Farmers' practices, metapopulation dynamics, and conservation of agricultural biodiversity on-farm: a case study of sorghum among the Duupa in sub-sahelian Cameroon

In many traditionally managed agroecosystems, populations of domesticated plants maintain high levels of genetic diversity. The threat of erosion of this diversity is a current conservation concern, motivating studies of how diversity can be maintained by in situ conservation measures. Precisely how the biological traits of plants and the cultural practices of farmers act on fundamental evolutionary forces - drift, migration, selection, and mutation - to create and maintain crop plant diversity has been little investigated in detail. We develop some elements of the framework required for studying such biocultural interactions, focusing on one component of management: farmers' decisions on what to plant, and the structure of germplasm exchange among farmers. We illustrate the approach with a study of Duupa farmers in northern Cameroon. Our results suggest that sorghum populations managed by the Duupa function like source-sink metapopulations. Fields of older farmers, larger and containing a greater number of varieties, act as sources, whereas fields of younger farmers act as sinks, becoming sources as their owners mature. In each field, seeds for sowing are selected from a small number of plants. The frequent exchange of germplasm among fields may counteract the genetic bottlenecks associated with the small number of genitors within each field. Identifying key processes and key individuals should facilitate the design of in situ conservation measures to maintain crop plant diversity against the threat of genetic erosion.     

Towards a methodology for on-farm conservation of plant genetic resources

The signing of the Convention on Biological Diversity at the ``Earth Summit' in 1992, its ratification and its subsequent entering into force have highlighted the need for an approach to biodiversity conservation that employs both ex situ and in situ techniques in a complementary manner. Though much research has focused on ex situ techniques, less progress has been made in developing methodologies for the conservation of genetic diversity in situ. The definition of in situ conservation used in the Convention on Biological Diversity encompasses two distinct processes: conservation of wild species in genetic reserves and of crops on-farm. Of these two, the latter, where the genetic diversity of crop land races is conserved within traditional farming systems, has been the less studied and remains less well understood. While there are still relatively few practical examples of on-farm genetic resources conservation, most genetic diversity of immediate and potential use to plant breeders is found among land races, and there is evidence that it is being rapidly eroded. This paper attempts to set on-farm conservation within the context of plant genetic resource conservation as a whole, to introduces a possible generalised model for the conservation of genetic diversity on-farm and to promote debate around the science of on-farm conservation.     

Towards the conservation of crop wild relative diversity in North Africa: checklist,prioritisation and inventory

Crop wild relatives (CWR) are wild species that are more or less genetically related to crops that can be used to introgress useful genes for improvement of productivity, resistance to biotic and abiotic stresses and quality of cultivated crops. They are important in crop improvement to achieve food security for an increasing population and to overcome the challenges caused by climate change and the new virulence of major diseases and pests. These genetic resources are increasingly threatened in their natural habitats through over-exploitation and land reclamation and degradation. Therefore, their efficient and effective conservation would be taxonomically and genetically valuable and will contribute to maintaining and promoting the sustainability of crop diversity, facilitating agricultural production and supporting the increasing demand for food, feed and natural resources. A checklist of 5780 Crop Wild Relatives (CWR) taxa from North Africa was obtained using the CWR Catalogue for Europe and the Mediterranean (PGR Forum). Of which consists 76% of the flora of North Africa. The checklist contains 5588 (~97%) native taxa and 192 introduced. Families with higher taxa richness are Fabaceae, Asteraceae, and Poaceae. These three families constitute more than 33% of the total taxa included in the checklist. About 9% (502) CWR taxa identified as a priority for conservation in North Africa using four criteria, the economic value of the crop, the relatedness degree of wild relatives to their crop, threat status using IUCN red list assessment, and finally the centre of origin and/or diversity of the crop. Of these, 112 taxa were assigned high, 268 medium and 122 low priorities for effective conservation. Those assessed as threatened using IUCN Red list and national assessment represent approximately 2% (119 taxa) of the CWR in the region. However, 21 taxa are assessed as critically endangered (CR), 53 as endangered (EN), and 45 as vulnerable (VU). Wild relatives of some globally important crops are present, with those related to wheat (Triticum aestivum L. and T. durum L.) and barley (Hordeum vulgare L.) among the highest priority crops for the North Africa region. Amongst CWR assessed as threatened, only 8 (6.7%) CWR are related to food crops, Avena agadiriana B.R. Baum. et G. Fedak (VU), A. atlantica B.R. Baum et G. Fedak (VU), A. murphyi Ladiz. (EN), Beta macrocarpa Guss. (EN), Olea europaea subsp. maroccana Guss. (VU), Rorippa hayanica Maire (VU) and Aegilops bicornis (Forssk.) Jaub. et Spach (VU). The wild relative of Safflower Carthamus glaucus M. Bieb is restricted to Egypt and Libya and assessed as rare in Egypt. The information available about the conservation and threat status of CWR in North Africa still lags behind, and more investigations are required.     

