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Evidence for indigenous selection and distribution of the shea tree, Vitellaria paradoxa, and its potential significance to prevailing parkland savanna tree patterns in sub-Saharan Africa north of the equator
Abstract
Aim Woody vegetation patterns in African savannas north of the equator are closely connected to human presence, but the distinctions between natural and anthropogenic landscapes have not been clear to many observers. Criteria for identifying savanna landscapes on a continuum of intensity of anthropic impact are explored.Methods A key savanna tree species, Vitellaria paradoxa (Sapotaceae), was used as model for evaluating anthropic impact. Fruits harvested from tree populations across the species range were analysed for variation in traits valued by indigenous peoples. A simple selection index was used to scale tree populations from a hypothetical wild state to a hypothetical domesticated state. Index values were compared with trait values along climate zone gradients and evaluated in the context of indigenous savanna management practices and historical species distribution reports.Results Trait values such as fruit size and shape, pulp sweetness, and kernel fat content show a significant influence of temperature and rainfall. At the same time, the mean values of groups of traits vary perpendicular to the general climatic zone gradient. Selection index values between Vitellaria populations vary up to sixfold, with highest values in central Burkina Faso. Comparison of present day Vitellaria distribution with historical range limits show range expansion by human migration.Main conclusions The prevalence of major economic tree species in the savannas of Africa north of the equator is a strong indicator of human involvement in tree dispersal. This conclusion is supported by paleobotanical evidence and by recent Vitellaria range expansion as a result of human migration. The presence of high mean values of several Vitellaria fruit traits in central Burkina Faso suggests that selection for desired characteristics has occurred. The impact of indigenous savanna peoples on woody species composition and spatial distribution is probably much greater than usually thought and is the result of a deliberate strategy of altering the landscape to provide needed human resources.
... Furthermore, since north-western Ghana continues to experience endemic poverty, agriculture and the exploitation of nature dominate their livelihood strategies (Kent, 2018). Hence, access to land and economic trees presents an opportunity to mitigate extreme poverty by adopting sustainable exploitation practices (Schreckenberg et al., 2006;Rasmussen et al., 2017;Mawa et al., 2021). ...
... According to Akinnifesi et al. (2006), the increase or decline in tree population is determined by how people are motivated to plant and protect the trees. According to Kepe and Scoones (1999), many grass landscapes are created through social processes (Maranz and Wiesman, 2003) and contracts (Fortmann, 1985;Sjaastad and Bromley, 1997), and the successes in the management of tree resources depends mainly on the human-ecology interactions and the definition of property rights. These customarily embedded human-ecology interactions are continuously negotiated and [re]defined by various actors by establishing social networks and alliances (Berry, 1993). ...
... As farmlands give way to urban infrastructure development in these communities, farmers are compelled to exit agriculture and adopt alternative livelihoods (Abdulai et al., 2021). The focus of this study on shea tree tenure in north-western Ghana is because the shea remains a crucial economic tree and the income obtained from participating in the shea value-chain remains very high (Poudyal, 2009;Kanlisi et al., 2014;Mawa et al., 2021;Derbile et al., 2022). ...
Introduction
The shea ecosystem provides critical ecosystem services. However, rapid peri-urbanization threatens the governance of peri-land and shea tree resources and poses multiple risks to urban and peri-urban households. Yet, studies on tree tenure in Ghana have focused on cocoa though shea possesses similar economic prospects. This study examines the customary land tenure systems in the Wa Municipality and their impacts on land and shea through a governance lens.
Methods
This study was purely qualitative and relied on data from focus group discussions and in-depth interviews with 64 purposely selected participants. To enable the retelling of the participants' stories, the data was first coded, thematised, and analyzed using NVivo 10 software.
Results
The results show that land and shea rights have been decoupled in peri-urban areas, and the grant of land for farming or housing is sequestered from the right to access and use shea trees without authorization. In view of this, urban usufructs cut shea trees to communicate their opposition to land transactions. Due to the fluidity of customary tenure, some family heads are redefining usufruct entitlements to land and counterclaiming the land and shea trees. In addition, the lack of incentives for smallholders to plant and manage shea trees inhibits shea governance and sustainability.
Discussion
This is exacerbated by the widespread tenure insecurity over land and investments in shea trees. Under family land jurisdictions, family heads must involve usufructs in all the processes of land transactions and assign them a clear mandate and entitlements in customary land administration to facilitate efficient land and shea governance.
... Variation in kernel fat and fruit pulp composition were also reported along climatic gradients when fruits were sampled across the shea belt [7,56,57] . Many authors sceptically attribute variation in fruit yield and seed traits to genetic make-up of the plant but Maranz and Wiesman [56] posit that the differences cannot entirely be explained by genetics. ...
... Variation in kernel fat and fruit pulp composition were also reported along climatic gradients when fruits were sampled across the shea belt [7,56,57] . Many authors sceptically attribute variation in fruit yield and seed traits to genetic make-up of the plant but Maranz and Wiesman [56] posit that the differences cannot entirely be explained by genetics. Despite the high DNA polymorphism in shea [1,53] , trees in drier savannas are consistently associated with higher mean kernel fat and seed length, whilst trees in relatively humid savannas have higher mean Total Soluble Solids in pulp with heavier seeds [56] . ...
... Many authors sceptically attribute variation in fruit yield and seed traits to genetic make-up of the plant but Maranz and Wiesman [56] posit that the differences cannot entirely be explained by genetics. Despite the high DNA polymorphism in shea [1,53] , trees in drier savannas are consistently associated with higher mean kernel fat and seed length, whilst trees in relatively humid savannas have higher mean Total Soluble Solids in pulp with heavier seeds [56] . This is noted as an adaptation mechanism where trees in drier savannas invest in seed fat to enhance seedling germination and establishment. ...
Vitellaria paradoxa (shea) has interannual variability in fruit yield patterns, which results in unpredictable export volumes. Research on factors accounting for this inconsistency is needed to manage tree stands for optimum yield, but existing studies on the topic have shown conflicting results. In order to synthesize research approaches used in examining determinants of shea reproductive success, and to identify research gaps, we reviewed the existing literature on the subject available in Scopus and Google Scholar from 2000 to 2021. Out of 119 primary research articles identified in our literature search, 40 articles met our predefined inclusion criteria. Geographically, most studies (75%) were conducted in West Africa, and six times as many studies used quantitative approaches compared with either qualitative or mixed method approaches. Fruiting emerged as the most studied aspect of shea reproductive biology (73% of studies), whereas less is known on floral biology and pollination. All studies that assessed the effect of agro-ecology, seasonality, pollination, and altitude reported significant effect of these factors on fruit yield. However, there were divergent outcomes on land use/management, dendrometry and parkland tree diversity on fruit yield. The majority of the studies examined single factor effects on yield for one flowering/fruiting season, which is a major weakness of the existing research. We recommended several strategies to improve the reliability of future studies on determinants of shea reproductive success, such as designing multi-factorial experiments to cater for extraneous variables, profiling land use history of the shea parkland and conducting experiments for multiple seasons.
... Both species are linked to humans in that they give the highest yield in the agroforestry parklands compared with fallows and forests (Sina and Traoré, 2002;Lamien et al., 2004;Souberou et al., 2015). The distribution range of V. paradoxa has probably been expanded by people (Maranz and Wiesman, 2003), and P. biglobosa is more often found in anthropic landscapes (e.g. agroforestry parklands) than in more natural landscapes (Hopkins and White, 1984). ...
... agroforestry parklands) than in more natural landscapes (Hopkins and White, 1984). Apart from the selection taking place when the farmers are clearing fallows and forest (Maranz and Wiesman, 2003), the domestication and improvement of indigenous fruit tree species has been slow (Kalinganire et al., 2008). ...
... Many other animals such as elephants, primates, and birds feed on the fruits but deteriorate the seeds (Bonkoungou, 1987). The seeds are recalcitrant and only viable for 2-4 weeks (Maranz and Wiesman, 2003). Vitellaria paradoxa has a cryptogeal seed germination where seeds germinate at the surface, but bury the plumule (i.e. ...
... With regard to total use values and provisional diversity, Viteralleria paradoxa (shea tree) is by far the most appreciated species by local people and is a typical AFPLS multi-purpose tree (Boffa 1999, Maranz et al. 2003. It fulfills all ES purposes except forage but it is significantly decreasing. ...
... Vitellaria paradoxa (shea tree). In the three study villages, it is clearly the most appreciated species by local people and it widely known to be an important food and source of income all over the Sahel, even as an export commodity (Maranz et al. 2003, Lykke et al. 2004. A recent national forest inventory has shown that Vitellaria p. is the most common tree species in entire Burkina Faso (Fischer et al. 2011). ...
... A recent national forest inventory has shown that Vitellaria p. is the most common tree species in entire Burkina Faso (Fischer et al. 2011). At the same time there are tree genetic studies of Vitellaria p. suggesting that it has been broadly domesticated in areas where it "naturally" would not occur (Maranz et al. 2003). Although often outside of their typical vegetation zone, the existence of socio-economic important tree species is widespread in Africa and is often linked to human presence ( Duvall 2007). ...
After large-scale famines and decade long observations of drought, the Sahel has received a lot of attentionfrom science, politics, media and civil society. While most scientists noticed serious land degradation anddesertification in the Sahel during the 1970s and 80s, a certain “regreening” trend has been observed inrecent years. But interestingly, there is also a completely different point of view suggesting an on-goingdegradation trend in woody vegetation. Various scholars have lately observed a decline in woody speciesdiversity in the West African Sahel. This paradox has recently led some authors to challenge the observedregreening pattern, and to question if a regreening is de facto taking place.The present study verifies both the regreening and the species decline through remote sensing, localknowledge, tree inventories and size class distribution analysis. Findings suggest that a regreening has trulyoccurred during the past 20 years, whereas a small number of exotic and drought resistant species areresponsible for the observed increase in woody biomass. Around 75% of all parkland tree species aresharply declining and evidence is found that the species decline is linked to both climatic and land usechange. The regreening pattern can partly be explained through increasing rainfall during the past 20 years,but human activities equally play an important role.Findings from this study broaden the discussion about the regreening in the Sahel. Even though aregreening has occurred, the majority of socio-economic important tree species are declining. Increasingtree species are definitely less appreciated by local inhabitants. Thus, the regreening can be linked to a shiftof Ecosystem Services for local livelihoods, which deserves considerable attention in this vulnerable region.
... Shea trees are allogamous, and cross pollination between trees can result in large phenotypic differences that are accentuated by environmental factors (Gwali et al. 2012). Differences in shea nut weight can be linked to soil fertility and variations in climate, particularly rainfall (lovett & Haq 2000b;Maranz & Wiesman 2003;Sanou et al. 2006). Furthermore, the various traits examined have different patterns of variation (Sanou et al. 2006). ...
... Possible domestication events -sometimes targeting different traits -linked to the species' long-term integration in traditional agrosilvicultural systems may have led to the high phenotypic diversity found today (Maranz & Wiesman 2003;leakey et al. 2004). For instance, the high fat content found in shea populations located on Burkina Faso's Mossi Plateau, where there is a history of continuous and dense habitation, suggests the anthropogenic selection of trees with fatty nuts in the area (Maranz et al. 2004a(Maranz et al. , 2004b. ...
