  The original study focused solely on Sheffield and finished in 2002, but  it was then extended to five cities across the U.K.    Professor K Gaston who led the study is now working at the University of Exeter.  The original study was important in that it revealed within Sheffield city, there was 33 km2 of wildlife habit was available within the city 360000 trees in the city limits 45000 nest boxes 25000 ponds and  50000 compost heaps Furthermore, there were in excess of a thousand plant species (flowering plants, ferns and conifers) and a diverse collection of invertebrates (bumblebees, hoverflies, beetles and spiders).  Whilst the diversity was in no way comparable to that of an ancient woodland (with veteran oak trees etc) or indeed of wetlands, it is significantly better than that found on farmland - particularly in those areas where the farming is intensive and characterised by monocultures (e.g. oil seed rape extending to the horizon).  Farmland now occupies some 70% of the landscape. Gardens, parks and urban areas are therefore an important resource for wildlife.  It is important as house building proceeds, on both brown and green field sites, that the associated gardens continue to provide ‘sanctuaries’ for wildlife, for example, by avoiding large areas of hard standing for cars (which also encourage  rain / water run off - which can overwhelm the drainage systems).  Professor Gaston has emphasised the importance of ‘dimensional complexity’ in gardens; that is a variety of trees, shrubs and plants of different shapes and sizes.  This provides a range of different niches / habitats for wildlife.  Of course,  in gardening to promote wildlife, there are the additional benefits (for householders) of physical and mental well-being.   Remember later this month, there is the Big Garden Birdwatch, organised by the RSPB. For further information, click on the image below:- [caption id="attachment_36525" align="aligncenter" width="670"] Ladybird 'stalking' aphids[/caption]
The sycamore : Acer pseudoplatanus.

The sycamore : Acer pseudoplatanus.

by blogs at woodlands, 30 December, 2021, 0 comments

Acer pseudoplatanus is known as the sycamore in the U.K, or the sycamore maple in the United States. It was first described in botanical terms by the Swedish naturalist Carl von Linné in 1753.  It is thought that the sycamore is an introduced species, as its native range is central Europe and Western Asia.  It probably arrived in this country in the Tudor period (circa 1500 CE).  That it has no old native names is perhaps indicative of its absence before Tudor times, (Some say it has been here longer and have suggested that it persisted in Scotland).  It was recorded in the wild in Kent in 1632.  The sycamore is probably best regarded as a neophyte.  A neophyte is a plant that is not native to a particular area / region and has been introduced in recent history. Whatever its background, the sycamore is now to be found spread across the country. Its spread is due in no small part to the capacity of a single tree to produce many hundreds, indeed thousands of seeds.  The seeds are ‘winged’.  The wing of each seed develops from an extension of the ovary wall.  Two seeds are joined together to form a structure termed a double samara - a 'helicopter-like' device.  The wings catch the wind and the fruit rotates as it falls from the tree. This slows the descent and enables seed dispersal over a greater distance.  The sycamore has been deliberately introduced in a number of countries as it is tolerant of air pollution, salt spray and wind and it readily invades disturbed ground (abandoned farmland, brownfield sites, roadsides etc).  It is now regarded as an invasive species in, for example, New Zealand.  The leaves of the sycamore are simple but large. Each leaf has five distinct lobes and five veins radiate from the base of the leaf into the lobes. The edge of the leaf is somewhat ‘ragged’ with rounded 'teeth'. The lower surface may bear some hairs. The leaves are arranged in opposite pairs around the twigs / stem. In Autumn,  heavy leaf fall can mean that the ground under a sycamore tree can be smothered with a significant layer of the leaves, consequently the diversity of the ground flora underneath the tree may suffer. In spring and summer, the leaves can support large populations of aphids. Evidence of aphids on the leaves may be seen in the form of honeydew; this is the sugary waste of their feeding.   It may fall onto lower leaves (and cars); it provides food for flies and other insects.  The aphids themselves are a food source for ladybirds.  Sometimes the leaves are covered with small, red 'blobs' / projections - these are galls caused by a mite (a small spider-like creature).  The female mite lays eggs in these structures. Sycamores can be coppiced, that is, cut down to a stump which will rapidly produce new growth - for poles etc.  The timber of the sycamore is close grained, white to cream in colour that turns ‘golden’ with age.  It can be used in making musical instruments (violins), furniture, wood flooring There are many other species in the genus Acer, for example, Acer platanoides - the Norway Maple, Acer campestre - the Field Maple, Acer palmatum - Japanese Maple, and Acer saccharum - the Sugar Maple.  All of these have a (diploid) chromosome number of 26. Interestingly, the sycamore has a chromosome number of 52 - the number of chromosomes per cell has doubled.  The sycamore is a polyploid. A couple of interesting historical points about sycamore ;  The Tolpuddle Martyrs' Tree is a very old sycamore. The tree was used as a meeting point (in 1833) for six local agricultural labourers to discuss low wages and their poor living / working conditions.  They are associated with the birth of the trade unionist movement.  The 'Tolpuddle Martyrs' (as they came to be known) were sentenced to seven years of penal labour in Australia and were transported to Botany Bay. Dule trees were used as gallows for public hangings and also used as gibbets for the display of the corpse after such hangings.  One such dule tree lies within the grounds of Leith Hall, near Huntly, Aberdeenshire. This tree is a sycamore. The strong timber of sycamore made it a favoured tree for this purpose. [caption id="attachment_36329" align="aligncenter" width="645"] emerging leaves[/caption]  
conifer woodland

