Case study: Reversion of arable land to lowland chalk grassland

Author: Lynne Roberts:  The RSPB’s Manor Farm, Newton Tony, Wiltshire

Aims and setting

Chalk grassland is one of the richest landscapes for wildlife in the UK and is a habitat which has suffered significant losses in past decades. This case study focuses on Manor Farm in Wiltshire, now the operational base of RSPB’s Winterbourne Downs nature reserve, which was acquired by the RSPB in 2005 with the overall objective of creating a habitat 'stepping-stone' for wildlife between two internationally important chalk grassland areas: Salisbury Plain and Porton Down.

To enable wildlife species to thrive on the farm and expand their range from the neighbouring chalk grassland areas, much of the arable farmland was reverted to lowland calcareous grassland, a UK priority Biodiversity Action Plan (BAP) habitat. An initial reversion of about 40ha in 2006 has been followed by further grassland creation projects at the rate of around 25ha per year, and now almost 200ha of the total farm area of 296ha has been reverted to semi-natural chalk grassland.

Agri-environmental scheme grants from Natural England and capital grants from the Heritage Lottery Fund were major contributors to the reversion works.
This case study describes in detail the reversion of a 24ha area of arable land, started in 2008.

Site preparation and sowing

In order to select the most conducive sites for reversion, soil samples from across the farm were analysed. It is recognised that land with low nutrient levels, particularly available phosphorous, is the most suitable for creating and restoring species-rich grassland - the best sites will have a phosphate index of between 0 and 1. The results of this showed much of the farm to have high soil phosphate levels and two fields totalling 24ha with a phosphate index of around 2 were selected.

Machine-sowing of harvested seed was chosen as the most suitable method of starting off the reversion process. Natural re-colonisation was thought to be unlikely to produce the right levels of target species, since this requires plentiful supplies of nearby seed - something which could not be guaranteed, especially over such a large area.

A mixture of brush-harvested wildflower and grass seed was sourced from four local downland sites, including the Salisbury Plain Training Area, where there are several thousand hectares of good quality calcareous grassland. Using locally sourced seed increases the chances that the plants will thrive, as they will be better adapted to the local conditions.

After harvesting the last arable crop from the selected fields, a sterile seed bed was created by spraying with glyphosate and cultivating with a spring-tine cultivator to provide a good tilth. A few weeks later, in mid-September, the wildflower/grass seed mix was sown using a pneumatic fertiliser spreader, which blows out the seed from tubes spaced 1m apart along an 18m boom width.

Seed Sowing

The seed was mixed with kiln-dried sand to improve the flow of seed through the spreader and sown at a rate of 20kg per hectare. Four complete passes of the spreader were made to ensure good distribution of the seed. The fields were then rolled with a Cambridge roller to ensure good contact with the soil.  The approximate cost for this (in 2008) was just under £900 per hectare, split between herbicide (17%), seed (76%), dried sand (2%) and labour and diesel (5%).

Early establishment and management

In the first year, the sites looked very patchy, although many chalk grassland species were showing by midsummer, such as salad burnet and small scabious. The fields were topped once in early May, timing the cut to catch most of the black grass and other unwanted plants such as thistles and docks before seed set.

Patchy coverage in the first spring after autumn sowing

An early cut avoids topping more than 25% of the yellow rattle, which is a key species in the arable reversion process. Yellow rattle is semi-parasitic on grasses and clovers, suppressing grass growth and increasing the light available for other wildflowers to prosper.

The side shoots from the yellow rattle and the other chalk grassland species were then allowed to flower and set seed and a further cut was made in July. The arisings from this July cut were collected and removed to prevent mulching and help drive down the nutrient levels, allowing the flowering species to compete effectively with the grasses.

Yellow rattle helps to keep the sward open

Sheep were introduced in the Autumn/Winter to create a short open sward with occasional tussocks, which created some habitat diversity in an otherwise flat field. In the following two years, hay crops were taken to further reduce soil nutrients levels, with aftermath sheep grazing from autumn to early spring. Supplementary feeding was avoided to prevent the import of nutrients.

Assessing for habitat quality

By the third year after sowing the plant community was typical of early grassland creation, with a large diversity of species present - 37 species were recorded inside the assessment quadrats, with a further 21 species elsewhere in the sward. These included species which are characteristic of chalk grassland and typical of nutrient-poor conditions. Analysis of the species makeup showed that there were five 'dominant' or 'abundant' wildflower species: yellow rattle, ribwort plantain, black medick, self-heal and white clover. Of those recorded at lower frequencies, several were chalk indicator species, including harebell, perforate St. John's wort and field scabious, as well as those listed in the Natural England ‘species indicators’ table below. The woodier perennials like greater knapweed, oxeye daisy and wild marjoram were establishing well.

Of the typical grasses present, sheep's fescue was dominant, with quaking grass, upright brome, yellow oat-grass, meadow oat-grass and common bent also recorded.