Role of informal seed system in promoting landrace diversity and their on-farm conservation: a case study of rice in Indian Himalayas

Role of informal seed system in landrace diversification, in situ conservation on-farm and sustainability in production were investigated as a case study for rice diversity in Indian Himalayas. The diachronic pattern of landrace occurrence revealed substantial increase, both in landrace number and frequency, in time. The local level seed supply in Uttarakhand Himalaya revealed that about 96% seed supply originated from informal system and a mere 4% seed supply is met from formal seed supply networks. In higher elevation ranges, beyond 1200 masl, largely landrace cultivation is practiced and a greater landrace diversification in traditional production was observed. Substantial variations due to environmental adaptations in niche habitats help provide important donor germplasm for crop improvement to users. Further, the population genetic structure also indicated enough diversity being maintained on-farm. Developing pathways for strengthening local level seed system for landrace diversification linked to sustainability in food production and conserving agro-biodiversity has been emphasized.     

Phaseolus genetic diversity maintained on-farm in central Italy

Thirty-one Phaseolus vulgaris L. and fivePhaseolus coccineus L. landraces reproduced on-farm werefound in central Italy. They were mostly grown by elderly farmers who usuallyselect for a certain type of seed. Different varieties are often grown in eachlocation and on each farm. They are maintained on-farm because of a local marketrequest for high quality products or because of sticking to traditional familyuse in cooking (21.2 and 75.8% of recorded cases, respectively). Three AFLPprimer combinations were used to assess genetic variation among collectedmaterials, a wild accession of P.vulgaris and commercial varieties of both species. Theyrevealed a quite high percentage of polymorphism (90.2% of polymorphic bands asan average). A wide genetic variation was observed among collected materials andeach accession showed a unique pattern of polymorphism. WithinP. vulgaris, landraces werediscriminated in two main subgroups, the former including the accessions fromthe Mediterranean area around the Lake Trasimeno and the latter includingaccessions from the humid Mediterranean area within the Appennine Mountains.These findings demonstrate the peculiar genetic identity of the landracesstudied also in relationship to human and environmental selection pressures.Possible on-farm conservation strategies are briefly discussed in relationshipto the information collected.     

Proposal to make the island of Linosa/Italy as a centre for on-farm conservation of plant genetic resources

In view of the remarkable interest of the flora, vegetation and landscape of Linosa island, a natural reserve should be suggested including protection of the traditional agriculture. Especially for the last aim completely new ways have to be elaborated. An integrated approach of nature protection and on-farm conservation could be the ideal conclusion.     

Use of a three-compartment model to evaluate the dynamics of cover crop residues

Cover crop (CC) residues protect the soil from erosion and their permanence on the surface is largely influenced by their biochemical constituents. In this study, the dynamics of CC residue decomposition by applying mathematical models was described. The kinetics of decomposition of residues was obtained from a laboratory incubation experiment. Three CC shoot residues were applied on the soil surface and incubated for 362 days (with eight sampling times). Oats and vetch residues decomposed the most than clover, where k values were 3.6 × 10^?3, 3.7 × 10^?3 and 5.3 × 10^?3 day^?1, respectively. The three-compartment model (nonstructural carbohydrates, cellulose–hemicellulose and lignin) to simulate residue decomposition presented a close fit between simulated and measured data. The decomposition rate constant (k) of CC can be used to estimate how long residues will remain in the field and how they could affect soil organic carbon.     

Macro-nutrient uptake dynamics in greenhouse tomato crop

This study verified the concentration over time of nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur (N, P, K, Ca, Mg, and S) in the leaves, stems, fruits, and roots of tomato plants. An indeterminate growth variety with ball-type fruits suited for greenhouse cultivation was used. The results showed that the distribution of minerals in the different organs of the plant varies over time. The minerals N, P, and K showed a tendency to decrease their concentration, while the concentration of Ca and S increased and that of Mg remained constant over time. The leaves had the highest concentrations of N, P, K, Ca, and Mg. The concentrations of K, for both leaf and stem, ranged between 20 and 30 g kg^?1. N and K were the most extracted minerals, while P was the least extracted mineral. The information presented in this paper allows a better fertilization plan for growing tomatoes inside greenhouses.     

