For biodiversity to flourish, a wide variety of microhabitats is needed.  With many micro-habitats, more species are able to thrive. It may seem counter-intuitive but deadwood offers opportunities for a diverse range of species. Within a woodland, there are various types of deadwood, providing shelter and food for many organisms.  Perhaps one of the most obvious examples of deadwood is standing but dead trees.  If the dead tree was a veteran, then it will provide a variety of micro-habitats.  Holes and crevices may be used by bats and birds, the decaying wood will be colonised by bacteria and fungi, bracket fungi may erupt - whilst the bark will continue to offer a substrate for mosses and lichens.  As the wood decays, the material becomes a home for saproxylic beetles. Stag beetle larvae feed on decaying wood underground,  whilst the adults rely on fat reserves built up during their larval stage. Adults can ‘drink' oozing sap  and the juice of soft, rotting fruit. In the UK, some 650 beetle species are associated with deadwood [visit Dr Ross Piper’s website for full details of these insects].  As with many insects, many saproxylic beetles are threatened with extinction - due to the decline in the number of veteran / ancient trees.  Saproxylic beetles, apart from being important in the recycling of materials, are also food for birds and mammals. A previous blog has extolled the virtue of dead hedges.  Dead hedges are simply piles of branches and twigs arranged to create a barrier / hedge. They represent  a way of disposing of material that arises from thinning or clearing operations in woodlands. This ‘waste material’ of saplings and side branches are sometimes referred to as “arisings" by tree surgeons, or "lop and top” by foresters. Using this material in this way is good for wildlife, particularly for small mammals and birds - as it gives them somewhere to shelter from the wind and rain, and protection from predators. It's also good for insects.  As the material rots and decomposes, it adds humus / nutrients to the underlying soil. Larger pieces of wood from the felling of trees can be arranged to form a stack or pile, by simply laying branches and logs on top of one another  Such a stack wil rot and decay over time, but will provide a home to a variety of wildlife. So, deadwood in its various forms, is an important part of woodland ecosystems. It has a role in delivering biodiversity, but it also provides ‘ecosystem services’, such as soil formation and nutrient cycling. Deadwood contributes to the detrital food chain, which is driven by fungi, bacteria and detritivores.   Below : All that remains of a historic tree - the Wilberforce Oak. It was here at Holwood House (Keston , near Hayes, Bromley) in 1788 that William Wilberforce resolved to address the task of abolishing the slave trade. It took some twenty years for his vision to be realised. [Thanks to Ruth for images of the Wilberforce Oak] https://en.wikipedia.org/wiki/Holwood_House

Electric bees ? Both bumblebees and flowers carry an electric charge.  Flowers have a weak negative charge, whilst the bees have a positive charge.  The attraction between these two opposing electric fields may help the bees sense flowers.  The electric charge of a bee may even stimulate a flower to release a burst of scent, aka volatile organic compounds.  This was true for petunias, but not snapdragons.  When a bee has visited a flower, the negative charge is briefly lost - maybe a signal to tell other bbees not to visit? Other work by Bristol University has indicated that synthetic fertilisers and pesticide can interfere with a flower’s electric charge for some time after spraying, and that this can modify the foraging of bumblebees. "Black bees" The black bee, Apis mellifera mellifera, faces a number of threats like the domestic honey bee.  It is also known as the European Dark Bee or the Black German Bee. It has been present since the retreat of the last Ice Age, but its distribution has become restricted as a result of habitat loss, parasitism by Varroa mites and viruses. The black bee can be distinguished from other honey bees by its stocky body and sparse abdominal hair (which is brown), and overall dark coloration - so they appear black or dark brown. Recent research (using DNA analysis) has shown that black honeybees can be found in many locations in Ireland and are not extinct, as previously suggested  Black bees are noted for their longevity and hardiness (ability to cope with winter temperatures); it is possible that if winters become shorter / milder that this change may not favour black bees. Weird weeds? It seems that our gardens may be home to ‘new’ or unusual species of plants.   The Royal Horticultural Society would like gardeners to report on interesting ‘weeds’ that might find as they could be rare plants or plants growing in unusual places / areas.  You are asked to take photographs of anything that you find interesting, and upload the images to iNaturalist. Reporting on unusual plants is not the only thing that the RHS is interested in. There are other garden projects that one can contribute to, for example, reporting sightings of garden pests such as the berberis sawfly, cellar slug, hemerocallis gall midge, lily beetle, rosemary beetle and spittlebug. Mycorrhizal networks. A common mycorrhizal network (CMN) is when fungal hyphae connect the roots of many plants (either of the same or different species) below ground.  They have attracted considerable attention in recent times (woodland wide webs), with claims, for example, that resources are transferred through CMNs to increase seedling performance and mature trees send resources / defence signals to offspring etc.  However, a recent report in Nature has suggested that there is a ‘bias’ towards citing the positive effects of CMNs and that, to date, knowledge of common mycorrhizal networks is limited.    

