Is the sward mightier than the pen?

Edinburgh is a city of traditions. Take the Edinburgh International Festival, and the Fringe and Tattoo which followed, all living examples of the capital city’s great love of a good time. Edinburgh Living Landscape is similarly successful in pushing a sound idea that heralds good times.

Visit the website of Edinburgh Living Landscape and you get a sense of better things in store for nature in our capital.  It tells the eager reader that “Edinburgh Living Landscape is a network for nature in our city. We think it is crucial for the future health, happiness and wellbeing of Edinburgh’s people and wildlife.

“Our  programme will demonstrate that investment in the natural environment makes economic sense, as well as increasing biodiversity and creating healthier urban ecosystems. 

“To do this we need to integrate nature into neighbourhoods across the city. Edinburgh Living Landscape will work to benefit local people and wildlife with an aim to make the city one of the most sustainable in Europe by 2050.”

That’s as good as it gets when it comes to statements of intent for nature. What’s more with an impressive list of partners you just sense that this is a project that will deliver, time after time. With bodies including Scottish Wildlife Trust, The City of Edinburgh Council, The Conservation Volunteers, Royal Botanic Garden Edinburgh,  Greenspace Trust, The University of Edinburgh, Butterfly Conservation Scotland, and RSPB you know that local people and native wildlife are in good hands.

The drivers behind changing the way we mange public spaces have never been more compelling. From the early 1930s there began a systematic loss of beneficial grasslands for nature, by the time a mere 50 years had come and gone that loss of habitat, and the food sources that went with it, was depressingly mainstream. Urbanisation, development pressures, intensive farming .. and so the list of challenges went on. 

And the damage didn’t stop there.  What was actually left even in urban areas was subject often to harsh management, including routine spraying and chemical treatments. This simply compounded the crisis. Something had to give, and thankfully it was the depressing descent into devastating loss that gave.

Today we are better informed. We know that creating and managing habitats specifically for nature is the way forward. This is particularly so if we want to achieve nature restoration and tackle climate change. It’s therefore great that our capital city is taking significant steps to ensure that on their patch habitat loss is reversed.

The method is a swing away from the old way of doing things towards a mixture of relaxed mowing regimes, sensitive planting and more sympathetic management of greenspaces for nature. Edinburgh has embraced a mixed approach. Take meadow creation and management as one example. There are a variety of meadows to find and enjoy in and around Edinburgh. By far the bulk at wildflower meadows. However, there was a stunning designed or pictorial meadow at Royal Botanic Gardens Edinburgh and this was a powerful way to get people thinking and talking about meadows. This approach can be, as the excellent Plantlife website explains, a means to an end, as it ‘… crucially, starts warming attitudes – opening minds to other possibilities beyond the mown ‘neat-and-tidy’ approach. You can see the bees and butterflies.”

Informative signage is increasingly important too. Perception has a vital role to play particularly when changing the management regime of public facing amenity grasslands leads to transformation which isn’t often an overnight fix. Where people are used to neat, clipped, mown parkland it often requires a little explaining to extol the virtue of letting the grass grow longer, planting for pollinators and letting nature take its course. 

Whist at their peak meadows speak for themselves, it is the case that when freshly mown, or lying dormant, you have to sometimes work to ‘sell’ what is going on.  Then it helps to explain that the space – viewed by some as superficially scruffy – is actually being managed for nature and that what lies before the curious onlooker is perfectly normal … and beneficial. It will offer a home for nature and not just a forage for food source, it’s a habitat that offers shelter, nesting sites and overwintering opportunities. Generally people get that and are receptive to positive messaging.

So when next you visit Edinburgh and soak up the cultural delights, bear in mind that across the city there are good things happening for nature. Nature restoration is rarely a quick fix, but in a city famed for being more cerebral than most it is arguably culture at its highest.

Sticky contrivances

 By Athayde Tonhasca

Somewhere in Britain during the Victorian years, a four-spotted moth (Tyta luctuosa) landed on a pyramidal orchid (Anacamptis pyramidalis), intending to sip some nectar. The moth certainly didn’t expect to end up with its proboscis – the elongated mouthparts of butterflies and moths used for sucking – covered with blobs of pollen. But that was the least of the moth’s problems, as disaster loomed: the hapless wanderer was captured by an unknown collector and became a model for George B. Sowerby (1812-1884), the illustrator of Charles Darwin’s masterpiece about orchid fertilisation.

An illustration from Charles Darwin’s book on fertilisation of orchids depicting the head of a four-spotted moth with its proboscis laden with several pairs of pollinia from pyramidal orchids. Names of the species involved have changed since then. 

Those globules of pollen attached to the moth’s proboscis are known as pollinia (sing. pollinium). Each unit contains from five thousand to four million pollen grains, depending on the species. The grains are stuck together with pollenkitt, an adhesive material found in almost all angiosperms pollinated by animals. A stalk-like structure connects the pollinia to a gluey pad known as viscidium, and the whole assemblage is often referred to as a pollinarium.

A pollinarium: the pollinia on the toothpick are held in place by the sticky viscidium © Frederick Depuydt, Wikimedia Commons.

