Friday 18 December 2020

Working with Argyll & Bute Council to trial a change in verge cutting times

Islay's verges some already species rich, act as
corridors to species like this Marsh Fritillary 
With the likes of organisations like Plantlife promoting the leaving of verges to flowers and pollinators, cutting late in the season after the flowers have finished and many councils up and down the country adopting these new management strategies the idea that this would be of value to Islay has evolved.  Many of the planting strategies promoted by Plantlife and other organisations  however would not fit in the Islay context, striping away the existing vegetation and re-seeding with flowers when our soils already have a rich and area-adapted seed bank would be expensive and intrusive.  

Through the Pollinator Initiative, Islay Natural History Trust and funded by The Botanist Foundation a two year study of the less major Islay routes on the Rinns was undertaken in 2017/18 to understand the value and importance of the verges for flowers and pollinators locally.  This work has been reported on through past articles and talks.  The next stage was to use this knowledge and persuade the Council to adapt and change it's strategy on verge management, after much negotiating a trial has now been agreed.

Islay Natural History Trust (INHT), The Botanist Foundation and Argyll and Bute Council will work together in a trial to seed areas of verge with Yellow Rattle a native plant that parasitises grasses that will subdue grass growth with the goal of reducing the need for mid-season cutting.  The plan is to seed up to 4km of verge around the north of Loch Gorm and Gruinart with Yellow rattle this autumn.  Verge growth and development next season will be closely monitored and these areas will be cut late August or later after the plants have seeded.

If successful the outcome will provide long term benefits for both flowers, habitat and council budgets creating a win-win situation for both sides of the biodiversity and budget lobby.

INHT and The Botanist Foundation, who will fund planting and monitoring developed the plan in discussion with council leader Robin Currie and local roads and amenity team leader, Julian Green.  The group also talked about verges that provide space for many orchids including areas about Port Wemyss and Portnahaven and the Mulreesh road (near Finlaggan).  It was agreed that short sections would be left for the orchids to flower and be cut and maintained by volunteers to ensure road safety. 

This is a great collaboration and hopefully one that will be the beginning of an adaptive approach to verge management here on Islay and Jura.

Yellow Rattle will be used as our catalyst for the suppression of grasses, the growth of which ultimately creates the major need for cutting at all.  This plant is an indicator species typically found in ancient meadows, it is an annual plant and requires the ability to set seed each year in order to persist in the grassland.  It has a parasitic nature, its roots latching onto those of surrounding grasses pulling nutrients from the grass roots for its own growth, thus the grasses round about these plants grow with less vigour. 

 With grasses less dominant the height of verge growth will be subdued and the need for mid season cutting less urgent.  It also provides opportunity for other flowering plants like clovers to have space amongst the sward providing more flowers for pollinating insects.  Flower rich verges act as bridges across areas of sheep grazed pasture and barley filled fields linking many areas of great habitat that Islay supports.

A verge on the Isle of Lewis low
growing, and herb rich

 Our verges on Islay are a mixed bag, some all grass, rampant in growth, others a more colourful mix of flowers of varying height and visual intrusion into the road users awareness and some an important area for orchids and other specialist plants.  Despite this variety there is one management strategy, a process of cutting when machinery is available and when the control of growth becomes a visible need at the end of May and through to July to provide good line of sight for the driver and for the pedestrian to step off the road with safety.  This cutting is welcomed by some and the loss of flowers coming into their peak cursed by others.

So next year look out for the signs indicating that verges are being left for the purposes of letting flowers flourish and enjoy the colour and beauty our rich flora provides. 



The facts about Yellow Rattle

Some facts to consider:-

  • Yellow Rattle is native and a viable local component in grasslands within the area and in no way aggressive in the manner suggested.  It is already present in the verges less than half a mile from the trial site.
  • Yes some of the roadsides around Loch Gorm are already rich in diversity, the most diverse have yellow rattle naturally as part of their make-up with dense patches of red clover and bird's foot trefoil both extremely good pollinator species enabled to grow amongst this. 
  • The main section 2.5km that is within the trial however is the least diverse and heavily burdened with thick grasses which do not allow much other plant diversity to take hold, most likely the result of better soil fertility as they run alongside improved grassland with associated fertiliser spill off. 
  • The reason for only introducing yellow rattle is to subdue grass and enable a more open sward for other diverse seed stock within the soil to have the chance to develop. 
  • There is no guarantee that the seed will germinate, the grasses are dominated with Couch grass and Cock's Foot both aggressive dominant grasses, I know as I have physically hand scythed the area to prepare the ground for seeding, I wouldn't waste my valuable time if I did not think it was worth it!