The onset of Spring brings a variety of blue flowered plants such a bluebells, hyacinths and squills in our gardens, parks and woodlands. The bluebell is ‘easily’ recognisable.  However, there are two or three different types of bluebells. The bluebell that is native to the UK has the Latin or Linnaean name of Hyacinthoides non scripta. Its deep blue and scented flowers hang from an elegantly arching stem. It is found in abundance in many deciduous woodlands and hedgerows across the UK, though it is unusual or rare in parts of East Anglia and Scotland.  The Spanish bluebell (H. hispanica) is also to be found. It is possible to distinguish between the two species – some of the differences are listed in the table below: Native Bluebell Spanish Bluebell Leaves are narrow by comparison to Spanish Bluebell, about half an inch or so wide Leaves broader, often an inch or more wide The flowers at the top of the stem droop to one side The top of the stem is much more erect The flowers hang from one side of the stem The flowers are arranged around the stem The flowers are deep violet blue The flowers are a pale or mid blue, and white and pink ones are also found The flowers have parallel or straight sides and have a narrow bell shape The flowers are more ‘open’ with a cone shaped bell The tips of the petals roll back somewhat as though they ‘want’ to touch the tube of the flower Not such obvious curving The pollen is a pale cream colour Pollen is a blue colour Flowers are scented No scent detectable The spanish bluebell can hybridise with the native bluebell, giving rise to types that have a mixture of the above characteristics.     The Natural History Museum is trying to map the distribution of these different bluebells and it is asking people to complete an online questionnaire about the bluebells in their gardens, local parks, hedgerows and woodlands. If you can help, go to: http://www.nhm.ac.uk/nature-online/british-natural-history/survey-bluebells/recording/index.html Since this was first posted in 2006, there have been various updates, but the bluebell survey link does not seem to be active now. See : https://www.nhm.ac.uk/take-part/citizen-science/bluebell-survey.html

Several thousand years ago, Scotland was extensively forested.  As the Ice Age came to an end, so the glaciers retreated and Scots Pine, birch, rowan, aspen and juniper populated the land, forming the Caledonian* Forest.  Pollen records indicate that Scots Pine was present in southern England some 9000 years ago, it then moved into Scotland.  Scots Pine is one of the UK’s three native conifers; the other two being Yew and Juniper. As the climate warmed, Scots Pine was lost from most of England.  The pine woodland that formed in Scotland was the westernmost part of the boreal forest that extended across most of Northern Europe.  At its peak, (about seven thousand years ago), the forest covered some 1.5 million hectares in Scotland.  It was a ‘home’ to beavers, wild boar, brown bears, elk and wolves.  These have since been ‘lost’, though in recent times, the European Beaver has been re-introduced. However, with the arrival and establishment of neolithic farmers, areas of heath and woodland were burned to encourage fresh growth of heather for their cattle and goats. Some time later (about 3000 years ago), there was period of cold and wet weather, peat bogs spread and the tree line was lowered. In places, broad leaved trees replaced Scots pine.  Throughout historical times, the felling of trees for timber and fuel continued, as did the grazing of livestock.  Later came extensive sheep farming and this was followed in Victorian times by deer and grouse shooting.  All of these limited woodland regeneration.  So what was once an extensive forest was reduced to a fraction of its former size. Remnants of this once great forest can still be found and even today these woodlands offer a rich habitat that supports a diverse flora and fauna, where pine marten, capercaillie, red squirrel, Scottish crossbill and wildcat can be found.  Glenmore is a National Nature Reserve with many mature Scots Pine, Glen Tanar is another area of Caledonian* pine forest, set within the Cairngorms National Park.  The woodland floor provides a habitat for many plant species typical of the Caledonian Forest - twinflower, creeping lady's-tresses.    Rare and unusual insects are also to be found such as the bumblebee robber fly. According to a recent study by “Trees for life” many of the the remnants of the ancient pine forest are on a ‘knife edge’. Large numbers of deer have and are damaging the woodlands.  The deer eat pine saplings and damage bark. This can result in birch replacing pine. Whilst there have been efforts to exclude deer in some areas by putting fencing in place, the fenced areas were often not big enough or over time the deer were able to breach the fencing and continue to forage.  Pine trees need time to establish themselves free from the impact of grazing. Some areas of pinewood suffered from the planting (in the 1950s) on non-native conifers, such as Sitka Spruce.  As these grow they can crowd out Scots Pine.  Many others areas are small and ‘isolated’. This leads to a reduction in biodiversity, so it is more difficult for natural regeneration to occur.  It also means that resilience is lost in the face of threats like climate change.   * the roman name for the area now Scotland was Caledonia.   Scots Pine is sometimes described as an ‘honorary hardwood', as it grows slower than certain conifers and produces better quality timber. The loss of forest across the Earth is a cause for concern - see https://theconversation.com/how-forest-loss-has-changed-biodiversity-across-the-globe-over-the-last-150-years-140968    

