Overstory #210 - Underutilised plant species and biodiversity
What is biodiversity and why is it important?
The term 'biodiversity' encompasses all variation found in living organisms, both between and within ecosystems, and includes species diversity and intra-specific genetic variation. Biodiversity is at the foundation of human society, because we survive on the range of products and services that it provides. Biodiversity is vital for the food security, proper nutrition, income and self-reliance of human communities, and also sustains the environment. In addition, through sometimes complex linkages with food habits, languages, traditional medicine, and religious and other practices, biodiversity sustains cultural richness and community identity, encourages organisation and communication, maintains social cohesion, and fulfils the aesthetic needs that allow societies to flourish (Brush, 2004).
Biodiversity is also essential for providing an adaptive capability in a world that is continually undergoing change - change that may be positive, such as general improvements in human health and increases in purchasing power - or pose challenges, such as global warming. In agricultural systems, adaptive pressures include the changing requirements of farmers and the markets they serve, which require adjustments over time in the types of crops cultivated and products offered.
Diversity among and within species is linked to the productivity and stability of ecosystems, including agricultural systems, in several ways. In a smallholder farm or micro-enterprise context, more diverse cropping systems often appear to be both more productive (improved mean incomes) and more stable (decreased variance in incomes, across seasons and years). This is because efficiency increases are possible when different crop species or varieties occupy different production niches (physically and temporally) in the heterogeneous environment typical of small farms. Also, resistance and resilience are generally higher when more diversity is present, because the risks presented by possible environmental and market fluctuations can be spread among different crops and products. Plant species diversity in agricultural ecosystems is also often crucial for the maintenance of the birds, bats and insects that are the principal pollinators of many crops, any decline in which has significant implications for food production, measured in billions of USD annually - witness for example recent concerns about bee population losses in the USA (McNeely and Scherr, 2001).
Complexities in linkages between diversity, productivity and stability in ecosystems
Whilst the interconnections between biodiversity and nutritive, economic and other values can sometimes be visualised in relatively straightforward ways, linkages with ecosystem productivity and stability are often rather complex. In farming systems, the utility of diversity depends on the different production environments of different crops complementing each other. Existing synergies may have evolved over centuries, and new interventions require careful choice of species if complementarities are to be maintained.
Issues to consider include the following:
- Available evidence suggests that, while there is often a positive relationship between species diversity and ecosystem function, this is conditional on the traits (e.g., growth characteristics) of the species in question and the level of environmental heterogeneity present.
- In order to maximise the efficiency of ecosystem processes, interventions are better to focus on the different functions of taxa, rather than the absolute number of species; that is, it may be best to give more detailed attention to fewer species that have optimally complementary traits. In addition, interventions must operate at a geographic scale that matches environmental heterogeneity.
- Although on-farm diversity can generally be seen as positive, its utility depends on how different production activities complement each other: there are instances when higher diversity can result in lower productivity and lower value, even in smallholder farming systems that are typically characterised by high variation. Thus, attention needs to be given to crop complementary when choosing species for cultivation.
- Dealing with many species simultaneously can sometimes lead to a 'lack of focus' for farmers, as accessing current knowledge for the proper management of a large number of crops can be difficult. Dealing with many crops can also lead to larger transaction costs in accessing markets, with volume and processing issues arising for small amounts of a wide range of products. Co-operative action can help overcome these limitations.
Impacts of species promotion on biodiversity
Increased contacts and exchanges of germplasm and knowledge between human populations over the last centuries have resulted in a few dozen crops dominating world agricultural trade (see the classic text of Harlan, 1975). During the Green Revolution of the 1960s and 1970s, a focus on the productivity of major crops led to large increases in yield through plant breeding and associated agronomic practices, and improved food availability for rapidly increasing human populations in the tropics and subtropics. At the same time, however, intensive promotion of a few widely available high-yielding cultivars of these crops has led to significant biodiversity losses in farm ecosystems, with displacement of traditional varieties and other species, and the simplification of human diets. This has been exacerbated by other worldwide trends, such as habitat destruction and extinctions caused by deforestation, increased international commodity trading, substitution of natural with manufactured products, and the consolidation of plant breeding enterprises. Global food security and agricultural incomes currently rely heavily on a few varieties of a very few crops - especially maize, wheat and rice - making humankind vulnerable to social and environmental changes.