In Africa’s ‘shea belt’, the shea tree (Vitellaria paradoxa) plays a central role in rural livelihoods and ecosystems. Yet, it faces many threats. The aim of this study is to examine local people’s classification systems and preferences for shea ethnovarieties in Burkina Faso to support domestication efforts that respect local priorities. Work was carried out among the Bobo, Sambla, Mosse and FulBe ethnic groups in two villages in south-west Burkina Faso. Participatory characterization and ranking matrices were used with 10 groups segregated by gender and ethnicity to understand if knowledge and preferences for shea ethnovarieties vary between gender and ethnic groups. Results show a general agreement across groups about top-cited ethnovariety names, characteristics and key criteria defining the classification system. Participants identified a total of 25 shea ethnovarieties according to 11 primary fruit and nut variants. The number of ethnovarieties cited varied slightly across groups, with greater consistency across ethnicities than across gender groups. Each ethnic and gender group identified certain ethnovarieties not cited by their ethnic or gender counterparts. Two ethnovarieties – ‘small shea fruit’ and ‘big shea fruit’ – were preferred across groups. The study highlights the value of gender-sensitive participatory research for understanding local botanical knowledge and preferences.
... It is also an interesting and wonderful tree crop because of its importance and high economic contributions to several World markets. According to Maranz; Wiesman, [1] and Masters; Yidana; Lovett [2], it covers about 5000 km wide belt of savanna including West African countries of Senegal, Mali, Côte d"Ivoire, Burkina Faso, Togo, Ghana, Benin, Nigeria, Niger, Cameroon, and further east in Uganda, Sudan and Ethiopia [3 and 4]. The area covered by the shea parkland is called "Shea belt" amongsheamerchants [5]. ...
This study assessed the activities of GIZ (German International Corporation) intervention technology on shea nut processors in Niger State, Nigeria. A two-stage sampling technique was adopted for the study. The first stage involved a purposive selection of 15 Local Government Areas of GIZ’s intervention. The second stage involved a proportionate random selection of 297 beneficiaries constituting 10% processors in the GIZ profile list. Also, in the same LGAs, snow-balling technique was used to randomly select 297 Shea nut processors that were GIZ non-beneficiaries, thereby making a total sample size of 594. Data were collected through interview schedule and were analysed using percentages and mean and multiple regression analysis. The study revealed that majority (75.1 %) of the respondents had non-formal education, 76.6 % were between 41-60 years with mean age of 48.1 years. All the respondents (100.0 %) were female and married with average of experience of 15.5 years. The most severe constraints were; inadequate funding (=1.875), poor market channels (=1.737) and inadequate extension contact (=1.542), and there was positive relationship between some selected socio-economic characteristics and the level of adoption of GIZ’s technologies (F=23.59, p <0.001). The results from this study showed that the processors were constrained by inadequate fund, poor market channels and inadequate extension services because the gap from the existing one is lower before the intervention of GIZ Shea nut technology due to high quality of production of premium shea butter produced by the beneficiaries which attracted income. The continuity of the GIZ’s intervention with effective extension services and provision of credit facilities to ameliorate the problem of inadequate fund is highly recommended.
... Sabatier (1999), Lauri et al. (2010) and Calonnec (2013) showed that the depth and fertility of the soil, the environment and the age of the individuals can influence the architectural development of a species. Maranz and Wiesman (2003), and Soloviev et al. (2004) also reported that climate or an ecological gradient had an effect on plant morphology. Similarly, Salazar and Quesada (1987) then Assogbadjo et al. (2006) reported that the origin of differences in tree morphology lies in factors such as soil type and the genetic characteristics of the sampled individuals. ...
Retrospective analysis provides access to long-term growth series to understand and interpret the structural functioning of tree crowns required for their sustainable management. The aim of this study was to assess the development and adaptation of crown shoots in Khaya senegalensis and Pterocarpus erinaceus to a changing environment in preparation for establishing permanent plots. The growth units (GUs) morphology of the axes of 420 young, adult, and old individuals was analyzed in full sunlight or shade during the rainy and dry season in seven locations in Côte d'Ivoire. The results showed that growth unit morphology is an indicator of the choice of growth conditions. Heterogeneous habitat had no significant effect on growth unit morphology (P > 0.05) in either species. The morphology of the growth units varied from one location (climate) to another due to distinct environmental characteristics (P < 0.05). The southern part of the gradient (Toumodi and Bouaké in the central region of the country) offers favourable and hence priority areas for reforestation programmes based on the two species. The age of the individuals influenced the number of phytomers per growth unit (P < 0.05). Young individuals (cuttings) are good ideotypes for the selection of suitable resistant genotypes. Whatever the species, the rainy season increased the success rate of plot establishment. The growth units of the two species are practically the same size (P > 0.05). Our results could be a decision guide for the selection of suitable environments for the implementation of reforestation or agroforestry programs based on Khaya senegalensis and Pterocarpus erinaceus, in order to conserve and sustainably manage these species in the current climate change context. Keywords: Khaya senegalensis, Pterocarpus erinaceus, Environment, Morphology, Growth Units (GUs)
... The tree is an excellent quality firewood that burns with a fierce heat while timber from the trees are strong, hard, heavy, durable, resilient and termite resistant. The roots and their bark have great medicinal values (Maranz and Wiesman, 2003). Oil-palm tree belongs to the family Arecaceae (Behrman et al., 2005). ...
Fungi associated with the rhizospheres of some economic trees namely date palm (Phoenix dactylifera), pawpaw (Carica papaya), Sheabutter (Vitellaria paradoxa) and oil palm (Elaeis guinensis) trees were isolated and identified in this study in order to know their roles, whether pathogenic or saprophytic. The rhizospheres were collected at 5, 10, 15 and 30cm distances away from the trunk of the plants respectively for fungal isolation and identification using standard methods. Aspergillus niger, A. terreus, A. candidus, A. fumigatus, Fusarium proliferum, Pyrenochaeta romeroi and Alternaria alternata were isolated from the rhizosphere of date palm; Aspergillus niger, Candida albicans and Botrytis cinerea were isolated from the rhizosphere of pawpaw; Aspergillus niger, A. glaucus, A. cremonium killense and Cunninghamella bertholletiae were isolated from rhizosphere of shea butter while Aspergillus niger, Penicilium italicum, Mucor sp., Trichoderma sp. and Rhizopus stolonifera were isolated from the rhizosphere of oil palm trees respectively. Aspergillus niger was common in the rhizospheres of all the trees studied, justifying its attribute as a contaminant. Majority of the fungal isolates identified in this study are pathogenic (A. terreus, A. candidus, A. fumigatus, Fusarium proliferum, Pyrenochaeta romeroi, Alternaria alternata, Candida albicans, Botrytis cinerea, Penicilium italicum, Rhizopus stolonifera and Cunninghamella bertholletiae) while only Trichoderma sp. is beneficial as a biocontrol agent. Efforts should be geared towards suppressing the growth of the pathogens amongst the isolates while the proliferation of Trichoderma sp. should be encouraged where it existed, i.e. rhizosphere of oil palm tree.
... It is also called a resourceful tree that can stand a wide range of climatic conditions.it has a high demand from several markets (Maranz and Wiesman, 2003a;Masters et al., 2004). It covers a vegetation of 5,000 km wide belt of savanna including West Afrian countries of Senegal, Mali, Cote d'Ivooire, Burkina Faso, Togo, Ghana, Benin, Cameroon, Nigeria, Niger, and further east in Uganda, Sudan and Ethiopia (Chalfin, 2004;Goreja, 2004). ...
... Shea butter is a fat-rich oil derived from the nuts of the African Shea tree. At room temperature, it is solid [6] . When raw, it is often yellowish in color, but unrefined, refined, and ultra-Shea butter are ivory or white in color [7] . ...
The ethnopharmacological uses of shea butter provides an evidence of its uses in our dishes and has been a tradition in many West African continent. This may be related due to it higher nutritional values, phytochemical content etc hence make it's a valuable material in African folk medicine. This study is aimed to evaluate the phytochemicals, proximate and physicochemical analysis of Shea Butter. The AOAC protocols were followed for the proximate and physicochemical analyses, whereas the Brain and tuner techniques were used for the qualitative phytochemical study. The qualitative phytochemical analysis reveals the presence of various phytochemicals such as Terpenoids, Alkaloids, Saponins, Flavonoids, Tannins and Cardiac glycosides, the proximate analysis shows the percentage composition of Moisture (1.233±0.033), Ash (0.090 ± 0.0), Protein (3.103 ± 0.023), Fat (92.91±0.069) and Carbohydrate (2.660 ± 0.098), whereas the Physicochemical analysis shows the Physical and Chemical parameters as; Slip point 0 C (68.67±0.67), Clear point 0 C (119.3 ± 0.66), Smoke point 0 C (162.0 ± 1.155), Flash point 0 C (198.7±0.67), Fire point 0 C (302.0 ± 1.155), Specific gravity (0.856±0.001) Refractive Index @25 0 C (1.531 ± 0.003), Free fatty acid Value (0.533 ± 0.0067), Saponification Value (186.9 ± 0.073) Iodine Value (30.78 ± 0.012), Peroxide Value (0.9367±0.012). The findings revealed that, the Shea butter contained certain phyto-constituents and it physicochemical parameters fulfilled the FOA/WHO criteria. Similarly, shea butter contains some nutritionally significant components and has health benefits in addition to its numerous industrial applications.
... Shea butter is a fat-rich oil derived from the nuts of the African Shea tree. At room temperature, it is solid [6] . When raw, it is often yellowish in color, but unrefined, refined, and ultra-Shea butter are ivory or white in color [7] . ...
The ethnopharmacological uses of shea butter provides an evidence of its uses in our dishes and has been a tradition in many West African continent. This may be related due to it higher nutritional values, phytochemical content etc hence make it's a valuable material in African folk medicine. This study is aimed to evaluate the phytochemicals, proximate and physicochemical analysis of Shea Butter. The AOAC protocols were followed for the proximate and physicochemical analyses, whereas the Brain and tuner techniques were used for the qualitative phytochemical study. The qualitative phytochemical analysis reveals the presence of various phytochemicals such as Terpenoids, Alkaloids, Saponins, Flavonoids, Tannins and Cardiac glycosides, the proximate analysis shows the percentage composition of Moisture (1.233±0.033), Ash (0.090 ± 0.0), Protein (3.103 ± 0.023), Fat (92.91±0.069) and Carbohydrate (2.660 ± 0.098), whereas the Physicochemical analysis shows the Physical and Chemical parameters as; Slip point 0 C (68.67±0.67), Clear point 0 C (119.3 ± 0.66), Smoke point 0 C (162.0 ± 1.155), Flash point 0 C (198.7±0.67), Fire point 0 C (302.0 ± 1.155), Specific gravity (0.856±0.001) Refractive Index @25 0 C (1.531 ± 0.003), Free fatty acid Value (0.533 ± 0.0067), Saponification Value (186.9 ± 0.073) Iodine Value (30.78 ± 0.012), Peroxide Value (0.9367±0.012). The findings revealed that, the Shea butter contained certain phyto-constituents and it physicochemical parameters fulfilled the FOA/WHO criteria. Similarly, shea butter contains some nutritionally significant components and has health benefits in addition to its numerous industrial applications.