Trade-offs between on-farm varietal diversity and highly client-oriented breeding — a case study of upland rice in India

On-farm varietal diversity is now highest in marginal agricultural environments because, unlike the case in more favourable areas, modern varieties have not been a sufficiently attractive option for farmers to replace their landraces. However, the continued survival of landraces on farm is dependent on the continuing failure of plant breeding to provide better alternatives. Highly client-oriented breeding can produce suitable modern varieties for areas that were dominated by landraces. We examine here the case of the adoption of two upland rice varieties in three states in eastern India, Jharkhand, West Bengal and Orissa, where our surveys had confirmed low adoption of modern varieties in the upland ecosystem. The two new upland varieties were readily accepted by farmers who rapidly adopted them on large proportions of their land. On-farm diversity is maintained by the need to trade-off among varieties but once a variety with overall superiority was found this incentive was removed. The new varieties from the client-oriented breeding did not have weaknesses that farmers had to trade-off against their landraces so they were more likely to replace them. They also replaced older modern varieties. Farmers had previously maintained them along with landraces because they had to trade-off the higher yield of Kalinga III against the more stable yield of landraces or the higher yield of Vandana against the higher gain quality of the landraces. Only mean count per household could be used to test the significance of the differences between individual years. In all states, this revealed a significant reduction in landrace diversity with the adopting farmers when the addition of the two new varieties was not considered. Trends across years for mean varietal count, total count and Shannon–Wiener index showed a significant decline in Orissa, irrespective of whether the two new varieties were included in the analysis or not. In Jharkhand there was a significant decline only for mean count when the new varieties were not included. In Orissa, it was possible to test if rare landraces were as readily replaced as more common ones. Landrace replacement was unmitigated by increasing rarity yet the most rare landraces have the highest priority for genetic conservation. Some landraces were completely replaced by the farmers in the sample despite a diverse variety portfolio being a risk-reducing strategy in a region where there is a high risk of crop failure. There was little environmental heterogeneity in the marginal, drought-prone areas to slow this decline. The new varieties had an impact on the farming system because sometimes farmers brought additional upland into cultivation. They also introduced these varieties into more favourable, medium land. The strategy of releasing two new upland varieties met with some success in maintaining diversity.     

Ameba community dynamics and diversity in a desert ecosystem

A field study was conducted to monitor the effect of different desert shrub ecophysiological adaptations on the composition, size, and diversity of soil free-living amebae. Population diversity was also analyzed using four morphological types. Samples were collected seasonally under the canopy of the common desert shrubs Artemisia herba alba, Reaumuria negevensis, and Noea mucronata. Control samples were taken from exposed interspace areas between shrubs. The composition and diversity of the ameba population were significantly affected by both season and plant species. Types 3 and 4 amebae were found to create a complementary system of adaptation in which type 3 was resistant and adapted to the harsh environment, whereas type 4 was much more vulnerable and existed for short periods of time when the environment allowed. The Reaumuria negevensis ecophysiological adaptation had a negative effect on type 4 amebae by creating a stressed environment.     

Effects of conservation education on reasons to conserve biological diversity

To examine factors that might influence how people subscribe to different reasons for conserving biological diversity, we modified Ehrenfeld's [American Scientist 64 (1976) 660] classic reasons for conserving species and habitats into consumption, tourism, medicine, science, education, environmental baselines, ecosystem services, intrinsic value, and added another, human cultural heritage. We then explored the opinions of undergraduates enrolled in a classic conservation biology course, or a people and conservation course, about these nine arguments, using a 27-statement questionnaire. By matching responses made before and after each course, we found that students, in general, became more committed to using most of Ehrenfeld's arguments but that this was highly contingent on which conservation course that they had taken. None became committed to the argument that linked wildlife conservation to human culture, however. Course and grade that students attained influenced the extent to which students were sympathetic to different arguments but gender had no effect. These findings show that the type of conservation knowledge imparted to students makes them differentially sympathetic to many of the arguments used to advocate wildlife conservation.     