Some years back, the Woodlands blog posted various articles about hedgerows,  noting the loss of many - due to the increased mechanisation of farming in the mid C20th.  Now, there is greater recognition of the importance of hedgerows, and there are initiatives to promote the maintenance and expansion of hedgerows. But what is a hedgerow? Natural England offers a definition as follows : A hedgerow is defined as any boundary line of trees or shrubs over 20m long and less than 5m wide, and where any gaps between the trees or shrub species are less that 20m wide (Bickmore, 2002). Any bank, wall, ditch or tree within 2m of the centre of the hedgerow is considered to be part of the hedgerow habitat, as is the herbaceous vegetation within 2m of the centre of the hedgerow.  This differs from the definition in the  Biodiversity Action Plan, which included references to ancient hedges / species-rich hedges.  The definition now includes all hedgerows consisting of at least one native woody species of tree or shrub (mainly), but it does exclude bramble and honeysuckle as ‘woody species’.  According to one source, there are some 550,000km of hedgerow in England, with over 400,000 km being actively managed.  Hedgerows are an important semi-natural habitat in what is otherwise a managed agricultural landscape. They are found across the country but there are more in lowland regions. Hedgerows in the south east are associated with large fields and fewer trees, the proportion of trees in hedgerows increases as one goes north and west.   The nature of hedgerows varies across the country but all are important as : They provide a habitat, shelter (micro-climate provision) and resources for many different species (from plants to insects, birds and mammals). Hedgerows are particularly important as nesting sites for birds. They support animals that have key roles within the broader ecosystem, for example pollinators and predators of pests. They offer an important source of nectar that helps support wild bees - adjacent farmland can be a poor source of nectar Hedgerows are known to support threatened (red listed) species Hedgerows capture and store carbon (above and below ground) Hedgerows offer ecosystem services eg. mitigation of water flux and availability, landscape connectivity, soil conservation / stabilisation. A number of studies indicate that increasing the number of hedgerows would help with landscape connectivity (for example, for hedgehogs) and that planting of blackthorn and hawthorn in association with later flowering species would help support a number of wild bee species.  Expanding the number of hedgerows could have some negative effects as they might offer a home to invasive species and / or pathogens; but one study has indicated that ash trees in hedgerows suffer less impact from ash dieback than trees in forests.  To date there does not appear to be any detailed research on whether increasing hedgerow coverage would have any impact on tree disease / pathogen spread. Hedgerows, like woodlands themselves, face a number of challenges due to climate change.  Warmer winters may mean that the ‘winter chill’ requirements of some shrubs / trees will not be met; this may mean flowers and fruits fail to form properly which in turn means less food for birds, small mammals etc.  Drier summers may stress some species, trees like Beech are susceptible to drought.  Extreme weather events (like Storm Arwen) can inflict damage on hedgerow trees.  If a hedgerow is next to farmland, then it may experience drift from pesticide and / or herbicide spraying  nutrient enrichment (eutrophication) due to the use of fertilisers. Hedgerows with a diverse structure, with plants, shrubs and trees of varying ages and heights provide the widest range of niches / microhabitats for wildlife.  The inclusion of dead / decaying wood offers opportunities for various fungi, saproxylic beetles, woodlice etc.  Some hedgerows are managed / reduced with a mechanical flail (see above !!!). If this is done annually, it can result in a loss of biodiversity. Trimming should be done on a 2 or 3 year cycle; and some sections of the hedge might be left for longer " see (https://www.hedgelink.org.uk/cms/cms_content/files/76_ne_hedgecutting.pdf).  Thousands of tree and hedgerow plants are being planted to create a flood defence project at Castlehill, East Hull.   The plan is to create some seven hectares of woodland and over five kilometres of new hedgerow, as part of a flood defence project (to store floodwater east of the city).  Trees such as field maple, downy birch, English oak, and black alder are being planted along with species of willow, dog rose, guelder rose and blackthorn and hawthorn to create hedgerows and scrubland.  Other species will be allowed to naturally develop in the area and the habitat is expected to reach ‘maturity in some fifteen to twenty years. There is a citizen science project that involves surveying hedgerows.  It is organised by the People’s Trust for Endangered Species [PTES].  The Great British Hedgerow Survey guidelines can be found here : https://hedgerowsurvey.ptes.org/survey-guidelines Some times hedges offer a home to other things         

