Storing up seeds to guard against future natural disasters
PUBLISHED: 10:00 27 May 2019 | UPDATED: 11:34 29 May 2019
No-one knows when the next tree disease like ash dieback will arise but a team of volunteers in Suffolk are collecting seeds from native species as an insurance policy.
The widespread loss of a well-loved tree or plant species is nothing short of a national disaster.
That was how the devastating effects of Dutch elm disease were perceived when the fungal affliction struck during the 1970s and 1980s, eventually wiping out more than 25 million trees in the UK.
Present day concerns are focussed on yet another fungal disease, ash dieback, which is expected to kill up to 99% of native ash trees over the coming decades, removing an iconic mainstay from the British landscape.
Ash dieback is believed to have originated in Asia and to have arrived here on imported ash trees - a stark illustration of the hazards of the global trade in plants and trees and how introduced diseases can threaten native populations that have not developed a resistance. Frighteningly, scientists recently warned there are 47 other tree pests and diseases that could have a severe impact on our native species if they become established in Britain.
And then there is climate change, which is anticipated to bring changes in temperature, drought, forest fires and shifts in germination patterns - native tree and plant productivity is expected to increase in some areas and decline in others.
In direct response to the ash dieback crisis and in anticipation of other threats to come, the Royal Botanic Gardens at Kew established the UK National Tree Seed Project (UKNTSP) in 2013, with a view to collecting and storing seeds from native trees and shrubs throughout the UK. Multiple collections are being made with samples from a range of locations across the country, in order to develop genetically representative collections, which will be stored at Kew's Millennium Seed Bank (MSB) at Wakehurst, near Haywards Heath in Sussex. Already over 10 million seeds have been successfully stored.
Suffolk Wildlife Trust has been involved in the project for the past four years - a small team of volunteers visiting its different fenland and woodland reserves to take samples from the many ancient and native tree species they find. Heading the team is Anna Saltmarsh, a trustee at the charity who used to work at Kew. She says her Suffolk team has been tasked with collecting 10,000 seeds each from 29 tree and shrub species - from wych elm, aspen and wild service to alder buckthorn, privet and guelder rose.
"With an increased representation of genetic diversity in the seed bank, it increases your chances of having one or two individuals that maybe resistant to whatever impacts we are facing," said Anna.
"We can't necessarily predict what the next problem will be and what species will be impacted in the future but what we can do is make some kind of insurance policy now that gives us opportunities in case of a catastrophic decline that we are not quick enough to deal with using surviving material in the wild."
I had arranged to meet Anna at a Trust fenland reserve in the north of the county where she and other volunteers, Meg and Marie, are collecting catkins from a row of fine looking grey willow trees. In the warm sunshine, it's a beautiful spot. I see a small frog and a lizard as I cross the meadow while a kestrel hovers overhead. As we speak, a cuckoo booms its eponymous call. All around us is a blizzard of fluff carrying the precious grey willow seeds.
Anna tells me that the team of volunteers have to be flexible and prepared to come out at short notice.
"The aim is to collect seeds at the point of natural dispersal - that is when they are most likely to be viable," she explained.
"We normally have a couple of weeks' windows depending on the species. I tend to be out and watching the species I know we are targeting."
In the post
The vagaries of the postal service and the working week also have to be considered. The team aim to collect at the start of the week, so the seeds can be posted to Wakehurst in time for researchers to examine and process them before the weekend and not risk them sitting in an in-tray for several days.
Anna continued: "As wind dispersed seeds, the grey willow produces tens of thousands of seeds per individual, which in a sense makes it easy to collect as we can pick one catkin and have several seeds there. But they are very tiny - a millimetre in length - and because of this they don't have the resources to survive very long and have short viability."
Once at Wakehurst, the seeds are separated from other materials, dried down to between 4% and 6% water content - the optimum for preservation - and then frozen at minus 20°C. A sample of around 50 seeds from each collection are x-rayed to check for live embryos and any infestations while germination and regular viability tests are carried out on the seeds, which are stored in rows of glass jars.
Anna tells me seed banking is a relatively new pursuit, so it is unknown how long the seeds at the MSB will last in storage although it is hoped that most species will be able to be kept for "centuries".
Anna and the team are motivated to volunteer their time for the greater good and for the opportunity to learn more about the local fauna.
But there is also the simple joys of being in some of the best wild country Suffolk can offer.
"I have come back to live in Suffolk and I am loving the opportunity to explore and get to know parts of the county I never had a reason to go to before," added Anna.
"And there are some really lovely places with some interesting species - even for me, as someone who has been very interested in plants for a long time, it's quite remarkable how little notice you take of what's what and what's growing where."