Agrobiodiversity and its conservation are highly relevant to informal seed systems, simply because these systems maintain a large amount of local crop genetic diversity. The first section of this chapter introduces biodiversity and agrobiodiversity as concepts, outlines various conservation strategies and relates these to linking formal and informal seed systems. The section elaborates how interventions in crop development (plant breeding, seed supply) can contribute to the conservation strategy referred to as ‘farmer/community agrobiodiversity management’ when they focus on informal seed systems and farmers’ use of local varieties. Interventions which take this approach go beyond a conservation ethic to a diversity-oriented one that stimulates the dynamic use of genetic diversity and promotes the adaptive capacities of agricultural systems.
Biodiversity
During the last few decades we have begun to realise that we are losing the wealth of living forms on our planet, and that we cannot foresee what the consequences of this loss will be. Particularly in agriculture, this biodiversity is partly shaped by human activities, as we use and further develop the biological resources that we encounter. In the course of these processes, biodiversity has always evolved with continuous gains and losses. The difference now is that we realise that the balance has turned negative.
Three levels of biodiversity are generally distinguished: genetic diversity, species diversity, and ecosystems or landscape diversity. Genetic diversity can be found at the basic unit of inheritance, the DNA. It is found in the chromosomes and controls the genetic identity of all living individual organisms. Genetic diversity refers to the variety of genes in all organisms from human beings to crops, fungi and viruses. Species are organisms that are closely related, are one distinct morphological unit, and mate to produce offspring. Species diversity therefore refers to the diversity among species: different plants in a forest, fungi in the soil, fish in the river, and plant species in the garden. Ecosystem diversity is both the sum and product of the other two levels of diversity. The diversity of species and different populations within species constitute a natural community that has developed or evolved in a physical (dry, cold, wet, hot, fragile, poor or rich) environment. The scale of ecosystem diversity is important as
one square meter in a forest can be considered an ecosystem, but so can the entire Rift Valley or Indian Ocean. Ecosystem diversity is thus a relative term: it is the diversity among systems. It places that one square meter in the forest in its broader environment, and puts the Rift Valley or the Indian Ocean in the ecosystem that we call the Earth.
Biodiversity in agriculture
These terms were developed in the field of ecology, which studies the relations between the different levels of diversity. The three levels can also be applied to biological diversity in agriculture, where we can distinguish between: varietal and other genetic diversity, crop, animal and other species diversity, and farming systems or agro-ecosystems diversity.
Genetic diversity in agriculture encompasses the many varieties of crops and breeds of animals, and can be very specific (e.g. a sweet potato variety with a very specific taste and use). Genetic diversity can be distinguished using different scales. It can refer to a population or group of varieties within a species; it can be a genetic pool or population in a certain crop (e.g. an early maturing local maize variety). Species diversity in agriculture relates to the different species that we use in agriculture, covering crops, animals and fungi. But it can also mean the diversity of crops found on one farm, the diversity of cereal crops as a category, or the diversity of all food crops. So different scales apply here too. A farming system can mean one farm or an entire region. A farm in the Ethiopian Highlands has a very different level of diversity to that of the rift valley in the Awassa region or a polder in the Netherlands.
One element very strongly distinguishes agrobiodiversity from natural biodiversity. Agriculture is a way for humankind to use its natural biological and physical resources to feed itself, to cure, to construct shelter, to make clothing, and to generate income. The role of humans – farmers – in the development of diversity in agriculture is very important. Many different agro-ecosystems, crops and varieties can be found all over the world. It is not only the natural conditions which have contributed to this diversity; human diversity has contributed enormously too. Some people therefore consider human diversity, with social and cultural elements, to be a fourth level of diversity, which encompasses farmers’ knowledge and practices regarding how to grow crops, their medicinal purposes, etc.
Loss of natural biodiversity
Biodiversity has never been and never will be static; it fluctuates as evolution adds new species, and extinction takes them away. Evolution and extinction are natural processes; they are the responses of populations of organisms to changes in their physical and biological environment. Change is, in a very real sense, a basic fact of life. However, the loss due to environmental changes occurring today is different in origin, order and magnitude to those recorded before. The current loss has several causes including the following:
• Direct destruction, conversion, or degradation of ecosystems result in the loss of complexes of different species;
• Over-exploitation, habitat disturbance, pollution, and the introduction of exotic species accelerate the loss of individual species within ecosystems;
• Selection pressures arising directly and indirectly from human activities can result in the loss of genetic variability;
• Exploitation, pollution or regional climate change may eliminate some genetically different parts of a population yet not cause extinction of the entire species though a part of its genetic variation;
• The accelerating rate of habitat destruction, particularly in tropical forests.
Loss of biodiversity in agriculture
Similar processes erode the biodiversity in agriculture as in nature, with humans playing a prominent role. However, humans can also play a more direct role in the maintenance of agrobiodiversity, to which they are a very active contributor. Loss of biodiversity in agriculture takes place at the three levels. Farming and agro-ecosystems change; crops are abandoned or marginalised. Most prominent in agriculture is the process we call genetic erosion, or the loss of genetic diversity.
