Forest Reproductive Material: Future Opportunities and Challenges1

A. Marcus, J. Robbins 2


An adequate supply of forest reproductive material, particularly seed, is a key factor for sustainable forestry. Technical opportunities and challenges to ensure quality and quantity can be found in the activities of identification, selection, procurement, propagation, conservation, improvement and sustained production of reproductive material. The social, legal and environmental issues of ownership, bioprospecting, invasiveness, and genetic engineering of reproductive material are currently of particular concern. Various international initiatives related to access and benefit-sharing of biodiversity and plant genetic resources, testing and certification of reproductive material provide important opportunities to address these issues. The overall challenge is to make best use of existing knowledge and ensure continued expertise through training and extension that matches local needs.


Forest reproductive material or germplasm (seed, cuttings etc.) plays a vital role in forestry. It is the means by which previous generations of trees and forests produce future generations. Demand for germplasm increases in direct proportion to regeneration programmes. There are many opportunities and challenges to ensure that the best material is used. Although this paper considers all germplasm, it focuses on seed as the most widely used reproductive material. Technical subjects such as identification and selection, procurement, propagation and improvement are discussed first, followed by political, legal, social, environmental, managerial and other matters.

Identification and Selection

Correct selection of suitable species and provenances must be the first step in obtaining germplasm. This requires clear objectives of regeneration, an understanding of the site, and knowledge of the natural habitat, qualities and previous performance of potential species.

Many institutions are involved in taxonomic, biological, and silvicultural research to provide such knowledge. They collaborate in networks at national, ecoregional, regional and international levels (e.g. the International Plant Genetic Resources Institute's (IPGRI) European Forest Genetic Resources Programme (EUFORGEN). There is extensive literature summarising such work, such as produced by the World Agroforestry Centre (ICRAF) and the Oxford Forestry Institute (OFI).

Despite these efforts, the effectiveness of some planting programmes is still constrained by lack of adequate information. The challenge is to improve availability and transfer of existing knowledge, as well as generating new. Electronic means of compiling data provide one opportunity e.g. CAB International's Global Forest Compendium (CABI 2002). However, site-specific trials that confirm species and provenance choice (e.g. the FAO Acacia and Prosopis International trials) will be continually needed. Older provenance trials such as those set up around the Mediterranean are of particular value.

Choice of reproductive material is an integral part of selection. Although seed remains the predominant kind of germplasm, increasing use is made of vegetative material, partly because many tropical species produce seed infrequently or are difficult to store.


Procurement is about ensuring that the right quality (genetic, physical, physiological and phytosanitary) and quantity of material is available for propagation. A comprehensive review of current issues can be found in Edwards, D.G.W. et al. (1999).

Planning of germplasm supplies requires knowledge of demand. At local level, demand for plantations can be calculated from planting programme estimates. But it becomes more difficult when small-scale planting needs e.g. trees on farms, are considered. A challenge is to develop methodologies both at local and global level to improve forecasts of supply and demand. ICRAF is currently studying this issue at farmer level.

Collection of seed requires consideration of management, logistics, and reproductive biology. Estimation of yield and optimum collection time is an inexact science and still needs improvement. Harvesting from forest trees can be difficult, and many techniques have been devised to develop safe methods of access. The most successful methods use modern mountaineering techniques and equipment. A challenge is to make sure they are applied in the field.

The number of commercial seed suppliers is increasing, and although many have built up a good reputation, the standard of some is poor. Research or development institutions provide material of high quality, but usually in small quantities. Directories of seed suppliers are available to guide the purchaser, such as that produced by ICRAF (Kindt, R. et al. 1997). They must be continually updated and used with care.

Reproductive material should be accompanied by recognised documentation of genetic, physical and phytosanitary quality. Users can help to promote quality by ensuring that they only procure material that has the necessary certification. Some schemes are mentioned later.

Proper handling and analysing is critical for maintaining the quality of reproductive material. Activities include reception of material at the centre of operations, processing, testing, storage, treatment, distribution, and documentation.

Current research on seed storability indicates that orthodox and recalcitrant seeds form extremes of a spectrum, and there are many intermediate types. There is collaborative work to improve the storability of the more recalcitrant seeds, e.g. by the Royal Botanic Gardens, Kew, UK and the Danida Forest Seed Centre (DFSC)-IPGRI Project on Handling and Storage of Tropical Forest Tree Seeds. Ultra-low temperatures for storage (cryostorage) is being developed for specialised reproductive material. Maintenance of cold stores can be a challenge where services are erratic.

Seed testing laboratories form the core of the many new dedicated seed centres. Rules and regulations for testing physical, physiological, and phytosanitary quality continue to be developed, and are essential for certifying seed quality. ISTA is the leading source of information on seed analysis (Gordon, A.G. et al. 1991). The International Union of Forest Research Organisations (IUFRO) Research Group "Seed physiology and technology" provides effective help to exchange information (see IUFRO). Such existing sources of expertise must be used.