... Since this shrub can grow fast, it constitutes an alternative to deforestation. The differences in skills and knowledge among various gender groups could thus, play an important role in the management of natural resources (Aguilar et al., 2011;Carney & Elias, 2006;Chalfin, 2004;Maranz & Wiesman, 2003). During the process of water fetching, women in South Africa identified some trees (Acacia erioloba, Ziziphus mucronata, Acacia Albida, Euclea divinorum, etc.) that play an important role in the avoidance of water pollution. ...
This paper aims to review the status of gender inclusivity in agriculture and natural resources management in sub-Saharan Africa under the changing climate. Gender inclusivity is a critical dimension in mitigating and adapting to the impacts of the changing climate since climate change is not gender-neutral. It has been widely documented that gender-differentiated roles, knowledge and preferences among various gender groups differ. Therefore, harnessing the differences in response to the changing climate is pivotal in mitigating and adapting to the adverse impacts. However, gender inclusivity in agriculture and natural resources management in the region has not been reviewed. The paper, consequently, reviews and provides useful insights on the status among smallholder farmers and informs future efforts aimed at harnessing gender inclusivity in the face of climate change. It serves as an informative and reliable reference for developing effectual mitigation and adaptation strategies in agriculture and natural resource management.
... [12] [36] and [31] have shown in their research that soil depth and fertility, environment and age of individuals can influence the architectural development of a species. [37] and [38] have indicated in their studies that climate or ecological gradient has an effect on plant morphology. Similarly, the studies of [39] [40] and [41] indicated that the origin of differences in tree morphology is due to factors such as soil type, age and genetic characteristics of individuals. ...
Parkia biglobosa is a much-loved and over-exploited African savannah spe-
cies for its socio-economic importance. Knowing and taking into account its
architectural unit, which is the basis for diagnosing phenology, productivity
and tree health, could provide a new perspective on its sustainable manage-
ment. The aim of this study is to establish the architectural development in
Parkia biglobosa by retrospective analysis. To achieve this objective, 390 indi-
viduals of all sizes ranging from seedlings to senescent trees were observed
and analysed under various soil and climatic conditions in Côte d’Ivoire. The
results showed that Parkia biglobosa is a light plant but shading tolerant. It is
a mixed vegetative axis plant, the stem is orthotropic* in its proximal part and
plagiotropic* (collapsing) in its distal part in young stage. The tree then tran-
sitions to an adult and old stage into a tree with a plagiotropic* axis in the
proximal and distal parts, the trunk is built up by superimposing collapsed
relay axes that gradually straighten, branching is sympodial*, growth is de-
fined and sexuality is terminal and lateral. The ontogeny takes place in three
phases: initiation of development and establishment of the crown (young),
then flowering and establishment of the architectural unity (adult) and finally
the death of secondary axes in the crown, duplication of the architecture by a
series of partial and total reiterations (old). The level of organisation is 5: the phytomere, the module or growth unit, the axis, the architectural unit and the
reiterated complex. Retrospective analysis of the modules showed that the
dimensions of the growth units are indicators of morphological variation and
species adaptation to a changing climate (P < 0.05). However, the equations
generated by the morphological and habitat dimension linkage models are
not significant (R2 and r < 0.7) to be used as a guide for field data collection.
This study represents an initiation into the architectural study of this species
and the information provided will serve as a basis for further research into
the architecture in relation to the sustainable use of this species
... Instead, shea agroforestry parklands, comprised of annual crops and scattered shea trees that can reach densities of 20-50 trees/ha in areas of strong shea culture, result from self-sown propagation and systematic management (selection and protection, as opposed to planting) by farmers through successive fallow and cultivation cycles. Farmer selection of preferred individuals and removal of inferior trees for charcoal production or building materials serve to increase the levels of locally valued traits, resulting in what has been called a semi-domestication of the species (Lovett and Haq, 2000;Maranz and Wiesman, 2003). ...
A defining component of agroforestry parklands across Sahelo-Sudanian Africa (SSA), the shea tree ( Vitellaria paradoxa ) is central to sustaining local livelihoods and the farming environments of rural communities. Despite its economic and cultural value, however, not to mention the ecological roles it plays as a dominant parkland species, shea remains semi-domesticated with virtually no history of systematic genetic improvement. In truth, shea’s extended juvenile period makes traditional breeding approaches untenable; but the opportunity for genome-assisted breeding is immense, provided the foundational resources are available. Here we report the development and public release of such resources. Using the FALCON-Phase workflow, 162.6 Gb of long-read PacBio sequence data were assembled into a 658.7 Mbp, chromosome-scale reference genome annotated with 38,505 coding genes. Whole genome duplication (WGD) analysis based on this gene space revealed clear signatures of two ancient WGD events in shea’s evolutionary past, one prior to the Astrid-Rosid divergence (116–126 Mya) and the other at the root of the order Ericales (65–90 Mya). In a first genome-wide look at the suite of fatty acid (FA) biosynthesis genes that likely govern stearin content, the primary determinant of shea butter quality, relatively high copy numbers of six key enzymes were found ( KASI , KASIII , FATB , FAD2 , FAD3 , and FAX2 ), some likely originating in shea’s more recent WGD event. To help translate these findings into practical tools for characterization, selection, and genome-wide association studies (GWAS), resequencing data from a shea diversity panel was used to develop a database of more than 3.5 million functionally annotated, physically anchored SNPs. Two smaller, more curated sets of suggested SNPs, one for GWAS (104,211 SNPs) and the other targeting FA biosynthesis genes (90 SNPs), are also presented. With these resources, the hope is to support national programs across the shea belt in the strategic, genome-enabled conservation and long-term improvement of the shea tree for SSA.
... Fruits from the Sylhet site contained higher amounts of sugar where the climate is (temperature and rainfall) cooler compared to the Chittagong and Cox's Bazar sites (Zafer Siddik et al., 2013). Moreover, fruit phenotypic traits also support these findings, shown in Table 1 and Table 4. Similar findings are mentioned by Maranz and Wiesman (2003) for Vitellaria paradoxa in Africa. A high correlation was observed between sugar and Vitamin A (Table 4). ...
Mangifera sylvatica Roxb. is an underutilised and threatened wild fruit species found in Bangladesh, which is highly valued by local people as a source of fruit and is an important source of nutrition. As part of a feasibility study of the domestication and cultivar development potential of M. sylvatica, a preliminary study examined the morphological traits (fruit, kernel and pulp mass), nutritional profile (carbohydrate, sugar, pH, fat, protein, mineral and vitamins) and medicinal traits (total phenolic and phenolic profiling). The fruit of M. sylvatica is small (27.00g ± 7.03g) with a comparatively bigger kernel fruit (40% of its body weight). M. sylvatica fruit pulp has been proved to be a good source of carbohydrate, Vitamin C, sodium (Na) and potassium (K) and also has good medicinal properties (mangiferin and quercetin). The kernel is also a rich source of carbohydrate and has a good fatty acid profile (rich in stearic and oleic acids) consistent with cocoa butter, which indicates its potential to be used in the chocolate and confectionery industry. There is continuous variation in these traits, indicating opportunities for multiple trait cultivar development targeted at the food and pharmaceutical industries. The information generated in the study can be used as a stimulus to the process of domestication and to encourage widespread use of the species, which will ultimately help to conserve this wild underutilised fruit species.
... Recent research has focused on fruit size differences [14,15] and the relationship between the environment and fruit characteristics [16][17][18]. Maranz and Wiesman [19] found that temperature and rainfall had significant effects on fruit size. Wu et al. [20] indicated that fruit size (length and width) decreased with longitude from west to east. ...
Quercus variabilis Blume is one of the most ecologically valuable tree species in China and is known to have adaptive mechanisms to climate change. Our objective was to quantify the variation pattern in the fruit morphology of Q. variabilis. Fruit samples were collected from 43 natural populations in autumn of 2019. Our results indicated that the coefficient of variation (CV) of the fruit length (FL) and fruit width (FW) were 10.08% and 11.21%, respectively. There were significant differences in the FL, FW, and fruit length-to-width ratios (FL/FW) among the studied populations. Also, there was a significant positive correlation between the FW and FL. The FL decreased with increasing precipitation in the wettest quarter (PWQ). A concave trend was observed in the variations in FL with the equivalent latitude (ELAT), longitude (LON), annual mean air temperature (MAT), and annual precipitation (AP). A similar concave trend was observed for the FL/FW with LON, MAT, and AP. A positive correlation was observed between the FW, FL and FL/FW, and the ELAT. The cluster analysis revealed five groups of the 43 natural populations. Our study findings suggests that Q. variabilis has high levels of phenotypic plasticity for geographical and climatic factors.
... Apart from its use for cooking, shea oil is also used in traditional medicine (nasal decongestant, treatment of wounds, child birth facilitation), in cosmetics (soap making, skin and hair moisturizers and skin lotion) and for rituals such as in traditional marriages as reported by Gwali et al. [17] in Uganda. Shea trees provide shade for farmers, herders and their animals and the ripe mesocarp (fruit pulp) is a key source of energy during the preparation of elds in the rainy season when grain supplies from the previous season are low [11,18,19]. The roots and bark also have numerous medicinal uses in the treatment of dysentery, suppurating wounds and other ailments [20]. ...
Background: Local knowledge and perception are crucial to undertake the domestication of useful species such as Vitellaria paradoxa that makes significant contribution to rural household economy in Africa. This study aims to document shea morphotypes diversity based on folk knowledge especially the main criteria farmers used to distinguish shea trees and to examine the influence of sociodemographic characteristics on that knowledge.
Methods: 405 respondents were surveyed across shea parklands in Benin using semi-structured questionnaire. We used the relative citation frequency of criteria followed by Kruskal-Wallis test to evaluate the influence of sociodemographic attributes on local knowledge of Shea morphotypes variation. Factorial Correspondence Analysis described the links between the different morphotypes and parklands, and Principal Components Analysis was used to characterize farmers perception on morphotypes’ abundance, fruits and butter yields.
Results: Respondents identified 13 morphotypes based on the five most cited criteria which are fruit size (55.5%), tree fertility (15.40%), bark colour (10.51%), timing of production (5.38%) and pulp taste (3.42%). The citation frequency of classification criteria varied significantly depending on the age, the education level and the sociolinguistic group of the respondent. The Bembèrèkè zone shea parkland revealed higher diversity of morphotypes traits. The small fruit type (‘Yanki’) was reported to be widespread. It produces higher fruit and butter yields according to respondents.
Conclusions: From our findings, farmers perceived an important diversity of shea traits that are used to classify morphotypes with economic or sociocultural importance. The revelation of that natural variation in shea tree is a key step toward the development of shea improvement program that could focus on the morphotype Yanki reported to be potentially high in fruit production and butter yield.
