Article

Effect of provenance on population structure and regeneration of six multiple-use tree species along Ouémé catchment in Benin: Implications for conservation

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  • Laboratoire de Biomathématiques et d'Estimations Forestières/Université d'Abomey-Calavi
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Abstract

Parkia biglobosa (Jacq.) G. Don, Pterocarpus erinaceus Poir, Milicia excelsa (Welw.) C. C. Berg, Prosopis africana (Guill., Perrot. and Rich.) Taub., Afzelia africana Sm. and Khaya senegalensis (Desv.) A. Juss. are the most highly valued indigenous tree species in the agroforestry systems of the Ouémé catchment area. However, information on the population structure of these species is lacking, thus limiting the development of their sustainable conservation, utilization and restoration strategies. This study addressed this gap. It assessed the population structures and regeneration status of the six species from Don, Tan-Houègbo, Atchabita, Bétékoukou, Glazoué, Tchaorou, Zagnanado, Tévèdji, Sinaou and Bétérou along the catchment. Data were collected from 78 permanent rectangular plots (50 × 30 m) randomly installed within 10 provenances. Dendrometric data including diameter at breast height (dbh) of adult trees (dbh ≥ 10 cm), collar diameter, total height of seedlings and saplings, number of individuals per species according to adult, sapling and seedling were recorded. The population structure was described using ecological and dendrometric parameters (relative frequency, importance value index (IVI), mean densities, basal area, mean height), and diameter size-class distributions. Seedling:sapling and sapling:adult ratios were also computed and analyzed for determining regeneration patterns. Based on IVI, Parkia biglobosa (95.85%) and Khaya senegalensis (65.92%) were the most represented species in the catchment area. The analysis of variances showed that dendrometric parameters of the six species varied significantly between provenances. Seedling:sapling and sapling:adult ratios were