Tradeoffs in management
The example of important commodity crops is illustrative of the tradeoffs often faced in agriculture. Greater use of a species often leads to a process of selection for a generally narrow set of characters, coupled with an intensification of production systems that is associated with a tendency toward monoculture and the displacement of other varieties and species.
Effects of selection
Selection by definition results in a narrowing of the genetic base and functional use of a crop, with production therefore becoming increasingly vulnerable to adaptive pressures, such as changes in market requirements or possible disease attack. For those species subjected to intensive selection, sustaining production in the medium- to long-term requires the periodic infusion of new variation from the wider gene pool, including wild relatives, through continual breeding and promotion of new cultivars. Sustaining high performance, therefore, carries the cost of maintaining diversity that is not 'immediately useful' in the production process. Such diversity can be classed as a 'public' or 'social' good, rather than a 'private' or 'personal' one, because the consequences of loss for farmers and wider society may not be experienced immediately. As a result, new ways, often outside 'mainstream' cultivation, may need to be found to maintain this variation; in the case of major crops, this is done partly through significant ex situ 'genebank' collections, which store and regenerate seed and vegetative materials at central locations.
The promotion of high-yielding varieties is often also accompanied by more variable production. This is because of the heightened sensitivity of modern cultivars to the availability of appropriate external inputs such as irrigation, fertilisers and pesticides, and the lack of 'micro-adaptation' to particular local conditions. Modern cultivars may therefore on average perform better than older varieties, but in particular situations, such as extreme events of drought or flood, they may do worse, showing higher variance in yield between 'good' and 'bad' seasons. Additional tradeoffs are therefore sometimes required between average returns and risks of production. For poor farmers who are unable to afford the inputs required to sustain the yields of modern crop varieties, reducing risks by growing older types may be more important than increasing returns, since the results of crop failure are often catastrophic.
Effects of intensification
Intensification of production systems with selected cultivars often leads to the displacement of other varieties of the promoted species, and loss of alternative crops and associated (plant and animal) biodiversity. Donald (2004) describes the process of intensification for a number of tropical and subtropical commodities (cocoa, coffee, oil palm, rice and soybean; see below). He indicates that low intensity cropping systems under alternative management regimes can, however, offer some advantages for both biodiversity and livelihoods. Such systems are more feasible for some species (e.g., coffee) than others, for which economically viable diversity-friendly management options may be rather limited (e.g., oil palm).
Donald (2004) makes the obvious, though often un-stated, point that the extent to which intensification has an impact on biodiversity depends on how degraded the current environment already is. If existing agricultural ecosystems are already low in variation, e.g., if they only contain modern cultivars, further intensification may make little difference to the biodiversity found in the immediate farm environment. In this situation, intensification appears a more appropriate option for farm management than in circumstances where biodiversity in farmland is still high.
Full-sun production of cocoa on large intensive farms in, e.g., Malaysia is generally unsympathetic to landscape biodiversity and has resulted in increased pressures from various pests and diseases, contributing to business collapse. In, e.g., Indonesia, however, traditional small-scale shade-production practices that protect diversity persist, in which part of the forest canopy is maintained during land clearance, or shade trees are planted over cocoa. These practices help prevent disease problems, and the cocoa business has faired better.
Like cocoa, coffee is grown in shade as well as non-shade systems, from almost wild conditions to monoculture. Shade systems that better support landscape biodiversity can help control pest problems and can (because of slower ripening) produce better tasting coffee that can be sold at a premium. In addition, although coffee is partly self-pollinating, yield depends to a degree on the presence of pollinating insects. These are more likely to be found in more biologically diverse landscapes.
Due to the biological characteristics of the crop and the way in which it is generally managed for efficient production and harvest, oil palm cultivation appears to have particularly negative consequences for biodiversity, with limited options available for improvement.
Many traditional varieties of rice were replaced by a few modern selected cultivars in India and elsewhere during the Green Revolution. How rice cultivation is managed has important consequences for biodiversity: flooding paddy fields during the fallow season can provide a habitat for birds, and can help control weeds and diseases. Planting of a more diverse range of rice varieties can be used as a strategy to control rice blast disease, thereby increasing yields, reducing chemical use and providing a friendlier environment for biodiversity. Using a more diverse range of varieties can also contribute to human nutrition, since traditional varieties often have better nutritive profiles than higher-yielding modern types (see also Frei and Becker, 2004).
