Blog - biodiversity
Professor Goulson on allotments, gardens and bees.
I recently attended the National Allotment Society AGM, where the keynote speaker was Professor David Goulson. His main academic studies focus on the threats to bees, bumblebees and other insects. He is based at Sussex University. Back in 2006, he founded the Bumblebee Conservation Trust; a charity which has grown to some 12,000 members. In his talk at the meeting, he made the following points : He loves allotments because they capture carbon and are rich in biodiversity. They produce a lot of food. Typically producing some 10 tonnes / hectare whereas farming productivity is about 3 tonnes per hectare. The record on a 1m2 in an allotment is 10 kg, which is the equivalent of 100 tonnes / hectare. Allotments not only produce good food for healthy eating, but people get good exercise through their gardening activities. A study shows the ‘over-60s’ with allotments have longer life expectancies [controlling for other variables]. [caption id="attachment_40124" align="aligncenter" width="675"] A bee at risk of extinction.[/caption] There are over 300,000 allotment plots in the UK and some 90,000 people on waiting lists. More allotments could help counter poor health and cut NHS costs. We should turn our cities, towns and villages into a network of nature reserves - essentially a form of urban rewilding. Gardens are a vital part of this, as there are some 400,000 hectares of them in Britain. Prof Goulson is really keen on less mowing, more ponds and no pesticides. Interestingly, France banned pesticide use in public and urban areas, such as parks, back in 2014 - it is an example that we should follow. Even pet flea treatment is damaging to insect life. The strength of the doses used means that the chemicals can pass into the environment - to grass, rivers, canals and pools. Sadly, now 8% of gardens have some plastic lawns, and plastic hedges (and Wisteria !). Plastic makes him despair.Plant diversity in pavements should be celebrated. Wild flowers / weeds are sources of pollen & nectar for pollinators. Verges should be nature reserves. A Scottish "On the Verge" group stopped councils mowing 8x a year and planted a seed mix to transform verges in their area. Councils should mow less. Some people may object, so people should strengthen their Council’s hands by writing to them and praising them for no-mow-May-type efforts. The Buzz Club - has been set up, this is a citizen science project to see what works best for insects. There are lots of short films on his youtube channel . Bees and other pollinators need help. He suggested lots of ways to help them, for example, drilling holes in logs for bug hotels. You can follow Prof Goulson on Twitter or Facebook. [caption id="attachment_40132" align="aligncenter" width="675"] Bumblebees 'enjoing' a small clump of poppies[/caption] [caption id="attachment_40129" align="aligncenter" width="428"] urban herbicide use[/caption]
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
Poplars belong to the same family as the willows. Like willows, they have a 'preference' for wet soil. There are a number of poplar species – white, grey and black poplar and the western balsam poplar, A poplar that is common is the Lombardy Poplar, it is a variant of the Black Poplar and probably the most recognizable poplar, as its branches grow almost parallel to the main stem. It is a tall, thin tree. The leaves of black poplar (Populus nigra) are arranged along the stems in an alternate fashion. The leaf has a long, slender leaf stalk – which is slightly flattened. The leaf is sometimes described as ‘triangular’ or ‘diamond shaped’. When first formed, the leaves may have a bronze tinge and the young shoots, leaves and stalks have fine, tiny hairs. The upper leaf surface is a dark green, whereas the lower surface is not such a deep green. In Autumn, the leaves may turn a vibrant 'banana' yellow. The bark of the Black Poplar is grey / brown and deeply fissured with age. The tree may grow to a height of 100 feet, but is usually smaller than this. The species is dioecious, that is, there are separate male and female trees. In some parts of the country, like Cheshire, the number of Black Poplars is falling, due to changes in land management, a reduced need for particular timbers and an ageing population of trees. The natural regeneration of black poplars is limited because : male and female trees need to be near each other the fertilised seeds are only viable for a short period and the seeds need to fall on damp ground Added to this, there is the risk of hybridisation with other forms of Poplar. So, The Canal and River Trust in conjunction with Chester Zoo have initiated a program to plant black poplar trees in Cheshire’s Weaver Valley. They have taken cuttings from native Cheshire trees and raised over 1,000 new trees, which have been planted in sites across Cheshire since 1995. For example, male and female trees have been planted by the River Weaver (Hartford) to encourage future natural propagation. Such black poplars can help promote biodiversity, providing homes for moths, bees, birds and butterflies. Should you have a portion of woodland that has damp soil, and are considering planting some black poplar, there is company that seems to specialise in Poplars : http://www.poplartree.co.uk/poplartree/. It lists some of the uses / benefits of poplars.
