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The first 50 years of tree breeding in Britain – Production of improved material

Home Research Tree improvement Tree improvement – the first 50 years of Tree Breeding in Britain The first 50 years of tree breeding in Britain – Production of improved material

Seed stands – the original and current National Registers

As previously noted, the identification and registration of seed stands had started during the early survey work of the 1950s. Registration of seed stands and certification of seed and plants derived from them was promoted firstly by the Scottish Forest Tree Seed Association, formed in 1956, and the Forest Tree Seed Association of England and Wales, initiated in 1959. These organisations combined in their management committees representatives of landowners' and forestry professional bodies, trade associations and the Forestry Commission. As such they were an effective joint initiative between state and private sector interests. They combined into a single Forest Seed Association in 1966.

When a new system of seed identity based on geographical location of the seed source was introduced in 1956 (replacing an original system in which lots of seed or plants were identified by a serial number within each calendar year), the opportunity was taken to bring the identification of seed stands in line with the new system. The Associations organised the inspection and registration of seed stands, maintained registers of sources and gave advice on stand management and seed collection. This system operated from 1956 until 1973 when membership of the European Economic Community (EEC) brought changes to selection criteria and the process of registration was reorganised. The table that follows summarises numbers and total areas of stands under the previous system and since 1973. In the former system, stands were classified according to quality as follows:

  • Category A
    The best quality stands, originally rated as 'plus' or 'almost plus'
  • Category B
    Normal good quality stands and small stands of Category A quality
  • Category C
    Older stands used for seed collection from fellings in times of short supply
  • Category D
    Young stands of appropriate seed origin being managed and developed for future seed production.

Categories A and B would be acceptable in the system introduced after 1973. The information on stands registered since 1973 indicates the total number registered since that time, together with those which remain on the register in November 1998. A number of stands registered in the old system were transferred and re-identified in the new one.

Summary of seed stand registration under the original and current systems

  Category Number of species Number of stands Total area (hectares)
1956-1973 A 21 125 1 352
B 27 226 3 226
C 15 144 1 842
D 5 71 2 094
Total registered since 1973 25 624 11 805

Currently active in 1998

22 250 4 297

Before 1973, staff of the Genetics Section were often involved in surveying areas for seed stand selection, assessing the size of seed crops from registered stands, organising seed collection and liaising over transport of seed and cones to the Alice Holt extractory and seed store. Expertise in climbing was common among most of the staff and a wide experience in seed-collection techniques had been developed (Seal et al., 1965).

After 1973, and particularly when the UK Forest Reproductive Material Regulations became law in 1977, this situation changed altogether. The branch then became the official inspectorate of all seed sources (seed stands and seed orchards) and as time progressed became much less involved in seed stand selection in order to retain independence for inspection and registration. This work, together with maintenance of the National Register of Basic Material, the inspection of cone collection in seed orchards and the provision of technical guidance to other parts of the Forestry Commission, retains a high profile in the work of the branch.

During the 1990s it was realised that the Forest Reproductive Material Directives, originally made by the EEC in 1966 were inadequate for the certification and control of the wider range of reproductive material now being used. In addition, a larger number of commercially important species had to be recognised within an expanded community which now included Mediterranean and Scandinavian countries. Forest Research Tree Improvement Branch provided representation on a Panel of Experts formed by the EU to suggest a form of revision of the Directives. At the present time the revised Directives are being considered by Member States.

Seed orchards

The establishment of seed orchards will be considered on a species basis. The following table summarises the planting of orchards for the main conifer species:

Summary of seed orchards established and family mixtures created

Larch Douglas
Progeny-tested clonal Number 9 4 2
Hectares 36 16 14
P years 78-89 77-92 85-91
Untested clonal Number 68 20 10
Hectares 44 39 8
P years 56-67 53-86 53-65
Seedling Number 2 11
Hectares 4 43
P years 87 79-89
Family mixtures Number 25 10
Years 82-98 87-95

Study of this table reveals that there have been clear phases of different activity within the species across time periods. These trends will be clarified in the treatment of individual species, but overall there were essentially two main phases of orchard establishment. During the early years of the breeding programme, up to the late 1960s, a programme of planting small orchards based on phenotypic selection only was steadily pursued across a range of species. One-hundred-and-fourteen orchards of this type were established and are summarised by Faulkner (1964). There then followed a decade during which no planting took place. In 1978 a second phase of planting of orchards based predominantly on progeny-tested clones began. The orchards planted since 1978 have all been based on the permutated neighbourhood design developed by La Bastide (1967) using software developed jointly by the Genetics and Statistics Branches (Bell and Fletcher, 1978).

Where appropriate, in Sitka spruce and hybrid larch, the use of vegetative propagation by cuttings to multiply small quantities of seed of mixed superior families is also considered. This work is also summarised in the above table.

Genetic gain trials

Although progeny testing provides estimates of genetic parameters which may be used to calculate the potential genetic gain from any particular scheme of tree breeding, it is important to have information on the extent to which such predictions are realised in normal forestry practice using improved material. This can be assessed by planting comparative experiments of improved material and unimproved standards.

The first fully replicated Genetic Gain Trials (GGTs) were planted of Sitka spruce in 1993. Preliminary GGTs for hybrid larch and Scots pine were planted on two or three sites in 1992, but the Sitka spruce GGTs were the first which were properly designed to demonstrate realised or actual gains over at least half a rotation. They were replicated over 15 sites throughout Britain and are being used to compare unimproved origins of QCI, Washington and (where appropriate) Oregon, with seed stand, seed orchard, and family mixture seedlots, and selected open-pollinated families collected from a seed orchard (see Lee, 1993d).

Data collected from these experiments will allow breeders to see how estimates or predictions of gain varied relative to the QCI control, in different parts of the country, and on different site types. They should begin to provide useful information over the next few years and will develop into effective demonstrations of the achievements of breeding. The numbers of such trials established by 1998 were as follows:

Sitka spruce 13
Scots pine 3
Corsican pine 2
Larch 6
Douglas fir 2

What's of interest

These pages review the work performed by the Forestry Commission and Forest Research on tree improvement following the 50th aniversary of its establishment which passed in 1998.The genetic background describes the scientific procedures of tree breeding and the technical terms used in the remaining pages.All species are referred to by their common name in English.

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