Year three - a herb-rich sward is establishing

The following table shows the criteria for success set out by Natural England for this type of habitat and how the reversion fields measured up against these criteria:

The importance of soil fungi and organic matter

We found that some species were slower to establish than others. This is likely to be due to the abundance and diversity of mycorrhizal fungi present in the soil. Intensive arable agriculture reduces this diversity, and some plant species will not be able to exist on the land until the correct fungi arrive. It wasn’t until about four years after the start of the reversion that the first signs of fungal colonisation, the ‘fairy rings’, could be seen and species such as dropwort and devil’s-bit scabious began to appear. It was more than five years after sowing before any orchids were spotted, which is likely to be an indicator of the developing populations of mycorrhizal fungi.

Some good indicator species like saw-wort, have still not been recorded, although we know the seed was sown. This could be due to the soil conditions or plant associations not yet being right for them to get established.

Fairy rings show signs of mycorrhizal fungi

The levels of organic matter in the soil were extremely low to begin with, at around 2%, which is consistent with the land having been in long-term continuous arable cultivation. The establishment of permanent grassland will cause the organic matter levels to increase over time, especially where the land is grazed. The soil analysis results for 2017 showed that the levels in the early reversions had generally gone up to around 5-9%. The increase in soil organic matter goes hand in hand with bacterial and fungal diversity and with the locking up of carbon, making semi-natural grasslands like chalk grasslands in our landscapes a natural way of helping to tackle climate change.

Achievements for fauna

We saw an amazing transformation from cultivated land to herb-rich sward by year three, and even by the second summer after sowing there was visibly and audibly more insect life in the new grasslands. The most obvious insects are of course the butterflies, and from the second year we saw meadow brown, common blue, small blue, dark green fritillary , marbled white, ringlet and small skipper.

Other insects, such as moths, beetles, bees and flies had also colonised the grasslands, although no formal assessment was made in the early years to compare with the baseline survey taken at the start of the reversion process. However, in an invertebrate survey undertaken in 2016, one new BAP Priority species (the bumblebee Bombus ruderatus) and eight new Nationally Scarce species were recorded, including the six-belted clearwing moth and the picture-winged fly Merzomyia westermanni.

When farmland is taken out of cultivation there is a risk that some bird species associated with arable cropping might decline, so it was important to ensure that the key requirements of these species were maintained. To help ensure seed food availability for farmland birds on the farm, some strips of wild bird seed mixes were sown alongside natural features such as hedges. Farmland birds are regularly seen in the floriferous arable margins and the bird seed plots, and whilst the figures from the Common Bird Census recording took a little while to show real signs of benefit, the ongoing provision of suitable habitat has reaped rewards. Local populations of farmland birds such as skylark, yellowhammer, linnet, lapwing and corn bunting, all of which are currently species on the Red List of Conservation Concern, have either increased or been maintained, as the chart below shows.

Lessons learnt

We have learnt a couple of important technical lessons regarding nutrient levels and seed sowing as a result of our reversion projects.

  1. Where we started the reversion process with a phosphate index of around 2, it sometimes produced a thick grass-dominated sward very quickly, crowding out some of the sown wildflowers and emphasising the need for a lower initial phosphate index. Although haymaking can be used as a way of reducing nutrient levels in the soil once the wildflower seed mix has been sown, we have found that growing barley for a couple of years without a compound fertiliser prior to starting the reversion is a more cost-effective way of reducing the levels of key nutrients, especially available phosphorous. These crops are best grown with the application of ammonium nitrate fertiliser; this helps the barley pull up the phosphates from the soil without contributing to the nutrient load, as nitrates will leach readily from chalk soils.

 

  1. We did not mix the seed with any other agent at first and found that the seed clumped together in the machinery (termed 'bridging'). Mixing the seed with the kiln-dried sand improved the flow, but we have found in other reversion projects that it is even better to use a fertiliser spinner, which broadcasts the seed through a wider aperture.

 

All photos supplied by Patrick Cashman, site manager RSPB Winterbourne Downs

For more information, contact: patrick.cashman@rspb.org.uk

 

 

Case Study: Managing hedges on an extended rotation – Using an excavator mounted finger bar and tree shear

Author: Fraser Hugill: Throstle Nest Farm, Sproxton, North Yorkshire

The Management Challenge

In recent years I have taken over the management of the family farm. The farm business consists of 350 acres, split over two different holdings, both with fantastic hedgerow networks that support lots of wildlife but with very different management needs. I wanted to find a way to manage the hedges myself that would be cost-effective and benefit wildlife.

The solution came in the form of digger-mounted finger bar cutter and tree shear. The results have been really good for hedges, wildlife and soil – and have given me the perfect excuse to keep the farm’s best big boy’s toy - the digger.

The two holdings that make up my farm business are Throstle Nest, on the southern edge of the North York Moors, and White House, on the northern edge of the moors. The farm is roughly 50% arable (Winter Wheat, Winter Barley, Spring Beans, Oats) and the remainder a mix of permanent pasture and grass/herbal leys supporting a herd of 50 pedigree Beef Shorthorn suckler cows.