Surveying the verges before trial. This verge shows
the barrier to seed spread that is along
most of the verge within the trial
The point raised as to the risk of spread into adjacent areas, is a viable point, one which has been considered.  In this instance the sowing is only within the one metre strip that the council cuts, bordering this on the full length of the roadside is at least a further 1-2m of thick matted grass, bramble, ditch or willow where stray yellow rattle seed will not take root and the adjacent grasslands are either sheep grazed or cut for silage which is likely to be before yellow rattle casts its seed and therefore the plant will not persist. 

Yellow rattle starts to develop and germinate in spring and completely dies at the end of the season, no roots or plant remains over winter.  Current farm management practices should naturally negate natural germination or development of cast seed and prevent spread of the plant beyond the verge area.

  • Fields are grazed by sheep prior to setting aside for silage and sheep will naturally graze out such growth.  I have witnessed sheep nipping off the flowering heads of yellow rattle so they will graze it out in preference and not enable seeding.
  • Once left for silage fertiliser encourages growth of grasses which will out compete species such as yellow rattle if they have persisted after sheep grazing.
  • Silage is cut earlier usually than the plant is ready to seed from late July onwards and even if it has got to the flowering stage will be cut and not supply the soil with seed for growth the following year.
  • There was mention of barley as a grass and hence would be adversely affected by yellow rattle. 
    • barley is not sown here until after the beginning of April and hence no yellow rattle would have grass roots to latch onto to germinate in time for the season.  
    • As far as I am aware all barley fields are sprayed with herbicide to kill off competing plants and therefore would kill off any yellow rattle which has germinated.

The problem for yellow rattle survival is that it is an annual and as such needs to seed every season to persist in the grassland.  Before the advent of early cutting for silage it would have been widespread in meadows cut for hay, modern farming has resulted in its wide decline and only persists where grasslands are regularly left uncut until late in the season, the large ancient meadow at Smaull Farm a prime example but this field is managed for this very purpose.  

INHT and The Botanist Foundation would never consider introducing any plant species that would cause harm to the natural environment.  This project is based on hard facts and consideration of scientifically collected data and not on a whim with disregard to the environment it will affect.  We would certainly not add yellow rattle in all areas, where verges are already species rich or the grasses already a minor feature, this would not add value to an already rich habitat.

Here are some links from across the spectrum including one from a farming forum where some consider they have some issue with yellow rattle, however most address the plant with the open outlook and consider the ease in eliminating it if some spread should occur.

Quote from Scottish Wildlife Trust information

"If Yellow rattle is no longer wanted on a site, flowers can be cut before they can produce seed and as there is no seed bank in the soil the plant will not appear the following year."

Fiona MacGillivray

Tuesday 23 June 2020

For the love of Peat

Marsh Fritillary on Marsh Thistle
INHT has been undertaking surveys on SPA (Special Protection Areas) sites on the Rhinns for the CANN peatland restoration project recording breeding birds and the populations of Marsh Fritillary butterflies for the past couple of years.  This has provided extra revenue for the charity and a chance to directly undertake recording of species for our database.  This fine weather (when the wind in not blowing a hoolly!), warm and sunny, has had the butterflies out and it is so nice to see the Marsh Fritillary, one of Islay's prettiest butterflies.  The adults are only on the wing for about 4-6 weeks so there is only a short time to see them and for them to have the right conditions to breed and set forth the next generation which spends the rest of the year as caterpillars.
Marsh Fritillary and Small Heath

Our peat bogs are wondrous places, colourful and with little gems for an observer to appreciate and photograph.  Specialised plants and birds making the most of insects and the limited nutrients the bog can provide.  When you get down low they are really forests in miniature, the Ling Heather and Bog Cotton are the trees and the sphagnum mosses the herb rich layer. 
Bog Bean

Round-leaved Sundew with trapped fly

Sphagnums provide a rich tapestry of colour, and though the species list for flowering plants is not vast is made up for in variety and colour.  Many were only just reaching the point of flowering, Bog Asphodel and Sundews budding and almost out.  The Bog Cotton is being gradually teased from the bud and floating or streaking in the wind to find a new position to set down roots.  Butterwort and the sundews (Round leaved and Long leaved) await unsuspecting midges or even a larger fly to get stuck to their sticky and dew tipped leaves, which gradually digest the insect absorbing the nitrogen released a nutrient not available in the peat where there is no contact with the soil and rock substrate.