Distribution of seed is a particular concern for programmes to promote tree planting outside forests on farms for their environmental benefits or use in agroforestry systems. There are various stages - distribution from centres, dissemination to farmers, and diffusion among them. The main challenge is to understand users' needs, how they perceive and actually use and promote a species within their communities.


Most propagation occurs in nurseries. A wealth of information on techniques has been developed for a wide range of species, and is found in many nursery manuals. For commercial production, containerised plants and mechanised planting systems continue to be developed. The importance of microsymbionts is now well recognised.

Silvicultural systems that promote natural regeneration in the field are being refined as reproductive ecology is better understood. Enough is known to ensure successful silviculture, and the real challenge is to put it into practice. Forest management criteria and indicators can help monitor effects of management with a view to improving such interventions over time (see CIFOR). Direct seeding is sometimes appropriate and practised in special cases (see DFSC). There has been detailed work to improve methods of vegetative propagation for plantations, individual trees, agroforestry systems (Longman, K. 1993). So-called bio-engineering provides new opportunities to use living plants to stabilise or rehabilitate degraded soils or contaminated waters (Howell, J. 1999).

Techniques of grafting and budding are well established for seed orchards. The most recent advances are in micro-propagation from very small plant parts, tissues, or cells grown under strictly controlled conditions in the laboratory. The aim is to multiply material for research purposes, or as a first step in planting programmes to rapidly increase desirable genetic stock. Tissue culture techniques include somatic embryogenesis (i.e. regeneration of embryo-like structures from callus cell suspensions) to produce young plants (micropropagules). Although procedures have been successfully developed for both hardwoods and some conifers, the cost is high and it is not always certain how well such micropropagules will develop in the field.

Table 1 summarises the different kinds of reproductive materials and current propagation methods.

Table 1: Kinds of Forest Reproductive Material and Propagation







Natural growth and development of tree
(i.e. internal reproduction)

Meristematic growth
Differentiation of tissues

Flowers etc.


Mature tree (from which forest reproductive material is produced)


Natural regeneration


Pollen +


Natural establishment


Artificial direct seeding

As above

As above

Seed coating
Sowing / broadcasting


Breeding and artificial regeneration

(Induced) Flowering
(Artificial) Pollination

Pollen +

Seed harvesting
Nursery germination

(Stumped plant)


Natural re-growth of existing plant

Growth of vegetative organs

Root Sucker,
, etc.

Shoot growth


Artificially induced re-growth of existing plant

Cutting (coppicing)
of stem

Tree stump

Stump coppicing
Shoot growth

New stems or branches

Lopping (pollarding)
of crown

Pollarded trunk

Pollard shoots

Re-sprouted crown

Natural regeneration of separate plants

Development of vegetative parts

or Plantule

Abscission Rooting

Rooted plantlets

(Parent tree = ortet offspring = ramet,
ramets from same ortet form a clone)

Shoot cutting


Planting Rooting

Rooted cutting

Shoot / bud and root-stock cutting and preparation

Scion or
Bud +
Root stock

Fusion of tissues

Grafted tree
In-grafted branch

Branch layering


Rooting Severance

Layered plant

Micro-propagation in laboratory (in-vitro)

Separation of fascicle


Rooting Planting

Rooted propagule

Excision of plant tissue (from meristematic tissue)


Callus formation > Treatment
Rooting/shooting Development
(= Organogenesis)


Callus formation / cell suspension
Treatment somatic embryos
Embryo development
(= Somatic embryogenesis)


As above + Artificial coating
Somatic (artificial) seed

Germination (as seeds above)


Conservation, Improvement and Production

There are many different types of in situ conservation areas currently defined by forestry and conservation organisations, differing in legal status, objectives and intensity of management. A key challenge is to ensure permanence in the field. Logging / harvesting carried out as part of environmentally sensitive forest management can help to maintain biological diversity, but requires that suitable codes of practice are implemented.

Ex situ conservation can be in clone banks, seed stands, or long-term storage facilities. There have been some notable advances e.g. The Millennium Seed Bank Project of the Royal Botanic Gardens, Kew, UK). New biotechnological methods have the potential for making it easier to conserve larger amounts of genetic variation for longer.

Genetic improvement has advanced to incorporate techniques of genetic engineering. The sequence can now be summarised as follows:

Species selection

Provenance selection

Plus tree selection

Seed stand establishment

Seedling or clonal seed orchards and controlled pollination

Advanced breeding techniques

Genetic engineering

Each of these stages provides opportunities for improving quality and quality of forest reproductive material. The challenge is to make sure each stage is adequately carried out and gains maximised, before advancing to the next.