Development of national crop wild relative conservation strategies in European countries

To generate European-wide information to contribute to the improvement of national and regional crop wild relative (CWR) conservation planning and the development of effective CWR conservation strategies, a questionnaire was sent to the members of the Wild Species Conservation in Genetic Reserves Working Group of the European Cooperative Programme for Plant Genetic Resources (ECPGR) to collate information on progress in developing and implementing national CWR conservation strategies and action plans. Responses from 30 countries were analysed and literature sources were consulted to fill some information gaps. Results showed that 13 countries were in the preparation stage of their national strategies, i.e. having no drafts prepared yet, 14 in higher stages (from the first draft prepared to the published and approved ones), and three have not yet started the planning process. Twelve countries included all categories of species autochthony (i.e., native, archaeophyte and neophyte) in their priority CWR lists. Wild relatives of human and animal food crops were selected as the highest priorities by 23 and 22 countries, respectively. Relative level of threat was identified as the most important prioritization criterion by 23 countries. Italy reported the highest number of CWR in its national checklist (10,779 taxa) and priority list (1118 taxa), whereas Ireland reported the lowest number of CWR in its checklist (171 taxa) and Portugal reported the lowest number in its priority list (20 taxa). Regarding the percentages of prioritized CWR, the strictest approach was applied in Portugal—only 20 out of 2262 CWR taxa, or < 1%, were selected as priorities for conservation action, whereas in Spain 578 out of 929 CWR taxa, or about 62% were prioritized. Eleven countries have proposed the establishment of genetic reserves, from one per country (Israel) to an extended network (Germany and the Netherlands). Only the UK had a formally established genetic reserve. The highest number of priority CWR taxa that occur in existing protected areas was reported by Spain—472 species, or 82% of the national priority list, whereas the lowest number—14 species, or 70% of the national priority list—in Portugal. Israel reported the highest number of priority CWR taxa (319 or 98%) conserved in gene banks. Among the limitations in the development of national CWR strategies highlighted by countries, was the lack of an EU agency responsible for genetic resources. The development of CWR conservation strategies is mostly within the domains of agriculture (13 countries) and environment (12 countries), although both domains are involved in eight countries. The most successful results in the development and implementation of CWR conservations strategies are achieved in the countries where multiple stakeholders, including ministries, research institutions, NGOs, local communities, protected area authorities and national PGR committees are involved. Some discussion and conclusions regarding further developments are provided.     

Setting conservation priorities for crop wild relatives in the Fertile Crescent

The aim of this paper is to contribute directly to the systematic, long-term conservation of crop wild relatives (CWR) in the Fertile Crescent by setting conservation priorities to secure and improve CWR conservation in situ and ex situ as a means of underpinning global food security. We established the first priority list of CWR within the Fertile Crescent following several criteria comprising production value (m × p), projected production value (m × p), production area (ha), projected production area (ha), native status, energy supply (kcal/capita/day), protein supply (g/capita/day), fat supply (g/capita/day), occurrence status, gene pool, taxon group, and threat status. An inventory of 220 priority CWR was established for the Fertile Crescent region. We followed twelve prioritisation approaches and assessed 21,080 species. About 4% of the total species (835 species) were identified as CWR that have socio-economic value for the region. These 835 CWR species were prioritised to create the CWR priority list which consisted of 220 species (1% of the total species assessed). The majority of the CWR priority list (185 species) were related to cereal, vegetable, and industrial crops and 35 of them are related to fruits and trees. The CWR priority list includes crop wild relatives of the genera Aegilops (20 species), Lactuca (11 species), Avena (11 species), Carthamus (11 species), Allium (9 species), Thinopyrum (10 species), and Triticum (3 species). We present the first inventory of 220 priority CWR for the Fertile Crescent. The inventory helps to improve in situ and ex situ conservation and the genetic diversity of CWR. Both the inventory and the methodology applied in prioritisation can be used in setting national, regional, and global conservation strategies. The recommendations will help the Fertile Crescent meet its targets in conserving CWR diversity as well as making sure that CWR genetic resources are preserved to prevent and tackle global food insecurity.     