Throstle Nest has a really intact hedgerow network, very similar to 1840s maps, with species-diverse hedges. Prior to our arrival these appeared to have been trimmed annually and were grazed by sheep, but were generally in a good condition. Throstle Nest also has heavy clay soils which are waterlogged throughout winter. This means that using a conventional tractor-mounted flail cutter was only viable in the Autumn as the wheels cause too much damage to the ground in spring.

White House has had very little hedgerow management - Dad pretty much ignored them, which created a good habitat, but hedges were starting to grow out and lacked structural diversity. Although Dad’s management had benefits for wildlife, this management could not go on indefinitely!

Both farms are in Countryside Stewardship with both agreements up for renewal. The current agreements include hedgerow revenue and capital options to gap up and coppice hedges, and these options will be included in the new agreements.

Managing Hedges with Excavator Mounted Equipment

Moving to Throstle Nest in 2012 involved a lot of infrastructure work so we purchased a 5-tonne excavator. The plan was originally to sell it once work was complete, however this prospect was akin to taking away a children’s favourite toy!  So, somehow this had to be justified. But how? By buying more toys to attach to it of course!

The first piece of kit was a Slanetrac 1.8 metre finger bar hedge trimmer which runs off the excavator’s third service. It works as a combine cutter bar using the same blades as our combine. Unlike a tractor-mounted flail, cutting is done in one single pass, so no going backwards and forwards which risks increased damage to the ground.

Cutting involves staying in one position to cut 4-5 metres off the hedge side and then from the top. Then moving another 4-5 metres forward to the next section. This gives excellent control, particularly when cutting larger sections of hedge.

 

Bar hedge trimmer cuts through 3 - 4 yr old hedge wood
Bar hedge trimmer cuts through 3 - 4 yr old hedge wood
Cutting several feet of mature hedge growth in one cut
Cutting several feet of mature hedge growth in one cut
Hedges.IMG_0856

One of the key advantages over a flail is the very pleasing clean neat cut, which is particularly important when managing hedges on an extended rotation.

So often I hear that if you don’t cut your hedges every year you get a “right mess” but the photos below help illustrate how clean the cut can be, and how strong regrowth is behind the cut.

Cost also comes into play, with the finger bar costing £2400 it was, in my view, not overly expensive, albeit our finger bar cutter is a little on the light side for our management objectives, the key is not to be in a rush and to learn the machine’s limitations.

Hedges..IMG_0876
Hedges...IMG_0878

The brash left behind has both advantages and disadvantages, depending on your personal viewpoint. I try to make a single cut so each piece of brash is as large as possible, making it easier to then bulldoze cut material together with the excavator blade and/or the front toothed bucket.

If the ground is very wet, this is often done at a later date, being mindful of breeding birds.  I have been pleasantly surprised how effective this actually is as the material acts as a rake. Note we have no roadside hedges. Touch wood, we have had no issue with thorns, either with cows or tyres as we use the tracked digger to clean up.

An advantage of the long sections of brash is you can actually clean up, compared to a flail which sends material everywhere. We don’t have sheep, but if we did, thorns might be a concern due to sheep’s ability to find danger!

Hedges cut on a 3-4 year rotation generate a lot of material, as the photos illustrate. The tidiest approach is to burn it, however that would be too conventional! As a result, where there are gaps in the hedge, the brash is used to fill them to discourage livestock and people with dogs (picture, left below) or to make habitat piles (picture, right below).

Where ditches are fenced off (our ditches are small and seasonally dry) I tend to leave the brash in situ to provide some dead wood but to also potentially slow flow and to help intercept sediment. Using the material from the hedges adds to the sustainability of our approach.

If I was a workshop tinkerer I would be making a Bailer to somehow get the material into our log biomass boiler!

Hedges.......IMG_3699
Hedges....IMG_3257

The second attachment for the excavator is a TMK tree shear, which again is operated via the third service. This machine basically grabs hold of a tree, branch or shrub pulling it across a cutting blade. The cut off material can then be placed in a pile or wherever the operator wants.  As with the finger bar I try to fill gaps with the material, and section out any timber for logs, but ultimately some of the brash is burnt. This machine has really helped with managing some of the bigger grown-out hedges.

The speed and ease of coppicing it provides is amazing and clearing up the material is so easy as you have hold of it in the comfort of a cab.  A key lesson is to take a long-term approach and not to blitz all the hedges at once just because you have a tree shear and have to get all CS capital works done in 2 years - owning a tree shear should perhaps come with a licence! Manage hedges over your lifetime not on an annual basis.

It should be noted that with larger material the tree shear/ cut is not especially "clean", however this is where compromise sometimes come in. With full coppice we tend to finish off stumps with the chainsaw to limit the ripping effect of the shear (picture below).

I am also playing with part managing grown out hedges through part-coppicing, digger-laying and generally mixing up diversity of management.