Dubh Loch with Bog Bean
Bog Bean
Water Lily

The jewels in the bog are the little Dubh Lochs, often set at the top of the rises and providing permanent water for Bog Bean and water lilies, and midges, that are food for dragonflies (Four-spotted chasers, Golden-ringed Dragonflies and damselflies), Dunlin and other waders like Redshank and Lapwing which have moved off the dry farmland in search of soft water logged ground for insects.

The rest of the bog is scattered with pink Heath Spotted orchid and every couple of hundred metres Skylark ascend to the sky singing their little hearts out a joy to the ear.

Traversing the terrain is hard going for a biped and wings would be so much easier but the little gems are worth the effort and the workout keeps the body in trim, I scoff at the app on my phone which has tracked my passage and tells me I have exerted merely a couple of hundred calories for the days exhaustion!

Sunday 24 May 2020

Investigation of the Honeybees Pollen Baskets

In my other role as Keeper of honeybees for the Islay Pollinator Initiative I have come to learn a great deal about flowers and pollination, attentive to what is in flower and the value of each for the honeybee.  There is always a fall off of pollen brought back by the bees and I collect up samples to have a closer look and learn a little more about what they are really foraging on.  Sheltering indoors with Saturday's rainy, windy weather I finally had the chance to look through a scoop of pollen collected from a hive a week or so back that did not make it through the queen excluder the bees were moving through. 

As with all flowers different by colour, shape and texture, so too are the pollen grains they produce.  Each pollen grain is essential for the plants to pass on to other flowers of their own kind in order for fertilisation to occur and new progeny in the form of seeds for plants to perpetuate their species.  Flowers have built a very complex relationship between themselves and various pollinators, butterflies, bees, wasps and hoverflies to name the main contenders.  Pollen is food for some (our honeybees in particular) providing protein and essential minerals and nutrients for the larvae to grow healthy and strong, the flowers provide nectar, a sweet energy rich treat for some and an enticement and reward for the insect which gets laden with pollen to transfer to the next flower. 

Honeybees are very important in this process, each bee concentrates on a particular flower so only visiting flowers of the same species in successive trips and therefore only the right pollen is taken to the next flower visited.  Some is passed on and some the bees pack into their pollen baskets (on their hind legs), each species of pollen has a different colour so by watching what colour pollen they return to the hive with you can get an indication of what flowers they are harvesting.  By observing what flowers are in bloom you can also predict what they might be foraging on at each stage in the year.

This is my collection of pollens in the sample, collected about the first half of May, two shades of yellow/orange a pale green and a creamy/white.  A pollen colour chart can give an indication of pollen colour for the month and by making a microscope slide and looking under magnification, shape and form can be seen and further identification made.
Pollens mixed with alcohol ready for slided
Slide of each pollen type

Individual coffee bean shaped pollen grains
Pollen 1 - pale creamy/yellow and under the microscope looks very much like coffee grains.  Using colour, and knowing what is in flower and checking pollen ID features these are Bluebell, worked hard by the bees as it provides a very good nectar source as well as pollen.

Pollen 2 - khaki green and under magnification distinctly triangular with circular features at the corners, ID features suggest Rosaceae family, and as there is an apple tree at the apiary and the colour matches, so it is from our apple tree which will bear lots of apples hopefully at the end of the summer, if this wind hasn't ripped all the blossoms off!
Individual triangular pollen grains of apple blossom

Pollen 3 - colour, a dull orangey yellow, looking at the colour charts I might have put these last two the other way around, however under magnification (although my cheap none-too high tech microscope shows none to clear) definition is not that great, the small round, poorly defined grains I put to be Dandelion.
Small circular pollen grains -projections on grain surface not discernible in image

Pollen 4 - deeper orange/brown and under magnification the grains were sometimes rounded and some rounded/triangular which clearly seemed a feature of Gorse from the guide.  I may be wrong and there was possibly some contamination of this last sample with some other grains mixed in.  Gorse is one of the most important flowers for our bees on Islay it flowers very early in the year (flowers even right through the winter) and the bees will visit them if the weather is suitable to fly out, late January this year we had a 'warmer' dry few days and the bees were bringing back Gorse pollen.
Gorse (?) pollen grains

Such studies bring another level of understanding to the complex relationship between flower and pollinator.  Once the current restrictions abate and normality ensues (whenever that will be?) we will have our microscopes available to look at pollens in the Nature Centre and we will get a more high resolution camera to take better pictures of the samples than my bargain Aldi/Lidl purchase of a few years back doesn't do justice to!
Fiona MacGillivray