No match for nonpareil ? Many varieties of apples have been around for centuries.  For example, the nonpareil which was bred (in France) back in 1696, the Egremonet russet much admired for its flavour and appearance dates from Victorian times. The  Cox's Orange Pippin is a cultivar first grown at Colnbrook in Buckinghamshire by Richard Cox.   By end the of the C19th, the Cox’s pippin was one of the most popular apples. However, there is a concern for these heritage apples in our changing climate.  In recent years, we have experienced warmer and wetter winters.  Such winters do not offer enough chilling hours for these trees.  Many trees need a period of cold in the winter months, where the temperatures are below 6oC but above freezing.  About 1000 chilling hours are needed for apples such as the nonpareil.  However, winters are present are offering approximately 600 chilling hours. Gala apple trees (developed in New Zealand) need only 600 chilling hours but it might be that they will not respond well to the wet winters we (currently) experience.  Some feel that they do not offer the complex flavours of ‘classic apples’.   Kew Gardens has now planted a varied selection of apple trees One third are heritage apple trees One third are ‘new’ varieties needing fewer chilling hours One third are varieties from countries warmer than the UK Over the coming years, the trees will be monitored to see which ‘do best’ in terms of cropping in London’s warming temperatures. The apple-growing industry in the UK is under considerable strain, with many growers unable to afford replanting this year.  Growers ‘refresh’ their orchards regularly, replacing older trees with new ones, but now many cannot afford to do this.   The sector is struggling with  a shortage of workers - made worse since the UK's exit from the European Union  high energy costs low returns from the supermarkets that buy their produce The option to ‘buy British’ may become a much rarer option.   Further details here Recovery after forest fires. Bacteria and fungi are the first to start rebuilding from the charred remains of burnt forest and woodland.  The number and variety of microbes falls dramatically after a fire.  Then, there was a microbial succession in the burned soil, that is, the number and types of bacteria and fungi changed quite quickly, with fast growing types able to advantage of the reduced competition for resources.  The situation is not dissimilar to what happens to our gut microbiome when we have to take antibiotics.  Antibiotics ‘knock out’ many of the useful bacteria in our gut, but gradually the microbiome is re-established.   Reporting on weeds. It seems that our gardens may be home to ‘new’ or unusual species of plants.   The Royal Horticultural Society would like gardeners to report on interesting ‘weeds’ that might find as they could be rare plants or plants growing in unusual places / areas.  You are asked to take photographs of anything that you find interesting and upload the images to iNaturalist. Reporting on unusual plants is not the only thing that the RHS is interested in. There are other garden projects that one can contribute to, for example, reporting sightings of garden pests such as the berberis sawfly, cellar slug, hemerocallis gall midge, lily beetle, rosemary beetle and spittlebug.

The world is warming and many scientists are concerned that the earlier springtime flowering of many plants will disrupt the ‘normal interactions between the plants and their pollinators, be they bees, butterflies, bats. Other subtle changes have been observed.  The flower ‘morning glory - Ipomoea is a weedy, vine-like plant in the States .  Between 2003 and 2012, the size of its flowers has increased (from a diameter of 4.5 cm to 4.8 cm).  The study also revealed that flowering occurred 4 days earlier and the flowers have increased their ‘floral rewards’.  That is they devote more resources in the production of pollen and nectar to attract the bees, flies and wasps that visit the flowers.  The changes were more noticeable in northern populations of the Morning Glory. Extra Growing time ? In the late nineteenth century, an Ohio farmer (Thomas Mikesell) kept detailed records on local trees*, noting their growth, daily temperatures, rainfall, dates of frosts, snows &  thunderstorms. With the death of Thomas Mikesell  [July 18, 1917], the world lost an dedicated student of nature and a remarkable phenological record came to an end. It forms the only detailed record of plant and tree growth in North America during the late C19th / early C20th. Since that time, significant global warming has occurred. Now researchers at Ohio State University have compared  Mikesell’s observations with growth data of present day trees - from time of bud burst to peak (autumnal) leaf coloration (for seven tree species). They concluded that trees now experience a longer growing season.  Leaves stay on the trees for approximately one month longer than they did a hundred years ago.  Quite how this longer growing ‘season’ affects the trees is not known, there may be a positive through increased carbon assimilation.  On the other hand, higher temperatures may stress the trees in ways which are not yet understood.     *A Calendar Of The Leafing, Flowering And Seeding Of The Common Trees Of The Eastern United States.