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Spreading the risk: species and genetic diversity


The golden rule of tree species selection; 'The right tree on the right site for the right reason'.

Today, tree pests and diseases are increasing and our climate is changing. We must act with URGENCY and plant a wider range of tree species, with a wider range of origin.

These pages can only provide you with ideas and information. There is no substitute to local site knowledge to inform forest planning and guide future planting stock requirements. It is up to forest managers to diversify forests to make them more resilient to a future climate

Take the time to look at existing 1950's, 1960's and early 1970's plantings. Foresters were not constrained by a limited palette of species. Visit your local arboreta, forest garden and botanical gardens. The species listed in the Forest Research Tree Species Advice are those where there is suffient experience of planting in England to guide sire selection. There are however many more species that foresters should consider in the future.

We have started to use a much wider range of tree species on our own land, confident that others will follow.

When thinking of tree species diversity at stand, or at a more intimate level, it could be helpful to understand natural assemblages. Many of our actions in the next few years will be experimental, using current evidence, and thoughts about what the future will bring. It is a time to have the confidence to be innovative and creative.  

Current recommendations from Forestry Commission England on seed source for adaptation to Climate Change.

 Current advice from Forestry Commission England when choosing origins for planting stock is taken from Forest Research Information note 086, 'the role of forest genetic resources in helping British forests respond to climate change', FCRN ‘Climate Change Impacts and Adaptation in England's Woodlands’ and the Forestry Commission Practice guide ‘Managing Ancient and Native Woodland in England’.    

It is recommend a portfolio approach is taken where biodiversity is the prime objective, and to plant a mix of provenances alongside the current population. The recommendations are that

  • natural regeneration is encouraged, however where there is a low chance of successful regeneration, then planting will be required.
  • seed must not be collected from a small number of seed trees as this can give a narrow genetic base.
  • Seed from the same region of provenance should make up a third of the planting stock and if timber is an objective then a significant portion of the restocking should be with improved planting stock from qualified or tested stands.
  • at least one source of seed from slightly warmer climates sources from 2 to 5° of latitude further south than the site is used. Eastern European sources should generally be avoided as they have proved unsuitable to England.

 Where timber production is high in the woodland objectives or the planting is not adjacent to a site recognised for its local genetic integrity then it is recommended that depending on the owners view towards accepting risk that an assisted migration approach be followed

  • Provenances from 2º south of the growing site generally outperform the local provenances and this is considered a safe distance over which to transfer material.
  • Provenances from up to 5 º south match to current climate change predictions to 2050

Trees for the Urban Environment

In the urban environment, the challenges facing trees may be more severe than in a forest environment. However there is a wider range of species to choose from. The 'Right Trees for a Changing Climate' database provides information of over 300 species to help identify suitable species for the future.

Many of the suggested tree species and origins may not be available from nurseries today. Think ahead and advise nurseries of your future requirements at least 2 years in advance

 

Bedgebury Pinetum

What's of interest

Forest research have made ESC 3 available with a wide range of species and the ability to test climate change scenarios. This is a low key launch to allow evaluation. Please remember that the output is only as good as your detailed input. Climate data is at a 5km square and the limiting factor may not be on your selected spot.

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