Tree shear on Alder

The ultimate sign of success, however, is the species using the hedges. We are perhaps culpable of not doing enough survey work, however the thing we have really noticed is the increase in yellowhammers.

This will not be solely down to hedges as we have winter bird food and supplementary feeding - however the hedges are a key component in the ecological jigsaw.

Yellowhammer Emberiza citrinella, adult male feeding on grain at Hope Farm,  April 2002

Why we take this approach to hedgerow management

Our approach comes down to circumstance and objectives and will not be for everyone.  Our aim is to:

  1. Maximise the ecological value of hedges by allowing flowering for pollinators and fruiting for birds and small mammals by pushing back cutting dates to as late in Feb as possible and extending the cutting cycle to have 75% of hedges in berry and flower production each year.
  2. Have control over hedgerow management, allowing flexible and responsive approach to management based on ground conditions and most importantly what I see while cutting the hedge. This is particularly relevant to hedgerow trees and allows me to first spot them and then not cut them.
  3. Have a diverse range of hedges at different stages of succession from regenerated through planting and coppicing to mature with future hedgerow trees establishing.
  4. Incrementally cut the hedges so they are not cut to the same point, so they expand overtime ultimately leading to being coppiced and the process starting again.
  5. Have hedges that provide shelter, function as a livestock barrier and contribute to the agricultural success of the farm.
  6. Minimise ground disturbance/compaction

The key thing however is mind-set, an uncut hedge to me no longer looks messy, whereas a bonsai flailed hedge looks like a massive missed opportunity. As farmers we tend to hate bare fallow and that’s how I feel about an annually flailed hedge when it is not getting the chance to produce a crop of flowers and/or berries

Hedge to right coming into third year after cutting has comparable flowering with unmanaged hedge to left
Hedge to right coming into third year after cutting has comparable flowering with unmanaged hedge to left
Same hedge close up - note, honeysuckle
Same hedge close up - note, honeysuckle

Sources of further information/ advice

Delivering Championing the Farmed Environment (CFE) events, in my role as Northern Co-ordinator has really helped develop my understanding of hedges over the years.

Events with Steven Falk, an excellent entomologist, have really highlighted the value of hedges and particularly the flowering cycle of hedgerows for pollinators early in the season, before habitats like nectar mixes and meadows come into play.

Hedgelink also produce excellent information about hedgerow management which we have used in events.

Encouragement received from Chris Tomson, who was our local RSPB adviser has also fostered a greater interest and understanding.

Case Study: Carabid beetles for natural-enemy pest control

Author: Kelly Jowett:

If there was an agent acting within your crops that could reduce eggs and first instar larvae of the cabbage root fly by up to 90%; reduce emerging wheat blossom midge by 81%; and reduce seed stock of crop weeds in the range of 65-90%, then I’m sure you’d want to keep it in there. Well, with a little effort you can have this voracious destroyer of pests working across your farm. Carabid beetles, sometimes known as ground beetles, eat ALL major crop pests, and weed seeds too, and are present in all farm habitats across the UK. This makes them ideal agents of natural enemy pest control.

Natural enemy pest control is a bit of a mouthful but is just what it describes: the eating of crop pests by the predators that would control them in a natural system. The problem for natural enemy pest control is that we are not dealing with a fully natural system. Since the post-war agricultural revolution, farmland has been subject to tremendous change. Over time this has caused substantial decline in the populations of carabid beetles and other natural enemies. Unfortunately, pest species are adapted to bounce back quicker - especially since large crop areas are ideally suited to support population booms. Whilst pesticide sprays are necessary in this system, they compound the problem - hitting the predators as well as the pests, added to associated resistance building.

The importance of biodiversity

Carabid beetles are incredibly variable. Of the 350 species in the UK, 30 of these are common in farmland. They range in size from 2mm to 3cm in length; some can fly long distances, some run up to 16cm per second; some breed in the autumn, and some breed in the spring. Each has their own habitat preferences, meaning that they are active at different times, tolerate different weather and farm management practices, and are better at eating different crop pests. Therefore, having a diverse range of carabid species will mean that you have the best chance of effective pest predation.

So what can we do to help boost carabid numbers and diversity?

Luckily carabid beetles are well studied and we already know a lot about what they need to thrive. We can break this down into areas to feed, areas to breed, and areas to shelter.

Areas to Feed

Of course we want them to feed in the crop or pasture area when pests are there- but pests are not there all the time (luckily for us!) to support the carabid beetles needs. So semi natural areas are essential to provide the invertebrate and plant resources for all year round food. Conservation headlands, grass/ flower margins, beetle banks and taking field corners out of management, can all provide these close to productive areas, so carabids can move quickly into the crop to eat the pests they prefer, when they appear.

Areas to Breed

Carabids lay their eggs in the soil, hatching into larvae- which take around 6 months to grow, before they pupate and emerge into adult beetles. The larvae are actually predatory on crop pests too, and eat more than adults as they need a lot of protein to grow. Some larvae also eat weed seeds, which is particularly useful as they live in the top soil levels in the crop area. To help larvae grow undisturbed in crop areas, minimum tillage systems may be useful.