Woodlands.co.uk was chosen as the sustainability sponsor for the February 2023 conference, State of Open 2023. Mostly held for those working in computing and data, this event was held at the QE2 centre in Westminster, with several hundred individuals who networked and learnt more about open source, open data and open standards. The highlight was the speech by Jimmy Wales, founder of Wikipedia, explaining that Wiki isn't just about free and open information but about structure: their whole model is unusually open. It's truly democratic amongst wikipedians and is the antithesis of top-down models which dominate most of the world's organisations. As sponsors, woodlands.co.uk committed to plant at least one tree for every conference delegate as a carbon-offsetting measure and to encourage biodiversity. It turns out that at this conference relatively little extra carbon was produced for various reasons - the QE2 conference centre itself has strong environmental policies and the delegates were mostly either UK-based or were travelling to Europe anyway for a related conference. Nethertheless many of them took away free eco-merchandise from the Woodlands stand, including seeds for planting and wooden pens. Lots of the conference attendees were also interested in buying land for tree-planting so that their company would be offsetting its own carbon footprint and the staff would have a nearby place to go and enjoy. Sustainability sponsors can occasionally be accused of offering 'greenwash" but in this case there was no risk of that because the OpenUK movement is already so committed to sustainability and to using software to reduce carbon emissions. And in this case, too, the sponsor was offering practical measures such as the planting of defined numbers of trees in the UK (in Kent) rather than a theoretical payment to a nebulous foreign project. Conference participants were offered the chance to take away seeds to plant their own oak, cherry, lime, chestnut or sycamore trees. The role of sustainability sponsors at conferences varies but can involve financial support or the promotion of sustainability initiatives. Some eco sponsors also offer energy audits, sustainability assessments or carbon footprint analysis. According to the AI chatbot, ChatGPT, "Overall, sustainability sponsors play a critical role in supporting the transition to a more sustainable future by providing resources, expertise, and advocacy to organisations working on sustainability issues."
How “sticky-up things” act as refuges to protect diversity against intensive farming
When you look across cultivated fields you are usually surveying an unrelenting monoculture -of earth or wheat or grass. Lots of pesticides and fertilizers are used and there are regular assaults by bladed machines. It's bleak for wildlife, whether plants or animals. But nature is resourceful and clings on where it can. And within intensive agricultural areas there is a pattern to the small oases of diversity. There is more diversity where an obstacle stops the machines in their track Sometimes that's a linear feature like a river or a hedge or maybe just a fence, but often it's just a sticky-up object. A tree, a pylon, a pole, or even a wind-turbine. At the base of objects sticking up in fields you often find a clump of plants, sometimes flowers, and shelter for small mammals and birds. Taking the train through northern France recently, I realised how extremely industrialised their countryside has become and it's the same in most of Lincolnshire. Hedges have been removed, single trees are rare and every effort is directed to increasing wheat / crop production. Diversity is not just discouraged but it is seen as the enemy - a small copse or hedge can harbour swarms of crop-eaters so these have usually been grubbed out (as have many ponds (see the woodlands blog on ghost ponds in Norfolk). Whatever the spin and rhetoric, the large scale farmer is at odds with biodiversity. The soil is a highly lucrative resource where farmers want to maximise their returns. Increasingly, they use modern technology with tractors guided by SatNav, planting twice a year, with harvesting dictated by accurate weather forecasts and sophisticated seedlings being protected and fed by brutally efficient pesticides and fertilisers. Lip service is often paid to the farmers' role in looking after the countryside but in reality most of them are businessmen and businesswoman wanting to optimise returns. Farming businesses' borrowings and financial objectives don't allow them to spend too long worrying about biodiversity or the "hundred harvests" concern - that, when treated badly, the soil will be mostly gone (e.g fenland blows) or made unusable within 50 or 100 years. Refuge is an important concept in ecology: the idea that an organism gets protection from predation by hiding in inaccessible areas. Coral reefs are an example of habitats where animals can take refuge, and rainforests contain numerous physical refuges. [The concept of refuges or refugia