Creating diverse woodlands and forests

by blogs at woodlands, 14 December, 2021, 2 comments

We know that forests are important to all life on the planet.  They have often been referred to as the ‘lungs of the earth’, a reference to the fact that they produce vast quantities of oxygen - which is essential for respiration for so many forms of life.  They also take up carbon dioxide and ‘fix’ it into complex organic molecules - from starches, to cellulose and lignin.  Thus, the carbon is locked away for months, years or even millennia.  The equatorial forests of Brazil and Sumatra are species rich, incredibly diverse, but deforestation and the expansion of agriculture are threats to many biodiverse, forested areas across the world. As so many forests and woodlands have been felled, there is now a movement to plant millions and millions of trees (across the world) in an attempt to mitigate climate change and in the UK to increase our percentage tree cover from a pretty low base.  Sadly, twentieth century forestry in the U.K was largely based on monocultures (for timber production). The trees planted were large stands or plantations of conifers - using Scots Pine, Larch and Spruce. These plantations not only lacked biodiversity, but were / are susceptible to wide scale pest infestation and extreme weather events.   Woodlands and forests that have a diverse range of tree species are not only healthier but show greater growth and carbon fixation. They are more resilient.  The diversity of trees ensures the each species accesses slightly different resources from the environment  - from soil minerals, water and light.  Diversity means that trees of the same species are less likely to be clustered together so pest and pathogen outbreaks are less common or less severe.  One area that has undergone an extensive and diverse planting regime is Norbury Park Estate (near Stafford).  Since 2009, over 100 different tree species have been planted, and the woodlands can now produce 1500 tonnes of new wood each year, and harvest 5000 tonnes of carbon dioxide from the air.  Not only can diverse woodlands / forests fix carbon, supply harvestable timber but they also offer areas for rest and relaxation. Whilst it is not possible to plant an 'instant' forest or woodland, it is possible to plant a range of tree and shrub species that will in time grow and mature to form a diverse and species-rich area.  As Charles Darwin said many years ago “more living beings can be supported on the same area the more they diverge in structure, habits, and constitution” [On the Origin of Species by means of Natural Selection, 1859] Managing woodlands for wildlife - see here.   N.B.  Opens a PDF.    
Masting