Pollen grains lumped together in a sticky package are not easily carried away by water or wind. As Darwin learned from his observations and experiments, this is done by animal vectors, mostly wasps and bees (although moths, beetles, flies and birds do the job for reasonable number of orchid species). Having pollen grains in a single unit reduces wastage during dispersal, but it’s a risky strategy: a lost pollinium means no pollination at all. So orchid flowers have undergone dramatic morphological transformations to assure their pollinia are picked up by the right pollinator. ‘If the Orchideæ had elaborated as much pollen as is produced by other plants, relatively to the number of seeds which they yield, they would have had to produce a most extravagant amount, and this would have caused exhaustion. Such exhaustion is avoided by pollen not being produced in any great superfluity owing to the many special contrivances for its safe transportal from plant to plant, and for placing it securely on the stigma. Thus we can understand why the Orchideæ are more highly endowed in their mechanism for cross-fertilisation, than are most other plants.’ (Darwin, 1862, Fertilisation of Orchids).

What are some of these contrivances mentioned by Darwin? Orchids’ stamens (comprising anthers and filaments, the male reproductive parts) are fused with the pistil (which are the female reproductive parts: stigma, style and ovary) to form a structure known as a column. The anther (the pollen-producing organ) is located at the distal – away from the centre – end of the column, and the stigma (the pollen-receiving organ) lies close by. Directly below the column there’s an enlarged petal named labellum or lip, which often is noticeably different from other flower parts in its colour, markings, or shape. For nectar-producing species, nectaries are located at the base of the labellum.

Parts of an orchid flower © Thomas Cizauskas, CC BY-NC-ND 2.0.

So the stage has been meticulously set. The distinct labellum is a perfect landing strip for an insect attracted by the orchid’s rewards, be they real (nectar) or not (when physical or chemical decoys are deployed). The pollinator lands on the labellum, touches the tip of the column, and goes away with pollinia securely adhered to its body by the viscidium, which works better on smooth surfaces such as the eyes and mouthparts of insects and beaks of birds. When the pollinator visits another flower, the pollinia are likely to be transferred to the stigma. Sticky pollinia and viscidium ensure secure removal of pollen, minimal wastage during transit, and a high probability of deposition on a receptive stigma. 

An orchid bee (Euglossa sp.) with pollinia attached © Eframgoldberg, Wikimedia Commons.

These morphological features have evolved independently in two plant groups: orchids (family Orchidaceae) and milkweeds (subfamily Asclepiadaceae of the family Apocynaceae). But pollinia are relatively more important for orchids; with more than 26,000 described species, they make up about 8% of all vascular plants and span a range of habitats in all continents except Antarctica; there are more orchid species in the world than mammals, birds and reptiles combined.

Merodon equestris (a hover fly) tangled with milkweed pollinia © Lloyd Davidson, Creative Commons.

Orchids’ highly specialized ‘lock and key’ pollination system reduces the chances of pollen being picked up by the wrong flower visitor or being transferred to the wrong plant species; the selective adaptations towards the right flower-pollinator association must have contributed to orchids’ enormous richness and diversity of forms. It’s amazing what a dab of glue here and there can do.

Figure 2 from the 1877 edition of Charles Darwin’s Fertilisation of Orchids. Darwin is demonstrating an early-purple orchid (Orchis mascula) pollinium adhering to a pencil inserted into the flower. Within 30 seconds, the loss of moisture makes the pollinium bend forward to become perfectly positioned to touch a receptive stigma, were the pollinium to be attached to a bee visiting another flower.

The queens of the Isle of Tiree

By Cathy Taylor

Great yellow bumblebees – Bombus distinguendus were once been found across the UK, they are now only found on machair grasslands in north and west Scotland, making it one of the UK’s rarest bumblebee species. The principal causes of the bee’s decline are the loss of flower-rich meadows and the intensification of farming and grazing practices. Great yellow bumblebees (GYBB’s) favour feeding on red clover, vetches and knapweed and require a continuous supply of flowers from May to September. 

The Isle of Tiree is home to one of the largest populations of great yellow bumblebees in the UK, making it an important refuge nationally. This is probably in part due to the vast planes and dunes of flower rich machair. In 2016 RSPB Scotland, in partnership with multiple other organisations, launched a project to enhance suitable forage for GYBBs and increased monitoring the of numbers of bumblebees. This project has now come to an end, but the RSPB continue to work on the conservation of GYBB’s on the island.

This is where I come in; I work for the RSPB, but my usual role is managing a busy urban nature reserve on the outskirts of Birmingham. I had the opportunity to undertake a sabbatical, to work on a different conservation project for a short time. This led me to the little piece of wildlife heaven that is the Isle of Tiree, to provide the RSPB Officer there with an extra person to survey for GYBB queens.

I surveyed for GYBB for 3 weeks on Tiree, June into July 2022. This coincided with the time that the great yellow queens would be emerging from hibernation. During this time, I repeatedly surveyed 9 machair sites, when the weather allowed. Each transect count involved one hour walking a random meandering route following the best patches of food providing flowers and recording all the bumblebees seen during this time. The phrase “think like a bee” rang in my head to determine the route of the transect, following the flowers.

I recorded the abundance of all 8 bumblebee species and collected associated data of flower usage and abundance of key flowering plants. Flowering kidney vetch was heavily favoured as the food plant of choice and was pretty much the only flower I recorded great yellows using (one hopped onto red clover for a taste before returning to kidney vetch). As it was early in the season there were fewer bees to count than would be found later in the season, so this resulted in covering more ground per survey than during the peak months. I was walking at least 1.5 miles per survey and I soon noticed that the kidney vetch seemed to have denser growth on slopes than on the flat machair planes. From this time on the majority of surveys were spent clambering up and down the steep flower rich dunes, a great workout. 

