by
M.J.W. Cock1 , M. Kenis and R. Wittenberg
‘Biosecurity’ in food and agriculture describes the concept, objective and process of managing biological risks associated with food and agriculture (in its broadest sense, i.e. including forestry). Biosecurity is emerging as one of the most important issues facing the international community. There is a growing trend by countries to establish national biosecurity systems, either to meet obligations under international agreements (for example, in the environmental sector) or to take advantage of opportunities (for example, in the trade sector). Such systems are traditionally based on sectoral areas, although a number of countries have started to establish cross-sectoral, integrated frameworks.
In the forestry sector, biosecurity encompasses three main fields of activity: forest protection and phytosanitary issues; naturalization of introduced forestry trees and their impact on ecosystems or individual species; and the release of new genotypes, including genetically improved tree varieties.
A global literature review, complemented by in-depth regional and national analyses, shows that the forestry sector is not always aware of the issue. There is a need to raise awareness of the actors involved, and to strengthen a biosecurity perspective when introducing, testing and managing exotic forest resources. This paper presents a summary of the main findings and recommendations of the global review undertaken by the authors for FAO.
‘Pests’ are defined by FAO as any species, strain or biotype of plant, animal or pathogenic agent injurious to plants or plant products, i.e. insects, mites, molluscs, nematodes, diseases and weeds. Indigenous pests may be chronic or occur in outbreaks, whereas introduced pests usually occur in an initial outbreak followed by continuous chronic damage. Both types of pest can cause severe losses in forestry, making them important factors to take into account.
Tropical and subtropical plantation forestry has often focused on a small number of fast-growing, pioneer species, normally planted as pure stands. Monocultures, especially of genetically similar trees, are associated with an increased probability of pest outbreaks and can also transform sporadic pests into permanent problems. Mixed planting of native (and exotic) trees is therefore increasingly preferred as a strategy for avoiding pest problems. Pest risks associated with a particular tree/location combination should be evaluated prior to planting and the results confirmed with test plots.
There is a growing trend towards adopting more sustainable management strategies for forest pests, particularly in developed countries. These changes are related to changes in the perception of the role of the forest, which is increasingly valued not just for economic reasons, but also for its ecological and social functions. Large monocultures are disappearing from many European and North American landscapes and are being replaced by smaller, mixed stands, which reduce pest risks as mentioned above.
Analysing and evaluating pest risk requires reliable information. As might be expected, more information is available on pests of trees grown in developed rather than in developing countries, and also for pests of trees grown in plantations rather than for pests in natural forests. Virtually nothing is known of the pests associated with those trees harvested from natural forests and not grown in plantations, at least in the tropics.
At operational level, in a majority of countries, quarantine and pest management services are generally under ministries in charge of agriculture, and their overall knowledge on pests specific to the forestry sector is often limited.
Alien species can be particularly damaging during plantation establishment, but can also have important impacts on natural forest biological diversity, especially in the tropics. An increasing number of accidental introductions can be expected as a result of the growing internationalization of trade, the increased movement of people and the resultant overstretching of quarantine services.
Little attention has been given so far to the phenomenon of invasiveness by woody forest species at global level. Just like other living organisms, some forest and agroforestry trees have the potential to become invasive when grown as exotics, particularly in the tropics, but it is difficult to predict which alien species are likely to cause serious damage if introduced. Species that are innocuous or minor pests in their area of origin can be devastating when introduced elsewhere. At present, the best guide to potential invasiveness is those species that have already caused problems when introduced into another part of the world. Thus, access to reliable information is critically important for assessing this risk. Studies are needed to determine why introduced trees become naturalized or invasive, and protocols for assessing the risks of introductions must be developed and validated. Pilot planting schemes should include monitoring for any indications of invasiveness. Safer options for introductions (e.g. sterile trees) may also be useful.
