GNHS

Machair Conservation: Successes and Challenges

Posters

• Cathy Fiedler: Factors affecting population density of the Northern mining bee, Colletes floralis on Islay
  
• R. Gulliver, M. Gulliver, C. Sydes & D. Long: The use of exclosures to produce a favourable grazing regime for the orchid, Spiranthes romanzoffiana, on the dune/hill intergrade - part of the machair complex, on Colonsay, Inner Hebrides, Scotland
  
• Louisa Hancock: Habitat management survey for conservation of the great yellow bumblebee (Bombus distinguendus) in the Outer Hebrides
  
• Anne MacLellan: Western Isles Local Biodiversity Action Plan − Machair Posters
  
• Lynne Osgathorpe: Croft economics, land management and bumblebee abundance
  
• David Palmar: Birds of the Machair - some photographs
  
• Maria Scholten, Bill Spoor and Niall Green: Machair corn: diversity and conservation of an historical machair component
  
• Edna Stewart, Morag Mackinnon, Richard Weddle & Lyn Dunachie: collecting wild flower seeds on the Uists for propagation
  
• Maja Kristine Thorsen, Stephen Woodward, David W Hopkins & Blair M McKenzie: Resilience of machair soil to amendment with kelp and synthetic fertilizer
  
• Stefanie Vink, Roy Neilson, David Robinson & Tim Daniell: Above and below ground responses to the Machair agricultural system
  
• Lorna Wilkie: Foraging preferences of the great yellow bumblebee Bombus distinguendus on Orkney
  

Abstracts

• Cathy Fiedler: Factors affecting population density of the Northern mining bee, Colletes floralis on Islay, Hebrides, with implications for habitat management and species conservation.
  
Populations of Colletes floralis (RDB3) are limited by the availability of suitable forage and nesting resources. By determining what constitutes a suitable resource, it provides the opportunity to develop habitat management strategies to help safeguard the species.
Vegetation surveys and analysis of pollen loads were used to investigate foraging behaviour. Optimal nesting habitat was investigated through study of burrow density in relation to topography and vegetative cover.
• R. Gulliver, M. Gulliver, C. Sydes & D. Long: The use of exclosures to produce a favourable grazing regime for the orchid, Spiranthes romanzoffiana, on the dune/hill intergrade - part of the machair complex, on Colonsay, Inner Hebrides, Scotland
  
9 plants of Spiranthes romanzoffiana were discovered in bloom in 1997 at one site - KA - at the back of dunes on Colonsay; and 24 at a second site - KB - in 1999, single visit data. At each site numbers in bloom have been monitored in each subsequent year. This includes the number at positions where flowering plants have never previously been recorded (2000 onwards).
Exclosures were erected to provide a Summer Grazing Break (SGB) in 2001.
The capsules of Spiranthes romanzoffiana do not develop as they do in S. spiralis, nevertheless the withered structures are now known to contain small numbers of seed. The grazing break allows seed development and hence the chance of population maintenance via sexual reproduction.
The number of plants in bloom has varied greatly from year to year. In 2008 numbers were the lowest ever recorded since 1998 in KA and were zero in KB. Possible causative factors, which may be acting in combination, are discussed.
Stock movement through and into the exclosures is facilitated by the two gates. S. romanzoffiana often occurs in disturbed habitats. One challenge at KA and KB is to ensure adequate levels of sward disturbance and heavy winter grazing following a recently altered grazing regime for the whole dunes.
At other sites in Scotland it may be possible to negotiate SGBs by management agreements rather than exclosures. Although some new sites are found in most years, these tend to contain 1 or 2 plants. The general trend in Scotland appears downwards.
Several aspects of the biology of the species and its interactions with a) competitors and b) habitat structure, are still unknown. A full understanding of the behaviour of the species above and below ground requires detailed research. Attempts to secure relevant funding are ongoing.
• Louisa Hancock: Habitat management survey for conservation of the great yellow bumblebee (Bombus distinguendus) in the Outer Hebrides
  