After a cool, windy and wet first few days which left me wondering if great yellow bumblebees were in fact mythical creatures, I was doing the last survey of the day in very slight drizzle and there one was. The unmistakable black stripe across the thorax meant no more puzzling over carder bees, wondering if they were GYBBs. Soon I was recording multiple GYBB queens per survey on my “good” sites. With a total of 38 surveys completed 3 weeks resulting in 51 great yellow bumblebee queen sightings. This is the highest ever number of queens recorded on Tiree and reflects the successful season that GYBB were seen to have in 2021. 

The other bee highlights of the island were the abundance of moss carder bees, the hairy ginger thighs of the red shanked carder bees and the swarms of male northern colletes. All set to a backdrop of white-sand bays with seals and otters bobbing in the shallows and machair plains covered in hares, lapwing, snipe and redshank. A truly stunning place.

With many thanks to Cathy Taylor of RPSB for providing this update.

Find out more: Tiree’s Great Yellow Bumblebee Project report

Pollinators with bad PR

By Athayde Tonhasca

When member of the serial killer community ‘Buffalo Bill’ decided to leave a message to his FBI pursuers, he stuffed the pupa of a black witch moth (Ascalapha odorata) down the throat of his last victim (The Silence of the Lambs, by Thomas Harris). Buffalo Bill may have been a psychopath, but he knew his insects: a target for superstition and ignorance, the black witch is considered a harbinger of doom in many countries. But the makers of the film version of Harris’ story wanted something even more dread-inducing: they substituted the black witch for the African death’s-head hawk moth (Acherontia atropos), another species with a long tradition of spookiness. 

An African death’s-head hawk moth © Muséum de Toulouse, Wikimedia Commons.

With a bit of imagination, you can see a human skull on the moth’s thorax, a feature that has tied the harmless creature to all sorts of legends and misconceptions. Starting with its name, A. atropos, and the names of the other two death’s-head hawk moths from Asia,  A. lachesis and A. styx, which are homages to Greek myths about mortality.

Atropos and Lachesis were two of the three Moirai, the goddesses of destiny, and Styx is the river that divides Earth from the underworld. Adding to the African death’s-head hawk moth’s capacity to awe and alarm, it can chirp when disturbed. You can listen to it here (volume up!) 

The three Moirai, by Alexander Rothaug (1870-1946).

Artists and writers have been inspired by the hawk moths’ mystique, from Edgar Allan Poe, John Keats and Bram Stoker, to stories about its nefarious influence on the mental health of King George III. The University of Cambridge’s Museum of Zoology holds a specimen taken from the king’s chambers by one of the royal physicians.

Dracula, by Bram Stoker (1847-1912), 1919 edition © British Library, image in the public domain.

All these loopy tales distract us from the tangible facts about the death’s-head hawk moth. Which is a pity, because this species is remarkable in many ways. It migrates seasonally from Africa to southern Europe, venturing now and then north of the Alps and into Britain, sometimes as far as the Shetlands, from August to October. The moth travels at night for up to 4,000 km, maintaining a straight path by adjusting its flight plan according to wind conditions. How do we know that? By fitting moths with miniscule transmitters and following them in an aeroplane (Menz et al., 2022). 

The moth’s large, unmistakable caterpillars feed on potato-related plants (Solanum spp.), and can be abundant in potato fields during years of high migration. The feeding habits of adults are less well known. Most adult hawk moth species have an extended proboscis suitable for taking nectar from flowers with long corollas. But the death’s-head’s proboscis is shorter, and it cannot reach the nectar of many flowers. So it adds to its diet by feeding on rotting fruit, tree sap, and, remarkably for a moth, honey. The death’s-head sneaks into colonies of honey bees (Apis spp.) to pilfer their honey – thus the moth’s alternative epithet: ‘bee robber’. It manages to survive such a daring raid thanks to chemical camouflage: moth and bees share some of the cuticular hydrocarbons that bees use to identify nestmates. The moth’s short legs and stout body also help it wiggle in and out of the hive. But these ruses don’t work all the time: beekeepers often find moth remains in their hives.   

A death’s-head hawk moth caterpillar © Erik Streb, and imago (adult stage) © Stahre, Wikimedia Commons.

The death’s-head hawk moth is a poor pollinator candidate, even though we know little about its ecology. At a first glance the other 1,400 or so hawk moths, also known as hummingbird moths, sphinx moths or sphingids (family Sphingidae) – mostly from Africa and the Americas – don’t look promising either. They don’t have pollen-carrying apparatus, and most of them are very good at keeping their distance from flowers. They usually feed by hovering in front of a flower, probing it with their straw-like proboscis. Hovering, a trait shared with hover flies, hummingbirds and some bats, is an energy-demanding flight mode, but it allows the moth to dart from approaching enemies and stay clear of spiders, frogs and other predators lurking on the flower. 

A convolvulus hawk moth (Agrius convolvuli) © Charles J. Sharp, Wikimedia Commons.

Plants however tell a different story. Flowers visited by hawk moths have characteristics that meet their visitors’ needs: in general, they open at night, produce copious volumes of sugar-rich nectar, are of white or pale colours, have long nectar tubes, and lack unnecessary landing zones. This fine-tuning between hawk moths and plants suggests adaptations for sphingophily, or pollination by hovering moths (a development from phalaenophily, which is pollination carried by flower-alighting moths). For plants, a smaller pool of specialised nocturnal visitors has the advantage of reducing the chances of pollen transfer between the wrong species. As a result, many plants are pollinated by hawk moths, of which certainly the most famous is the Darwin’s orchid (Angraecum sesquipedale). 