The longer an alien species remains undetected after its introduction, the less chance there is for successful intervention: there are fewer options for its eradication, containment or control, and the costs of intervention rise. Often the key to a successful and cost-effective solution is eradication, but this requires both early detection and a rapid response. Once eradication is no longer feasible, the options for control of an alien species include biological control by the introduction of exotic natural enemies from the pest’s area of origin. However, this approach should always be based on an appropriate risk assessment and risk–benefit analysis, following international protocols.
Invasive tree species tend to be multisectoral in their impact, and thus need to be addressed with a multisectoral approach. In some cases invasive trees provide useful products or services and, when eradication is not possible, management options should be identified in order to balance the positive and negative aspects. A paper by Haysom and Murphy in this issue of Forest Genetic Resources highlights the global issues associated with exotic invasive forest trees.
The introduction of new tree genotypes could potentially have adverse impacts, e.g. through the displacement of indigenous taxa or genotypes, or the transfer of genes to local tree populations with the possible development of novel ecological characteristics. However, as yet, there are few documented records of such impacts in the forestry sector. Introductions of other species associated with forestry, including biological control organisms, pollinators, mycorrhizae, etc., should be considered with caution and on a case-by-case basis.
The development of genetic modification has created new challenges in risk assessment. Although the first generation of GM products was not particularly relevant to forestry, there are numerous ways in which the technology could be used in forestry, and research in the field is extremely active. There seems to be considerable potential for improving forest trees by developing new genotypes with useful biological traits. However, assessing risks in long-term crops such as forest trees is difficult, and uptake of GM technology is likely to be slow unless national and international protocols that reliably assess the risks are developed, tested, and agreed upon.
Forestry activities can contribute to the introduction of alien species in several ways, including the movement of forest reproductive materials and germplasm, solid wood packaging materials, trade in unprocessed timber, and contaminants of forest produce. The forestry sector needs to work with other relevant sectors to prioritize the risks associated with these various activities and to find ways of addressing them.
In establishing the objectives of a biosecurity programme, it is critically important to consider the full range of stakeholders and their various interests in order to identify areas where cooperation is necessary and where synergies and efficiencies may be sought. In doing so, the whole regulatory cycle and the full range of players must be considered. Several groups may need to contribute to the definition of objectives and to the assessment of risks. Raising awareness, training and capacity building should therefore be important components of any biosecurity programme.
While several international and national programmes target the issue of alien invasive species, especially in forest and fragile ecosystems, there are relatively few data on the phenomenon of introduced forest trees turned naturalized or invasive. The issue is all the more important since the global movement of forest reproductive material, either through intentional or unintentional ways, is likely to increase in the future. The following paper by Haysom and Murphy is the first global attempt to fill the information gap.
Managing potential pathways for the introduction of alien species is often more efficient than trying to prevent the introduction of individual species.
There is an urgent need for more research on tropical forestry pests, both to develop management methods and for developing pest risk assessments.
The authors thank all persons who helped to prepare some of the case studies included in the full report (Cock, 2003). The study was carried out in March 2003 and was financially supported by the FAO-Netherlands Partnership Programme on Agro-Biodiversity.
Cock, M.J.W. 2003. Biosecurity and Forest: an Introduction, with particular emphasis on forest pests. Forest Health and Biosecurity Working Paper FBS/2E. Forestry Department. FAO, Rome. (E) http://www.fao.org/forestry/site/16447/en
FAO. 2003. Biological Risk Management in Food and Agriculture: Scope and Relevance. Technical Consultation on Biological Risk Management in Food and Agriculture. Bangkok, Thailand, 13-17 January 2003. ftp://ftp.fao.org/es/esn/food/tc_bangkok/tc_brm_03_2en.doc
Haysom, K.A. and Murphy, S.T. 2003. The status of invasiveness of forest tree species outside their natural habitat: a global review and discussion paper. Forest Health and Biosecurity Working Paper FBS/3E. Forestry Department. FAO, Rome. (E). http://www.fao.org/forestry/site/16447/en
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