Tree Seed Provenance (where the seed comes from)
RJ Trees and Hedging grows a wide range of tree species for forestry and productive woodlands and each year, Ray Jenkins carefully selects suitable provenances of seed in the appropriate species.
Choosing the right seed source is critical in forestry and productive woodlands as it can be many years before poor choices become obvious and by that time it is too late to do anything about it. The implications for the yield or timber quality are enormous so we indicate for each species on our website which species are grown from “improved” orchard seed (currently Betula pendula, Acer pseudoplatanus and Prunus avium all taken from Future Trees Trust origin stock, or select stand seed and Ray is always available to indicate which provenances we have available – please don’t hesitate to call if seed provenance is an important factor in your tree buying decision. With Government plans in all parts of the UK to dramatically increase tree planting (see our blog on UK tree planting targets) there is an opportunity now to develop homegrown timber resource and therefore, more than ever before, it is important to consider which planting material is used.
When planting trees of any type, selecting an appropriate provenance is an important decision – as important as selecting the range of species of tree to be used at a planting site. The seed source is important to tree survival rate, biosecurity, resilience, growth rate and longevity.
GB provenance seed is generally considered to be
- Better able to withstand our local weather conditions
- More productive and with a higher success rate in establishment
- Well adapted to the local wildlife so that pollen and fruit is available at the “right time” for indigenous birds, animals and insects – a particularly important factor for conservation woodland creation
The importance of using local provenance of native species when planting woodlands and forestry assumes that the local tree population has become adapted to the range of climatic, soil and pests present in the place where they are growing. From 1999, a framework was developed for sourcing appropriate material by defining a system of 24 native seed zones (see photo). These zones form a sub-division of the four regions of provenance (ROP) into which GB is divided under the Forest Reproductive Materials Regulations.
The larger two digit numbers (10, 20, 30 and 40) relate to the four regions of provenance (ROP) into which GB is divided under the Forest Reproductive Material Regulations.
The smaller 3 digit numbers are the 24 native seed zones.
For timber production, especially for elevated planting sites, you should try to buy plants grown from seed collected at a similar elevation. It is preferable to buy plants that come from seed that has as local a provenance as possible. However, we know that UK native trees are highly variabl
Seed orchards producing “improved” material
Species which are important to British forestry are now being grown in seed orchards which are designed and managed to provide seeds of a superior quality to select stands or unimproved stands (wild) with the intention of bringing “improved” seed to the market in the short and medium term. This is done by selecting plus trees (individuals with superior timber form) across the country, taking cuttings from these trees and propagating them by grafting, growing them in pots until semi mature, and then planting these grafts out as clonal seed orchards in a location where there will be no competition with other trees of the same species to avoid competition from foreign pollen, and from which it will be easy to collect seed. The trees are widely spaced to ensure good crown development which encourages flower production and hence maximises seed production. By bringing together these outstanding individual trees and allowing them to cross-pollinate, the seed they produce is likely to be of an improved quality for productive forestry with potentially greater growth rates and better form. Over subsequent years, further improvements will be made to the trees in the orchards In addition, because the material is drawn from unrelated “plus” trees selected from across the country, the trees in an orchard have wide genetic diversity and the design and management of orchards encourages random mating, all of which can produce tree saplings with a better chance of adaping to future climate and invasive pests and diseases.
Currently there are 13 orchards in production or recently established containing more than 1,200 plus trees for seven of the most important broadleaved species planted for timber. There are 3 orchards producing improved silver birch, 3 sycamore and 3 wild cherry. There are also 2 recently established sessile oak orchards, 1 pedunculate oak and 1 sweet chestnut which will begin producing seed in 10-20 years. RJ Trees and Hedging grows trees from all available seed orchards and will broaden our range of “improved” material as more species begin to produce seed from these orchards. Currently the silver birch, sycamore and wild cherry orchards are producing “Qualified” material as defined by the Forestry Reproductive Materials regulations. In due course , assessments will be made of the plus trees in the orchards to see whether they truly are genetically superior (by assessing their offspring – this is call “progeny trials”). Progeny trials take 15 years for sycamore, silver birch and wild cherry and up to 25 years for oak and sweet chestnut). Reselecting parents for new seed orchards (via genetic thinning) can then take place and these orchards would then be described as producing “Tested” material under the FRM regulations.