Two species pollinated by hawk moths: the greater butterfly-orchid (Platanthera chlorantha) © Jörg Hempel, and jasmine tobacco (Nicotiana alata) © Carl E Lewis, Wikimedia Commons.

Hawk moths are among the strongest flying insects; some are capable of commuting for several kilometres in search of flowers, sustaining speeds of over 19 km/h. They may carry only a few pollen grains attached to their proboscis or other body parts, but this pollen can be dispersed over large areas, which is advantageous for plants’ genetic diversity. Long-distance distribution may reduce the impacts of habitat fragmentation, which is the inevitable result of human occupation of natural areas. Indeed, Skogen et al. (Annals of the Missouri Botanical Garden 104: 495-511, 2019) showed that pollen dispersal by the white-lined sphinx or hummingbird moth (Hyles lineata) promotes gene flow between populations of the endemic Colorado Springs evening primrose (Oenothera harringtonii). You can watch hawk moths at work here.

A white-lined sphinx © Larry Lamsa and Colorado Springs evening primrose © Juanita A. R. Ladyman, Wikimedia Commons.

The role of moths as pollinators is poorly understood, but this gap in our knowledge is understandable. It is not easy to study pollination in daytime: at night, data collection is downright difficult. But we are learning more and more about moths’ contribution to the pollination of wild plants and crops. Nocturnal moths comprise around 90% of the 180,000 or so known species of Lepidoptera, so there is much to be discovered about busy but secretive hawk moths. 

The Hireling Shepherd, by William Holman Hunt (1827-1910). The cheeky shepherd boy shows a death’s head hawk moth to the girl, who looks unimpressed.

Zetland Park celebrations

In 1880 the Earl of Shetland gifted land in the centre of Grangemouth for the creation of what became Zetland Park. It’s safe to say that raingardens at that time were not on the agenda. Fast forward to a glorious sunny day in 2022 and a newly created raingarden was one of the stars of the show as Grangemouth turned out to celebrate its impressively transformed public park.

Mind you changes in Zetland Park aren’t entirely new.  For the duration of  World War Two a corner of the park, previously housing a popular rose garden, was given over to allotments. And it is that very corner of the park that now boasts a striking nature-based solution in the shape of a brand new raingarden.

The Rose Garden, we should stress, lives on, but by integrating a raingarden this corner now has a versatility it perhaps lacked before.  Prone to occasional flooding, the rose garden will benefit from a highly sustainable drainage solution. It’s a piece of blue-green infrastructure well worth celebrating. The rain garden in essence means the rose garden has a better future.

Created by the Green Action Trust, who tapped into funds provided by NatureScot, National Lottery Heritage Fund and Falkirk Council, this is a slice of sustainable drainage which will demonstrate a range of benefits in an urban setting.  These include showing how we can create sympathetically designed nature based solutions which offer much needed mitigation against pressing climate change issues such as the threats of flash floods and drought.

Creating the rain garden

What’s more the raingarden is good news for biodiversity and will provide habitat for a range of species, including pollinators and other insects. One of the biggest bonuses for people will the health and wellbeing opportunities; good quality greenspaces which allow people to connect with nature are widely acknowledged to help tackle a range of health issues, from encouraging active outdoor activities to improving our mental health. With raised beds the opportunities for more people to get involved.

And what a result. The stunning rain garden at Zetland Park, set in a tranquil corner

“Working in partnership with the Green Action Trust on the development of Zetland Park Raingarden has been a really positive experience”, according to Allana Hughes, the Zetland Park Project Officer at Falkirk Council. “Using their knowledge and ability to secure funding to further support the project, we have transformed the park’s rose garden from an area which frequently flooded and was in decline into a garden which is once again loved by the community.”

The local council are justifiably proud of the regeneration of Zetland Park which boasts meadows, a naturalised pond and both young fruit trees and mature trees.  The ‘Grand Re-Opening Event’ in late August, which fell on a glorious sunny day, was designed to celebrate that progress and invite the local community to enjoy and rediscover their local park.

The event brought together a partners village where a range of nature focussed groups including The Scottish Wildlife Trust, RSPB, Froglife, and NatureScot were able to share examples of their work.  A range of activities organised by the Friends of Zetland Park, including a raucous duck-race, sports events and live music,  provided a cheerful back drop to a fantastic day. Money raised from this event will be used to continue to develop the rose/rain garden.

The Friends of Zetland Park should be delighted with the carefully designed transformation of this popular public greenspace, and the Earl of Shetland would surely have been delighted to see his legacy living on.

The ‘rain garden team’ from Green Action Trust. Left to right – Laura Shofield (Development Manager), Emilie Wadsworth (Operations Director), and Rachel Howlett (Raingardens Development Officer)

Notes: The Green Action Trust worked with a range of partners including Falkirk Council and the local Grangemouth community. Financial assistance came from bodies including NatureScot (who manage the Scottish Government’s Nature Restoration Fund), National Lottery Heritage Fund, and Falkirk Council.

Images 1 and 2 courtesy and copyright of Falkirk Council.

