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1.
Conservation and utilisation of South Coast renosterveld,an endangered South African vegetation type
《Biological conservation》1986,37(4):363-377
South Coast Renosterveld is a small-leaved shrubland confined to the semi-arid and sub-humid coastal forelands of the southern and south-eastern Cape, South Africa. The flora of this vegetation type is biogeographically complex and includes numerous local endemics, many of which are geophytes. Much of the renosterveld is being converted to cereals and artificial pastures; conservation status is critical. There is evidence that the renosterveld has been derived in historical times from a Themeda triandra-dominated grassland. It is suggested that the reestablishment of a vigorous grassy sward would be the most effective long-term conservation strategy since utilisation would be compatible with conservation. Management models to improve the grazing status of South Coast Renosterveld should consider the biological attributes of key species. On the basis of phenological and other life history data on the dominant undesirable shrub (Elytropappus rhinocerotis, Metalasia muricata) and desirable grass (Themeda triandra) species, autumn is considered the optimum season of burn for the re-establishment of grassland. 相似文献
2.
The objective of this study was to test the hypothesis that distance is an important factor affecting attitudes towards wolves, i.e. people living far from wolf territories have more positive attitudes towards wolf conservation than those living within or close to wolf territories. We used multiple regression (an ordered probit model) with both socio-economic variables and information about the respondents’ distance to the nearest wolf territory. We found that favourable attitudes towards wolf conservation were positively associated with distance to the nearest wolf territory. The variable distance to the nearest wolf territory affected attitudes just as much as the variables of membership of nature conservation organisations, being a hunter, owning livestock, or owning a hunting dog. This was true even on the micro-level, i.e. people living in wolf territories had a more negative attitude towards conservation of wolves than people living just outside. Furthermore, we suggest that attitudes towards wolves are more likely a result of indirect experience than direct experience of wolf presence. Our findings are important when interpreting studies of human attitudes towards conservation of controversial species in general and large carnivores in particular, and should be used when designing future surveys of human attitudes towards conservation and management initiatives. 相似文献
3.
Fluctuations of bird abundances have been attributed to such factors as supplemental feeding, landscape change, and habitat fragmentation. Notably absent from consideration, however, is the role of private landowners and their actions, such as owning free-ranging domestic cats (Felis catus; cats allowed free access to the outdoors). To understand the impacts of cat predation on birds, we surveyed all 1694 private landowners living on three breeding bird survey (BBS) routes (∼120 km) that represent a continuum of rural-to-urban landscapes in Southeastern Michigan, where the majority (>90%) of land is privately owned. Our data indicate that among the 58.5% of landowners that responded, one quarter of them owned outdoor cats. On average a cat depredated between 0.7 and 1.4 birds per week. A total of 23+ species (12.5% of breeding species) were on the list of being killed, including two species of conservation concern (Eastern Bluebirds and Ruby-throated Hummingbirds). Across the three landscapes there were ∼800 to ∼3100 cats, which kill between ∼16,000 and ∼47,000 birds during the breeding season, resulting in a minimum of ∼1 bird killed/km/day. While the number and density (no./ha) of free-ranging cats per landowner differed across the rural to urban landscapes, depredation rates were similar. Landowner participation in bird feeding showed no relationship with the number of free-ranging cats owned. Similarly, selected demographic characteristics of landowners were not significantly related to the number of free-ranging cats owned. Our results, even taken conservatively, indicate that cat predation most likely plays an important role in fluctuations of bird populations and should receive more attention in wildlife conservation and landscape studies. 相似文献
4.
Niels Strange Ida Theilade So Thea Arvid Sloth Finn Helles 《Biological conservation》2007,137(2):223-236
Cambodia forms part of the Indo-Burma hotspot. Its extent of biodiversity, however, is subject to considerable uncertainty, as there has been little systematic collection of flora and fauna. During the Khmer Rouge regime institutions were banned, academics were prosecuted and written documentation systematically destroyed. Compared with neighbouring countries Cambodia has a low population density and relatively large natural areas that are still intact. However, deforestation is expanding rapidly and a significant but un-estimated area of forest has been degraded by development of agro-industries, encroachment, illegal logging, over-harvesting and forest fire as well as the use of chemicals during war. The purpose of the paper is to: (i) apply reserve selection methods to design more robust conservation networks when knowledge of species occurrence is incomplete and habitat is threatened, and (ii) evaluate the usefulness of systematic conservation planning in a developing country where data are limited and institutions for implementation are weak. This study investigates the performance of four non-probabilistic strategies: (i) a so-called ‘rule of thumb’, (ii) hotspot, (iii) minimum cost representation, and (iv) maximum coverage; and one probabilistic design strategy, i.e. maximum expected coverage. The maximum expected coverage approach is between 15% and 24% more efficient than the non-probabilistic strategies. Finally, the relevance of such tools to real-world conservation planning in Cambodia is investigated. By incorporating experts in the generation of data, running the models and setting up premises, they acknowledge that it is possible to contribute to more systematic conservation planning in developing countries. 相似文献
5.