Seed production areas or seed orchards continue to be established, but many biological constraints remain. Flowering and seed setting of forest trees is often erratic and cost-effective methods of stimulating seed production have not been devised. Even if fruiting is abundant, actual pollination may be poor so that many seeds are empty. The actual time of seed harvest is important to ensure that seed is at its peak physiological maturity. Tackling these constraints requires a good understanding of the reproductive biology of the species.

Social and Environmental Opportunities and Challenges.

The ownership of forest reproductive material is now a key concern. Who actually owns or has property rights to the material; the diversity of its genes; the local, indigenous knowledge; or the varieties developed as local people selected and replanted trees and crops? Is it a common heritage for all peoples? Or is it the property of nations who own the forest; the companies who discovered a particular chemical; the local communities who have lived in and made use of the forest for centuries; or the private individuals who own the land and the trees on it? For a review of these issues, see Midgley, S. and Boland, D. (1998).

The term bioprospecting can include all the exploratory work done on forest reproductive material in the past. It is now applied, in a more limited context, to the search for specific traits in genes (such as pest or disease resistance) or chemicals from which new drugs can be developed. Profits could be substantial, but if not equitably shared, material and benefits are effectively pirated - sometimes called biopiracy. A major challenge for all involved in commerce and research is to avoid this happening in the future.

The weediness of some introduced species is causing concern. Although climatic differences in the new environment may mean that a species may not reproduce at all, in other cases, ease of natural regeneration and lack of pests or diseases result in the species becoming uncontrollable. Invasiveness is not only a physical problem, but also biological when the species alters a native ecosystem in a way that is undesirable. So-called "alien invasives" are presenting serious problems in many countries, and require stringent control, usually by eradication, management, or rendering the plant sterile, and banning of import and further propagation. It is possible to be pre-emptive by studying the reproductive biology of the species and its growth characteristics in its natural habitat (Hughes 1994), and ensuring that proper consideration is given to all aspects, including invasiveness, in species introduction and management.

Genetic engineering takes a radical step in selection and breeding. Rather than using existing variation on which to base improvement, this is increased further by adding, moving, or modifying chromosomes and/or their genes to produce a genetically modified (GM) or transgenic organism. It is an advanced technique of biotechnology, a term that can also encompass traditional plant breeding. Such engineering is used extensively in agriculture, and requires substantial investments and corresponding returns. In forestry, it is being tested to introduce herbicide and pest resistance, or to reduce or modify the lignin content of wood. Experiments are most advanced for poplar, pine and Eucalyptus. No commercial plantations of GM trees have yet been reported.

The technique causes concern because of the potential unknown effects of interfering with the genes. These can be either to the organism itself as it develops and reproduces; or to other organisms where interbreeding of the modified organism occurs (such as through natural pollination), or - in the case of food - to the people as they use or consume the organism. The problems associated with GM trees are similar to agricultural crops, although there are differences due to the fact that trees are relatively undomesticated, and have a long life cycle. A useful account of the pros and cons of genetic engineering, in the context of certification, is given in Strauss, S. et al. (2000). The challenge is to use the technique wisely after sufficient testing.

Political, Legal and other Opportunities and Challenges

Many of the issues mentioned are rightly the concern of the many international agreements, policies, legislation and standards about forests in general and reproductive material in particular. They provide unique opportunities to work to agreed principles and standards - the over-riding challenge is to put them into practice.

The Convention on Biological Diversity (CBD) helps promote conservation and sustainable use of biodiversity, the equitable sharing of benefits, and desirable in situ and ex situ conservation measures. It recognises national sovereignty of countries over forest reproductive material rather than being a common heritage, but calls for countries to facilitate access mainly via bilateral agreements. The practical implications of access and benefit sharing present many challenges, and are the subject of continuing dialogue and study in various fora and work programmes. The Statement of Forest Principles is also relevant to forest genetic material. The so-called Cartagena Protocol, governing the transboundary movement of living modified organisms, is under the CBD umbrella.

The recent legally-binding International Treaty on Plant Genetic Resources for Food and Agriculture (ITPGR) is compatible with the principles of the CBD, and promotes multilateral agreements. It covers all plant genetic resources for food and agriculture (including crop, forest, domestic animal and fish genetic resources). The treaty includes a Multilateral System for Access and Benefit Sharing (ABS) which presently applies mainly to food crops. One forestry genus, Prosopis, is included, and several woody species. Terms and conditions are set out in Material Transfer Agreements (MTAs). They concern access and benefit sharing by any person or organisation wishing to use genetic resources, and cover purpose of access, facilitation, documentation, intellectual property rights, future availability, and national legislation. MTAs have been in existence for several years to cover forest reproductive material, and are currently used on a multi- or bilateral basis by institutions such as CSIRO, ICRAF, OFI, and DFSC.