Masting

by blogs at woodlands, 10 December, 2021, 0 comments

‘The Fall’ in the eastern United States has been colourful and plentiful this year.  There have been bumper crops of acorns, maple seeds and pine cones.  It is a Mast Year.  The trees have produced enormous numbers of potential offspring. These seeds and fruits will have significant 'knock on effects' in the ecosystems for some years.   Beeches and oaks can release so many seeds that they significantly increase the organic content of the soil and its nutrient value.  This fuels fungal and microbial growth. Small mammals feast on the acorns / mast and their numbers increase.  They, in turn, are food for foxes, owls and other predators *.   Quite what drives a mast year has long been a cause of speculation.  Ideas have included  masting evolved to overwhelm seed predators (mice, squirrels etc.) and thus ensure that at least some seeds survive to germinate and grow on.  fluctuations in nutrient availability affect the trees and flower / fruit production environmental prediction - that masting occurs in those years when seeds are likely to have good weather for sprouting in the following Spring.   even sunspot activity has been invoked Recently, a database [MASTREE] was created of mast years (for Beech and Norway Spruce) that extends back centuries.  This has enabled scientists to explore the environmental prediction idea, that is, whether masting is correlated with climatic events and occurs when seeds are likely to have favourable weather for germination and growth in the Spring after their production. On comparing the data with climate records, they found masting events [in beeches] correlated with climate patterns associated with the NAO - North Atlantic Oscillation, i.e. changes in air pressure between Iceland (low) and the Azores (high).  A “positive” NAO phase favours both masting and subsequent seedling growth; that is warm wet winters promote seed production and dry springs favour seedling growth.  Quite how the trees turn such climatic events into ‘signals’ for masting is another matter. Not all are convinced however. Some argue that the resources used up in producing so many seeds / fruits mean that the trees are exhausted and it takes time for these resources to be replaced and for the tree to flower and fruit fully again.   Professor David Kelly has a somewhat different hypothesis related to weather .  He suggests greater warmth in the previous growing season(s) may be the trigger.  Quite how the trees ‘remember’ the warmth that they have experienced is not known; but one thought is that it is due to what is termed ‘epigenetic marking’.  It is possible that the DNA of the genes that affect flowering is changed by the warm temperatures.   The activation of particular genes can be altered by their DNA undergoing methylation - a process where methyl (-CH3) groups are added (or removed) from the DNA.  Further information on masting and climatic effects on trees - visit science.org * [Sadly, a Swiss study found good masting years were later associated with a rise in tick-borne disease.]  
Drought and pollinators

Drought and pollinators

by blogs at woodlands, 30 November, 2021, 0 comments

Climate change is affecting all parts of the world, from the melting of the ice caps in Antarctica, to droughts in Australia and California.  On a more local level, we may see changes in our rainfall pattern.  Certainly for many parts of the UK, it has been a very dry start to the Spring, coupled with some very cold nights. Cold and dry weather affects plant growth in significant ways.  Warmth is needed for a plant’s enzymes (catalysts) to work, speeding up reactions and allowing growth.  Similarly, if water is in short supply, growth is stunted; plants do not realise their full ‘potential’. They are smaller overall as is the number and size of flowers that they produce.  Flowers attract visitors by colour, size and scent; or combinations thereof.   Smaller and fewer flowers, in turn, have ‘knock-on effects’ for their pollinators - bees, bumble bees, hoverflies etc. The effects of drought on pollination has been recently investigated by researchers at Ulm University in Germany.  They studied the effect of drought on field mustard (aka Charlock) : Sinapsis arvensis.  This is an annual plant that is to be found in fields, waysides and field margins across Europe.  It has bright yellow flowers, with four petals.  It is visited by many different pollinators (it cannot self-pollinate).   The researchers compared the number of visits by bumblebees (Bombus terrestris) to drought-stressed plants to well-watered ones.  The data showed that as the number and size of the flowers decreased so did the number of pollinator visits.  [caption id="attachment_21589" align="aligncenter" width="600"] Bumblebees also favour the teasels[/caption] The ‘attractiveness’ of the plants / flowers to pollinators was reduced, and it is possible that the smaller flowers were more difficult for relatively large pollinators (like the bumblebees) to ‘deal with’.  If pollen movement is reduced, then fewer fruits / seeds will be set and (insect pollinated) plant populations could decline.  The effects of reduced rainfall and water stress need to be considered alongside the declining number of pollinators.  The reduction in pollen movement has lead some to speculate that it might lead to a selective pressure for self-pollination / self-fertilisation, with plants dispensing with the need for visiting insects.  Other Woodlands blogs have reported on the falling numbers of insects / pollinators. Featured image : garlic mustard.
November’s Fungi Focus - The Earpick Fungus (Auriscalpium vulgare)