Invasive plant suppresses charismatic seabird - the construction of attitudes towards biodiversity management options 总被引：1，自引：0，他引：1
Public attitudes towards biodiversity issues and the value judgments underlying biodiversity management and conservation are still poorly understood. This has raised serious concerns regarding the effective use of public participation in biodiversity policy making. We conducted quantitative face-to-face interviews with members of the general public in southeast Scotland to assess attitudes towards biodiversity management and examine attitude formation. For this, we applied social psychological attitude-behaviour theories to a case study investigating biodiversity management options for an island ecosystem in which the abundance of a charismatic seabird, the Atlantic puffin (Fratercula arctica) is compromised by the expansion of a tall invasive plant, tree mallow (Lavatera arborea). We found that attitudes as expressed by members of the public are informed by both value- and knowledge-based elements. Our research provides clear support for the notion that, in a conservation context, value-based principles matter to the public. Out of a set of seven conservation-related values, ‘balance’ and ‘naturalness’ were important factors that related strongly to the respondents’ attitudes. These relationships were even stronger for individuals emotionally involved with the topic. Other value-based principles such as uniqueness, autochthony and endangeredness of the species involved appeared to be of lesser relevance. The findings provide evidence that attitudes can be considered as distinct constructs that offer valuable and meaningful information to biodiversity policymakers and managers, and allow empirical insights into the way value judgments influence biodiversity management and conservation. 相似文献
6.
Tourists represent important stakeholders in the management of natural disturbance in protected areas. This study examines tourists’ attitude towards large-scale bark beetle infestation in the case of Bavarian Forest National Park, Germany. Three alternative conceptual models for predicting attitude are specified and compared using structural equation modelling (SEM) and a post-hoc modified model is derived. We find that tourists overall have a neutral attitude towards the bark beetle and are slightly against controlling the insect in the park. Tourists with higher affinity for the national park, better knowledge about the bark beetle and who expect a recovery of the affected areas have a significantly more positive attitude. Our results support a policy of selective non-intervention in the case of natural disturbance. This should be combined with educational measures aimed at raising awareness of the ecological mandate of protected areas and increasing tourists’ knowledge of the specific disturbance. 相似文献
7.
Biodiversity in Africa, Madagascar and smaller surrounding islands is both globally extraordinary and increasingly threatened. However, to date no analyses have effectively integrated species values (e.g., richness, endemism) ‘non-species’ values (e.g., migrations, intact assemblages), and threats into a single assessment of conservation priorities. We present such an analysis for the 119 ecoregions of Africa, Madagascar and smaller islands. Biodiversity is not evenly distributed across Africa and patterns vary somewhat among taxonomic groups. Analyses of most vertebrates (i.e., birds, mammals, amphibians) tend to identify one set of priority ecoregions, while plants, reptiles, and invertebrates highlight additional areas. ‘Non-species’ biological values are not correlated with species measures and thus indicate another set of ecoregions. Combining species and non-species values is therefore crucial for assembling a comprehensive portfolio of conservation priorities across Africa. Threats to biodiversity are also unevenly distributed across Africa. We calculate a synthetic threat index using remaining habitat, habitat block size, degree of habitat fragmentation, coverage within protected areas, human population density, and the extinction risk of species. This threat index is positively correlated with all three measures of biological value (i.e., richness, endemism, non-species values), indicating that threats tend to be focused on the region’s most important areas for biodiversity. Integrating biological values with threats allows identification of two distinct sets of ecoregion priority. First, highly imperilled ecoregions with many narrow endemic species that require focused actions to prevent the loss of further habitat leading to the extinction of narrowly distributed endemics. Second, less threatened ecoregions that require maintenance of large and well-connected habitats that will support large-scale habitat processes and associated area-demanding species. By bringing these data together we can be much more confident that our set of conservation recommendations serves the needs of biodiversity across Africa, and that the contribution of different agencies to achieving African conservation can be firmly measured against these priorities. 相似文献
8.