Areas to Shelter

Carabids have two main periods when they need shelter: hibernation, and aestivation, which is a summer rest period when conditions are too hot and arid. At these times, the beetles take advantage of permanent habit with structure that creates a protective microclimate- such as hedges, ditches, banks, and at a small scale the tussocks created by some grasses.

Another important aspect is the shelter from machinery and chemical applications. These can cause direct mortality, or affect the carabids ability to feed and breed, so safe areas near to crops allow some beetles to thrive and repopulate when such management is necessary.

Linking up farm habitats

To preserve or enhance the diversity of carabids on your farm it is important to have a range of habitats, but also for them to be linked up. Firstly populations need those seasonal and foraging movements, but as conditions change, different species can immigrate into your farm from surrounding areas to boost your assemblage of species. Carabids move in the landscape in a variety of ways, flying species will use habitats as stepping stones, whilst running species may need ‘corridors’ of hedges and margins to encourage them to move around the farm.

Farm habitats for beetles. a) grass and flower margins, along with hedges provide food resources year round, and connect other habitats;
 b) beetle banks create stable resources in the centre of fields, to encourage beetle presence in crop areas;  (c) Peter Thompson
c) taking corners out of management encourages scrub and tussocky grasses- ideal for sheltering carabids.

Farm habitats for beetles: a) grass and flower margins, along with hedges provide food resources year round, and connect other habitats;  b) beetle banks create stable resources in the centre of fields, to encourage beetle presence in crop areas;  c) taking corners out of management encourages scrub and tussocky grasses- ideal for sheltering carabids.

But there is still work to be done

Although scientists have done a lot of research on carabids, there is still a lot we don’t know. My recent work has shown that different species are associated with different landscape features such as field boundary habitats, crops, soils, and management such as tillage regimes. If we can better understand which habitats are most beneficial for different beetles, it will become possible to tailor your farm habitats to get a good selection of predatory species that suit a farms particular pests.

Pitfall trapping to monitor farm habitats

Pitfall trapping is a quick and easy way to see what carabids you have on your farm, and if you do pitfall trapping periodically, you can track how the populations vary over time relative to your farm management interventions. For details see my factsheet:

 How to pitfall trap on your farm: Factsheet

Feed-back to scientists, especially me!

The main knowledge gap is how these habitats work in practice, over time. This is where we need to work with farmers closely, monitoring farm habitats, seeing what works, where, and why. But also, crucially, we need to know which interventions fit well into your farm business. Even if something works for beetles, if it’s going to be difficult for farmers to apply, it will not be widely applied!

Which leads me on to my plea: I need farmers to take my survey!

Watch my animation: Here.

Take a short introduction to ID quiz: Link to ID Quiz

Then take my beneficial beetles survey to tell me your opinions on carabids, management that may be useful for them, and monitoring. Link to survey

If you are motivated after reading this article to carry out pitfall trapping or set up monitoring on your farm, I would be happy to help with advice, and support with verification of carabid identification.

Email : Kelly.jowett@rothamsted.ac.uk or contact me on twitter: @kelly_jowett

Case Study: Pasture for Pollinators

Authors: Owain Rowlands ( Menter a Busnes ) & Anna Hobbs ( Bumblebee Conservation Trust )

 

Welsh dairy farmers and bumblebees don’t normally crop up in the same context but a group of organic dairy farmers in Wales, who market their products under the Calon Wen brand, are hoping to change things.

Six of the Calon Wen farmers have been growing multi-species Herbal leys, which include flowering herbs, legumes and grasses, for a three-year European Innovation Partnership (EIP) Wales project.

The project is aiming to show that some simple changes to grassland management can go hand in hand with boosting pollen and nectar resources for bumblebees and other pollinators.

Herbal ley plants in flower. © Anna Hobbs

In 2018, each of the farmers sowed a Herbal ley from Cotswold Seeds which includes bird’s-foot trefoil, clovers (red, white, sweet and alsike), sainfoin, and other species which can help to enhance pollinator populations.

During the silage season, the farmers have been leaving a 100m by 4m uncut (or ungrazed) strip along a field margin.  During first or second silage cuts, they are leaving one headland uncut; then at the next silage cut the previously uncut area is mowed and a different area of headland is left uncut. Late grazing of permanent grassland has also been explored by some of the farmers.

These grass management techniques aim to help provide bees and other pollinators with the continuous supply of flowers they require to forage on. By alternating headlands, they can also keep the whole field in good agricultural condition.

Uncut margin in herbal ley silage field © Anna Hobbs

Monitoring by Bumblebee Conservation Trust staff in 2018 and 2019 has shown higher numbers of bumblebees and other pollinators, and also greater numbers of pollinator species, in the uncut/ ungrazed margins compared to cut/ grazed field margins.