Tested improved seed
Most tree breeding programmes focus on conifers. There is currently no UK data available on the gain in height and diameter that can be achieved from using Qualified seed from orchards in broadleaf species but some conifer species give interesting data. For Douglas Fir in Canada the gain was between 10 – 16% in height and diameter which equates to 28-49% increase in volume of timber. The UK Sitka Spruce breeding programme has predicted gains of 9 – 13% for diameter growth and 15 – 21% for stem form which gives predicted volume gains of 25%. The only broadleaf examples available are silver birch from Finland which reported a gain of 29% in volume, and a relatively new oak improvement programme in Croatia which predicts a gain of 12%.
The Future Trees Trust is a charity dedicated to using research to improve broadleaf trees and they have a lot of interesting information on their website.
Seed can be collected from registered “selected” stands which are proven to be phenotypically superior. Select stands have been identified as having trees of superior quality suitable for seed collection. Generally, the trees will show good growth rates, be healthy, have straight stems without defects. The number of registered stands in Britain needs to be increased. Details of the process for inclusion onto the National Register can be obtained from www.forestry.gov.uk/frm under the National Register section. All seeds taken from select stand trees will have similar genetic diversity (having been taken from trees all growing together in one stand)
Source identified, often referred to as local provenance seed
Source identified seed are of known origin (from within a single region of provenance or native seed zone with an altitude band) but do not have proven superiority. Whilst not proven to have any superiority, they are eminently suitable for woodland planting where timber harvesting is not a main objective and for hedging plants. The known provenance (zone number) makes the trees that grow from these seeds well acclimatised to local weather conditions.
European selected seed
If no GB seed from orchards or select stands is available, it can be, in some cases, preferable to use European selected seed in preference to UK source identified seed. The importance of using “selected” seed varies by species. Whilst having a preference to growing from GB seed, there are some circumstances in which we use seed from Europe either because there is a shortage here (eg due to poor seed development due to weather conditions) or where European seed has been proven to be “better” in some aspect of its performance eg Hawthorn seed from Italy is less prone to powdery mildew and that reduces pesticides and maintenance cost to us and to you, so we use our experience to grow certain non-GB seed as well as GB. If it is important to you that the seed is GB provenance or you are looking for a particularly local provenance zone, please contact us by phone or email before purchasing.
Registering a stand of trees for seed collection
Seed stands are specifically defined areas or groups of trees in the landscape with identified boundaries. They can be source-identified, selected or tested. Any landowner can register a stand of trees for seed collection and the Forestry Commission has a helpful page on assessing whether a stand of trees might be useful for seed collection and how to go about registering it – https://www.gov.uk/government/publications/forestry-register-seed-stand-or-seed-orchard-as-a-source-of-basic-material.
Or we can put landowners in touch with the forestry seed merchant directly or with foresters who undertake seed collection.
e (largely due to wind pollination) and the potential to adapt to local weather and soil conditions is high.
Seed provenance and climate change
Climate change is making seed selection more complex and there is insufficient evidence and research into this topic despite its long term implications for woodland and forestry management. Given that the establishment of a woodland is a long term project, a balance may have to be found between use of plants which are assumed to be well adapted to the current climate and plants that will be better adapted to the future climate.
Southward movement of genetic material within GB (in the region of hundreds of kilometres) is like to lead to a loss of vigour compared with more local material. Northward movement of genetic material (again in the order of hundreds of kilometres) may result in a gain in vigour compared to local sources but the long term implications are unknown – it may be more susceptible to late spring frosts or early autumn frosts which could lead to poor stem form due to forking. Very low temperatures may be more seriously damaging. The impact on wildlife is unknown.