Large-scale soybean production in locations such as Brazil has displaced smallholder farmers, who have cleared new, previously forested, land. Soybean cultivation has slowed down the development of other more sustainable crop production systems.
Possible interventions for underutilised plant species promotion
As a means of supporting farmers' livelihoods and maintaining and enhancing biodiversity, Jaenicke and Höschle-Zeledon (2006) advocate renewed emphasis on the cultivation of underutilised plants species as agricultural crops, and indicate five 'maximum impact' areas for their promotion:
Generating new knowledge
For example, by studying specific cultural practices for underutilised plants, and through improved determination of important species that producers, processors and consumers are interested in. Also included is further scientific research on: characterising available genetic resources and their value, the genetic enhancement of priority species, how to better maintain genetic and species diversity, how to supply farmers with germplasm, more appropriate crop management procedures; and improved methods for post-harvest handling and processing.
Better communication of knowledge
For example, through more farm demonstration sites, by collecting and disseminating successful promotion stories, by reducing information asymmetries during promotion, through lobbying of policy makers and other influential interest groups, by more targeted media campaigns, and through the continued development of school curricula that promote underutilised crops.
Better policies to remove barriers to production and marketing
For example, by initiating national dialogues on underutilised crops, by promoting policies that enhance access to existing and new markets (e.g., through less costly certification schemes and by the reduction of other non-tariff barriers), and through better protecting farmers' intellectual property rights to local knowledge on taxa.
Improved market development
For example, through increased entrepreneurial training to support value chain development, by fostering more public-private partnerships, through organising buyer-supplier fora, through demonstrations and trade fairs, by promoting credit and grant schemes for marginalized stakeholders, and by carrying out more market surveys on preferences, risks, compatibilities, etc.
Better partnerships amongst all stakeholders
For example, through further encouraging strategic alliances on underutilised crops, by promoting multidisciplinary research teams and regional networks, and by strengthening relationships among all participants in value chains.
The relationships between markets and diversity for three crops
Important in understanding how current agricultural practices impact on biodiversity is the relationship with markets. Nill and Böhnert (2006) reviewed the work processes and actors involved in the production, processing, trade and end consumption of three species grown in low income countries - potato, coffee and argan oil - and assessed development opportunities and biodiversity implications of different value chains for each. The results for each crop are summarised below:
Potato in Peru
Around 2,000 varieties of potato are grown in the Peruvian Andes, a centre of diversity for the crop. Potatoes cultivated in Peru enter different value chains: for immediate fresh consumption, in the form of traditionally processed preserved potato (e.g., chuño and tunta, for 'bitter' varieties); and for industrial processing (e.g., into chips and crisps). All three chains can support farmer livelihoods, but only the first two make any noteworthy contribution towards the conservation of biodiversity. Local markets for immediate fresh consumption contain many different varieties, while traditional products are made from several dozen types, which are generally grown by smaller farmers. Only a few varieties of potato are, however, considered suitable for industrial processing nationally. This market is generally supplied by bigger farms, which can meet large volume requirements. Market measures to support potato diversity include the sale of mixed varieties as branded products in Peru's biggest supermarket chain, and the organisation of farmers into groups to supply such products.
Coffee in Ethiopia
Several hundred 'arabica' types of coffee grow in their centre of origin in Ethiopia, where most production centres on smallholder plantations, though some coffee is collected directly from the wild and from mixed wild-cultivated systems. Support measures for coffee production from the 1970s initially involved activities such as the breeding of disease-resistant varieties and the development of centralised washing stations. These measures have not, however, been able to maintain farmer incomes during periods of coffee oversupply on the world market. More recently, emphasis has been placed on increasing quality and promoting access to specialised global markets, including through various certification initiatives (e.g., through Fair Trade and the Rainforest Alliance). These activities support community organisations and use the uniqueness of Ethiopian arabica types, and certified adherence to social and ecological standards, as selling points to achieve higher prices. These measures target poverty reduction measures to smallholder producers, and help conserve the diversity of the arabica types that these farmers' manage.