We demonstrate a novel method for spatial conservation prioritization at a community-level that takes account of: (i) an environmentally-based classification of the landscape into community classes; (ii) similarities between community classes to allow for community complementarity-based selection; (iii) variation in species richness; (iv) variation in human impacts on ecological integrity; and (v) requirements for maintenance of upstream-downstream connectivity in riverine systems. While this technique has generic application, we demonstrate its application using a biologically-trained environmental classification of New Zealand’s river network. Our analysis produces a priority ranking of planning units (here 4th order catchments or sub-catchments) and performance estimates in terms of expected biodiversity returns given varying degrees of geographic protection. Accounting for community similarity ensures high protection for distinct habitat classes with low similarity to other classes; our results indicate a 28% loss in conservation efficiency of the highest-ranked 10% of the landscape if it is ignored. Accounting for human pressures and connectivity also had clear influences on spatial priority rankings, indicating the need to consider these factors in the conservation planning process. 相似文献
9.
Krithi K. Karanth Randall A. Kramer Song S. Qian Norman L. Christensen Jr. 《Biological conservation》2008,141(9):2357-2367
Biodiversity conservation issues are often contentious and complex. Polarized debates on the effectiveness of protected areas and role of people inside them, charismatic species as conservation foci, and on specific policy initiatives are common among Indian and global conservationists. We surveyed Indian conservationists about the conservation effectiveness of protected areas and charismatic species, as well as status of conservation and research efforts. We expected differences among people based on professional affiliation, and educational background. We examined participants’ opinions on conservation policies like Project Tiger and Elephant, the Forest Rights Act, and the Tiger Task Force Report. Participants ranked Indian research efforts as average, and identified a bias towards terrestrial species and ecosystems. Ninety-percent of participants considered reserves to be effective, many (61%) participants felt that the situation of people living inside reserves is unsustainable, and many (76%) felt the use of force to protect reserves from illegal human activities is acceptable. Classification and regression tree models for these questions suggested that non-academics were more likely than academics to agree with these positions. On the success of Project Tiger and Elephant, older participants were more likely to think these initiatives were a success. Many (63%) participants felt the Forest Rights Act needed revision, particularly if they had doctoral degrees. Sixty-two percent of participants did not think Tiger Task Force was effective. Overall, participants’ professional affiliation, age, and academic degree were important predictors of participants attitudes towards conservation initiatives. 相似文献
10.
Problems and correlates of success in the conservation of Africa’s rain forests were evaluated for 16 protected areas in 11 countries, representing approximately half of all protected areas in this biome. Data were obtained from questionnaires, published and unpublished accounts, and direct observations. Despite numerous problems, all protected areas conserved indigenous rain forest biodiversity more effectively than did alternative land uses. More than half the protected areas suffered extensive ecological isolation. Effective management of protected areas was seriously compromised by inadequate funding and government support. Dense human populations, often resulting from immigration, constituted major threats to protected areas. Perceived conservation success was greatest for large protected areas surrounded by similar habitat with strong public support, effective law enforcement, low human population densities, and substantial support from international donors. Contrary to expectations, protected area success was not directly correlated with employment benefits for the neighboring community, conservation education, conservation clubs, or with the presence and extent of integrated conservation and development programs. Studies are needed to better understand what shapes positive pubic attitude towards protected areas because none of the conventional public outreach programs were correlated with public attitude. We also identify apparent deficiencies in foreign assistance to these protected areas. The single most important short-term strategy was considered to be the improvement of law enforcement effectiveness through greater technical and financial support. Nine medium-term strategies are identified, including provision of adequate and secure long-term funding, establishing research and monitoring programs, and developing more appropriate conservation and development programs. Long-term strategies deal with two ultimate causal factors, mainly attitudes and value systems, and stabilizing human populations. Future success of Africa’s protected areas is contingent upon long-term international assistance including contingencies mandating realistic performance standards. 相似文献
11.