The humongous fruit, the tiny pollinator and the duplicitous fungus

By Athayde Tonhasca

Among the range of exotic fruits available to us on grocery stalls, we are not likely to find jackfruit (Artocarpus heterophyllus). But that could change, as the worldwide cultivation and consumption of the fruit have been increasing steadily, fuelled in part by its use as a meat and starch substitute. Jackfruit is a source of dietary fibre and it’s high in potassium and vitamin B. The pulp can be eaten fresh, dried or roasted; seeds can be boiled, roasted or ground into flour. Pulp and seeds can be turned into soups, chips, jams, juices, and ice cream. The jack tree requires little care once it’s been established, and produces high-quality, rot-resistant timber used for furniture and musical instruments. The species is cauliflorous (flowers and fruits grow from trunks and large branches), yielding 150-200 fruits per year. The jackfruit is the largest of all tree-borne fruits, reaching up to 60 cm in length and weighing up to 50 kg. You don’t want to take a nap under a jack tree.

A jack tree loaded with fruit © Crops for the Future, an opened fruit © Kinglaw, and jackfruit seeds and flesh © Aznaturalist. Wikimedia Commons.

Because of all these good points, the jackfruit is frequently cited as a potential contributor to food security throughout the tropics, especially considering the tree’s capacity to withstand high temperatures and droughts. But despite the growing interest in jackfruit, we know little about its reproduction. 

The jack tree is monoecious, that is, it has male and female flowers on separate inflorescences. We are not sure how pollen is transferred between flowers: wind, some beetles and flies have been proposed as possible pollinating agents. Researchers in Florida, USA, found an unexpected candidate: a hitherto unknown species of gall midge (family Cecidomyiidae), Clinodiplosis ultracrepidata (Gardner et al., 2018. International Journal of Plant Sciences 179: 350-367). These midges are attracted by the sweet scent released by the flowers. A midge may get some pollen attached to it when visiting a male flower, and a subsequent visit to a female flower could result in pollination. 

A female C. ultracrepidata and a grain of pollen adhering to the abdomen of a midge © Gardner et al., 2018. International Journal of Plant Sciences 179: 350-367.

But there’s a twist in this relationship: pollination by C. ultracrepidata may depend on the jack tree being sick.    

The fungus Rhizopus artocarpi is a common fungal disease of jackfruit flowers and fruit. It initially infects male flowers, later spreading as a greyish growth of mycelia. The fungus advances slowly until the whole inflorescence or young fruit rot and fall off. Fruit rot, as the disease is known, can cause total loss of fruit if conditions are right for fungus development.

A fruit (A) and a male inflorescence (B) infected with Rhizopus sp. © Ghosh et al., 2015. Biological Control 83: 29-36.

Fruit rot could be bad news if unchecked, but some fungus-covered inflorescences are needed by female midges to lay their eggs and by their larvae to feed and develop. Absence of fungal infestation may break the reproductive cycle of C. ultracrepidata, with unknown consequences for jack tree pollination.

This tale illustrates important facts about pollination. First, we have only the vaguest idea of the players involved; C. ultracrepidata likely originated from Asia, sneaked into America by accident, and remained unknown to science until someone bumped into it. There must be countless other anonymous species quietly pollinating crops and wild plants. Second, we have a partial, often highly speculative understanding of processes. For example, we don’t know how relevant C. ultracrepidata is for the pollination of jack tree flowers in Florida or elsewhere: the study did not rule out other insects or wind as contributors. We also don’t know the equilibrium point in this tripartite relationship, i.e., what’s the level of fungal infestation that’s tolerable for a jack tree and sufficient for midge reproduction.  

There is much to be learned in the field of pollination ecology. Considering its relevance to food security, the economy, and to our health, questions about pollination mechanisms and pollinating agents are worth pursuing.  

Jackfruit for sale in New York City. You may be needing a bigger bag © EdwinAmi, Wikimedia Commons.

Aberdeen’s natural progress

Of late Aberdeen City Council’s Environmental Services team has adopted a more natural approach to managing many of the city’s greenspaces. That’s good news for nature, and the people of Aberdeen.  As the team in the north-east are quick to point out, managing urban spaces specifically for nature is an effective conservation strategy to help protect biodiversity, while spending time in nature-rich green spaces helps improve our mental and physical health.

There is a rapid coming to terms with the need to take action across Scotland to manage greenspaces more sustainably. There are two towering drivers. One is to mitigate against the impacts of climate change, the other is to support biodiversity. 

Fernielea Green Space natural wildflowers.

In the biodiversity mix are our pollinators. Our bumble bees, solitary bees, hoverflies, butterflies, beetles and moths are under pressure, with habitat loss, disease, pesticides and climate change on the charge list. The philosophy adopted in Aberdeen, which restores and creates habitat, would work well across the country and take some of the pressure off pollinators. 

Aberdeen’s changes are, by adopting common sense approaches such as reducing grass cutting, planting trees, shrubs, and wildflowers, boosting habitats for many species. What’s more they do so in a way which doesn’t exclude people and supports the urban environment.

That latter point will strike a chord with many to are increasingly looking to good green infrastructure to provide nature based solutions and improve city living.  In Aberdeen the act of planting more trees alone improves the local air quality and reduces rainwater run-off.

The is no doubt that Aberdeen’s goals were hampered by the Coronavirus outbreak. The subsequent lockdowns meant that their Environmental Service was effectively stood down. This placed significant restrictions on much of the work that the service carried out. But in the background it was providing an opportunity to take stock of how the city manages its greenspaces and contemplate changes that could be made. And we know that across the globe the challenges of lockdowns reconnected people with nature.

Steven Shaw who is Aberdeen City’s Environmental Services Manager, was one of those who seized the moment to turn things on their head.