With one year of monitoring to go, the results indicate that this is a practical management technique for livestock farmers to help support bumblebee and other pollinator populations, especially in terms of ‘bridging gaps’ in nectar and pollen forage resources throughout the season.

In one survey in 2019 at Cop House Farm, Chester where David Edge milks 300 proCROSS cows producing an average of 7500 litres per cow, pollinator numbers rose from 12 in the cut part of the field to 189 in the uncut margin.

Common carder bee on clover. © Anna Hobbs

Anna Hobbs, the Bumblebee Conservation Trust Officer responsible for surveying the farms remarked “the results that we have collected so far are really encouraging.”

David Edge, Calon Wen farmers says “We’ve run this project as farmers which I hope will show others how bumblebee conservation can be practical and beneficial to the farm. I believe that more often than not, wildlife conservation can go hand in hand with productive farming.”

Pollination is one of the most critical services that nature provides, underpinning food production and biodiversity. Around a third of the global food crop and three-quarters of British wild plants are dependent on pollination. Compared to horticultural and arable systems, much less attention has been given to how grass-based livestock farming, such as dairying, can benefit pollinator populations.

Watch the Video. for a visual summary of the project.

Case Study: Providing food and shelter for invertebrates in Autumn

Author: Catherine Jones, Buglife

As the days continue to shorten, temperatures drop and the morning frosts start to appear, the value of autumnal vegetation for wildlife should not be underestimated.

In addition to creating the striking frost-bitten scenery in autumn and winter, allowing tussocky grass and wildflower seed heads to remain uncut through winter, in field margins, along tracks and roadside verges, and in gardens, will provide food and shelter for invertebrates and other wildlife.

© Gethin Davies

The remaining seed heads of the summer flushes of wildflowers such as willow herbs, thistles and even dandelions supply food for goldfinches, linnets and other seed eating birds and shelter for invertebrates. Ladybirds and earwigs may shelter in large wildflowers seed heads.

© Guy Sharrock

© Jodie Randall

Tall tussocky grass provides shelter for many overwintering invertebrates, and spiders construct their webs between long fronds that collect water droplets in the early morning mists. Grass tussocks may also hide ‘runs’ where mice and voles move from place to place protected by the dense vegetation above. Carder bee queens, emerging from hibernation, will search for nesting sites at the base of grass tussocks in spring.

Autumn is a great time to cut areas of long grass, including wildflowers meadows, and to remove the cuttings to help wildflowers to thrive the following year which in turn produce nectar and pollen to feed our valuable pollinators. But leaving leaving some patches of long tussocky grass and tall wildflower seed heads back then has now provided food and shelter in hardest months and nesting opportunities next spring.

© Gethin Davies

Additional information on managing farmland for pollinators is available from:

Bug Life: Helping Pollinators at Farm Scale

Bug Life: Helping Pollinators at Field Scale

Case Study: Managing Farmland for Grey Long-eared Bats

Author: Craig Dunton, Grey long-eared bat Project Officer, Bat Conservation Trust

Species: Grey Long-eared bat:

© Craig Dunton/www.bats.org.uk

 

Why is farmland important for this species?

With as few as 1000 individuals In the UK, the grey long-eared bat is one of our rarest mammals. Their distribution is restricted to the southern coast (Devon, Dorset, Somerset, Hampshire, Isle of Wight and Sussex) and there are only 9 known maternity colonies; meaning that this species is on the brink of extinction in this country. Currently, work is being carried out to conserve this species as part of 'Back from the Brink' – a Heritage Lottery funded conservation project aiming to save 20 species from extinction. https://naturebftb.co.uk/

Farmland is vitally important to all bat species. 70% of land in the UK is used for agriculture, so for very mobile species that utilise the whole landscape, farming practices can have significant impacts on bat populations. Some bat species are more resilient than others, but for those that have very low populations, are particularly sensitive to light and disturbance, and have very specific habitat requirements, there are significant threats to their survival.

Like all bats, the grey long-eared bat needs some key elements throughout its range in order to survive and thrive.

Roosts: Bats utilise a wide variety of structures to roost in, as their requirements change throughout the year. Roosts are needed for different activities – hibernation roosts, maternity roosts, night feeding roosts (for some bats) – these are all needed at different times of the year, and different bat species choose different structures for different activities.

Many bats hibernate underground, using caves, mines, cellars and tunnels that have a cool and constant temperature that bats need to hibernate. Many farms have these types of features, so it is important to be aware of their importance for bats. Some bats roost in a variety of different tree features; cracks, splits, woodpecker holes, loose bark – so it is important to retain trees that have ‘interesting’ features.

Grey long-eared bats are mostly associated with man-made roosts – usually the roof spaces of large, traditional, stone buildings with slate roofs. There are some records of them using caves and rock crevices, but no records of them using bat boxes in England.