There is an obvious need to incorporate biodiversity concerns into the policies and practices of sectors that operate outside protected areas, especially given the widespread devolution of power to local (municipal) authorities regarding land-use decision-making. Consequently, it is essential that we develop systematic (target-driven) conservation planning products that are both user-friendly and user-useful for local government officials, their consultants and the elected decision makers. Here, we describe a systematic conservation planning assessment for South Africa’s Subtropical Thicket Biome that considered implementation opportunities and constraints from the outset by developing - with stakeholders - products (maps and guidelines) that could be readily used for local government land-use planning. The assessment, with concomitant stakeholder input, developed (i) Megaconservancy Networks, which are large-scale conservation corridors of multiple ownership that achieve targets principally for biodiversity processes; (ii) conservation status categories (critically endangered, endangered, vulnerable, currently not vulnerable) for all biodiversity features, identified on the basis of available extant habitat to achieve conservation targets, and (iii) a conservation priority map which integrates (i) and (ii). This map was further interpreted for municipal-level decision-makers by way of corresponding guidelines for land-use in each of the conservation status categories. To improve general awareness of the value of biodiversity and its services, a handbook was compiled, which also introduced new and impending environmental legislation. Within 18 months of the production of these products, evidence of the effective integration, or mainstreaming, of the map and its guidelines into land-use planning has been encouraging. However, more effort on increasing awareness of the value of biodiversity and its services among many stakeholder groups is still required. Nonetheless, our approach of planning for implementation by considering the needs and obligations of end users has already yielded positive outcomes. We conclude by providing suggestions for further improving our approach. 相似文献
12.
This analysis presents a conservation planning framework for decisions under uncertainty and applies it to the Arctic Coastal Plain of Alaska. Uncertainty arises from variable distributional shifts of species’ ranges due to climate change. The planning framework consists of a two-stage optimization model that selects a nominal conservation area network in the first stage and evaluates its performance under the climate scenarios in the second stage. The model is applied to eleven at-risk species in Alaska including the threatened Spectacled Eider and Steller’s Eider sea ducks and the polar bear. The 109th United States Congress and 2008 federal budget proposed opening for oil and gas development the “1002 Area” of the Arctic National Wildlife Refuge, which intersects the Plain. This analysis finds that, if Arctic Alaska experiences 1.5 °C of warming by 2040 (as predicted by the Intergovernmental Panel on Climate Change’s A2 scenario), then potential habitat will decrease significantly for eight of these at-risk species, including the polar bear. This analysis also shows that there is synergism between oil and gas development and climate change. For instance, climate change accompanied by no development of the 1002 Area results in an increase of potential habitat for Steller’s Eider. However, if development accompanies climate change, then there is a 20% decrease in that area. Further, this analysis quantifies the tradeoff between development and maintenance of suitable habitat for at-risk species. 相似文献
13.
Geoff L. Stoneman 《Biological conservation》2007,137(4):558-566
The model of ‘ecological forestry’ has evolved as a part of the development of the concept of ecosystem management. ‘Ecological forestry’ emphasises that manipulation of a forest ecosystem should consider, and as far as practicable work within the limits of, natural disturbance patterns prior to extensive human alteration of the landscape. This paper evaluates the extent to which forest management practices in jarrah (Eucalyptus marginata) and karri (Eucalyptus diversicolor) forests of south-western Australia align with this view of the characteristics and appropriate silviculture of ‘ecological forestry’. Characteristics and appropriate silviculture of ‘ecological forestry’ are evaluated in relation to (i) the stand level decisions of stand structure and harvest timing and (ii) the landscape level decisions of harvest levels and age structures, and spatial patterns of harvest. Forest management in south-western Australia is found to align with appropriate silviculture under this model of ‘ecological forestry’. Additionally, the landscape triad of areas managed to ‘ecological forestry’ principles, conservation reserves and areas managed to production forestry is in place in the south-western forests of Australia. Strengths and weaknesses in the model of ‘ecological forestry’ and the ability to interpret consistency of practices in the forests of south-western Australia with the characteristics of ‘ecological forestry’ are identified. 相似文献
14.
Miguel A. Ortega Huerta 《Biological conservation》2007,134(1):83-95
Patterns of fragmentation in current distributions of 35 species of birds and 19 species of mammals that are considered endangered, threatened, or with restricted distributions were modeled in relation to 3 biosphere reserves (El Abra-Tanchipa, El Cielo, Sierra Gorda; ‘BRs’) and 13 areas identified as priorities for conservation in northeastern Mexico (PAC-Priority Areas for Conservation). Core area percentage of landscape (CPLAND) and aggregation index (AI) were used to summarize fragmentation trends in species’ geographic distributions, modeled using ecological niche modeling techniques. Overall (median) CPLAND and AI revealed: (a) for birds, El Abra-Tanchipa BR and neighboring areas exhibited the lowest fragmentation (high CPLAND and high AI), whereas Sierra Gorda BR was the most fragmented; (b) for mammals, El Abra-Tanchipa and El Cielo BRs exhibited lowest overall fragmentation, while Sierra Gorda BR was the most fragmented. Although there were areas (i.e., El Abra-Tanchipa BR and Parras de la Fuente PAC) with higher combination of CPLAND and AI values, El Cielo BR stands out because of its high CPLAND and AI values along with the highest species richness. 相似文献
15.
