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Saving the UK’s tree seeds: a resource for science

Clare Trivedi
14 August 2014
Blog team: 

The UK National Tree Seed Project (UKNTSP) is working to better understand and conserve seeds from the UK’s woody flora. The project will build a national ex situ seed collection that is both genetically comprehensive and comprises sufficient seeds to support research and conservation.

Over recent years, a series of high level reports to the UK government have made the case for conserving, restoring and extending woodland cover in the UK in order to develop a coherent ecological network, resilient to the impacts of climate change and other environmental change pressures.

Each of these reports outlines the many ecosystem services that can be provided by trees and woodlands in our landscapes, both rural and urban. These include carbon storage, climate regulation, flood mitigation, soil stabilisation, and providing space and corridors for wildlife. Well-managed forests can also provide a source of sustainable timber. In addition to these supporting, regulating and provisioning services, the benefit to the nation’s physical and mental health associated with the use of woodlands for recreation has also been widely recognised.

Bluebells in woodland in the Loder Valley Reserve, Wakehurst Place

While the benefits of trees and woodlands have been clearly articulated, the increasing risks they face from changing phenology, drought, fire, invasive species and increased incidence of pests and diseases are also considerable and well documented. The number of pest and disease outbreaks has escalated with breathtaking speed in the last decade. Many, such as the fungus-like oomycete Phytophthora ramorum, are already causing widespread economic and ecological damage. The way in which woodland cover should be expanded to provide a resilient ecological network therefore needs careful consideration.

Understanding which particular species, of which provenance, are most appropriate for woodland expansion, was identified as an essential area of research in the 2012 Final Report of the Independent Panel on Forestry. This report also recommended that research on tree and woodland diseases, resilience and biosecurity controls should be given additional Government investment, to speed up delivery of the Tree Health and Plant Biosecurity Action Plan. Initiation of such research depends on the availability of high quality plant material, of known provenance and taxonomy. If the research is to be carried out quickly and cheaply, researchers will require immediate access to such material.  

It is in this context that the UKNTSP was launched by Kew’s Millennium Seed Bank in May 2013. Thanks to support from players of People’s Postcode Lottery, over the next five years the project will collect and conserve genetically representative collections from at least 50 species. These collections will be accessible to researchers and conservation projects in order to meet the many challenges facing UK trees and woodlands.

Photo of a bag of alder seeds

Alder seed collections ready to put in the dry room at the Millennium Seed Bank (Photo: S. Kallow)

The job is too big for Kew to take on alone and so over the past 18 months we have been talking to a wide range of partner organisations who will join the project. These range from small NGOs (e.g the Small Woods Association, Community Tree Trust), through to the larger conservation organisations (e.g. Woodland Trust, Wildlife Trusts). The Forestry Commission has been involved in the project since its conception and continues to play a significant role in the collecting programme.

Photo of UKNTSP tags

Mother trees are tagged and georeferenced wherever possible so that researchers can return to them (Photo: S. Kallow)

A key challenge for the project is deciding where to make collections of each species. For every target species, seed collections will be made in each of the Forestry Commission Seed Zones where it is native. The first step was to understand the distribution of the target species across the UK. This was achieved by first putting distribution data from the Botanical Society of the British Isles (BSBI) into Geographical Information System (GIS) software. For each target species, all hectads (10 by 10km Ordnance Survey grid squares) where the species is known to be native were used in the analysis, which was carried out by Simon Kallow and Sharon Balding. The Forestry Commission’s Seed Zones map was digitised and used as an overlay in a GIS to determine the seed zone for each of the hectads. Using this information, for each of the target species, the seed zone coverage was determined. 

Photo of Kew staff collecting alder in December 2013

Kew staff collecting alder in December 2013 (Photo: S. Kallow)

Having determined within which seed zones the species should be collected, the next step is to decide which woodlands in a given area to visit, in order to collect the target species. We need to ensure that we do not collect from trees that have been planted, but only from those which are native to the woodlands in which they are found. This takes time and effort but the result will be a much improved knowledge of the local provenance of seed sources for a wide range of species. These can be used to gather seed for large scale planting schemes in the future.

 

Photo of data collection in the field

Field data is gathered alongside all seed collections and can be made available to users of the seed (Photo: S. Kallow)

In order to develop a better sampling strategy to make ‘genetically representative collections’, the project includes a set of activities aimed at better understanding the state of knowledge of the population genetics of the UK’s trees. Maintaining genetic variability in natural populations is key to preserving resilience to emerging pests and diseases, and changes in the environment.  Perhaps surprisingly, very few of our tree species have been subject to studies to elucidate their population genetics. The project will first seek to document what is already known and then to develop some actual studies for the highest priority species. It is hoped this work will bring together UK population geneticists from Kew, other botanic gardens and universities. This information will feed directly into species specific sampling strategies.

 

Black poplar seed is difficult to collect and store. Experimental collections have been made in 2014. (Photo: S. Kallow)

Another key constraint to the collecting programme is that some species  have ‘difficult’ seeds, and are either difficult to store in the seed bank using conventional procedures, or are very short-lived in the bank, or both.  Again, the project will conduct a review to flag such species and overcome as many of the identified constraints as possible. This work will be carried out by seed scientists at the MSB, in conjunction with our partners in Forestry Commission and elsewhere.

Ash seed displaying the perfect stage of ripeness to achieve maximum longevity in the seed bank (Photo: S. Kallow)

Just one year into this exciting project we are already made great progress. In 2013 Kew, Forestry Commission and Woodland Trust worked together to make 50 seed collections. The majority of these were of ash (Fraxinus excelsior) and juniper (Juniperus communis), which are both subject to intense threat from pathogens. Seed was collected from ash trees right across eastern and central England – the regions under highest threat from ash dieback. Over the course of the project I’m looking forward to developing close collaborations with a wide range of scientists, conservationists, foresters and keen volunteers to achieve the ambitious goals which we have set ourselves.

- Clare -


References

Independent Panel on Forestry (2012). Independent Panel on Forestry. Final Report. Available online 

Read, D.J., Freer-Smith, P.H., Morison, J.I.L., N., West, C.C. & Snowdon, P. (eds). (2009). Combating climate change – a role for UK forests. An Assessment of the potential of the UK’s trees and woodlands to mitigate and adapt to climate change. The synthesis report. The Stationery Office. Edinburgh

National Ecosystem Assessment (2011). National Ecosystem Assessment Synthesis of Key Findings. UNEP-WCMC. Cambridge

Tree Health and Plant Biosecurity Expert Taskforce (2013). Tree Health and Plant Biosecurity Exert Taskforce Final Report.


 

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