... Mesoamerica and the Amazon have been centres for research on ancient forest management (Peters, 2000;Levis et al., 2012). Southeast-Asian forests have also been widely studied in this regard (Wiersum, 1997;Michon, 2005), but African forests less so (Maranz and Wiesman, 2003). Research indicates that humans have manipulated a range of trees and palms 2 for food through selective harvesting, managed regeneration and cultivation for several millennia (Clement, 2004). ...
(Full document can be obtained via: http://www.fao.org/documents/card/en/c/cb2488en)
EXECUTIVE SUMMARY
Products and services derived from trees in forests, on farmland and within other landscapes provide benefits to hundreds of millions of people in the tropics, but these benefits from the trees and their genetic resources have not been well quantified. This is the case, in part, because trade often takes place outside formal markets; there are a multiplicity of species, product sources and ways in which trees are used; and the value of genetic diversity within tree species has not been properly considered.
This study reviews what is known about the value of trees for tropical rural communities and considers the following:
• Non-timber products harvested from trees in natural and managed forests and woodlands.
• The various products and services obtained from trees planted and/or retained in agroforestry systems.
• The commercial products of tree commodity crops.
The study focuses, where possible, on the role of intra-specific genetic variation in determining the value of trees in supporting livelihoods in each of the above three contexts. The more systematic, standardized approaches to quantifying non-timber forest product (NTFP) value applied in the last decade or so have illustrated the importance of NTFPs for marginalized households and for women’s incomes. Analyses of wild tree foods from forests have considered the diversity of foods available but have also shown that availability does not necessarily mean that humans consume these foods. In the tropics, significant changes in fruit properties have taken place in many fruit trees over several millennia be- cause of human selection that better conforms to the communities’ food needs. Knowledge of these changes can help guide future domestications.
To improve the lives of rural people through NTFP harvesting, they need technical sup- port in harvesting and processing, business support to establish enterprises, and they need market information to be shared, among other interventions. The ecological implications and genetic aspects of NTFP harvesting regarding productivity, sustainability, etc. have received limited attention and require further research.
Database searches indicate a wide range of agroforestry tree products (AFTPs) such as timber, medicine and fuel, which are commonly mentioned. Examples that show larger benefits from having trees on farms are soil fertility replenishment, timber production and fodder provision. There are specific opportunities to bring into cultivation food trees through participatory domestication methods, making use of the great biological diversity found within and between indigenous fruit tree species in tropical regions, and improving human diets by filling nutritional gaps.
Human-driven climate change and forest displacement mean that tree products and services will in future be sourced increasingly from farms. Key constraints to agroforestry, however, must be addressed in policies, markets, and in developing and delivering appropriate high-quality tree planting material and farm management methods. Delivery systems should involve small-scale, local, entrepreneurial tree seed, seedling and clone suppliers, supported with business and technical training and with starter germplasm.
Many tree commodity crops are grown by smallholders, often in locations away from the centres of origin of the tree crops. This emphasizes the importance of international cooperation in exploiting genetic resources for sustaining and enhancing commercial production of these crops. The value of wild resources of tree commodity crops needs to be properly quantified. The geographic separation of origin and production centres for these commodity crops presents a dilemma for conservation, which also applies to other widely cultivated tree species.
Although tree commodity crops play an important role in supporting rural livelihoods, it will be necessary to better understand the complicating factors that result in land being converted to monoculture production systems, and to understand the impact of single- source incomes on a community’s food and nutritional security. Commodity varieties that are highly productive in mixed farming systems are needed, making use of intra- specific genetic diversity to develop varieties that most favourably interact with the other components of the farming systems.
... Vitellaria trees produce shea nuts (Figures 7B,C) (also known as karité nuts in French) from which a fat is extracted from the seed kernel that is known as "shea butter" (Figure 7D) (Maranz and Wiesman, 2003). The value of shea was widely recognized by British and French colonial administrations of West Africa in the nineteenth century, leading to the start of shea exports worldwide (Carney and Elias, 2006;Elias and Carney, 2007). ...
There is a general unawareness of food crops indigenous to the African continent that have contributed to Western culture. This under-appreciation is particularly relevant in the current context of societal movements to end historic racism and value the contributions of peoples of African origin and African skin colors. Lack of awareness of the contributions of Africa's crops has negative practical consequences, including inadequate investments in preserving and maximizing the use of crop diversity to facilitate breeding. This paper provides an overview and analysis of African crops that have made significant contributions to the United States and globally, and/or hold potential in the twenty-first century. The paper specifically discusses watermelon, coffee, kola, rooibos, oil palm, shea, cowpea/black eyed pea, leafy greens, okra, yam, sorghum, pearl millet, finger millet, teff, and fonio. The review focuses on the intersection of these crops with racialized peoples, with a particular focus on African-Americans starting with slavery. The analysis includes the sites of domestication of African crops, their historical migration out of Africa, their sociocultural contributions to cuisines and products around the world, their uses today, and the indigenous knowledge associated with traditional cultivation and landrace selection. The untapped potential of local genetic resources and indigenous agronomic strategies are also described. The review demonstrates that African crops played an important role in the development of American cuisine, beverages and household products. Many of these crops are nutritious, high value and stress tolerant. The paper concludes that African crops hold significant promise in improving the resiliency of global food production systems, to mitigate climate change and alleviate food insecurity and rural poverty, especially in dry regions of the world. It is hoped that this review contributes to teaching the next generation of agriculturalists, food scientists and international development professionals about the valuable contributions of Africa's resilient crops and peoples.
... The phenotypic diversity was also greatly determined by the maximum temperature of the warmest month for which high values in the Sudanian zone was associated to good performance in terms of seeds weight/fruit weight ratio. The positive relationships between rainfall and morphological traits in A. senegalensis were also reported for other species including Vitex doniana Sweet (Hounkpèvi et al. 2016) and Adansonia digitata L. (Assogbadjo et al. 2005) in the same study area, and by Maranz & Wiesman (2003) on Vitellaria paradoxa C.F.Gaertn. in Mali and Burkina-Faso. On the contrary, other studies, (e.g., Abasse et al. 2011) found a negative relationship between rainfall and fruit size for Balanites aegytiaca Delile in Niger where larger fruit size was found in drier conditions. ...
Background and aims-Geographic patterns of phenotypic variability can inform understanding of the resilience potential of plant species to environmental hazards such as climate change. Such understanding provides support for conservation and domestication efforts. Here, we investigated natural morphological variation of the individuals, fruits, seeds, and leaves of the tropical shrub Annona senegalensis Pers. along a climatic gradient. Methods-Morphological data were collected on shrubs, fruits, seeds, and leaves of 150 shrubs from five populations in the three climatic zones of Benin. Linear mixed effects models were used to test the variability of the morphological traits of the species and also to estimate the variance components in order to tease apart the importance of each source of variation. The most important morphological descriptors discriminating climatic zones were identified using a stepwise discriminant analysis. Redundancy analysis was then used to determine the relationships between discriminant morphological traits and bioclimatic variables. Key results-Morphological traits of A. senegalensis varied greatly both within and among climatic zones. A substantial part (42%) of the among-climatic zones phenotypic variability in the species was attributable to climate, mainly rainfall and temperature. Morphological traits such as big shrubs, big fruits, and high number of seeds per fruit were associated with high mean annual rainfall and low mean temperature of the warmest quarter. Conclusions-The findings suggest an important zonal adaptation of the species to climate variability. The phenotypic diversity pattern that we highlighted can be useful when designing conservation policies for the species. However, quantitative genetics through common garden or reciprocal transplantation experiments related to the species' populations would enable to explore the heritable part of the observed variability to support effective conservation and domestication efforts.
... These results can be explained variation of the morphological characters expression as reported by McGowen et al. (2010). The impacts of climate on the expression of morphological characters have also been reported in Northern Equator (Maranz and Wiesman, 2003), Mali (Sanou et al., 2006;Tchabi and Adechi, 2014), Benin (Kougblénou et al., 2012;Kafilatou et al., 2015) and Uganda (Gwali et al., 2012). Moreover, in area of study the mineral composition of the soil, varying from one ecological zone to another, would have also influenced the expression of morphological characters as reported by Sanou et al. (2006), Moore (2008) and Bondé et al. (2019) respectively in studies on the vegetative characteristics of shea tree parks in Mali, Eastern Ghana and West Africa. ...
Agromorphological diversity structure of the elite shea trees identified in village lands and conserved in situ in the districts of Bagoué and Tchologo by the shea breeding program of the University of Peleforo Gon Coulibaly (UPGC, Côte d'Ivoire), are not known. In the present study, we characterized the agromorphological parameters of 220 elite shea trees using a set of 12 quantitative traits. The results showed that elite shea trees population has been structured into three morphological clusters or genetic pools that do not overlap with the original geographic areas. Morphological Cluster I contain elite shea trees with small trunk diameters carrying large leaves and producing fewer fruits per tree. Morphological Cluster II consisted of elite shea trees with stronger trunks bearing small leaves and producing a high number of fruits per tree. Morphological Cluster III regrouped elite shea trees of medium trunk diameters carrying medium sized leaves; fruit production level is intermediate compare to preceding groups. The elite shea trees of morphological Clusters II, which are more interesting from an agronomic point of view, can be used as grafting trees for the production of high-yielding grafted plants for farmers in Côte d'Ivoire.
... These authors also demonstrated that the weight of the fruits varied significantly according to the ecological zones. The morphological variations observed on the fruits between and within the climatic zones also corroborate the results of past studies on other fruit species (Kouyaté and Van Damme, 2002;Maranz and Wiesman, 2003;Diallo et al. 2010;Kouyaté et al. 2011). ...
ARTICLE INFO ABSTRACT This study, carried out in the centre-east of Niger, aims to analyse the variability in morphological characteristics of Balanites aegyptiaca, based on the climatic gradient. Thirteen (13) morphological descriptors were defined and used to characterise the natural populations of B. aegyptiaca. They concerned measurements on the morphological aspects of the leaves, thorns and fruits of six (6) spontaneous populations of Balanites aegyptiaca. For each population of B. aegyptiaca, a random selection of 30 individuals carrying fruits was made. On each individual, measurements were made on 10 fresh leaves, 10 fully developed thorns free from parasites, and 10 ripe fruits showing no signs of physical damage. In total, 1800 fruits, 1800 leaves and 1800 thorns coming from 180 individuals of Balanites aegyptiaca were subjected to measurements. The results of the study showed that populations from the sahelo-sudanian zone are characterised by heavy and big fruits, long leaflets and petioles, and thorns with large diameters. Those from the strictly sahelian zone were characterised by large endocarps and a thick pulp. Those from the sahelo-saharian zone were especially characterised by long thorns. This study has demonstrated the morpholoigcal variability of populations of Balanites aegyptiaca according to the climatic gradient, confirming the adaptability of the species in relation to the climate's aridity. This ability to adapt explains the wide ecological dispersion of the Balanites aegyptiaca. The current study is a contribution to an improved understanding of the different morphotypes of Balanites aegyptiaca, and constitutes a step towards the domestication of the species. Copyright © 2020, ABDOU HABOU Maman Kamal et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
... Comparison of this result on climatic variable can only be made with other studies in Africa. There was observed significant differences in morphological traits in Baobab in relation to climatic conditions (Assobadjo et al., 2010;Maranz and Wiesman, 2005) in Shea tree (Vitellaria paradoxa) and (Soloviev, 2007) in Balanites aegyptiaca and Tamarindus indica. ...