Ke Jin Wim M. Cornelis Donald Gabriels Wouter Schiettecatte Stefaan De Neve Junjie Lu Tineke Buysse Huijun Wu Dianxiong Cai Jiyun Jin Roger Harmann 《CATENA》2008
Soil erosion from agricultural lands is a serious problem on the Chinese Loess Plateau. In total, 28 field rainfall simulations were carried on loamy soils under different management practices, namely conventional tillage (CT), no till with mulch (NTM), reduced tillage (RT), subsoiling with mulch (SSM), subsoiling without mulch (SS), and two crops per year (TC), to investigate (i) the effects of different soil management practices on runoff sediment and (ii) the temporal change of runoff discharge rate and sediment concentration under different initial soil moisture conditions (i.e. initially dry soil surface, and wet surface) and rainfall intensity (85 and 170 mm h− 1) in the Chinese Loess Plateau. NTM was the best alternative in terms of soil erosion control. SSM reduced soil loss by more than 85% in 2002 compared to CT, and its effects on runoff reduction became more pronounced after 4 years consecutive implementation. SS also reduced considerably the runoff and soil loss, but not as pronounced as SSM. TC resulted in a significant runoff reduction (more than 92%) compared to CT in the initial ‘dry’ soil, but this effect was strongly reduced in the initial ‘wet’ soil. Temporal change of runoff discharge rate and sediment concentration showed a large variation between the different treatments. In conclusion, NTM is the most favorable tillage practices in terms of soil and water conservation in the Chinese Loess Plateau. SSM can be regarded as a promising measure to improve soil and water conservation considering its beneficial effect on winter wheat yield. 相似文献
16.
A. Marm Kilpatrick 《Biological conservation》2006,128(4):475-485
Research has shown that avian malaria plays an important role in limiting the distribution and population sizes of many Hawaiian birds, and that projected climate change is likely to eliminate most disease-free habitat in Hawai’i in the next century. I used a modeling approach, parameterized with demographic data from the literature and the field, to examine alternate management scenarios for the conservation of native Hawaiian birds. I examined the feasibility of using management in the form of rodent control to facilitate the evolution of resistance to malaria by increasing the survival and reproduction of native birds. Analysis of demographic data from seven native species, Akepa (Loxops coccineus), ‘Akohekohe (Palmeria dolei), Elepaio (Chasiempis sandwichensis), Hawai’i’amakihi (Hemignathus virens), Hawai’i creeper (Oreomystis mana), Omao (Myadestes obscurus), and Palila (Loxioides bailleui), suggest that differences in life history cause some species to be more susceptible to local extinctions from the transmission of malaria. Modeling results demonstrated that rodent control at middle, but not high, elevations can facilitate the evolution of resistance to malaria in several species of Hawaiian birds. Advocating a management approach that encourages evolutionary change in endangered species contrasts with the traditional conservation paradigm but it may be the best strategy to reduce the impacts of one of the multiple stressors that have devastated the native bird community of Hawai’i. 相似文献
17.
Ascelin Gordon William T. Langford Matt D. White James A. Todd Lucy Bastin 《Biological conservation》2011,(1):558-566
To reduce global biodiversity loss, there is an urgent need to determine the most efficient allocation of conservation resources. Recently, there has been a growing trend for many governments to supplement public ownership and management of reserves with incentive programs for conservation on private land. At the same time, policies to promote conservation on private land are rarely evaluated in terms of their ecological consequences. This raises important questions, such as the extent to which private land conservation can improve conservation outcomes, and how it should be mixed with more traditional public land conservation. We address these questions, using a general framework for modelling environmental policies and a case study examining the conservation of endangered native grasslands to the west of Melbourne, Australia. Specifically, we examine three policies that involve: (i) spending all resources on creating public conservation areas; (ii) spending all resources on an ongoing incentive program where private landholders are paid to manage vegetation on their property with 5-year contracts; and (iii) splitting resources between these two approaches. The performance of each strategy is quantified with a vegetation condition change model that predicts future changes in grassland quality. Of the policies tested, no one policy was always best and policy performance depended on the objectives of those enacting the policy. This work demonstrates a general method for evaluating environmental policies and highlights the utility of a model which combines ecological and socioeconomic processes. 相似文献
18.