November’s Fungi Focus – The Earpick Fungus (Auriscalpium vulgare)

by Jasper Sharp, 24 November, 2021, 0 comments

Not all mushrooms have gills. Some, like the boletes, have pores on the underside of their cap. Others have arrays of downward-facing spikes that look like teeth. This third category are described as hydnoid, and include such aptly named species as the Wood Hedgehog (Hydnum repandum) and this month’s fungi focus, the Earpick Fungus (Auriscalpium vulgare), also known as the Pinecone Mushroom or Conetooth. These teeth, like gills and pores, constitute the ‘hymenium’, the fertile surface in basidiomycetes fungi on which spores develop and from which they are released. Look under a microscope at a mushroom gill or the inside of a pore or the edge of one of these teeth, and you will see it coated with thousands upon thousands of tiny spore-bearing structures known as basidia (as opposed to the other group of fungi, the ascomycetes, where the spores develop and are fired out from tubelike structures known as asci). These gills, pores and teeth are nature’s ingenious way of maximising the spore releasing area that contain the basidia.  Two toothed fungi species - The Ochre Spreading Tooth and the Fused Tooth It should be pointed out that not all of the toothed fungi are of the mushroom-shaped cap-and-stem variety. There are also bracket and resupinate hydnoid types, like the Ochre Spreading Tooth (Steccherinum ochraceum) or the leaf litter-dwelling Fused Tooth (Phellodon confluens). However, all these examples point to the important rule I always emphasise when trying to identify fungi or taking a photo for someone else to do the job for you – always look underneath! To be honest, you’d find it pretty hard to mix up the Earpick Fungus with anything else at first glance anyway. Not only does its felty brown kidney-shaped cap, perched atop a slender but bristly stem, with row upon row of downward-pointing teeth on its underside, make it look like some weird alien monster you’d expect to see in a film like Little Shop of Horrors or in a Pokémon game. Its identity is also defined by its specific substrate of pinecones or other conifer-related litter. Earpick Fungus That is if you notice them in the first place. Earpick Fungi don’t tend to get much larger than 5cm in height and their caps reach around 3cm across at their widest point – as mentioned, the caps are kidney-shaped rather than circular, with the stem on one side of it rather than the centre. Their dun colouration makes them blend in with their conifer cone hosts, so you’ll probably only find them if you’re actively looking. But get down to ground level and look closely and you’ll see nothing else like these stunning little things. Just how unusual are they then? There seem to be a number of other species in the Auriscalpium genus (the Latin name literally translates as ‘ear pick’), according to its Wikipedia entry, but Auriscalpium vulgare is the only one found in the UK thus far. Indeed, it is considered the type species for Auriscalpium - the first of its kind discovered (in 1821 by the British mycologist Samuel Frederick Gray) to which all others in the genus are compared. Earpick Fungus The First Nature entry describes them as “infrequent and apparently localised”, which could mean that they are under-recorded because they are so inconspicuous and that the few people who do know where to look and what to look for are the same ones recording their discoveries on general websites like iRecord or more fungi specific ones like The Fungus Conservation Trust database. Fungi recording being the piecemeal process that it is, they may be a lot more widespread than we might assume, and indeed, photos turn up on various specialist fungi social media groups fairly regularly. This is not to say I would personally pick them, even to take home for closer analysis or to look at spore samples. I know there are plenty of foragers out there who are beholden to the mantra that a mushroom is only the fruiting body of the larger fungi organism and therefore picking them does no harm. As they argue, the rest of the mushroom is in the form of an expansive network of mycelium that is hidden underground, so it is essentially the same as picking an apple from a tree. Clearly the logic is flawed for both the Earpick Fungi and many other species, even if it did make a for a particularly choice edible (which by all accounts it doesn’t). Clearly the mycelium of this particular specimen is limited by the edges of its pinecone substrate, and therefore the ratio of its fruitbody size to the entire organism can only be very low.  Earpick Fungus In other words, the effort that the Auriscalpium mycelium in the pinecone channels into putting up a single fruitbody must be considerably more than that of, say, an ectomycorrhizal species like a Russula or Agariuc, where the mycelium forms an expansive network stretching around and beyond the roots of its host tree. Therefore picking it removes a substantial part of the organism, if we assume the fruitbody to be an inseparable part of the organism. If you do come across one, it is probably best to leave it there intact to continue releasing its spores rather than picking it from the cone and risking killing it off entirely.
autumn leaves