ABSTRACT
The once sustainable agroforestry system in the Sudano-Sahelian zone of Cameroon has been abandoned and trees overexploited. A study on the variability in seed and seedling traits of Faidherbia albida (DEL.) A. Chev populations from different climatic zones was carried out. Six populations were selected from Sudanian (Poli, Garoua III, and Figuil) and Sahelian (Yagoua, Moulvoudaye and Maroua I) climatic zones and harvested seeds were transported to the experimental farm of IRAD Yagoua for pretreatment and growth experiment. Four pretreatments (98% sulfuric acid, hot water, scarification and soaking in water for 24 hours) were used to initiate the germination. After one month, the rate of germination (%) was recorded and seedlings were transplanted in three substrates for seedling growth evaluation. Growth traits (Survival, plant height, root collar diameter, number of leaves, root length, plant fresh weight and plant dry weight) were measured after three months. The experimental design was a single tree plot randomized complete block design with 30 blocks. Results indicated there was significant difference (p = 0.002) among pre-treatments for the germination. The highest rate of germination was recorded with seedlings from scarified seeds (78.33%), followed by those from seeds treated with sulfuric acid (76.67%). Seeds and seedling traits were significant among populations with Yagoua recording the highest in most of the traits measured. Scarification can assist in seed germination and movement of seeds between populations and climatic zones should be considered during conservation programs. © 2019 International Formulae Group. All rights reserved.
Keywords: Faidherbia albida, agroforestry parklands, seed pretreatments, seedling traits, conservation, Sudano-Sahelian, Cameroon.
... The shea caterpillar Cirina butyrospermi ( Fig. 1) only feeds on the leaves of the shea tree (Vitellaria paradoxa). This is a wild tree that has been selectively retained in agricultural fields across western and sub-saharan Africa, a stretch of land known as the shea belt, with fields referred to as shea parklands (Maranz and Wiesman 2003). The nuts from the trees are collected to make shea butter, used in food, confectionery and cosmetics (Lovett 2010). ...
Edible insects are found in agricultural systems worldwide, and are an important source of food and income. However, many edible insects are also pests of important food crops, which raises the question of how far their presence might be costly to farmers in terms of reduced crop yields. In this study we aimed to understand the impact of defoliation of shea trees by edible caterpillars on yields of shea and maize in a mixed agroforestry system in Burkina Faso, West Africa. We collected field data in two consecutive years. Our results suggest that tree defoliation by caterpillars has no effect on shea fruit yields, and that defoliation may have a positive effect on maize productivity. We conclude that this appears to be an example of an agricultural system in which nutritionally and economically important plants and insects are both harvested by humans without risking yield reductions of harvested plants.
... Within the same agroecological zone, we reported significant differences in land use types (on-farm and wild) and altitudes where the T. indica individuals grow, which could have also been the possible cause of the obtained differences. Maranz and Wiesman [46] reported that important variability in Vitellaria paradoxa fruit and seed sizes in relation to climate gradient was found throughout the entire sub-Saharan Africa zone located at the northern part of the equator. ...
An investigation was carried out on variations in the morphological traits of Tamarindus indica LINN. fruits (length, breadth, mass, and pulp mass) and seeds (number and mass) from the different agroecological zones and land use types of Uganda. Fruits were collected from the two land use types in the three agroecological zones and measured for various morphological traits. The study sites were located between 593 and 1,096 meters above sea level. ANOVA was used to test the differences in morphological traits of fruits and seeds between agroecological zones and land use types. The morphological traits relationship was determined using Pearson Correlation Coefficient (R). There were significant (P≤0.05) variations among the T. indica fruits and seed morphological traits within the agroecological zones and land use types. Lake Victoria Crescent agroecological zone recorded higher fruits morphological traits values. Wild and on-farm land use types were superior in fruits and seed traits, respectively. Many seeds per fruit (17) were recorded in Uganda (Eastern agroecological zone) than those recorded elsewhere. Significant uphill positive linear correlations between all morphological traits (P≤0.05) were observed, with the strongest relationships being between seed mass and seed number (R=0.79), fruit mass and fruit length (R=0.75), pulp mass and fruit mass (R=0.73), and seed mass and fruit mass (R=0.73). However, fruit breadth presented slightly weaker positive linear correlations with all other morphological traits. This is the first quantitative evaluation of T. indica morphological traits variation in Uganda. Dispersion/variation and correlation relationships suggest that all the studied morphological traits can be used for selection of plus trees for tree breeding improvement such as yield per tree. The observed variations are probably attributed to influence of agroecological zones’ factors, environmental factors, climate, land use types, and farming systems, a reflection of T. indica adaptation to different conditions showing high genetic and phenotypic differences to be exploited.
... Such indications imply that the seed oil may be low affecting antioxidants, thus reduced potential use for industrial and medicinal purposes. This variation in the seed oils may have been attributed to environmental factors as indicated by Maranz and Weisman (2003) and Di-Vincenzo et al. (2005). ...
Seeds from different indigenous watermelons were analysed for their chemical composition such as phenolics, proteins, oils, minerals, ash and fibre content as well as antioxidant activity measured in methanol extract using 2.2-diphenyl-1-picrylhydrazyl (DPPH) assay. The morphological variations of watermelons, which revealed diversity in terms of fruit and seed colour were also assessed. Average
percentages for lipid content, total proteins, crude fibre, ash and total carbohydrates as 34.4, 16.5, 23.1, 3.99, and 3.16%, respectively, were recorded for Capricorn district and 31.6, 14.9, 22.0, 4.58, and 5.26%
were recorded for Sekhukhune landraces. The Capricorn landraces had higher content of flavonoids (0.222 mg/g) than Sekhukhune varieties (0.130 mg/g). But, landraces from Sekhukhune had higher
antioxidant activity (46.5%) which corresponded to higher total phenolic content of 0.59 mg/g. Thus, suggest that watermelon seeds may serve as potential source of natural products for food, feed and
pharmaceutical applications.
... Indigenous communities appear to have favoured edible-fruit-yielding species normally found in the wetter Sudanian and Guinean phytogeographic zones (Maranz, 2009). Their density tend to be generally higher in farmed versus nonfarmed areas (Maranz & Wiesman, 2003). ...
Aim of study: Edible products from tree species were identified in Burkina Faso and their contribution to the diet in the lean season was assessed. The main threats affecting most consumed food tree species were also documented.
Area of study: Six villages across two phytogeographic regions of Burkina Faso
Material and methods: Focus group discussions and semi-structured interviews, including a 7-day dietary intake recall targeting women; semi-structured interviews targeting key male informants.
Main results: The number of edible tree products consumed was found to vary according to phytogeographic region and ethnic group. A few tree species played a disproportionally greater role in the diet and were characterized by very high frequency of consumption by the majority of households in both phytogeographic regions and across ethnicities: Adansonia digitata, Parkia biglobosa and Vitellaria paradoxa. These species are not critically endangered at country level but they are perceived as scarcely available at local level. Considering that the main threats on priority tree species (fires, drought, pest and diseases) vary across regions, to maintain sustainable sources of nutrients in the landscape, mitigation measures should be diversified and adapted to local pressures.
Research highlights: Priorities for conservation are emerging clearly, but research efforts should also target underutilized tree species for their potential to diversify nutrient-poor diets.
... L'aire écologique de Vitellaria paradoxa correspond au climat soudano-sahélien avec une pluviométrie allant jusqu'à 1 000 mm (Kassamba, 1997). On dénombre 16 pays producteurs, formant une ceinture de 5 000 km et s'étendant de la région Ouest jusqu'à l'Est du Sud Soudan (Maranz and Wiesman, 2003 ;Masters, 2004). Cette ceinture appelée « ceinture de karité » par les commerçants (Ferris, 2001) intègre les pays suivants : le Bénin, le Burkina Faso, le Cameroun, la République Centrafricaine, la Côte d'Ivoire, la Gambie, le Ghana, la Guinée, le Mali, le Niger, le Nigeria, l'Ouganda, le Sénégal, le Sud Soudan, le Tchad et le Togo (Chalfin, 2004 ;Goreja, 2004). ...
... Shea butter is obtained from the nuts of Shea tree (Vitellaria paradoxa), which exist in the wild in most parts of Africa [1]. It is a native of the dry Savanna belt of West Africa [2], where it grows wild across a 5000km wide belt of Savanna [3], inhabiting West African Countries of Senegal, Burkina Faso, Cote d'Ivoire, Mali, Ghana, Togo, Benin, Nigeria, Cameroon, Niger, and further east into Sudan, Uganda and Ethiopia [4]. Shea butter is solid at room temperature, edible and used in food preparation in Africa [5]. ...
... Sub-Saharan farmers' association of trees and annual crops has created the concept of 'parkland systems' around villages throughout the region (Grolleau, 1989). The parkland system is based on the selection of desirable woody plants, which includes preferred species and preferred individuals within a species (Maranz and Wiesman, 2003). The parklands that form the most widespread farming systems in the savanna zone of West Africa are those in which annual crops are grown under scattered remnant trees that were preserved by farmers during the initial woodland clearing (Bayala et al., 2015). ...
In most developing countries, there has been a long-standing conflict of interest between using land for agriculture and the conservation of biodiversity. This paper reports on a study of factors influencing farmers’ decisions to integrate trees into their agricultural practice. We also discuss the possibility of protecting and managing planted and naturally regenerating trees on farmland in order to restore degraded land and improve biodiversity. Data were collected from interviews with farmers in the Center-West region of Burkina Faso and analyzed using Principal Component Analysis, multiple linear regression and binary logistic regression. The results show that farmers’ decisions to incorporate trees into their farmland were mainly influenced by silvicultural knowledge and skills, participation in farmers’ groups or other social organizations with an interest in tree conservation, the social value of biodiversity in the rural landscape, and the perceived economic benefits of trees on farmland. The most important factors associated with variation in levels of motivation to conserve trees on farms included household wealth, gender, age, education level, marital status, residence status, farmland size, household size and technical support. We conclude that an agroforestry project will be more successful if the local biophysical conditions and diversity of smallholder socio-economic characteristics and their perceptions, needs and preferences are considered in its design. There is also an immediate need for coordinated development of information and training to raise local community awareness of the potential of agroforestry as well as to disseminate information about adding value to tree products in order to encourage farmers to protect on-farm trees.
... Moreover, fruit phenotypic traits also support these findings, shown in Table 4.1 and Table 4.4. Similar findings are mentioned by Maranz and Wiesman (2003) for Vitellaria paradoxa in Africa. A high correlation was observed between sugar and Vitamin A (Table 4.4). ...