The role of saiga poaching in rural communities: Linkages between attitudes, socio-economic circumstances and behaviour 总被引：1，自引：0，他引：1
Effective conservation of exploited species requires an understanding of the motivations experienced by resource users. When use is illegal, it can be particularly difficult to distinguish users from non-users. The attitudes of local people are critical to conservation success, because they interact with social circumstances to determine behaviour. In this study we explore the factors influencing inferred poaching behaviour of the Critically Endangered saiga antelope (Saiga tatarica) in six communities in three countries of the former Soviet Union. We show that local people have a good understanding of the species’ status and positive attitudes towards its conservation, regardless of their household’s inferred poaching status. Poaching is a low prestige occupation, and our analyses suggest that it is carried out by poor, unemployed households who have the means to hunt. These results are consistent for all villages. However we find important regional differences in hunting behaviour, linked to saiga population density and migration patterns, which have implications for the likely effectiveness of different conservation strategies. Community-based interventions are more likely to be appropriate in Russia, where saigas are present year-round and hunting is more subsistence based, than in the strongly seasonal Kazakhstan populations where economies of scale require organised poaching by fewer households. This case study illustrates the complex linkages between attitudes, social circumstances and behaviour in resource user behaviour, and highlights both the consistencies and differences in drivers of poaching between locations at a range of spatial scales. 相似文献
19.
Michael C. Calver Jacky Grayson Maggie Lilith Christopher R. Dickman 《Biological conservation》2011,(6):1895-1901
Despite evidence that pet cats prey on urban wildlife and may transmit disease, there is uncertainty over whether they cause declines in wildlife populations. The uncertainty fosters disagreement about whether and how pet cats should be managed, and hampers the implementation of regulations. We suggest that the precautionary principle could be used in this context. The principle mandates action to protect the environment when there is a scientifically plausible but unproven risk, and provides a rationale for immediate intervention to protect wildlife from pet cats while we await definitive studies. In applying a 4-step guide for implementing the precautionary principle, we argue that: (i) current data documenting wildlife mortality caused by pet cats satisfy the precautionary trigger of scientifically plausible risk; (ii) the risk of significant declines or local extinctions of threatened wildlife, coupled with uncertainty in establishing population declines in response to pet cats, argue for strong levels of precaution; (iii) precautionary measures that should be considered include, but are not limited to, restrictions on the maximum number of cats allowed/household, mandatory sterilisation and registration of pet cats, curfews, requiring pet cats roaming outdoors to wear collar-mounted predation-deterrents or compulsory confinement of cats to their owners’ premises; and (iv) the principle’s requirement for extensive consultation in implementing precautionary measures should encourage collaborations involving conservation biologists, veterinarians, animal welfare activists, concerned citizens and municipal officers. Adherence to these steps should assist in choosing actions that have broad support and are applicable to unique local circumstances. 相似文献
20.
Failure to take into account the ecological complexity of landrace populations of crop plants limits our ability to conserve their genetic resources in situ. Soil seed banks are a central feature of the ecology of landrace populations of cassava; their existence has consequences for conservation. Seedlings recruited from seed banks are incorporated by farmers into their stocks of clones of this vegetatively propagated crop, transforming pure clonality into a mixed clonal/sexual reproductive system. Soil seed banks, and farmers’ responses to them, play an important role in maintaining diversity in populations of cassava landraces. In a study combining genetic and ethnobiological approaches, we showed the following: (i) Recruitment from soil seed banks increased diversity of populations at the local scale. At the level of a field, the presence of plants issued from seeds resulted in significantly greater diversity of genotypes and phenotypes than if only individuals planted by farmers had been present. (ii) Farmers’ use of seed banks has enabled indirect ‘exchange’ of locally adapted cassava germplasm between cultural groups, without requiring that groups actually encountered one another and engaged in social exchange of cultivars. (iii) Farmers have responded to catastrophic crop failure by using seed banks to regenerate stocks of clones. This use of seed banks should enable cassava populations to respond to disasters by an increase of genetic diversity, rather than by a narrowing of the genetic base, often feared in such situations. 相似文献