has developed in recent years]. In the case of the arable fields of Britain, it seems as if it is mainly the "sticky-up things" and linear features (hedgerows etc.) which provide refuge, but not just from animal predation but from humans and their machinery. Nature is reacting to humans as if they are the predators. There are thousands of objects in the countryside which act as refuges - it's a benign and unintended consequence of landscape clutter. For example signposts, pillar boxes, mobile phone masts, abandoned fence posts, and even discarded farm equipment. These objects can also offer a structure for plants to climb up in their quest for sunlight and they can provide shelter from wind, but mostly they offer protection against the farmer and the machines. Unfortunately, the natural human instinct is usually to tidy up everything in sight, which often works to the detriment of biodiversity. It would be better to protect vegetation and stop mammals from being mashed up by mowers / machinery, and it is often the residual sticky-up features that protect these small refuges. Perhaps we need less rural de-cluttering of the British landscape, and more ‘mini refuges’.
In 1820, John Keats famous poem “To Autumn’ was published. Its opening line often serves to describe autumn as ‘The season of mists and mellow fruitfulness’. Indeed, Autumn has arrived here. Woodlands have been transformed into a 'tableau' of red, yellows, and oranges as the leaves are shed and the woodland floor has become a veritable fungal jungle, (as Jasper has described). Hawthorn and other bushes are laden with berries, conkers and acorns are generously strewn across woodland floors, squirrels are eating hazelnuts (and hiding them as a winter food store). But this cornucopia of fruits and seeds may be in response to the long, hot and very dry summer we have experienced. Trees and shrubs have been stressed by the heat and drought. Some have responded by mobilising their reserves / efforts into producing more fruits and seeds, to ensure that they pass on their genes to the next generation. Different trees are responding in other ways. Some are ‘holding on’ to their leaves for longer, whilst others (like some birches and rowans) have already shed theirs - in order to limit the damage from wilting and water loss during the intense heat and drought of summer. [caption id="attachment_39130" align="aligncenter" width="675"] Autumnal colour[/caption] Blackberries appeared early this Summer and few are to be seen this Autumn, some animals (like the dormouse) will search in vain. [caption id="attachment_39026" align="aligncenter" width="675"] Black Bryony berries (photo by Art Symons)[/caption] Will this Autumn be long and mild? It may extend into the traditional winter months. There is also the threat of extreme weather events (like Storm Arwen that brought severe winds across the UK last November). Whilst we might welcome mild weather (with the high price of gas and electricity), it could be mean an increase in bacterial and fungal infections, not only of plants but also affecting overwintering insects - tucked up in cocoons and pupal cases. Prolonged cold periods, coupled with frosts limit the spread of such infections. The cold of winter is also the traditional signal for animals like hedgehogs to hibernate. If they are still active in winter when food is scarce, then they will lose condition and possibly starve to death. Milder weather in Autumn and Winter also affects the migratory behaviour of birds, some birds may choose to overwinter here. Some seeds need to experience cold temperatures before they will germinate in the following Spring. Climate change and severe weather events are here to stay until there is a coordinated and concerted effort to reduce greenhouse emissions on a global scale. On a local scale, our gardens (which represent some 400,000 hectares of land) can make a contribution by encouraging wildlife / pollinators and promoting biodiversity. Gardens can also help to some extent with extreme rainfall. During heavy rain, water runs off hard surfaces and into the drains, these may also deal with sewage. When the drains are overwhelmed by storm water, sewage is discharged into our rivers (and the sea). Gardens can help by reducing hard landscaping, so that rain can soak into the soil instead of running off into the drains making use of water butts. They capture water, so it does not enter the drainage system. It is also there to use when the garden needs water (and there is a hose pipe ban) mulching the soil with a layer of plant material. It is an effective method of conserving water in the soil and it reduces surface runoff, increasing the infiltration / penetration of water into the soil. It helps keep the soil moist in times of drought, and helps reduce run off during heavy rainfall. Particularly important when planting young trees / shrubs. [caption id="attachment_38957" align="aligncenter" width="675"] a light mulch (in Art's garden)[/caption]
Saving meadows ?