Seed size and the growth environment are important variables that influence seed germination, growth and biomass of seedlings and future tree harvest and should thus be taken into account in agroforestry and reforestation programmes for endangered species like Pterocarpus erinaceus. In the present study, to assess seedling germination and vigour in P. erinaceus as a function of seed size in two environments, 1080 seeds and 360 seedlings were evaluated at two separate sites in Côte d'Ivoire. The results show that large seeds had very high germination rates (up to 100%) and produced more vigorous plants better able to adapt to climate change. The maternal environment and seed size had a significant influence on seed germination (P < 0.05) and seedling development (P < 0.05) and biomass (P < 0.05). Seedlings were most successful at the site with a humid tropical climate (Daloa). Seedling leaves had the same resistance regardless of seed size and study site, but leaf moisture content was more stable in seedlings grown from medium and small seeds. These results will help guide conservation strategies for the species and are key factors for rural populations, loggers, and forest management structures for the silviculture of this species.
Pterocarpus erinaceus is over-exploited for its multiple uses. Its exploitation and trade are
strictly prohibited in many countries, including Côte d'Ivoire, to prevent its extinction. It is nevertheless
imperative to restore populations of this species, while accounting for its germinative capacities and its
adaptation to changing climates. The aim of this study was to assess the seed germination and seedling
development in Pterocarpus erinaceus in three different environments. A total of 2,160 seeds from different
seed trees and 540 individuals germinated from seeds were selected and evaluated. The trials were conducted
at three sites with distinct microclimates (two nurseries in Côte d’Ivoire and one greenhouse in France). The
results showed that the environment had a significant influence on germination parameters (P < 0.05),
whereas the seed trees did not (P > 0.05). The environment influenced the height and internodes length of
the seedlings (P < 0.05). However, the diameter, number of leaves, and the length and width of the leaves of
the seedlings were statistically identical from one site to another (P > 0.05). Seed trees influenced the number
and length of seedlings leaves (P<0.05). PCA showed that the seedlings developed better in the Montpellier
greenhouse and at the Daloa site than Korhogo site. This information could guide the choice of ideal
environments for the implementation of reforestation or agroforestry programs based on Pterocarpus
erinaceus in the current context of climate change from a nursery. This study could be extended to other
species in order to regenerate important species in disturbed ecosystems.
Keywords— Pterocarpus erinaceus, nurseries, greenhouse, environment, germination and seedling
morphology, Côte d'Ivoire.
Interpretation of primary growth markers (modules) is neglected in sustainable resource management processes, yet it opens up prospects for long time series on tree crown development, necessary for their characterization in the current context of climate change. This study aimed to assess the morphological variation of crown shoots in Parkia biglobosa in the face of a changing environment. Axis growth modules of 420 individuals of different ages were retrospectively analyzed in the presence or absence of shading during the wet and dry seasons in seven localities in Côte d'Ivoire. The results showed that the developmental environment of individuals did not influence the growth modules dimensions (P > 0.05). However, module size remained significantly different between locations (P < 0.05). The southern part of the gradient is still favourable and has priority for the establishment of permanent plots. The modules morphology differs from the youngest to the oldest individuals (P < 0.05). The rainy season remains the ideal period for the implementation of agroforestry reforestation programmes based on this species (P < 0.05). Par-kia biglobosa is a monochasial sympod (Pseudo-monopod) with a relay axis that follows the Paul Champagnat architectural model in the young stage, and transits to the Wilhelm Troll model later in the adult and old stage. This information contributes to the understanding of the functioning of crown and the adaptation of this species to a varying environment. It could guide choice of suitable environment and ideal genotype for the implementation of a reforestation or agroforestry programme based on Parkia biglobosa.
The development of cultivated landscapes under the influence of food production has decisively shaped the composition and appearance of West African savannas as present today. With trees and shrubs forming an important constituent of such landscapes, and its composition characterizing different types of land-use, anthracology is a tool particularly well suited to trace developments and changes through human exploitation of the landscape. Within the West African savanna belts, regions shaped by prolonged annual floods, such as the Middle Senegal Valley, the Inland Niger Delta and the Chad Basin, offer particular ecological preconditions for land-use. We present here a charcoal study for the Chad Basin of northeast Nigeria, demonstrating the special development of a cultivated landscape in an alluvial context. Charcoal samples from stratified Late Stone Age and Iron Age sites within the southwestern Chad Basin, Nigeria were analyzed. Main focus is on the site Mege, spanning more than 2500 years of occupation history. The results are supplemented with and compared to data from other, earlier as well as contemporary sites, in similar or slightly different environments and representing different settlement types, in order to discern general trends.
Knowing how well fruit species root sucker naturally, can be used to start development programs, based on methods to multiply vegetatively, which do not cost much, especially in zones of adverse pedoclimatic and socioeconomic conditions. This study was carried out on the densities of natural root suckers of S. birrea in three areas (reserved forests, mature and new fallows), as well as on particular characteristics of these root suckers. This up to date study shows that the amount of root suckers in the mature fallows (34.28 ± 22.28 root suckers / ha) is significantly superior (p = 0.005) to those of the new fallows (12.36 ± 7.98 root suckers / ha). 41.1% of mature S. birrea produces some, and more than 70 % of the mature ones, which root sucker, have 1 to 3 suckers. Half of the root suckers are carried by roots with a diameter between 2 and 4 cm. Under the crown of the mother plants, we can count 41 % of the root suckers, whereas the rest grow in the full light. Less than 17 % escaped by creating adventitious roots. These root suckers ability could be used for woodland management.
A better knowledge of the impact of environmental conditions on shea tree’s fruit
production is critical to improve the species management. Fruit production of 237
shea trees was monitored over five successive years (2014–2018) to understand how
climatic variables, shea tree population and land use could affect fruit production
patterns of the species in Burkina Faso. Data were collected in 12 shea tree populations
distributed in three climatic zones with two contrast land use systems. The results
showed that fruit production was negatively correlated with mean annual
temperature, temperature seasonality, rainfall seasonality and solar radiation, while it
was positive with annual rainfall. Therefore, fruiting modelling is needed to predict
the impact of future climate change on reproductive ability of the species. In each
climatic zone, fruit production was significantly different among shea tree populations
(p < 0.05). Within populations, fruit production greatly varies among years with
specific patterns of variation. Land use had significant effect on fruit production of
shea tree (p < 0.05). Annually, shea trees produced about 12 times more in agroforestry
parklands than in protected areas. Interannual variation in fruit production at
individual tree level was higher in protected areas. The cultivation of shea tree is
recommended to improve its fruit productivity.
K E Y W O R D S
Burkina Faso, climate change, fruit production, land use, shea tree population
Main conclusion:
Over the last 25 years, the process of domesticating culturally-important, highly-nutritious, indigenous food-tree species. Integrating these over-looked 'Cinderella' species into conventional farming systems as new crops is playing a critical role in raising the productivity of staple food crops and improving the livelihoods of poor smallholder farmers. This experience has important policy implications for the sustainability of tropical/sub-tropical agriculture, the rural economy and the global environment. A participatory domestication process has been implemented in local communities using appropriate horticultural technologies to characterize genetic variation in non-timber forest products and produce putative cultivars by the vegetative propagation of elite trees in rural resource centers. When integrated into mainstream agriculture, these new crops diversify farmers' fields and generate income. Together, these outcomes address land degradation and social deprivation-two of the main constraints to staple food production-through beneficial effects on soil fertility, agroecosystem functions, community livelihoods, local trade and employment. Thus, the cultivation of these 'socially modified crops' offers a new strategy for the sustainable intensification of tropical agriculture based on the maximization of total factor productivity with minimal environmental and social trade-offs.
Shea trees (Vitellaria paradoxa Gaertn. f.) have been for perhaps as long as 3000 years probably the most economically and culturally important tree species in Sudanian agroforestry systems. The existing studies show that the specific magnitude and limits of shea tree presence and shea products’ advantages are highly variable. This synthesis paper gathers and updates most of the scattered knowledge on shea trees and parklands, reported by category of knowledge: socio-economic potential of shea production, current means of enhancing shea domestication, tree impacts on environmental resources and associated crop production. It concludes with a proposal for a systemic and participative bio-economic modelling approach in order to simulate intensification of shea parklands’ production using process-based research results on their economic, agronomic and environmental performance.
Recently, achieving to a cost-effective method of treating industrial wastes with maximum level of removing contaminant and microorganism has been researched by many scientists. Anaerobic bioreactors are important tools and platforms in biological and microbiological technology to manage such kind of huge quantity waste. Today is widely used in purification of factories’ waste due to their being low energy consumption. In this review article, benefits and defects of anaerobic process and 3 main properties of bioreactors i.e. uniformity, instability of time and location reviews. In order to increase the efficiency, parameters of waste refining like temperature, pH, retention time, organic loading rate and reproduction of bacteria are calculated and controlled. Internal parts can improve retention time even mass transfer.
This chapter contributes to critical inquiry literature regarding various ways that indigenous knowledge intersects with technology, especially in regards to female knowledge systems. Using Lave and Wenger's community of practice framework, this chapter illustrates how animations assist women in knowledge sharing on best practices in shea butter processing. Making use of state of the art technology, "Scientific Animations Without Borders" (SAWBO) proposes a new approach to capture, preserve and share indigenous knowledge globally. This program creates short animations showing scientific best practices while still incorporating indigenous knowledge. These animations can be viewed with video capable cellphones or on portable projection systems. This approach has the potential to keep indigenous and local knowledge alive, and allow for its spread across geopolitical, cultural and linguistic borders. Through this case study of shea producers, the authors examine how video animations provide a mechanism that amplifies traditional knowledge sharing through new technologies.
Shea (Vitellaria paradoxa C. F. Gaertn.) is arguably socio-economically and environmentally the most important plant species in the semi-arid and arid zones of Africa where it is widely distributed. Apart from the economic gains in international export markets where shea butter is valued for use in luxury cosmetic, pharmaceutical and confectionary industries, locally the fat (butter) is the main cooking oil for over 86 million inhabitants. Research during the past decades has acknowledged the chemical and nutritional composition as well as the ethnobotanical uses of shea which has resulted in its butter being used in a wide array of products. This review summarizes the current knowledge of the morphological and genetic diversity; propagation, initial growth, and management; ecology and population structure; chemical and nutritional composition as well as the socioeconomic and livelihood empowerment potential of shea. Little is known about the fruiting behaviour and the responses of shea to the inevitable changes in climate. We suggest ecophysiological and dendrochronological studies as an option to predict how the domestication of this multipurpose tree species can be sustained even under the prospects of global climate change.