Argan oil in Morocco
Argan oil is pressed from the nut of the argan tree that grows in the Arganeraie region of Morocco. The oil is a premium product for food use and skincare, and is traded locally, nationally and internationally. However, argan populations are being reduced through inadequate regeneration and deforestation. Argan oil can be produced both by hand-extraction and mechanical pressing: in the first case, harvesting and oil extraction are undertaken in rural areas, whereas in the latter case rural communities only collect the nuts for processing elsewhere. Measures implemented to help rural communities in production include training local women in processing, helping them to organise into groups, and the establishment of new argan stands. Through certification and partnership with international buyers, higher prices will be achieved, while new plantings based on improved markets, and the recognition of the Arganeraie as a UNESCO biosphere reserve, will facilitate conservation of the species.
Conclusions and recommendations for UPS promotion
Incorporating more biodiversity into farming systems should not be seen as an end in itself - that is, simply for conservation purposes - but as an important intervention that brings benefits to rural communities in improved livelihoods and in a better living environment. Supporting biodiversity, such as through the promotion of underutilised crops, requires both proactive and reactive measures, i.e. promoting the introduction of new biodiversity into farms, and ameliorating ongoing biodiversity losses.
The relationships between biodiversity and outcomes that are important for farmers can be complex. Certain tradeoffs are often necessary, and the promotion of any one species or variety can have implications for wider landscape diversity that may be negative, and that are sometimes difficult to predict and prevent. To minimise any negative consequences of promotion, activities should generally focus on those species for which diversity-friendly management systems are at least conceivable. Intervention should also normally take a 'spear and shield' approach, in which, while certain (or even just one) crop may be the focus of concerted action, the use of a much wide range of other species is also promoted at the same time in 'piggy-back' fashion.
The practices, innovations and experimentation of the poor depend upon the particular range of limitations and opportunities that they face, but activities centre on improving the livelihoods of their families and communities. Practical experience shows that germplasm availability and market access are crucial factors in determining what is planted on farms. Key interventions to support diversity therefore include improving access to planting material and associated knowledge for a variety of species and cultivars, and the development of 'intelligent markets' for a wide range of products.
Brush S (2004) Farmer's Bounty: Locating Crop Diversity in the Contemporary World. Yale University Press, New Haven, USA. 327pp.
Donald PF (2004) Biodiversity impacts of some agricultural commodity production systems. Conservation Biology, 18, 17-37.
Frei M, Becker K (2004) Agro-biodiversity in subsistence-oriented farming systems in a Philippine upland region: nutritional considerations. Biodiversity and Conservation, 13, 1591-1610.
Harlan JR (1975) Crops and Man. The American Society of Agronomy and the Crop Science Society of America, Madison, Wisconsin, USA. 295pp. (1985 reprint.)
Jaenicke H, Hschle-Zeledon I (eds.) (2006) Strategic Framework for Underutilised Plant Species Research and Development with Special Reference to Asia and the Pacific, and to Sub-Saharan Africa. International Centre for Underutilised Crops, Colombo, Sri Lanka and the Global Facilitation Unit for Underutilized Species, Rome, Italy. 33pp.
McNeely JA, Scherr SJ (2001) Common Ground, Common Future: How Ecoagriculture can Help Feed the World and save Wild Biodiversity. The World Conservation Union, Gland, Switzerland and Future Harvest, Washington, USA. 24pp.
Nill D, Bhnert E (2006) Value Chains for the Conservation of Biological Diversity for Food and Agriculture. Potatoes in the Andes, Ethiopian Coffee, Argan Oil from Morocco and Grasscutters in West Africa. Deutsche Gesellschaft fu_r Technische Zusammenarbeit, Eschborn, Germany and the Global Facilitation Unit for Underutilized Species, Rome, Italy. 78pp.
This article was excerpted with the kind permission of the authors from:
Dawson, I.K., Guarino, L. and Jaenicke, H. 2007. Underutilised Plant Species: Impacts of Promotion on Biodiversity. Position Paper No. 2. International Centre for Underutilised Crops, Colombo, Sri Lanka.
About the authors
Ian K. Dawson is interested in optimising the use of underutilised plant species in farm systems through better management of genetic and species diversity. He has a particular interest in tropical tree crops. He works as a consultant from his base in the UK.
Luigi Guarino has been involved in the conservation and use of plant genetic resources, including of underutilised species, for a number of years. He is currently doing so at the Global Crop Diversity Trust.
Hannah Jaenicke has been interested in the effect of promotion on biodiversity since working on the vegetative propagation and domestication of indigenous trees in the 1990s. She is the Director of ICUC. Contact Hannah at Tel: +94-11-2880193; e-mail: firstname.lastname@example.org; Web: http://www.cropsforthefuture.org/