It is depressing to pick up a paper or turn on the news to be met with a catalogue of distressing and difficult stories. There is also the overarching problem of global warning and climate change. Only recently, there have been reports of flooding in Sydney after torrential rain, fires are springing up again in Colorado and other States, and India experienced a heat wave (combined with a drought), with some cities experiencing temperatures of 40o+C. This has resulted in the deaths of individuals, and as the heat wave occurred in the final weeks of the wheat growing season it has killed many crops before harvest. In Balochistan, the peach and apple harvest has been severely impacted. Here in the UK, there are a number of problems, indeed we have been described as “one of the most nature-depleted countries in the world”. We have lost plant and animal species, such losses could lead us into an ‘ecological recession’. This occurs when ecosystems systems lack the diversity needed to function well. Much of the damage to (or loss of) our ecosystems is associated with the industrial revolution followed by the intensification of mechanised farming. The 1950’s and 1960’s witnessed the loss of vast tracts of hedges and the removal of small copses to increase the area for farming / food production, and allow the use of heavy duty mechanised machinery. There was also the extension of road networks - motorways etc. and urban sprawl /development. Though woodlands and forests were being eroded long before the industrial revolution; woodland, forest and pasture covered much more of the land than now. There were areas of ‘wilderness’ that were home to animals and plants that have long since gone or are now very rare - ranging from wolves, bears, to beavers and red squirrels. Whilst woodlands were and are havens for many plant and animal species, meadows and pastures have suffered too. The PlantLife charity has suggested that the UK has lost some 97% of its wildflower meadows during the course of the last century and what remains could be under threat. Lowland meadows are rich sources of biodiversity, both plant and animal, they also store carbon in the soil and ‘knit’ the soil together, so that it is not subject to erosion. [caption id="attachment_38489" align="aligncenter" width="700"] A meadow, partly mown and partly 'wild'.[/caption] Many species are dependent on these habitats, but with the expansion of agriculture and construction of motorways - the landscape has become fragmented and many species cannot across the formidable barriers. The Scottish primrose is now only to be found on the north coast of Scotland and Orkney, and some orchids are described ‘as just hanging on’. Species like the common blue butterfly is reliant of bird’s foot trefoil, Greater Bird’s-foot-trefoil, Black Medick and white clover for food for its caterpillars. The great yellow bumblebee is sadly now one of the rarest British bumblebees. It is limited to flower-rich areas in the Orkneys, Caithness and Sutherland. It is particularly associated with red clover. It is a large species, and was once widespread across the U.K. Creating space and opportunities for wild flowers has been PlantLife's foremost objective from “No mow May”, “Save nature on our roadside” (see the woodland blog here and here) ’Fight for sites” all of which aim to increase the number of sites for wild flowers and their pollinators to flourish. The Scottish Government has been helping establish wildflower meadows at some of its national nature reserves - notably St Cyrus, Flanders Moss and Forvie, and they are working with PlantLife to create an action plan for Scotland’s grassland. It is keen for farmers to be involved, offering areas of wild flowers on their farms. By increasing the areas in which wild flowers (and their associated insects) can flourish, the connectivity can be restored (at least in part). The creation of biological corridors allows plants and animals to move, which is particularly important in these times of climate change.
The loss of animal species, and the effects on fruit and seed dispersal.
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.