L’objectif de la thèse est d’analyser les relations de pouvoir et les changements sociaux et environnementaux engendrés par la mondialisation du commerce des amandes de karité dans l’Ouest du Burkina Faso. Dans le premier chapitre, nous montrons que la mondialisation du commerce des amandes de karité n’a pas conduit à de profondes modifications de l’organisation de la chaîne de valeur dans l’ouest du Burkina Faso. Le maintien du pouvoir d’un réseau de grossistes de karité au niveau régional s’explique à la fois par les spécificités du karité et par l’efficacité de leur organisation. Le deuxième chapitre décortique comment la croissance de la valeur économique des amandes de karité contribue à modifier l’accès à l’arbre et à ses produits. Nous montrons les mécanismes qui contribuent à modifier les règles d’accès et détaillons comment ce changement de l’accès au karité peut affecter la différenciation sociale locale. Dans le troisième chapitre nous analysons plus en détail, et à l’échelle intra-ménage, la différenciation socio-économique en partie issue des effets de la mondialisation du marché des amandes de karité. Nous croisons les analyses des changements d’accès à l’arbre avec les rapports de pouvoir intra-ménage pour définir une typologie des ménages. Cette typologie met en relief les disparités dans la place du revenu karité et son partage dans le ménage. Le dernier chapitre apporte une vision historique et critique du discours dominant sur l’écologie du karité. Ce chapitre met en perspective la façon techniciste dont la science coloniale a pensé les projets de gestion du karité, et le fait que les traits saillant de ce discours colonial sont repris aujourd’hui dans les discours des industriels du karité et des gouvernements.
The overall question addressed here is the effect of different degrees of biodiversity on the function of savanna ecosystems. Function can be interpreted in two different ways. It can refer to the flow of energy and nutrients through an ecosystem or to the flow of species populations through time, i.e., the persistence of species populations and their properties, which we call the structure of the system. Here we discuss the effect of biodiversity on ecosystem function in this second sense. The role of biodiversity in the flow of energy and nutrients is addressed in Chapter 10.
Tropical savannas, defined as ecosystems formed by a continuous layer of graminoids (grasses and sedges) with a discontinuous layer of trees and/or shrubs, are the most common vegetation type (physiognomy) in the tropics. Tropical savannas are found over a wide range of conditions: rainfall from approximately 200 mm to 1500 mm a year, temperature from subtropical regimes such as the South American Chaco and the South-African savannas with temperature seasonality and cold-month average temperatures below 10 °C, to low-latitude savannas with no temperature seasonality, and soils from volcanic soils such as in parts of the Serengueti plains in Tanzania to dystrophic soils such as in the Brazilian cerrados. The one constant climatic characteristic of tropical savannas is rainfall seasonality. Yet the duration of the dry season can vary from 3 to 9 months, with a mode of 5 to 7 months.
Biodiversity and Savanna Structure and Function.- 1 The Diversity of the Savanna Ecosystem.- 2 Determinants of Tropical Savannas.- 3 Biodiversity and Nutrient Relations in Savanna Ecosystems: Interactions Between Primary Producers, Soil Microorganisms, and Soils.- 4 Biodiversity and Water Relations in Tropical Savannas.- 5 Ecophysiological Aspects of the Invasion by African Grasses and Their Impact on Biodiversity and Function of Neotropical Savannas.- 6 Relationships Between Biotic Diversity and Primary Productivity in Savannas Grasslands.- 7 Biodiversity and Fire in the Savanna Landscape.- 8 Diversity of Herbivorous Insects and Ecosystem Processes.- 9 Biodiversity and Stability in Tropical Savannas.- Summary and Areas for Future Research.- 10 Biodiversity As Regulator of Energy Flow, Water Use, and Nutrient Cycling in Savannas.- 11 Biodiversity, Fire, and Herbivory in Tropical Savannas.- 12 Savanna Biodiversity and Ecosystem Properties.- 13 Summary and Conclusions.
Human alteration of Earth is substantial and growing. Between one-third and one-half of the land surface has been transformed
by human action; the carbon dioxide concentration in the atmosphere has increased by nearly 30 percent since the beginning
of the Industrial Revolution; more atmospheric nitrogen is fixed by humanity than by all natural terrestrial sources combined;
more than half of all accessible surface fresh water is put to use by humanity; and about one-quarter of the bird species
on Earth have been driven to extinction. By these and other standards, it is clear that we live on a human-dominated planet.
Jojoba plants were grown in large pots in temperature-controlled phytotron glasshouses. The flowers were hand-pollinated and the seeds were grown under a range of eight temperature regimens from 15/10 to 36/31¦C (8/16 h; photoperiod 16 h). The concentration of wax in the seed was determined by nuclear magnetic resonance and the wax composition and the composition of the ethanolysis products of the wax were determined by gas chromatography. At 21/16¦C the wax concentration increased with seed growth until the seed reached 75% of its mature weight and then stabilized at about 45%. The wax concentration in mature seeds was only slightly affected by temperature, except for the extreme treatments of 15/10 and 36/31¦C where the concentration was reduced. The main effect of temperature on wax composition was the depression of the percentage of waxes with carbon chain lengths greater than 40 at temperatures over 30/25¦C. This depression was associated with a reduction in the percentage of C22 and C24 fatty acids and alcohols. The effects of temperature will have to be taken into account by plant breeders selecting for high wax content or for a particular wax composition.
Spatial patterns of woody individuals were studied in a semi-arid savanna of West Africa located in Burkina Faso at and around 14 12 N and 2 27 W. The study was based upon a 10.24 ha plot within which individuals were mapped. Spatial pattern analysis was carried out using second order characteristics of point processes as K functions and pair correlations. The overall density amounted to 298 individuals ha-1. The most abundant species were Combretum micranthum G. Don., Grewia bicolor Juss. and Pterocarpus lucens Lepr. Anogeissus leiocarpus (D.C.) G. et Perr. was also an important constituant of this vegetation type, owing to its taller stature. Clumped spatial distributions were identified for all species except for two, for which complete spatial randomness (CSR) was found (including P. lucens, a dominant woody plant). No regular pattern was found even when tall individuals were considered alone. Aggregation dominates interspecific relationships, resulting in multispecific clumps and patches. The overall aggregation pattern was constituted by two different structures. A coarse-grain pattern of ca. 30–40 m was based on edaphic features, and expresses the contrast between sparse stands on petroferric outcrops and denser patches on less shallow soils. A finer-grain pattern made of clumps ca. 5–10 m wide, with no obvious relation to pre-existing soil heterogeneity. There was no overall pattern for saplings (between 0.5 m and 1.5 m in height) irrespective of species, and thus no obvious common facilitation factor. For species with a high recruitment level there was no significant relationship between mature adult and saplings. The only case of clumped saplings with randomly distributed adults was found in P. lucens. However, this cannot be unequivocally interpreted as density dependent regulation since the existence of such a process was not consistent with the spatial distribution of dead P. lucens individuals (victims of the last drought). The mean density around dead P. lucens was lower than around surviving ones, indicating that the last drought tended to reinforce clumping rather than promote a regular pattern of trees. Spatial pattern analysis yielded no evidence supporting a hypothesis of stand density regulation through competition between individuals. Other processes, as surface sealing of bare soils or insufficient recruitment, may play a more important role in preventing a savanna-like vegetation from turning into denser woodlands or thickets.
The Sheanut tree (Vitellaria paradoxa Gaertn.), a multi-purpose species highly valued for the oil obtained from its seeds, is commonly maintained in the semi-arid
parklands of sub-Saharan West Africa. An inventory in the West Gonja District, Northern Region, Ghana, revealed that on intensively
farmed land this species constituted 79.7 ± 7.2% (Basal area = 2.19 ± 0.64 m2 ha−1) of the woody biomass, on low intensity farmland 84.2 ± 10.0% (2.16 ± 0.57 m2 ha−1) and only 10.2 ± 3.3% (0.92 ± 0.23 m2 ha−1) in unmanaged woodland, with similar environmental characteristics. No significant differences were found between total Sheanut
tree densities on different land use intensities, although as a proportion of all trees surveyed, large trees were more common
on farmed land. Participatory surveys revealed that these populations are a direct result of anthropic selection as local
farmers eliminate unwanted woody species on farmland, leaving only those Sheanut trees that meet criteria based on spacing,
size, growth, health, age and yield. Characteristics that could affect population dynamics during traditional management and
harvesting including short viability seeds and cryptogeal germination are also discussed with reference to unconscious selection.
Tree improvement is currently constrained, as true to type varieties are difficult to propagate. It is proposed that Sheanut
trees on farmland are semi-domesticated having been subject to long-term anthropic selection during cycles of traditional
fallow and crop cultivation.
A pollen diagram from Oursi in Burkina Faso is compared with anthracological (charcoal analysis) results from three sites in northeast Nigeria (Konduga, Gajiganna, Lantewa). The present-day vegetation at all four sites is Sahelian or Sahelo-Sudanian and under heavy human impact. At Oursi, a closed grassland with only few trees and almost no Sudanian elements can be reconstructed for the middle Holocene. At the Nigerian sites, on the other hand, Sudanian woody plants were present during this period. We assume that the Sahel was not a uniform zone during the middle Holocene but rather a mosaic of different vegetation types according to local site conditions. In the light of these results, a simple model of latitudinally shifting vegetation zones is not applicable. Around 3000 B.P. the closed grassland at Oursi was opened by agro-pastoral activities, and at Gajiganna, plants characteristic of pasture lands can be directly related with the presence of cattle. Human impact seems to have been the dominant factor in the vegetation history of the Sahel from 3000 B.P. until today, masking possible effects of climatic change.
The Sheanut tree (Vitellaria paradoxa C.F. Gaertn.) is highly valued for oil obtained from its seeds and frequently maintained in the semi-arid parklands of sub-Saharan Africa from Senegal to Uganda. Although variation has been noted for V. paradoxa subsp. paradoxa, few studies have been undertaken on patterns of phenotypic or genotypic diversity. Results are presented from 294 accessions collected in Ghana, using easily quantifiable morphological parameters.
Productive mature trees varied from shrubby multi-stemmed individuals (height <5 m) to 30-m straight-boled trees with high compact canopies. The leaf lamina (tree mean _% coefficient of variation of total mean) varied from 9.2 to 22.5 cm (_15.0%); seed length from 1.74 to 3.74 cm (_11.7%); and fat content from 29.1 to 61.9% of dry kernel weight (_9.4%). Clinal trends significantly correlated with location parameters that in turn related to environmental variation.
Population variation of seed characteristics increased to the Northeast, perpendicular to the annual movement of the inter-tropical convergence zone. It is proposed that this is a consequence of past climatic changes, coupled with a lack of methodical selection for seed type when trees are maintained on agricultural land. Isozyme analysis revealed moderate to high levels of heterozygosity (He 0.2142) and high geneflow (Fst = 0.0124, Nm = 19.9), supporting results obtained from morphological studies. Isozyme and multivariate morphology analyses showed similar but weak geographical separation patterns.
Ecologists still search for common principles that predict well-known responses of biological diversity to different factors. Such factors include the number of available niches in space, productivity, area, species' body size and habitat fragmentation. Here we show that all these patterns can arise from simple constraints on how organisms acquire resources in space. We use spatial scaling laws to describe how species of different sizes find food in patches of varying size and resource concentration. We then derive a mathematical rule for the minimum similarity in size of species that share these resources. This packing rule yields a theory of species diversity that predicts relations between diversity and productivity more effectively than previous models. Size and diversity patterns for locally coexisting East African grazing mammals and North American savanna plants strongly support these predictions. The theory also predicts relations between diversity and area and between diversity and habitat fragmentation. Thus, spatial scaling laws provide potentially unifying first principles that may explain many important patterns of species diversity.