The process of replacement of local, indigenous, traditional varieties or landraces by modern, high-yielding varieties is often equated with the loss of genes, and is called genetic erosion. However, the agricultural processes must be examined with respect to the loss of genes, gene combinations, or allelic forms. Gene replacement occurs when local varieties are replaced by introduced ones. Genetic erosion can be seen in two forms: genic or allelic erosion and genomic erosion. Replacement of landraces by new ones within a crop causes a dramatic change; there is complete replacement for those alleles which differ between the local and the new one. The replaced alleles are lost or eroded if they are not conserved, maintained or used elsewhere. Also lost is the specific combination of genes that occur in the replaced variety.43
Apart from the physical loss of allelic forms, gene combinations, genes or local or farmers’ varieties, knowledge about specific crops and varieties is threatened by a similar process of erosion. The development of modern agriculture leads to globalization of agricultural practices, eroding local skills for managing and using specific crops or varieties. Monica Opole44 from Kenya in Africa refers to women in
the rural area of her country who now send their daughters to school where they learn how to grow tomatoes and cabbage to be good modern mothers and farmers. Yet the mothers have started to realise that they are no longer taught about indigenous leafy vegetables, so that knowledge about important plants which are plentiful on and around the farm is gradually lost – and not only the knowledge of the species, but also the knowledge of their special medicinal and culinary properties, and ways of processing and preparing them.
Another form of genetic erosion occurs at the intermediary level in between agriculture and nature. In centres of origin and evolution, most crops still have related wild and weedy species. Where crops are grown in the direct environment of these non-domesticated species, some introgression may occur. The maize-teosinte complex in Mexico is an example of a system in which a wild relative grows in the neighbourhood of the crop. Various researchers have investigated this interaction,
looking for specific characteristics of the local maize varieties which may originate from the wild teosinte plants. Through modern plant breeding and biotechnology, all related plants to a crop species may be a source of important traits for breeding in the future. Due to destruction of specific habitats, such wild relatives of important crops may disappear.
Conservation strategies
Writers on biological conservation define it as the effort to maintain the diversity of living organisms, their habitats and the interrelationships between organisms and their environment.45 These authors stress that conservation is not just about individual
plant and animal species, but also includes all aspects of biodiversity which form ecosystems. Conservation practices in recent years can best be identified by approaching biodiversity either from the ecosystem or from the genetic perspective. In nature conservation, interest is mainly focused on conservation at the habitat and ecosystem level, while for agricultural biodiversity, the main focus has been on conserving genetic diversity. Less progress has been made in the development of an overall system for genetic conservation that approaches biodiversity at the three levels, and also covers the human component in agrobiodiversity.
Conservation of crop genetic resources has been approached through two ultimately complementary strategies which approach biodiversity from the ecosystem and from the genetic level. The two strategies are differentiated according to where the conservation activity takes place. Ex situ conservation means the conservation of components of biological diversity outside their natural habitat, while in situ conservation means the conservation of ecosystems and natural habitats and the maintenance and recovery of viable populations of species in their natural surroundings and, in the case of domesticated and cultivated species, in the surroundings where they have developed their distinctive properties.46
Ex situ conservation
Ex situ conservation of plant genetic resources is effectuated through genebanks,
which store samples of seeds or other plant materials under controlled conditions of temperature and humidity, mostly in refrigerators and deep freezers for medium (4˚ C) to long term (-20˚ C) storage. The aim is to conserve as much as possible of the existing genetic diversity, ensuring its availability for future generations. Materials are collected through plant exploration and are briefly described (passport data) before being stored. The techniques for ex situ conservation are generally considered appropriate for the conservation of crops, crop relatives and wild species. The conservation of germplasm in field genebanks is another version of the ex situ strategy. It involves collecting of material from one location and transfer and planting of the material in a second site. It is usually the answer for the seeds of species such as rubber, coffee, banana, cassava, sweet potato and yam, which cannot be dried and frozen without loss of viability.
Over the past few decades, genebanks have proved vulnerable to several problems, including failing infrastructure (electricity cuts), under-funding and political instability. There are very sad stories of, for example, the genebank of the Rice
Research Station in Sierra Leone in West Africa, which was deliberately destroyed by bandits. In many genebanks the germination rate of accessions now falls well below the internationally agreed acceptable level of 85%. This is the case, for example, with the famous collection of the genebank of the Vavilov Institute in Saint Petersburg in Russia.
