Aspen Bristle-moss was once thought extinct, and although it was rediscovered at a few sites in Scotland in the early 2000s, it is still very rare.

So when a tree that was holding the largest population of Aspen Bristle-moss in the country fell, it meant that soon a huge portion of this incredible species would be lost.

Our conservation team in the Cairngorms, led by Senior Ecological Advisor Sam Jones, jumped into action and started exploring how they could help save it.

This led to what is believed to be the first-ever documented translocation, where a species is taken from it’s home and moved to a new safe habitat, of an epiphytic moss, which is a moss that grows on a living plant such as a tree, without harming it.

Without intervention, the moss on this tree would die as the bark started to decompose and other species moved in to outcompete it. This meant it was a race against time to save the Aspen Bristle-moss that was on the tree – but it also gave the perfect opportunity to explore whether this technique could be used to help increase the population of the whole species.

We have teamed up with partners including the RSPB to build a brand new plant nursery in the Cairngorms in the hope of saving a rare and iconic little plant, Twinflower Linnaea borealis.

Once found all over the Highlands, Twinflower is now considered ‘Vulnerable’ on the IUCN Red List.

In fact it is thought there are fewer than 800 individual plants left in the UK, with most clinging on to fragmented patches of Scots Pinewood in the Cairngorms.

Sadly, clearance of these native woodlands, in particular in the early 1900s, resulted in severe losses of the species. And continued habitat loss and changes in woodland management have left the remaining Twinflower patches isolated and declining. 

In 2003 Aspen Bristle-moss, which was thought to be extinct in the UK, was rediscovered by a chance finding. Now, thanks to a team effort – moss experts, landowners and volunteers discovered 3 times the amount of Aspen Bristle-moss at one site. This brilliant find led to the known population of this rare moss doubling in Scotland in a single afternoon.

This amazing feat was thanks to a training session organised by our Resilience and Recovery, Helping Rare Species Adapt to a Changing World Project Manager, Sam Jones, where volunteers were taught how to ID this marvellous moss. 

The elusive epiphyte (a plant which grows on the surface of another plant) is particularly tricky to identify, with tiny features that distinguish it from the other mosses that can be found growing alongside it. 

This event, helping uncover hidden populations of Aspen Bristle-moss gives hope for it’s future.  

Read on below as Sam explains more about the day and this special species. 

Learning How to ID the Rare Aspen Bristle-moss

On 6 November last year, we had our first day looking at Aspen Bristle-moss in Deeside. A total of 12 of us — moss experts, local land managers, and keen volunteers — spent around 4 hours staring very closes through hand lenses at Aspen bark.

Our experts taught us exactly which tiny features to use to distinguish these mosses from all the others we might see on Aspen bark. We learned about the importance of wetting the mosses before trying to identify them.

Then we walked all over the site which is a very rare dense exclusively Aspen woodland covering around 5 hectares. About 20 of these trees were known to support Aspen Bristle Moss, nearly half of the total known UK population. On our sweep we increased the population on site to 49, nearly doubling the total known population in 1 afternoon alone.

How are we Protecting this Rare Moss?

It seemed a logical choice to focus on such an understudied local specialist species. While working to protect this moss, we are also hunting for and protecting other rare Aspen epiphytes, such as Blunt-leaved Bristle-moss Nyholmiella obtusifolia, Showy Bristle-moss Lewinskya speciosa, and Bark Sulphur Fire-dot Lichen Caloplaca flavorubescens.

We are early in our journey towards protecting these species. Alongside preserving and enhancing Aspen woodland, work led by the Cairngorms National Park and Trees for Life, we are focused on learning the status of these species, and what we can do to protect them.

The first step for Aspen Bristle-moss (and all these under-studied epiphytes) is to update our records.

In 2000 it was thought to be extinct in the UK but has since been rediscovered at 3 sites. It takes quite the specialism to record it, and so there is a good chance some populations remain undiscovered. So, our first objective is to re-survey the 3 known populations, and to get people out and looking for it across Aspen woods more widely.

What’s Next for Aspen Bristle-moss?

This year we’ll be surveying the other 2 populations, getting more people trained up to look for and appreciate these rare species, and developing a better idea for how it is doing. We’ll also be encouraging trained volunteers to check Aspen trees whenever they can, as it is very possible many sites remain undiscovered.

As our understanding of these species expands, we may start to look at what can be done to protect these tiny remnant populations. Obviously, we must continue to promote and protect Aspen woodlands. We also may look into transplanting mosses between trees or assisting their colonisation into new sites.

We will have to see what develops as we work to protect and promote these often-overlooked tiny green gems.

I’ve been spending a lot of time reading what little information there is on One-flowered Wintergreen, Moneses uniflora, doing site visits, and chatting with other experts. I’ve been trying to figure out what has caused its sharp decline in abundance and distribution globally, and how we can help prevent it here in Scotland.  

The uncomfortable answer I’ve come to is that we still don’t really know all that well. Around 10% of the Scottish population is in the Cairngorms, the rest distributed sparsely across the Highlands. In the last 50 years, I estimate that we’ve lost half of our populations, and of those remaining, only a few are stable or improving. We may soon lose all One-flowered Wintergreen in the UK without intervention. 

Saving One-flowered Wintergreen

Thousands of years ago, before significant human alteration to the landscape of Britain, perhaps One-flowered Wintergreen existed in a particular niche. It may have relied on the bare ground made by a wild boar digging for roots in the woodland, or the wood pulp made by a beaver chopping a tree, or the trampled ground under the hoof a mighty Auroch. 

In the modern world humans create this niche for them more than animals, and sadly, our modern management of pine woods has favoured it less. Through research and collaboration, we will be able to manage woodlands holistically, providing a mosaic of habitat for One-flowered Wintergreen in Scottish pinewoods, as well as other rare native species. 

In Autumn 2023 we translocated 109 individual One-flowered Wintergreen rosettes from two sites in to RSPB Abernethy, reinforcing a tiny relic population. This is a very early trial, as much a learning experience for future work, as it is to improve the condition of the Abernethy population.

I have been cautious to publicise this work, as, given no one has ever translocated One-flowered Wintergreen before (or even worked towards conservation of this species), I was prepared for total failure. However, the good news is, after 9 months at their new site, survival of rosettes remains above 70%. This is excellent for a plant translocation and bodes well for further Wintergreen translocations.

We hope to do more translocations to allow genetic mixing between populations and to rescue them from threatened sites. In addition to collecting plants for translocation, 12 plants went to Royal Botanic Gardens Edinburgh, where they have been working towards understanding the complex fungal interactions which One-flowered Wintergreen relies upon to survive, and in particular, to germinate.

Why is One-flowered Wintergreen in trouble?