Many buildings on farms can provide important roosts for grey long-eared bats, particularly large stone buildings with slate roofs and large, open roof voids. These can provide vital maternity roosts, temporary day and night roosts and opportunities for hibernation. As all bat species are protected, if you are planning to carry out any work that might impact bats or their roosts, the National Bat Helpline will point you in the right direction, please email enquiries@bats.org.uk

Foraging sites: As with roosts, different species of bats have different types of habitats that they favour for foraging. All UK bat species are insectivores, and depending on their size, flight habits and other physical adaptations, different species need different insect prey and therefore different habitats for foraging in. Greater horseshoe bats are large bats and so favour large prey, particularly around the maternity period. Cockchafers and dung beetles are their food of choice. Daubenton’s bats are often seen foraging over water, trawling insects from the surface of the water with their specially adapted, large hairy feet.

© Craig Dunton/www.bats.org.uk

Grey long-eared bats have a close association with unimproved lowland grassland and riparian (wet) habitats such as meadows and marshes.

Managing permanent pasture more extensively with very low or no inputs will benefit grey long-eared bat populations, offering more opportunities for invertebrates including the moths and craneflies that grey long-eared bats favour. Managing land to maintain or increase species diversity (more flowering plants) as well as structural diversity (a range in sward height), will give insects food and shelter resources. If possible, consider transitioning land back to hay meadow management as opposed to silage production, as this allows insects and plants to complete life cycles and thrive.

In terms of cultivated land, increase pollen and nectar plots and wildflower margins, and manage by cutting or grazing to maintain plant diversity. These areas alongside trees and tall hedgerows have proven benefits for some bat species. Minimise pesticide use and consider crops that contain lots of flowering plants such as herbal leys.  Within arable land, conservation headlands or low input cereals can be beneficial if management results in increased invertebrate numbers. These are all ways of increasing foraging opportunities on less productive areas of land for grey long-eared (and other) bats.

Farming organically has many advantages, including huge benefits to biodiversity, natural resource protection and reducing greenhouse gas emissions. Following organic principles should be considered if aiming to encourage bats and other biodiversity.

Connectivity: For so much of our wildlife, good habitat connectivity is critically important. Linear features in the landscape such as hedgerows, watercourses and ditches, enable different species to flow freely through the landscape, enabling opportunities for feeding, interacting and breeding. For bats, good connectivity is vital, as many bats use linear features to navigate through the landscape, using their echolocation to move from roosting sites to foraging sites. When these features are well managed, they can also provide foraging opportunities as well as providing obvious features to allow free movement. Extensive hedgerow management (2-3 year cutting cycle) allows hedgerow plants to flower and fruit, providing vital resources for insects. Buffer strips along streams and rivers not only provides increased opportunities for foraging, but can also protect watercourses from nutrient and pesticide run off, protecting aquatic flora and fauna.

For more information on land management for grey long-eared bats contact Craig Dunton (Grey long-eared bat project officer) on cdunton@bats.org.uk

 

 

 

Case Study: Adding Value to Chalk Grasslands: Creating Chalk Banks to benefit butterflies and other insects.

Author: Lynne Roberts . Farm: The RSPB’s Manor Farm, Newton Tony, Wiltshire

Aims and setting:

Manor Farm is a 296 ha working farm strategically placed between two of the largest tracts of semi-natural chalk grassland in the British Isles – Salisbury Plain and Porton Down. The RSPB purchased Manor farm in 2006 and have been reverting former arable land back to species-rich chalk grassland to create a landscape-scale stepping stone between these two areas.

Whilst this reversion has been very successful in establishing flower-rich grassland, even after several years the ex-arable fields still have unsuitable soil conditions for the plant species typical of very thin, nutrient-poor chalky soils. The fields are also rather flat as a result of historical cultivation, lacking the humps and hollows of natural grassland which help to create a variety of microclimates for a wider range of plants and insects.

For these reasons, in 2013 it was decided to create two large mostly south-facing banks to support viable populations of species characteristic of thin, chalky soils. Butterfly banks and scrapes can provide ideal conditions for butterflies, with sheltered sunny spots and bare ground for basking, alongside a mosaic of nectar-rich flowers for foraging adults and specific foodplants for growing caterpillars.

Funding for the creation of the banks was provided by the SITA Trust (now SUEZ) “Conservation of the small blue butterfly at RSPB Winterbourne Downs” project, and the Biffa Award “Saving a special place for Wiltshire’s endangered butterflies” project. Appropriate permissions for the work were also obtained.

Construction:

The site for the butterfly banks was flat terrain with a 20cm layer of flinty loam over chalk. Two large banks measuring 150m x 12m and 180m x 12m were constructed in two different fields. The loam topsoil was bulldozed into an S-shaped mound, oriented so that most of its length faced south. The mound was then covered with the chalk from the beneath the soil, leaving a wide 'scrape' area of bare chalk alongside.

