#20 Yellow Rattle by Kelly Harmar
Meet Kelly Harmar, Biodiversity Officer at Nidderdale AONB!
Nidderdale AONB (Area of Outstanding Natural Beauty) stretches from the high moorland of Great Whernside south and east across farmland, reservoirs and woodlands towards the edge of the Vale of York. Kelly helps manage nature conservation projects and also looks after the species, habitat and environmental data collected by the AONB and its volunteers each year. Kelly runs a meadow restoration project each summer, helping to restore and enhance wildflower rich hay meadow habitat. You can contact Kelly at kelly.harmar@harrogate.gov.uk and you can keep up to date with Nidderdale AONB on their website or follow them on twitter at @NidderdaleAONB.
Yellow Rattle
Kelly’s chosen species is Yellow Rattle Rhinanthus minor. A cheerful yellow flower with dark green toothed leaves, it is common in traditional species-rich hay meadows and produces large round seed pods with flat kidney shaped seeds that ‘rattle’ in their pods as they ripen and dry out. It is an annual plant that needs to set seed and produce new plants each year. Yellow Rattle is a hemi-parasite, meaning that it relies partially on the roots of other plants for water and food. You can find out more about this species on the NBN Atlas.
Species rich hay meadow habitat has declined by 97% in the UK over the last 100 years, with remnant meadows, and meadow species, now largely confined to scattered areas in the uplands. Where the habitat and management are suitable, Yellow Rattle will grow in profusion, dominating areas of the meadow, so it is still considered a common species and is not protected. It is also not very choosy in terms of soil type and will grow in both heavy clay acid soils and on thin limestone soils.
Thankfully, the coverage of species rich meadows, and the distribution of Yellow Rattle in North Yorkshire, has gradually increased over the last 10-20 years as meadows have been restored. Yellow Rattle is a key species for meadow restoration. It often partners with grasses and this parasitic relationship can be effectively utilised to suppress the height, density and vigour of competitive grasses, allowing other wildflowers to get a foothold and establish in a meadow. Yellow Rattle is a great example of a conservation tool – an ecosystem engineer that can alter its habitat and act as a gateway for other species. It’s also an early indicator of progress, flowering the first year after restoration, unlike other species. If there’s lots of Yellow Rattle in the first year, it’s a good sign that a restoration will be successful. It is also an excellent plant for solitary bees, bumblebees, and hoverflies, so restoration can benefit wider species even in the first year.
“Yellow Rattle is a great example of a conservation tool – an ecosystem engineer that can alter its habitat and act as a gateway for other species”
Large amounts of yellow rattle amongst other meadow species.
In Nidderdale AONB, Yellow Rattle seed for restoration is sourced from local ‘donor’ meadows. The meadow restoration project has been running for ten years. Donor seed is collected using a brush harvester, a large hoover that runs across the top of the hay crop and brushes seed into a collector. Using local donor seed ensures that plants are well adjusted to local conditions and ensures that we retain local genetic diversity, including local subspecies of Yellow Rattle. As Yellow Rattle seed is ready to collect in early July and meadows are generally cut from mid-July it can be a race against time to collect seed! So that donor fields aren’t depleted, only one third of each meadow is harvested and only once every three years.
Yellow Rattle is a big part of Kelly’s working life as she spends each summer searching for, recording and harvesting it. For small projects, she will collect seed by hand and dry this in the office or at home, turning the seed several times a day and separating the seed from the seed pods. After a walk through a summer meadow she often finds the distinctive seeds in boots, socks and the turn ups of her trousers!
The dry seed heads of Yellow Rattle.
Even in the uplands, species rich hay meadows remain vulnerable habitats and, as Yellow Rattle is an annual plant, even temporary changes in management could mean that it is easily lost - plants will not seed if meadows are grazed too late in the year or cut too early. The same properties of Yellow Rattle which suppress grasses and help with meadow restoration also means lower yields for farmers. Farmers within agri-environment schemes are compensated for losses in yield in restored meadows, but Kelly worries that with recent reductions in the coverage of agri-environment schemes, it may be that some restored fields are again lost and the distribution of Yellow Rattle will contract.
Monitoring
Nidderdale AONB have a wonderful group of dedicated botany volunteers who undertake meadow surveys in June and July each year. Surveys are undertaken in wildflower rich ‘donor’ meadows to make sure there is enough Yellow Rattle to harvest and to pick up on any negative changes to the donor meadow so that it can be rested from harvesting if needed. Species poor ‘receptor’ meadows are also surveyed before any seed is added so that we can establish a baseline for monitoring: allowing us to track improvements in species composition and abundance over time.
Monitoring of Yellow Rattle populations can be complicated by the parasitic nature of the plant as it can go through boom and bust cycles, depending on the availability and vigour of its host plants, meaning numbers can vary in the same field over time, even though management stays the same.
Further information and acknowledgements
NEYEDC would like to thank Kelly for her time and expertise in helping to create this blog.