The Organisation for Economic Cooperation and Development (OECD) Scheme for the Certification of Forest Reproductive Material moving in International Trade defines four broad categories of genetic quality: (1) Source-identified material, (2) Selected Material, (3) Qualified Material, and (4) Tested Material. There are also seven types of basic materials: (1) Seed Source; (2) Stand; (3) Seed Plantation; (4) Seed Orchard; (5) Parents of Families; (6) Clone; and (7) Clonal Mixture. These categories and types are used to define fourteen authorised combinations for the purposes of certification. The new European Union directive on marketing of forest reproductive material is harmonised with the OECD scheme.

The International Seed Testing Association (ISTA) provides rules and regulations defining procedures, conditions and tolerances required for tests. Laboratories accredited to ISTA can issue internationally recognised certificates of seed physical and physiological quality, and it should be the aim of all seed centres to meet these standards.


This paper has looked briefly at various aspects of forest reproductive material, and some of the opportunities and challenges presented. When considering how to respond to them, it is always wise to keep in mind the purpose of adequate supplies of seeds - it is to provide the right trees for the right people. As in all aspects of forestry, meeting peoples' needs should guide how we take up these opportunities.

An overriding challenge will be to ensure that projects and programmes concerned with forest reproductive material are effectively staffed, managed and supported in the long term. It is important to use the existing technical knowledge more effectively. This will be especially relevant in countries where the technical base has been depleted because of war and diseases (such as HIV). To do this will require continued attention to transfer of knowledge and skills through training and extension, building on the expertise that is already in existence, and taking full advantage of modern technology as well as the traditional. With regard to users of tree seeds and germplasm, adequate attention must be given to poor farmers, whose requirements will usually be distinct from those of larger scale plantation programmes.


CABI (CAB International) 2002 - For information on the Global Forest Compendium, visit the website: http://tree.cabweb.org/Compendium/compenfrm.asp

CIFOR (Centre for International Forest Research) Criteria and Indicators. For information, visit the website Http://www.cifor.cgiar.org/

DFSC (Danida Forest Seed Centre). For full details of the publication titles, many of which are available on line, visit the website: http://www.dfsc.org

Edwards, D.G.W. Compiler 1999. Forest Tree Seeds at the End of the 20th Century: Major Accomplishments and Needs. A State of the Knowledge Report on Forest Tree Seeds. IUFRO Unit 2.09.00 Seed physiology and technology. Available on-line at: http://iufro.boku.ac.at/iufro/iufronet/d2/wu20900/skr20900.htm

Gordon, Dr.A.G.; Gosling, Dr.P.; Wang, Dr B.P.S. 1991; ISTA Handbook of Tree and Shrub Seed Testing, International Seed Testing Association (ISTA).

Howell, J. 1999; Roadside Bio-engineering: a reference manual. His Majesty's Government of Nepal, 160 p.

Hughes, C.E., 1994. Risks of species introductions in tropical forestry. Commonwealth Forestry Review. 1994, 73: 4.

ITPGR (International Treaty for Plant Genetic Resources). For the full text of the Treaty, see the website: http://.fao.org/ag/cgrfa

IUFRO (International Union of Forest Research Organisations) Seed physiology and technology research group. Unit 2.09.00. For further information, visit the website: http://iufro.boku.ac.at/iufro/iufronet/d2/hp20900.htm

Kindt, R.; Salim, A.S.; et al. 1997. Tree Seed Suppliers Directory: Sources of seeds and microsymbionts. Published by ICRAF (International Centre for Research in Agroforestry).

Longman, K.A., 1995. Tropical Trees: Propagation and Planting Manuals Vol 1-5, Commonwealth Science Council.

Midgley, S and Boland, D.,1998. Influences on the international exchange of forest genetic resources - An Australian Perspective in: Forest Genetics and Sustainability, edited by Csaba Mátyás, Forestry Sciences : Volume 63, November 1999 , 300 pp.

Strauss, S.H.; Coventry, P.; Campbell, M.M.; Pryor, N.R.; Burley, J. 2001 Certification of genetically modified forest plantations. International Forestry Review 3(2), 2001. pp 87 - 104

1 This paper is based on the findings of a study carried out by the author, at the request of FAO, and funded by the Agrobiodiversity component of the FAO-Netherlands Partnership Programme. The study reviewed a wide range of information sources related to forest seed and germplasm, and full details of these can be found on the newly established FAO web-site on forest reproductive material: www.fao.org/forestry/seeds.

2 Independent Forestry Consultant,
119 Harefields, Oxford,
OX2 8NR, UK.
Member of theNRgroup (development professionals)