The S-shape ensures that there are sides facing all possible directions, creating a variation in topography and diverse range of micro-climates. The idea is that this helps to increase the resilience of both plants and insects to the more extreme conditions predicted as a result of climate change. In the mornings, butterflies, bees and other warmth-loving insects can warm up on the east-facing side of the banks, which catches the early morning sun. During the main part of the day, they can use the warm, sunny, south-facing side. If it gets too hot on the south side, the insects can retreat to the north-facing side. As expected, during the middle part of the hottest July day on record in England in 2015, all the bee activity was on the banks’ north-facing slopes.

Construction begins

The first bank was initially seeded with a generic chalk grassland and wildflower mix as well as kidney vetch and horseshoe vetch, which are vital food plants for small blue, chalkhill blue and Adonis blue butterflies. On the second bank, only the kidney vetch and horseshoe vetch were introduced. The banks could have been left to regenerate naturally, but the butterfly foodplants were not growing in the vicinity and therefore seeding with specific species was preferred to ensure that the right plants established.

Development over time and ongoing management

The vetches were the first plants to establish and were flowering in the first summer after autumn sowing. Over the following two years other species, such as small scabious, ribwort plantain, harebell and quaking grass appeared, the coverage developing into a patchwork of abundant flowering species interspersed with bare areas - the ideal structure for butterfly habitat.

Vetches establish quickly on the bare chalk

The vegetation on the banks has become denser over time but has required little ongoing management as the tough conditions prevent many unwanted species from colonising. Sheep are our management tools, grazing from August onwards, when most flowering is over. This helps us to keep on top of any scrub encroachment and keeps the sward open, with some disturbance of the ground surface to create germination opportunities. Cattle would probably cause damage to the banks, so are avoided.

Where necessary, brush cutting is carried out in the summer and the arisings removed and taken to other areas of the farm which are species-poor and could benefit from wildflower sowing.

Brush cutting the coarser vegetation

Achievements:

Colonisation of the banks by breeding small blue butterflies was impressively quick - within the first three years, as the kidney vetch established readily. The abundance of suitable foodplants is particularly important for sustaining viable populations of butterflies, so the fact that small blues were seen on the banks in August, probably a second brood from eggs laid in June, was a good indication that suitable habitat for breeding had been achieved.

Small blue on its larval foodplant, kidney vetch

Other chalk grassland butterflies have also been recorded on the banks in the last few years: common blue, brown argus, marbled white, dark green fritillary and, excitingly, the marsh fritillary, a species in severe decline which has been attracted to Manor Farm by the abundance of scabious plants in the grassland. Good numbers of these species are now being seen on the farm as they are moving in from the neighbouring strongholds on Salisbury Plain and Porton Down. We have yet to record chalkhill blue, but the Adonis blue was a new record in 2018, so hopefully it will just be a matter of time before the chalkhills arrive.

The diversity of flora species continues to develop, with some of the less common chalk specialists such as devil’s-bit scabious, starting to appear on the banks.

In addition, we have shown that the fields containing the banks can still be used as grazing land, albeit in a carefully managed way.

Our experience and lessons learned:

Five years on we found that some plants had been harder to establish on the banks than others. The pioneer species kidney vetch and horseshoe vetch, two of our key butterfly food plants, established readily from seed and plug plants were not required. However, we didn’t have the same success with common rock rose, the food plant of the brown argus and cistus forester moth. This was easier to establish from plugs, although the sown seed may germinate eventually when conditions are favourable and the seed coat has weathered a little. Plugs are more expensive, so a pragmatic approach may be to try sowing seed first and then supplementing with a few plugs after a couple of years if the seed has not germinated. Germination rates of common rock rose can be improved by scratching the seed surface (scarifying) prior to sowing.

Where we sowed the generic mix, some of the taller plants have become dominant, greater knapweed particularly, shading out some of the foodplants, such as horseshoe vetch. We have therefore had to manage some of the less desirable species in order to help the key plants thrive.  This was not such issue on the second bank, where we had just sown the foodplants, with just the odd thistle to deal with.

We suspect that by creating the base of the banks from the flinty loam topsoil, the longer rooted chalk grassland species may be accessing nutrients from this base and gaining an advantage. Ideally, the bank would be created from pure chalk and the removed soil utilised elsewhere. A chalk-only bank would create the harsher alkaline conditions which favour the more extreme chalk specialists, including the kidney vetch and horseshoe vetch, and would slow the rate of encroachment by scrub species.

Although our butterfly banks are very large it is important to note that banks of any size can make a big difference to the survival of butterfly populations - even just moving soil around to create variation in the topography of reverted arable fields or pasture can help. Butterflies exist in small populations which are linked to create larger ‘metapopulations’, so even quite small areas of suitable habitat could provide a vital link in the chain.

All photos supplied by Patrick Cashman.   
For more information, contact: patrick.cashman@rspb.org.uk

Further examples of butterfly banks

Organisations such as Butterfly Conservation and Buglife have been constructing butterfly banks on several sites, both rural and urban, as a way of creating breeding habitat suitable for a number of different butterfly species. For further information see the following links:

Butterfly Conservation Fact Sheets

Case Study: Bare Ground for butterflies and moths