‘When the service resumed,” he says, “it was seen as a perfect opportunity to trial a different way to manage green space, with a focus to do so in a more natural way, to help with climate change mitigation and increase biodiversity benefits, but ensuring also that the Aberdeen public continued to enjoy access to good greenspaces.“The simplest way to manage these open spaces for nature was to reduce grass cutting and encourage nature to bloom.  Many of the areas were, and remain, popular areas for walking, running, cycling and dog walking, and are away from the surfaced path network. To maintain access for these activities, wide paths have been cut though the areas of longer grass.

“Routes for these paths were chosen by following ‘desire lines’ where usage revealed the natural paths people were taking. This was often a link between points of interest or access to any existing surfaced path network. The extent of mown paths will be regularly assessed on a site-by-site basis. If more paths are requested the service will look to include them.”

An example of a mown path through biodiversity friendly grassland

An impressive list of sites across Aberdeen are now managed in a more natural way and benefit from relaxed mowing regimes and new planting.  Sites benefitting from the new approach include 

  • Stonehaven Road 
  • Riverside Drive
  • Garthdee Road 
  • Heatheryfold
  • Maidencraig
  • St Fitticks Park
  • Westfield Park
  • Raeden Park
  • Parkway former Trunk Road Verges
  • Culter Bypass
  • Fernielea Park
  • Kingswells Bypass
  • Eric Hendrie Park
  • The Woodies, Broomhill Road
  • Skene Road Verges
  • Riverview Drive

It is an impressive list, and what’s more it is particularly pleasing that the Aberdeen team didn’t just assume they had got it right. They surveyed the sites to see what changes had taken place, and noted the species thriving. That provided cast-iron confirmation that they were making a difference.

Around 80 species of wildflowers and plants were found in the list of sites. Those flowers included northern marsh orchids, buttercups, hawkbits, dandelions, scentless mayweed, ox-eye daisy, meadowsweet, cow parsley, bugle, sorrel, red clover, white clover, and birds-foot trefoil. Inevitably this had a beneficial knock on effect for a host of pollinators ensuring that there was variety and something in flower at different times.

It is important to emphasise that there is not always a ‘one size fits all’ solution to sites. All these areas will therefore receive a site-specific maintenance programme.  This will include a mixture of different regimes, from areas being left alone, to grass being cut and uplifted once a year, through to grass that is cut twice per year.  Of course, for the mixed use agenda to thrive grass paths and access points will need to be regularly cut and maintained.  It’s that willingness and determination to go back and see what has worked and what needs tweaked that will serve Aberdeen well.

There is also a ‘softer’ dividend in the form of partnership working. As Steven noted “The new methods are ideal in developing skills and confidence around managing land for nature and biodiversity.  What’s more they are highly visible and lead to increased interaction and engagement with other like-minded organisations enabling the Aberdeen Council team to strengthen green connections and networks between organisations and partners.”

He goes on to explain that “Changing the management regimes of public greenspaces is a move which is gaining momentum up and down the country. From ‘No Mow May’ to relaxed mowing there is a growing realisation that amenity grassland can work much better for nature with some tweaks.

“With increasing awareness of climate change, there is a need to take action to manage greenspaces more sustainably.

“Aberdeen’s Environmental Services believe that a managing spaces for nature is positive greenspace management and here to stay across the city.  The new natural areas in Aberdeen are evidence that we are moving towards a greener, healthier city, and this has to be good news for Aberdeen’s people and its nature.”

Parks from London, to Newcastle, to Aberdeen are on the front line in the battle to better green our cities. Our greenspaces were a vital resource for communities in the pandemic, and they are a permanent opportunity for our hard pressed wildlife.  That’s why the strides being made in the way Aberdeen manages its greenspaces should be applauded and encouraged.

Cheaters and cheated in the pollination game

By Athayde Tonhasca

Somewhere on the southern British coast, an early spider-orchid (Ophrys sphegodes) blooms. It’s time to attract insects to transport its pollen to another flower so that fertilisation happens. But most pollinators are not interested: the orchid produces negligible amounts of nectar, and its pollen grains are stuck together in inconvenient masses known as pollinia, a feature of orchids and many plants in the milkweed family. On top of that, the flower’s labellum – the lowermost petal – looks like a legless spider, which is not at all an inviting sign. 

An early spider-orchid © Stefan.lefnaer, and its flower © Orchi, Wikimedia Commons. 
An Ophrys apifera flower with its pollinia clearly visible © Esculapio, Wikimedia Commons.

The early spider-orchid does not offer the temptations usually found in many flowering plants to attract pollinators. But it has one trick up its sleeve, and it’s an effective one: its flowers release an aroma bouquet comprising dozens of alkanes and alkenes. These organic compounds, consisting of carbon and hydrogen atoms, are the main constituents of the natural waxes that help waterproof plants and regulate their water content. For the orchid, these chemicals have another important property: they mimic the scent of virgin female buffish mining bees (Andrena nigroaenea). You can see where this is going: male bees will be very interested in paying a visit.

A male buffish mining bee © gailhampshire, Wikimedia Commons.

About a quarter to a third of the estimated 30,000 orchid species in the world resort to trickery to be pollinated. They may use food deception, ‘pretending’ to give away edible stuff: some species for example release scents similar to nectar volatiles, thus attracting queen bumble bees to their nectar-free flowers. Other orchids – such as the 140 or so species of the genus Ophrys – rely on sexual deception: they produce flowers that look or smell like female insects, luring males to a non-existent receptive partner. Chemical mimicry is just part of this ruse: once the male is persuaded to approach, visual and tactile cues entice him to land and grab the flower. This contact could be fleeting, but some orchid species induce males to a greater amorous display; they try to copulate with the flower. During the deed, known as pseudocopulation, the Lothario accidentally dislodges the pair of pollinia, which get stuck to its head and transported to another flower. You can join David Attenborough in watching this deceitful liaison taking place.