Two investigations were carried out in the Outer Hebrides during September 2005. Firstly, the management practices of crofters on machair were established where the great yellow bumblebee is known to occur. Secondly, an assessment of the areas set aside for the benefit of corncrakes as suitable for the bees. The management regime used by crofters on machair was established in areas of South Uist where research into great yellow bumblebees was in progress. It was not possible to contact all landowners, but evidence gathered suggests that the same procedures are generally followed:
• Seaweed and occasionally manure is used as a fertiliser
• A rotation system is in place of a year each of crops and fallow
• Natural regeneration is preferred to seed use
• Machair is cut for silage and/or grazed over winter
Areas set aside for corncrake conservation were assessed for great yellow bumblebee suitability based on a series of habitat attributes including floral diversity, availability of nesting habitat and size of area. This gave each site a ‘score’ determining its suitability for bees. This could then be used to focus conservation efforts. The results show that no sites achieved the highest possible ‘score’. This does not mean that the bees do not use these sites, but it does give a number of options for conservation efforts:
• Improving the ‘best’ sites to encourage bee use
• Focusing on ‘medium scoring’ sites which would be relatively easy to improve
• Concentrating on low scoring sites to give a wider range of sites suitable in some way
An alternative strategy could be to focus on sites which are not managed for corncrakes so there is no direct conservation conflict and the site developed principally for conserving the great yellow bumblebee.
• Anne McLellan: Western Isles Local Biodiversity Action Plan − Machair Posters
  
The 3 machair posters are part of a bilingual (English & Gaelic) Crofting & Biodiversity Exhibition produced by the Western Isles Local Biodiversity Action Plan Partnership in May 2008. The posters highlight the key role of crofters in maintaining machair biodiversity through traditional practices. These include seasonal or rotational grazing by livestock, rotational cropping that allow some years of fallow and the growing of both cereals and hay using natural fertilizers, seaweed and farmyard manure. The use of these natural fertilisers adds bulk, improves fragile soils and increases productivity.
Rotational or seasonal grazing − the removal of livestock for the summer or rotation of one half of the machair to another for a number of years − is advantageous to stock and to wildlife. Keeping cattle and sheep at appropriate stocking levels gives a variety of plants the opportunity to flower and form seed, which is beneficial to both insects and birds.
The cereal crop in the western Isles is grown in various mixtures of small oat, rye and bere barley. These mixtures are useful in the rigorous conditions of the Hebridean summer where experience tells that they will give the best crop possible in any given year. The total cereal crop in the western Isles is a tiny percentage of the Scottish crop, but it is hugely important, as winter-feed for cattle, in the way it supports biodiversity and in its survival as a genetic resource.
Small rotational plots of hay, corn and potatoes provide a variety of habitats which in turn support a greater range of plants, birds, insects including bumblebees. Reserving a portion of the crop for stooking also maintains numbers of small birds such as corn buntings that benefit from the associated spillage of seed. Many of these same birds have a beneficial impact in summer when feeding their young on insects and other invertebrates gathered from crops.
• Lynne Osgathorpe: Croft economics, land management and bumblebee abundance
  
