We are nearly halfway through the UN decade on ecosystem restoration which aims to halt the degradation of the world’s ecosystems and reverse their decline. Across the world, projects are ongoing to help nourish exploited land and life back to health – whether that be through tree-planting, peatland bog rehabilitation or the reintroduction of keystone species that will do the restoration for us.
Image 1: UN Decade on Ecosystem Restoration logo
Humans must be mindful to not repeat mistakes of the past by ensuring restoration is achieved with good scientific backing and knowledge of the land – something that can be achieved by working scientists, conservation professionals and local/indigenous communities.
We will not accomplish restoration by planting the wrong trees in the wrong places or by indeed just planting plants alone – much in the same way we couldn’t restore a classic car by replacing only the chassis. We must think about restoring ecosystems wholly – ensuring that the components necessary for resilient and functional ecosystem are present. This means we need to understand keystone species – those species that are integral to the functioning of an ecosystem – and ensure their inclusion in restoration efforts.
The wolves of Yellowstone National Park (USA) are a well-known example of how effective keystone species can be in restoring landscapes. The reintroduction of this predator was so influential on the landscape, that in just the first 15 years, they reduced grazing by elk on aspen trees from 100% to less than 25%. This in turn had a positive impact on beaver and bison populations with the increased availability of food and reduced competition; in short, balance was restored (Ripple and Beschta, 2012). It is not only top predators, however, that are crucial for a healthy landscape.
There are smaller, but equally crucial actors. The most obvious example is bees, who alongside other insects, pollinate plants and facilitate their reproduction. Ants are another highly influential group often playing a role not only as a keystone species but also as an ecosystem engineer – organisms which are responsible for structural or biochemical engineering within an ecosystem. In the case of Yellow meadow ants (Lasius flavus), the ants create physical mounds within grassland ecosystems which also have properties that differ from the surrounding landscape. Their mounds have warmer soils because of ant activity and increased access to sunlight (by virtue of their height). The nitrogen and phosphorous soil concentrations in mounds also differ to the surrounding soil and mounds have more bare soil, as examples (Ehrle et al., 2021; Bierbaß et al., 2016; Holec and Frouz, 2006). The ants create these small islands of difference within the meadow which plant and animal species then exploit. The Green woodpecker, Chough, Burnet moth, Common blue butterfly and many other species have been observed benefiting from their mounds - to feed from or to lay eggs on, for example.
Image 2: Yellow meadow ant (Lasius flavus) tending to aphid colony (c) Andy Murray (Wikimedia commons)
As a biome, temperate grasslands have experienced the greatest exploitation, whilst being afforded the least protection, globally (Wills and Landis, 2018). In Europe alone, we have witnessed the rapid loss of 90% of semi-natural grasslands and this large scale loss is echoed across landscapes around the world. Grasslands are important for fighting climate change, being more efficient and reliable in carbon storage than forests (Dass et al. 2018). They are also important for wildlife and the loss of this habitat has significantly affected groups such as pollinators. There is an urgency to to protect and restore grassland habitats because they can help to build our climate and biodiversity resilience in the face of multiple crises.
This brings us to RSPB Loch Leven near Kinross in Scotland and Lochore Meadows. At RSPB Loch Leven is the Bumblebee meadow, a piece of former agricultural land that has been converted into a species-rich grassland for pollinators. Lochore meadows, managed by Fife Council and Fife Coast and Countryside Trust, has within its mosaic of habitats, some of the most ancient grassland in the region of Fife and a very healthy and abundant population of Yellow meadow ants.
Image 3: The Bumblebee Meadow at RSPB Loch Leven
I am currently undertaking PhD research at these two sites to answer the following:
1. Do Yellow meadow ant (Lasius flavus) mounds provide important resources for pollinators?
2. How do Yellow meadow ants affect the restoration of grasslands undergoing restoration?
To answer the first, I have been roaming around the meadows of the National Trust Belton House Estate and Lochore Meadows in my native Fife (Scotland). Over the spring and summer of 2024, I spent many days (in quite astonishingly variable weather conditions) counting flowers, taking temperatures and watching mounds (for a total of 27 hours). At this juncture I’d like to add a quick note to thank undergraduate student Elena Marco Pardo, my best friend Steven McGee-Callendar and my incredibly patient partner Alexandra Koulouris for donating their time to helping with this endeavour. I am now examining this data and early signs point to a promising pattern of increased flora, temperature and bare ground availability on mounds compared to normal grassland – however, now the serious part begins, the analysis to reveal the truth.
To answer the second question, we had to get experimental. We needed to identify a grassland which was undergoing restoration and that did not yet have Yellow meadow ants present so that we could introduce the species and observe its impact on the grassland. My good friend James Silvey told me about the bumblebee meadow at RSPB Loch Leven and indicated that it might be a good candidate for translocation. Whilst Yellow meadow ants are a widespread and common species, they are not found nesting on land that has been ploughed because of the destructive nature of the practice. The bumblebee meadow used to be agricultural land, and it is likely that it was ploughed in the past. Before translocation, surveying was undertaken to identify which ant species were already present at the site. We didn’t detect the presence of any ant species, and all the mounds we found were mole hills – giving us the first green light we needed.
Then began the green light marathon, seeking approval from RSPB, Fife Council, Fife Coast and Countryside Trust, Historic Scotland, the local farmer and the University of York ethics committee….phew! Once everyone was suitably on board, and volunteers were located (thank you very much RSPB Scotland, Fife Coast and Countryside Trust and a local youth employability group), it was time to go.
In March of 2024, nice and early in the season before the ants are too active and after the ground has thawed, we dug up and moved eight yellow meadow ant mounds from Lochore Meadows to the bumblebee meadow at RSPB Loch Leven.
Image 4: Ant mounds were loaded into a trailer for transport to their new home.
Because these ant nests existed in ancient grassland, they were a lot larger and more extensive than we previously realised, with many intricate and beautifully carved out tunnels being found within. We did our best to limit the damage to the mounds but also to ensure the entirety of the colony was translocated – including the all-important egg-laying queen who gives purpose and life to the colony.
We also moved big chunks of ant-free turf to the bumblebee meadow, making fake ant mounds, so that in two years’ time – we can understand – are the ants making the change or is it just the introduction of something new?
Image 5: Ant mound before removal (top left), ground after removal (TR), volunteer team (BL), mound at new site (BR)
During the gloriously rainy summer of 2024, I visited the translocated mounds in their new home. With ecstasy and relief, we discovered that not only were all the colonies active, they were so healthy that they were churning out the next generation of flying ants (who will go on to reproduce and form new colonies). This is a brilliant sign that not only the colonies are surviving, but also thriving – a testament to the resilience of ants considering the turmoil they went through.
Yellow meadow ant colonies have been successfully translocated before (King and Balfour, 2019; Box, 1987; Pontin, 1969), but the consequences of this translocation, particularly on the restoration process, has not yet been investigated. We are thrilled to have the opportunity to take a closer look at the role that ants play and perhaps illuminate whether their inclusion in grassland restoration initiatives is key.
In 2025 and 2026, we will return to examine if and how the plant and pollinator communities have changed. We will also take soil samples to investigate how bacterial and fungal life have changed in the hopes of better understanding how ants impact the restoration of soil health.
Can ecological surgery of ant mounds help to restore grassland habitats? We wait in ant-icipation.
This project is a partnership between the University of York, UKCEH, RSPB Scotland, Fife Coast and Countryside Trust and the National Trust. It is funded by the John Lewis Partnership Foundation.
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