A male Dasyscolia ciliata (a scoliid wasp), pseudocopulating the flower of a mirror orchid (Ophrys speculum) © Pietro Niolu, Wikimedia Commons.

Sexual deception seems like a counterproductive tactic. By putting all its efforts into attracting only male buffish mining bees, the early spider-orchid misses out on every other potential pollinator (this orchid is pollinated by other bees in continental Europe, but the argument is the same). The Orchidaceae is the only plant family engaged in sexual deception, yet the strategy has evolved repeatedly within the group; so it must be advantageous. Scopece et al. (The American Naturalist 175: 98-105, 2010) suggested that pollination efficiency is the answer. By measuring pollen transport of 31 orchid species in Australia and Italy – all known sexually deceptive orchids are from Australia or Europe – they observed that deceived pollinators tend to be reliable; they go from one orchid flower to another of the same species, wasting little time and few pollinia in the process. Orchids with many pollinators had more pollen taken from their flowers, but more of that pollen is accidentally dropped or deposited in flowers of the wrong species.

Sexual deception works for the orchids, but how about the cheated pollinators? They don’t seem to benefit at all from these encounters, which may interfere with their reproduction. Some orchids induce vigorous pseudocopulation that ends up in ejaculation, which is an energetically costly wastage. 

L: A male Darwin wasp (Lissopimpla excelsa) pseudocopulating a Cryptostylis subulata flower. R: A flower after a pollinator visit: the pollinia were removed, pollen was deposited on the stigma, and a blob of ejaculate was left behind © Gaskett et al., 2008. The American Naturalist 171: E206–E212.

Flower visitors learn to avoid deceptive orchids, so perhaps the number of encounters with fake sexual partners is not sufficient to affect males’ overall mating success. Or the balance between plant and pollinator is maintained by the insect’s genetic system: most sexually deceptive orchids are pollinated by a haplodiploid species (males and females develop from unfertilized and fertilized eggs, respectively). If females don’t mate, they don’t produce female offspring, but male offspring is not affected; and if females are fertilised with insufficient sperm, they usually produce more males than females. Therefore sexual deception may lead to a male-biased sex ratio for the pollinator, which would compensate for those males worn-out from overenthusiastic dates with flowers. 

There’s more to the success of sexual deception than specialised pollen carriers and male-female sex ratios. The strategy depends also on synchronisation. As it is the case for many bee species, male buffish mining bees emerge from their nests before females. So the interval between male and female bee emergence is crucial. If the orchid flowers before it, there will be no pollinators around; if after, the orchid will have to compete with the real thing – female bees. Fertilisation rates for sexually deceptive orchids are naturally low; if the phenologies of orchids and bees get out of sync, say for example as a consequence of climate change, pollination rates may plunge. 

Orchids’ amazing variety of forms, colours and shapes fascinated Charles Darwin: “it really seems to me incredibly monstrous to look at an orchid as created as we now see it. Every part reveals modification on modification” (letter to American botanist Asa Gray). So it’s not surprising that Darwin chose orchids as the subject of his next book after On the Origin of Species. His observations, field experiments and discussions with a network of botanists, gardeners and commercial growers convinced him that orchids’ diversity was linked to animal pollination, at a time when the prevailing view was that plants mostly self-pollinated: “In my examination of Orchids, hardly any fact has so much struck me as the endless diversity of structure,—the prodigality of resources,—for gaining the very same end, namely, the fertilisation of one flower by the pollen of another.” (On the various contrivances by which British and foreign orchids are fertilised by insects, and on the good effects of intercrossing, 1862). 

Since then we have learned a great deal more about orchids’ shenanigans to get themselves pollinated, which granted them epithets such as bizarre, cunning, devious, ‘masters of deception’, and ‘purveyors of empty promises’. Darwin probably would have smiled knowingly.

Orchis mascula as an example of adaptations for insect pollination: the diagram from Darwin’s book shows all the petals cut away except the labellum, which extends back to form a tubular nectary below the column © Dave souza, Wikimedia Commons.

Mellow Meadow

The Battleby Meadow is going over now. It’s the natural order of things, nevertheless it can make you feel a little sad as you realise summer is fizzling out. Consolation comes in the shape of two pollinator-friendly flowers.  Nothing too showy, nothing spectacular, but special nonetheless. Bird’s-foot trefoil and knapweed epitomise the relaxing, uplifting, nature of meadows, set boldly as they often are against increasingly fading grasses.

Bird’s-foot trefoil is known to many as a larval foodplant of the common blue butterfly (it is also a food plant for the rather unflatteringly named dingy skipper, and green hairstreak). Found in grasslands, verges, brownfield sites, and heathlands, it is a low-creeping plant and a member of the pea family, which is reflected in the similar style  of flower.

This plant enjoys a rather fetching and easily understood nickname.  An older relative might well recall that it was once popularly known as ‘bacon and eggs’ due to vivid yellow and orange colouring of the flowers. In Shetland the name ‘cat’s claws (Kattikloo)’ appeared, less flatteringly it has also been memorably named ‘granny’s toe-nails’. 

Bees actually have to work some nifty footwork to gain access to the rich nectar and pollen the plant offers. As an earlier blog by Athayde explained ‘It has an irregular corolla with two lateral petals and two lower ones, which are united at their edges to form a landing platform. Once on a flower’s platform, bees prise open the lateral petals to get access to the pollen inside. The bee’s intention is to take all pollen to its nest and store it as food for the larvae, but some grains will become attached to the bee’s underside and released in the next flower visited, ensuring pollination.