广西那坡县风水林植物物种多样性及其保育对策

采用线路踏查法和样方法相结合,调查了位于广西西南部那坡县8个屯的风水林。结果表明:(1)共有维管束植物241种,隶属于79科163属;(2)风水林为典型的热带季雨林,多数保护较好;(3)种子植物区系以热带亚热带成分占优势;(4)8个村屯的乔木层以及林下植物物种多样性差异较大。最后提出风水林植物物种多样性保育的对策。     

Landraces in central Italy: where and why they are conserved and perspectives for their on-farm conservation

Four hundred and twenty-seven landraces belonging to different plant species (forages, cereals, pulses, garden crops and fruit trees) were found on-farm in central Italy during exploration and collecting missions carried out since 1981. Open field crops are mostly grown under modern agricultural techniques by relatively young farmers on quite large farms for Italian standards. Garden crops are mostly grown by elderly farmers, running small farms or home gardens and using traditional farming systems which include the use of mechanical tools for soil preparation and occasionally the use of chemical fertilisers. There is no unique situation in on-farm conservation and management in the investigated area: the main factors involved appear to be a fragmented habitat and the presence of relatively elderly farmers. Most landraces are directly used by farmers' families, but a part is sold at local and wider markets. The main reasons why these landraces have been maintained on-farm are: their resistance/good productivity under difficult or harsh climatic conditions, traditional reasons or organoleptic peculiarities, which make them highly valued and expensive on the local and city markets and/or simply because they are appreciated by the families. Three example cases of effective on-farm conservation are presented. Social problems seem to be the main cause of genetic erosion. Perspectives and constraints to on-farm conservation and management are briefly discussed.     

Using landscape suitability models to reconcile conservation planning for two key forest predators

Protection of area-limited species is an important component of plans to conserve biodiversity, but the habitat needs of such species can be different and important habitats may not align with existing reserves. We used empirically derived landscape suitability models for the spotted owl and the fisher to evaluate the overlap in habitat suitability for these two old forest-associated predators in an area of northern California affected by the Northwest Forest Plan (NWFP), a bioregional conservation plan. The area includes designated Wilderness areas and new reserves (Late-Successional Reserves, LSRs) established under the NWFP. We used the site selection algorithm MARXAN to identify priority habitat areas for each species, and for both combined, and to compare these areas with reserves. Sites were selected under two constraints, to achieve a threshold proportion of total habitat value and to select new areas equal to the total current area in existing reserves. The rank correlation between predicted value for the two species was low (0.11), because areas of highest predicted habitat value were more widely distributed for the owl. This difference also meant that the sites selected to optimize habitat value were more aggregated for fishers than owls, resulting in greater overlap of owl habitat and current reserves. To capture 25%, 50% and 75% of total habitat value for the owl required 14.0%, 29.2%, and 47.3% of the planning units, respectively; capturing the same for the fisher required only 5.3%, 13.5%, and 27.2%. A combined owl-fisher scenario resulted in areas that overlapped only ∼50% of existing reserves. The current location of LSRs may not be the best solution to maintaining well-connected habitats for these area-limited species in northwestern California. Whether LSRs are a better solution to protecting the diversity of other lesser-known taxa (i.e., salamanders and mollusks) is the subject of related work.     

Savanna herbivore dynamics in a livestock-dominated landscape. II: Ecological, conservation, and management implications of predator restoration

Conserving African wildlife in human-occupied landscapes requires management intervention that is guided by a mechanistic understanding of how anthropogenic factors influence large-scale ecological processes. In Laikipia District, a dry savanna region in northern Kenya where wildlife share the landscape with humans and livestock, we examined why five of nine wild ungulate species suffered protracted declines on properties receiving the greatest conservation investment. Of 10 alternative causes examined, only an increase in predation, interacting with brief periods of high and low rainfall, was consistent with the timing, synchrony, duration and species composition of observed ungulate declines.The principal factor causing predation to increase was a shift in land use from cattle ranching, under which predators and plains zebras were severely suppressed, to wildlife conservation and ecotourism. This prompted a 5-fold increase in plains zebra abundance, and created a demand for living predators. Plains zebras ultimately comprised more than half the available prey biomass, and supported a substantial predator community, but were not limited by predators. We infer that increasing predation pressure caused predator-susceptible prey species to decline, via mechanisms that included apparent competition.Herbivore dynamics in Laikipia shared features with previously reported responses by prey communities to predator manipulation in Kruger and Serengeti National Parks. All featured one or a few numerically dominant herbivore species, which were primarily limited by rainfall and density, supporting a predator community that in turn limited the abundance of other prey species. In each case, predation had a profound effect, but on only a subset of prey species, reducing the evenness component of prey diversity.The presence of cattle in the landscape may affect predator-prey dynamics in both direct and indirect ways, depending on rainfall. In extreme years (floods or drought), episodic die-offs temporarily subsidize scavenging predators. In low rainfall years, competition between plains zebras and cattle, which negligibly support predators, may indirectly limit predator carrying capacity. Consequently, removal of cattle may favor not only zebras, but also their predators, and further depress predator-susceptible prey species.