Thomas Meehan : American autumnal colours

by blogs at woodlands, 16 November, 2021, 0 comments

The changing colours of the leaves in autumn is a phenomenon that affects the vast majority of deciduous trees (and some conifers, eg. Larch).   The leaves change from green to various shades of yellow, brown, orange, red and even purple.  The nature of these changes has been the topic of a previous blog. What is interesting is that this colour change is particularly marked in the trees of the North Eastern region of the United States. Indeed, bulletins are published listing the best places to see the myriad of colours that the trees display.  This difference in the colours of American and European trees was commented upon by Thomas Meehan,  back in the nineteenth century.  Meehan first worked as a gardener at Kew but later moved to Philadelphia (where he is credited with saving Bartram’s Garden). His botanical studies led to him being the editor of The Gardener’s Monthly, writing articles for various newspapers and authoring 'The Native Flowers and Ferns of the United States'.  In 1881, Meehan noted in a paper presented to the Proceedings of the Academy of Natural Sciences of Philadelphia, (Vol 33)  that the intensity and variety of autumnal colours was much greater in the States than in Europe.  He suggested that the difference might be due to the “American light” and that European trees might (after many generations) adapt to this light and then show similar colours.  Recently,  Renner and Zohner* have investigated this difference.  Their paper(s) offer a number of observations / findings: American trees start to break down their chlorophyll earlier in autumn than European trees, so the period in which the leaves operate as photosynthetic 'factories' is shorter. The earlier onset of senescence means they are at greater risk of light mediated damage in the bright days of early autumn (particularly if coupled with cold nights). Trees growing at a particular latitude in Eastern North America receive significantly more light than trees growing at the same latitude in Europe. North American trees react differently to the shorter days of autumn that European trees - when grown in the same area / garden. A greater percentage of North American trees produce anthocyanins - which give the red and purple colours. Anthocyanins absorb light over a wide range of wavelengths.  They act as a sunscreen, protecting the leaves at a time when they are undergoing rapid and complex changes that allow them to export valuable nutrients / resources to other regions. It would seem that Meehan’s comments about the ‘American light’ were remarkably prescient some 140 years ago. Renner and Zohner’s detailed papers are available here :  https://nph.onlinelibrary.wiley.com/doi/epdf/10.1111/nph.15900 https://www.research-collection.ethz.ch/bitstream/handle/20.500.11850/416178/nph.16594.pdf?sequence=3&isAllowed=y [caption id="attachment_36385" align="aligncenter" width="650"] Thanks to Oliver for this photo of autumn colour at Westonbirt[/caption]

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