“Only some insect species, mostly solitary bees and bumble bees, are able to deal with the complex flower morphology of legumes. As a consequence, some bees became highly specialized on these plants; in fact, the decline of several bumble bee species has been linked to the reduced availability of clover, bird’s-foot-trefoil and other legumes. 

“In Scotland, three of our scarcest bee species are believed to be completely dependent on bird’s-foot-trefoil’s pollen; the pine-wood mason bee, the mountain mason bee and the wall mason bee.”

Knapweed presents fewer challenges for insects.  But as with bird’s-foot trefoil this perennial flower has a range of interesting common or historic names including ‘Hardheads’, ‘Blue bottle’ and ‘Iron knobs’. These names share in common an acknowledgement of the tough heads on these plants. 

You can find knapweed in meadows and pastures, along road verges, on railway embankments, and in scrub and urban waste grounds. 

From June to September this tussocky plant, which resembles a thistle, draws in butterflies, beetles and bees, and there is plenty of it on the Battleby Meadow. We should celebrate this as the bright purple flower head is made up of hundreds of tiny tubular flowers or florets brimming full of nectar. 

In some respects knapweed is one of those plants that keeps on giving; soon it will be providing seeds for the cheery looking goldfinches scouring the retreating meadow. 

There has been a big take up in ‘No Mow’ campaigns of late and for those who embraced allowing their lawn to become a mini-meadow and flowering oasis there is a strong chance that bird’s-foot trefoil and knapweed will feature. Bird’s-foot trefoil, with it’s fairly short stems, it is a very popular splash of colour in these natural lawns.  If you allow a little more height then knapweed is a possibility.

Should you make a bee line for your local meadows, or indeed the Battleby Meadow, chances are you can catch a glimpse of these two popular plants without too much difficulty. Better still what a great opportunity to try a Pollinator Monitoring Scheme FIT-Count (Flower, Insect, Timed Count). Knapweed is one of the target flowers in that project. Whatever you choose to do, enjoy the sight and sounds of two pollinator-friendly gems.

This Side of Paradise

“My irregular lawn, well shaved by Gatsby’s gardener” observed Nick Carraway in The Great Gatsby. Fitzgerald wrote his masterpiece in the 1920s, and for many years after the well-shaved lawn became part and parcel of popular gardens. Now, as they will tell you in Glasgow, that neat and tidy philosophy is wilting fast.

The Jazz Age, Long Island, life of Gatsby is long gone, today more and more of us are looking to go easy on the mowing, let the flowers flourish, tolerate a bit of untidiness.  Often with the specific aim of helping pollinators. Glasgow is one Scottish city that has totally embraced a pollinator friendly approach to greenspace management – they even have their own Pollinator Plan and grasp that pollinators are a key part of Scotland’s biodiversity.

Take a walk around this vibrant city and you will see charming pictorial meadow strips (1m wide) which have sprung up across Scotland’s largest urban community. Created at the front of uncut grass, harbouring a variety of species and aesthetically pleasing heights, they are seeded with cornfield annuals and have been a big hit, the emphasis is on ‘big’ as they total 7,500 square metres over 23 sites. 

And that is just one string to Glasgow’s ever-productive bow in creating green havens.  At Hogganfield Park and Queen’s Park you will find greenspaces that are labelled as Pollinator Parks. It’s a bold sign that Glasgow takes its biodiversity duties seriously and is comfortable mixing park uses and introducing new nature friendly approaches.

There is a clear purpose to the council’s actions and they are adept at calling on the help of expert partners. Anthony McCluskey is a fine example of this method. Well known for his work with bumblebees and butterflies he works with Glasgow City Council to deliver ‘Helping Hands for Butterflies’ at the city’s Ruchill, Elder and Springburn Parks.

Perhaps pride of place in Glasgow’s suite of insect friendly project should go to the Green Connectors project,  Phase 1 of which was funded by the NatureScot  Biodiversity Challenge Fund.  As a result Glasgow City Council has been able to commit £1.5 million from its budget over five years to implement this drive across the rest of the city. Even to the most sceptical onlooker this innovative green infrastructure approach surely shows the level of Council support for pollinators. 

In a mosaic of projects some catch the eye for their uncanny success in drawing people and nature together.  Various Friends of Parks groups offer the council vital support in carrying out wildflower planting and Glasgow has embraced  the initiative that Buglife got underway in the shape of imaginative and much needed B-Lines running through the city. 

RSPB Scotland have been consistently good partners for Glasgow, and they cut and lifted the highly popular existing wildflower meadow behind Kelvingrove Art Gallery in a bid to reduce nutrients and enhance biodiversity. Additional TCV meadow management – a total of 6 days’ work (168 hours) was carried out at four sites – Elder Park, Glasgow Necropolis, Ruchill Park and Springburn Park

Glasgow is enthusiastically embracing the new relaxed mowing, better-managed greenspace philosophy. It can point to 13 large meadow sites across the city managed by a contract farmer and 15 smaller sites managed by The Conservation Trust with help from the Council. This habitat creation is exactly what we crave more of in the environmental sector.

All of these planting efforts and pollinator savvy approaches mark Glasgow out as a city that recognises nature has a problem and needs our help. Even Gatsby’s gardener would surely have approved of a shift that is gradually delivering an urban pollinator paradise.