The great yellow bumblebee (Bombus distinguendus) has undergone dramatic declines (>95%) in its range and distribution throughout the UK in the past 50 years and is now only found in the Western Isles, Orkney and along the north coast of Scotland. The species is strongly associated with herb-rich machair habitats, which are maintained by the traditional Scottish agricultural system of crofting.
However, traditional crofting methods are disappearing as they are become increasingly economically unviable. The resulting increase in the use of intensive management operations or the complete abandonment of land has serious implications for the existence of the great yellow bumblebee in crofted areas.
For B. distinguendus conservation to be effective in this region an understanding of the relationship between croft economics, land management and bumblebee abundance is essential. It is anticipated that using models to examine the socio-economic factors currently influencing crofter behaviour, and including ecological data, croft production decisions and their potential impacts on bumblebees could be predicted, and the outputs used to make informed decisions about the future of crofting and the conservation of B. distinguendus.
• David Palmar: Birds of the Machair - some photographs
  Machair provides a suitable bird breeding habitat with its diversity of plant species.
  Important populations of ground nesting birds breed on the Uist machair, over 17000 pairs in 1983, including large numbers of waders, but are now declining. The main wader breeding species are Lapwing, Dunlin, Ringed plover, Redshank, Oyster catcher and Snipe. Large declines in numbers of these species had occurred by 2000, overall a 22% decrease.
  In South Uist and Benbecula, hedgehogs, introduced in 1974, are a threat to wader eggs. In areas with hedgehogs, a 39% decrease in wader populations has occurred between 1983 and 2000. Many wader breeding sites are protected by conservation measures.
  In addition to the waders, important populations of Corncrake breed on or near the machair, and there are large wintering populations of Barnacle geese, Turnstone and Purple sandpiper.
• Maria Scholten, Bill Spoor and Niall Green: Machair corn: diversity and conservation of an historical machair component
  
The contribution of local cereal cultivation to machair wildlife is well-researched and well-documented. However, about the ‘corn’ species and specific local varieties less is known. This poster aims to provide information on the three species and their conservation.
The most frequent, ‘small oat’ is a rare historical crop and a different botanical species (Avena strigosa) from the common ‘white’ or mainland oat (A. sativa). All three machair cereal species, A. strigosa, bere (Hordeum vulgare) and rye (Secale cereale) are locally produced. Bere and small oat are not in commerce and the islands have to be self-reliant for seed.
Local varieties that have been locally produced over generations are known as landraces. They are very rare and rapidly disappearing forms of agricultural diversity. The few surviving Scottish landraces tend to fall out of mainstream agricultural research and, being cultivated plants, also outside the remit of biodiversity conservation. However, international conservation treaties such as CBD and IT summon national governments to conserve landraces both in situ and ex situ. The Scottish Government therefore has a nominal commitment to conserve Scottish landraces.
Recently a step in this direction has been taken by the creation of a Working Group within the Scottish Biodiversity Forum Rural Land Use Working Group (RLUWG). Also, a start has been made with an ex situ collection of these local varieties that aims to form a safety back-up for local growers. This collection is based at SASA, Edinburgh.
Aspects of local varieties diversity and conservation will be explained in the poster. Also, the role of conservation organisations and institutions, active in machair conservation, in the conservation of local agricultural varieties and their diversity will be discussed.
• Edna Stewart, Morag Mackinnon, Richard Weddle & Lyn Dunachie: collecting wild flower seeds on the Uists for propagation
  
Three volunteers from Glasgow Natural History Society visited the Uists for a week in September 2005 to collect seeds from plants known to be used by the Great Yellow Bumblebee over the months when it is active. Six sites were visited and a useful amount of seed (just under 1kg) was collected for many of the species; some of this stock has since been used for reseeding in the Balranald area.
The conclusions of this feasibility study were that seed collecting is labour-intensive and would need be done over a longer period during the year in order to cover the full range of species adequately. The yield of seed was low relative to amount of seed-heads collected, because some of the seed had already been lost through natural dispersion or consumption by invertebrates etc.
Propagating seed for inclusion in seed mixes, though a useful aim, was not achievable in the timescale of this project, though it remains a medium-term objective. The most effective procedure would be to harvest seeds mechanically from successful ‘cover areas’ areas on each island, and to use the cleaned seed for reseeding those, and other, areas in the same locality.
In the meantime, bumblebee habitat areas will be created or improved using existing wildflower seed-mixes and allowing natural reseeding from nearby areas.
• Maja Kristine Thorsen, Stephen Woodward, David W Hopkins & Blair M McKenzie: Resilience of machair soil to amendment with kelp and synthetic fertilizer
  