An important characteristic of genebanks is that they ‘freeze’ evolution or local crop development because genotypes are taken from their original environment and are no longer subject to the continuing adaptation to changing environment conditions and farmer selection. If properly stored, genebank accessions can be reproduced with little change after a long period of conservation. Yet, if the same population had been allowed to survive in situ or on the farm where it was collected, it might have undergone considerable evolution or crop development. Ex situ conservation also misses elements which may be essential for the future because the germplasm in farmers’ fields co-evolves with diseases and pests, changing farming systems and climatic conditions.47
The information on accessions in genebanks is rather limited or inaccurate. The quality of the material stored is not only dependent on its viability but also on the availability of information on the material being stored. Passport data rarely include characteristics described by farmers or refer to the ecological conditions from which the material originates. Plant explorers often spend only a few minutes on each sample they collect. There is no time to chat with farmers and record their knowledge. The bond between the farmers or users’ knowledge and the biological material is thus broken.
Genebanks have also been criticized in the global debate on property rights in relation to genetic materials. For local communities, ex situ genetic resource collections are effectively extinct. Material kept in the genebank is made available to plant breeders and researchers, but not to the farmers and communities it came from.
Another issue related to property rights is the question of whose property the material is. According to the Convention on Biological Diversity,46 national states
have the sovereign rights over biological resources. This may be in direct conflict with the interests of local communities. They may choose to maintain their germplasm themselves or to give them to governmental genebanks under a black box agreement. In such an arrangement, the material is stored in the formal storage facility, while documentation remains with the owner, and material can only be taken out with their authorization. Such arrangements have developed to counterbalance the rise of intellectual property rights over genetic materials. It is alien to most open mechanisms of seed variety exchange in informal seed systems.
In situ conservation
In situ conservation as defined above aims at leaving species in their natural habitat,
allowing adaptation and evolution to continue. This strategy has been adapted from those used in nature conservation. In the conservation of agricultural biodiversity, in
situ conservation is specifically used to conserve semi-wild species or the wild relatives
threat. These habitats can be natural, but may also have a clear human management component.
An example of such human involvement in in situ conservation is the conservation of grasslands or pastures. In situ conservation may imply that the grazing intensity of such pasture is managed in such a way that certain populations of wild species remain. Stopping grazing could cause other more competitive species to erode the target species. The GEF project on in situ conservation in Turkey aims to establish gene management zones or genetic reserves in areas that are rich in the targeted wild species related to the crops. This project works on the conservation of wild wheat species, for example, and its methods include controlled grazing, mowing or fire management to discourage perennial species, especially perennial grasses, from displacing the annual wild wheat relatives.48 Another example of in situ conservation is
the national coffee conservation programme of the Biodiversity Institute in Ethiopia. A special effort is being made to conserve the semi-cultivated coffee by small-scale farmers in areas, where forest coffee occurs spontaneously. This complements field collections now being maintained in a field genebank.49
Conservation by farmers or farmer management
Another approach associated with in situ conservation entails the conservation of local varieties by farmers. In farmer management of genetic resources, the farming system or agro-ecosystem is considered the habitat where the genetic diversity originates from. People from conservation programmes tend only to consider such farming systems as important if the crop developed in that habitat (the centre of origin), as in the earlier mentioned definition of the Convention on Biological Diversity for in situ conservation. This approach was the subject of discussion in the 1990s, and has been recognized by the CBD and the FAO. It recognizes the role that farmers play in complementing ex situ conservation strategies. It is evident that maize has its origin in Mexico and Guatemala, but this does not mean that local diversity developed in the Horn of Africa or Brazil is irrelevant. This conservation strategy emphasizes the maintenance and continued use of this diversity. The same counts for example for bean and cassava diversity (both with an origin in South America) that is encountered in Africa: the conservation and use of this diversity by African farmers is valued and supported by this strategy.
Farmer management of genetic resources involves the maintenance of crop varieties or cropping systems by farmers within local agricultural systems. On many farms, especially in marginal production environments, local varieties or landraces are sown and harvested; each season the farmers keep some of the harvested seed for re- sowing. Thus the local variety is continuously grown in the specific production environment of the farmers. It is highly adapted to the local environment and is likely to contain locally adapted alleles. On-farm conservation has been a concept developed by conservationists rather than an objective of farmers. It is therefore important in this context that farmers become more active in the process of crop development. Hardon and De Boef50 conceptualized local crop development as the complex of
maintenance, utilization and improvement of crop genetic diversity by farmers; it is a continuous and dynamic process in which farmers manage crop diversity within
specific agro-ecological and socio-economic environments. Elements of local crop development are exchange of varieties, their maintenance and utilization, their enhancement and seed multiplication, processing and storage. It is built on farmers’ knowledge and capacity to innovate with germplasm and seeds.
Conservation by farmers builds on the dynamics of local crop development, which anchor it in space and time. Different components of the seed system (e.g. seed source, seed flow, seed production, farmer selection, seed processing and storage) can (but do not necessarily) contribute to gene flow, migration, selection, mutation, and recombination. They constitute examples of adaptive processes that contribute to viable agricultural systems, and their contribution is highly context-dependent.14 We
have to realize that farmers’ management within the informal seed system changes continuously, like the biodiversity or the genetic diversity itself; this dynamic is the critical point within this ‘conservation strategy’. Here lies the relevance of interventions in the name of conservation strategies to this book about farmers’