Between the Sahel and the rainforest, deforested areas carry populations of trees of which the composition, density, and utilization are of great significance to man. The most deforested areas are only exceptionally the most continually cultivated. Except for edaphically-controlled savanna, river valley bottoms and flooded hollows, the most homogeneous tree populations are the most marginal in terms of yield. Some tree species are integrated into different types of agrarian enterprises and landscapes. Baobab is also intimately associated with traditional rural life, its trunk providing water, and its fruit, leaves and bark systematically collected for a variety of purposes. -P.J.Jarvis
Structural, energetic, biochemical, and ecological information suggests that germination temperature is an important selective agent causing seed oils of higher-latitude plants to have proportionately more unsaturated fatty acids than lower-latitude plants. Germination temperature is predicted to select relative proportions of saturated and unsaturated fatty acids in seed oils that optimize the total energy stores in a seed and the rate of energy production during germination. Saturated fatty acids store more energy per carbon than unsaturated fatty acids; however, unsaturated fatty acids have much lower melting points than saturated fatty acids. Thus, seeds with lower proportions of saturated fatty acids in their oils should be able to germinate earlier and grow more rapidly at low temperatures even though they store less total energy than seeds with a higher proportion of saturated fatty acids. Seeds that germinate earlier and grow more rapidly should have a competitive advantage. At higher germination temperatures, seeds with higher proportions of saturated fatty acids will be selectively favored because their oils will provide more energy, without a penalty in the rate of energy acquisition. Macroevolutionary biogeographical evidence from a broad spectrum of seed plants and the genus Helianthus support the theory, as do microevolutionary biogeography and seed germination performance within species of Helianthus.
In the debate on the stability of savanna vegetation, spatial processes are often neglected. A spatial simulation model based on a cellular automata approach was constructed to identify the factors and processes crucial to the coexistence of trees and grass, and their effects on the spatial arrangement of trees in arid and semiarid savannas. 2 The simulation shows that the traditional key determinants of savannas-rain, fire and grazing-generate and sustain a coexistence of trees and grasses only under specific conditions. 3 An increase in the rainfall (improved tree establishment) or in grazing (reduced competition from grass), led to an increase in the woody component in the model. Where this trend was reversed by occasional fires, the simulation indicated that trees would be patchily distributed in thickets that excluded fire. 4 For an intermediate range of fire, grazing and rainfall variables this strongly clumped distribution pattern of trees represented a stable tree-grass mixture for more than 20 000 simulated years. 5 The hypothesis is formulated that factors or processes other than competition for moisture, herbivory and fire are needed in addition to induce a long-term persistence of scattered trees. 6 By exploring the long-term and spatial consequences of altering the variables that were thought to be key determinants of savanna vegetation, this spatiotemporal model provides a novel insight into the understanding of savanna dynamics.
Asexual embryos of cacao were grown for 40–50 days in a modified Murashige and Skoog liquid medium with sucrose concentration
increased stepwise from 3 to 27% at temperatures of 10, 17, 20, 23, 26, 29, 32 or 35 C. Temperature influenced overall embryo
growth as well as lipid accumulation and composition. Maximum growth occurred at 29 C, whereas maximum lipid and fatty acid
accumulation occurred at 26 C. The proportion of individual fatty acids as total fatty acids accumulated per asexual embryo
was constant at each temperature but varied with temperature from 10 to 35 C. The fatty acid composition of asexual embryos
grown at 26 C was the most similar to that of cocoa butter, the lipid from mature zygotic embryos produced in vivo.
Growth of the capsule and seed of jojoba were followed from pollination to maturity at eight temperature regimens ranging from 15/10 to 36/31¦C (8/16 h; photoperiod 16 h). There was an initial lag before the onset of rapid (linear) seed development, during which the capsule expanded, and this lag varied from 106 days at 15/10¦C to 7 days at 36/31¦C. The wax concentration in the seed was low during the initial stages of development, but reached a maximum when the seeds were 70-75% of their final dry weight. The maximum rate of dry matter accumulation in the seed increased with temperature up to 33/28¦C but, because of the longer growth period at low temperature, seed size at maturity was greatest at 18/13¦C. The current work suggests that prolonged periods with temperatures above 36/31¦C, or below 15/10¦C would be harmful to the development of jojoba seed. The high optimum temperature for growth rate of the seed (33/28¦C) and sensitivity to a temperature of 15/10¦C, puts jojoba into the same group as many subtropical species. However, the lower optimum temperature for seed weight at maturity (18/13¦C) is close to that observed for the temperate cereals.
The probability of the occurrence of temperatures suited to the production of high quality sunflower oil has been examined for 37 locations in eastern Australia. The results indicate that temperatures suited to development of oil with =62% linoleic acid occur throughout the potential cropping season with a probability =0.6 in Tasmania, south-western Victoria, south-eastern South Australia and the highlands of New South Wales. In most established cropping regions probabilities of this level are reached only in the later third or half of the sunflower growing season. The probability of temperature suited to production of oil with = 72 % linoleic acid is less than 0.6 in all regions for much of the season, and in any environment only very late-sown crops can be expected to yield oil of this quality. The results are discussed in the light of factors controlling the distribution of sunflower production, and it is concluded that, with existing genotypes, adequate supplies of high quality oil to meet market requirements will not be reliably available from the Australian crop.
Fruit trees and shrubs dominate the edible flora of Africa. Does their geographic distribution differ significantly from that
of the woody flora in general? Based on analyses of macro-scale geographic variations in the species richness (hereinafter
SR) of southern Africa’s trees and shrubs, there is a west-to-east trend of increasing edible-fruit-providing SR that is similar
to that of woody plants as a whole and in accord with changes in climate and vegetation. Distinct from this pattern, the percentage
of edible fruit-providing species increases northwards and towards the interior of Africa, with an unexpected broad subcontinental
zone of relatively high percentages of edible fruit species separating rich nutritional resource areas (high edible SR) from
nutritional deserts (low edible SR). This is consistent with humans and other wide-ranging vertebrates (e.g., elephants) dispersing
edible fruit species into normally less than ideal (nutritional) environments during cyclical and/or episodic periods of wetter
climate.
Charcoal, fruits and seeds of woody plants have been studied from a settlement mound in the Sahel of Burkina Faso. The archaeobotanical results provide information on economy and environmental conditions at the periphery of the medieval kingdom of Songhai at around 1000 A.D. Millet (Penniselum americanum) was the basic crop, cultivated in fields in which also grew useful trees (park savannas). Besides millet, fruits of the park savanna trees and other wild woody plants were an important part of the diet. Stratigraphical changes in the charcoal diagram indicate that millet production was intensified and the park savanna system established in the course of mound formation. The charcoal results show that the vegetation around 1000 A.D. was more diverse than today, containing many Sahelo-Sudanian elements which cannot be found in the area any more. This indicates slightly higher precipitation than today but also less severe human impact.Ltude a port sur des charbons, des fruits et d'occupation du Sahel burkinab date autour de 1000 A.D. Les rsultats archobotaniques permettent une comprhension de l'conomie et des conditions environnementales en priphrie de l'empire tait la principale rcolte, cultiv dans des champs avec des arbres utiles (savane-parc). Outre le mil, les fruits des arbres de la savane-parc et d'autres plantes sauvages constituaient une part importante du rgime alimentaire. Des changements stratigraphiques dans le diagramme des charbons indiquent que la production du mil tait intensifie et le systme de la savane-parc tait tabli au cours de la formation de la butte. Ltude des charbons monte une vgtation autour de 1000 A.D., plus riche qu'aujourd'hui avec plusieurs lments sahlo-soudaniens disparus de la rgion. Cela indique des prcipitations lgrement suprieures aux actuelles mais aussi un impact humain moins svre.
Because biodiversity is debated primarily from western perspectives, the significance of threatened taxa has not been properly
assessed in the cultural and ecological contexts of their use. Instead, conservable species tend to be identified by outsiders
who are culturally and politically detached from the threatened environments. However, over the last decade or so a growing
number of studies document why and how indigenous knowledge and people can become part of development and sustainable conservation.
Presented here is a Nigerian example that illustrates how formal conservation efforts are handicapped by their failure to
take into account local environmental knowledge. I argue that the potential erosion of biodiversity in Hausaland has been
checked by the varied management of cultivated and other lands, and by the use of plants in overlapping contexts—as medicines,
foods, and the like.
Social science analysis has helped to explain the rapid and recent deforestation supposed to have occurred in Guinea, West Africa. A narrative concerning population growth and the breakdown of past authority and community organization which once maintained “original” forest vegetation guides policy. In two cases, vegetation history sharply contradicts the deforestation analysis and thus exposes the assumptions in its supporting social narrative; assumptions stabilized within regional narratives based more on Western imagination than African realities. For each case and then at the regional level, more appropriate assumptions are forwarded which better explain demonstrable vegetation change and provide more appropriate policy guidelines.
Human alteration of Earth is substantial and growing. Between one-third and one-half of the land surface has been transformed
by human action; the carbon dioxide concentration in the atmosphere has increased by nearly 30 percent since the beginning
of the Industrial Revolution; more atmospheric nitrogen is fixed by humanity than by all natural terrestrial sources combined;
more than half of all accessible surface fresh water is put to use by humanity; and about one-quarter of the bird species
on Earth have been driven to extinction. By these and other standards, it is clear that we live on a human-dominated planet.
Travels in the Interior Districts of Africa, 1795-7 / Mungo Park Note: The University of Adelaide Library eBooks @ Adelaide.
Misunderstandings of Sahelian land use ecology
- Turner
Turner, M. (2000) Misunderstandings of Sahelian land use ecology. Seminar 486, 1–10.
Forets reliques en Afrique Occidentale Francaise.
- Aubreville
Aubreville, A. (1939) Forets reliques en Afrique Occidentale Francaise. Revue de Botanique Appliquee, 19, 479–484.
Standard methods for the analysis of oils, fats and derivatives Ibn Batouta (1843) Voyage dans le Soudan. Translation of de Slane, Tree spacing and coexistence in semiarid savannas
- M G Imprimerie Royale
- Paris Jeltsch
- F Milton
- S J Dean
- W R J Van Rooyen
IUPAC (1979) Standard methods for the analysis of oils, fats and derivatives, 6th edn, 170 pp. Pergamon Press, Oxford. Ibn Batouta (1843) Voyage dans le Soudan. Translation of de Slane, M.G. Imprimerie Royale, Paris. Jeltsch, F., Milton, S.J., Dean, W.R.J. & Van Rooyen, N. (1996) Tree spacing and coexistence in semiarid savannas. Journal of Ecology 84, 583–595.
This research was supported by the Dibner Foundation and European Union INCO-DC program Official methods of analysis of AOAC interna-tional, 16th edn, Vols I and II
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