During the previous decade, deeper ploughing and partial substitution of kelp by inorganic NPK fertilizer has occurred in response to socio-economic pressures on machair crofts. The effects of these agronomic changes on the machair, are not known. This study reports on processes important in stabilizing machair soil, and what effects decreased kelp spreading may have on soil stability. Ongoing work focuses on how kelp affects soil stability by dynamic association with soil microorganisms. We are testing these associations in field and microcosm experiments. The degradation of kelp is being studied using isotope analysis; C and N dynamics assessed as changes in soil microbial composition and activity, and linking both to soil aggregation.
• Stefanie Vink, Roy Neilson, David Robinson & Tim Daniell: Above and below ground responses to the Machair agricultural system
  
Intensification of traditional low input agricultural systems has contributed to the loss of diversity both above and below ground. Organic and low input agricultural systems, such as the machair, are reported to have higher diversity of micro-organisms than intensely managed farms, potentially making such systems more sustainable and resilient to disturbance.
Arbuscular mycorrhizal (AM) fungi and eubacteria, two key components of soils, are important determinants of the ecosystem processes which drive above ground community composition. While there have been many studies conducted on machair vegetation there has been little study of the biotic communities in the machair soils, despite the potential importance of these below ground components.
A study examining variation in the bacterial and mycorrhizal community structure of machair soil and vegetation was conducted in 2007. Individual cores containing soil and roots of each of two plant species were taken at three different times, at ten different locations and with three different land uses. DNA was extracted from the roots and from bulk and root zone soil from each core. Ribosomal gene targets were amplified by PCR and the community structure of eubacterial and AM fungi was assessed with Terminal Restriction Fragment Length Polymorphism (T-RFLP). In addition, a survey of the plant communities was carried out at the summer sampling point and various abiotic soil factors were measured.
Principal component analysis of the T-RFLP patterns shows that the microbial community reflects the variation in land use on the machair. There are significant temporal (P<0.001), land use (P<0.001) and soil compartment (P<0.001) influences with a number of interactive effects. Results also suggest a link between the above ground vegetation, below ground bacterial community and moisture content of the soil within the different land uses and soil compartments.
Preliminary results of the AM fungi community structure analysis show significant host species (P<0.001), temporal (P<0.01), location (P<0.01) and land use (P<0.05) effects.
• Lorna Wilkie: Foraging preferences of the great yellow bumblebee Bombus distinguendus on Orkney
  
The great yellow bumblebee has become scarcer and more limited in its distribution in the last century, and in the UK is found only in the Western Isles, Coll, Tiree, Orkney and on the north coast of mainland Scotland (International Bee Research Association, 1980). In summer 2006 a study was undertaken on RSPB reserves in Orkney to explore the foraging preferences of this species. The data collected were compared to historical bee records and to studies carried out in the Western Isles.
Analysis of pollen taken from foraging bees showed that bees from two sites foraged on Trifolium sp. and Phacelia tanacetifolia. However statistical analysis suggested that the presence of these plants at a site does not increase the likelihood of bee presence. Historical records from throughout Orkney suggest great yellow bumblebees use a wide range of plant species, with preference depending on geographic location.
There were differences between the suite of forage plants used in the Western Isles and on Orkney. On Orkney great yellow bumblebees form colonies relatively late, in June or July, and forage plants such as Stachys sp. and Centaurea nigra are needed until late-September. Forage species used in the Western Isles, such as Lotus corniculatus, may flower too early on Orkney for bees to utilise.
Two nests were found at Marwick Head. A full list of flowering plants within a 250m radius of the first nest was compiled to identify where the bees were foraging. Pollen samples taken from the bees comprised mainly of Trifolium sp., however no clover patches were found within 250m of the nest, and no marked bees were observed in adjacent patches. This suggests that great yellow bumblebees may not establish their nests in areas where food is immediately available, and that they travel more than 250m from the nest to forage.