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... Purposively, Ouémé Catchment was selected because of the occurrence of traditional farmland for agroforestry practices, the growing incidence of degradation of native tree species as a result of the increase in cultivation of exotic tree species and farm-households represented the main economic source (Lokonon et al. 2022). ...
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Your article is protected by copyright and all rights are held exclusively by Springer Nature Switzerland AG. This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com". Vol.:(0123456789) 1 3 Modeling Earth Systems and Environment https://doi. Abstract Forests are the most important terrestrial ecosystems providing sustenance not only to biodiversity but also to the rural communities. These resources are subjected to constant degradation and exploitation due to anthropogenic activities and changes in the climatic phenomena. Thus, present study examined the inherent forest vulnerability in one of the important Himalayan state, Uttarakhand in India. Site specific landscape parameters were chosen to analyze the vulnerability. GIS based analytical hierarchy process (AHP) was utilized to identify the important drivers of forest vulnerability in the study area. Findings revealed that of the total forested area, most of the area (61%) was under very high vulnerability followed by high vulnerability (36%). AHP analysis revealed that the main drivers of the inherent forest vulnerability were open forest cover, high disturbance in the forested areas, low biological richness and high road density. Findings of this study may help in understanding of the inherent forest vulnerability and adapting sustainable forest management strategies to control further forest degradation in the study area.
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Article
Ouémé catchment experiences increasing degradation of its natural resources due to anthropogenic pressure. Consequently, most of the agroforestry species as well as the cultural and Indigenous knowledge related to them are facing a very high risk of extinction. The present research aimed to assess the biodiversity of the useful woody species in this area and their cultural importance and then prioritize these woody species for conservation purpose. An ethnobotanical survey was carried out among 411 randomly selected households followed by an ecological survey conducted in 69 random plots of 0.15 ha. Ecological and ethnobotanical parameters were calculated and then analyzed. To determine the local priorities species for conservation, a local conservation priority index (LCPI) was computed for each species. The high value of LCPI for a given species indicates the need for a greater level of attention for conservation and management. Forty-five useful woody species belonging to 21 families dominated by Leguminosae (24.44%) and Anacardiaceae (8.88%) were reported. The forty-five species were categorized in six use categories by the informants: food, medicinal, construction, fuel, veterinary and technology. The most useful species were Elaeis guineensis (UV=0.24), followed by Parkia biglobosa (UV=0.19) and Vitellaria paradoxa (UV=0.18). The prioritization method yielded top ten ranked species: Adansonia digitata, Parkia biglobosa, Pterocarpus erinaceus, Irvingia gabonensis, Milicia excelsa, Tamarindus indica, Vitex doniana, Prosopis africana, Diospyros mespiliformis and Pterocarpus santalinoides. With the aim of establishing the sustainable management in the catchment, we suggest that more attention be paid to the aforementioned species as part of rehabilitation activities.
Chapter
In this chapter, you will find information about (a) the problem of vegetation sampling regarding methods, criteria, and plant measurements; (b) the phytosociological parameters commonly used to describe communities; (c) the similarity and distance indices employed and the means of their estimation; and (d) recommendations on the use of different indices in ethnobotanical studies.
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This study was carried out to obtain information on the distribution and socio-economics of Parkia. Biglobosa and Tamarindus indica, as well as other constraints to their production in the Sudan and Guinea savanna agro ecologies of Nigeria, using structural questionnaires that were administered to farmers and herb sellers/herbalist who are not less than 40 years of age. The data generated showed that P. biglobosa and T. indica were commonly found in and around the house-hold compound (40%), while plantation of these tree species were rarely in existence within the agro ecologies (10%). It was gathered from the findings that these tree species play great role in socio-economic (100%) and trado-medical life (50%) of the rural people. Many of the respondents (40-90%) reported insect pests and disease as major constraints to their cultivations, while some admitted that low seed germination greatly hindered the cultivation of these trees within the agro ecologies.Global Journal of Agricultural Sciences Vol.2(2) 2003: 122-126
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In the West African Sudanian regions, people depend on natural products, especially on highly valued species as source of income, fuel wood, food, medicine, fodder for livestock etc. However, land-use management coupled with unsustainable uses of highly valued trees might jeopardize the long-term viability of some species’ populations. Thus, we compared the population structures of two trees, Afzelia africana and Pterocarpus erinaceus and the extent of bark and foliage harvesting within two contrasting land-use types using a random stratified design with 45 replication plots for each species. For both species, population structures were stable in the protected area whereas they showed a declining structure in the agroforestry parklands with lower densities of seedlings and adults as well as a total lack of saplings and young mature trees. In addition, both specieswere over-exploited. More individuals of A. africana and P. erinaceus were harvested with a weak to severe intensity in the parklands, while only few individuals were harvested in the protected area, with a higher proportion of weak to medium intensity. To ensure conservation of these highly valued species, participatory introduction of juveniles and sensitization for seedling protection are required in the agroforestry parklands.
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The use of a surrogate taxon in conservation planning has become questionable because recent evidence suggests that the correlation of species richness between pairs of taxa is highly variable both taxonomically and geographically. Species richness is only one measure of species diversity, bowever, and recent studies suggest that investigations of cross-taxon congruence should consider a broader range of assessment techniques. The cross-taxon congruence of community similarity between sites among taxa has rarely been examined and may be the most relevant measure of species diversity in the context of course-filter conservation strategies. We examined cross-taxon congruence patterns of species richness and community similarity (Bray-Curtis similarity) among birds, butterflies, and vascular plants in montane meadow habitats in the Greater Yellowstone Ecosystem. Although patterns of species richness (Spearman rank correlation) varied between taxa, we consistently found a positive correlation in community similarity (Mantel test) between all pair-wise comparisons of the three taxa (e.g., sites with similar bird communities also bad similar butterfly communities). We suggest that the success of a surrogate taxon depends on the technique used to assess surrogacy and the specific approach to conservation planning. In the context of coarse-filter conservation, measures of community similarity may be more appropriate than measures of species richness. Furthermore, the cross-taxon congruency of community similarity in our study suggests that coarse-filter conservation may be tenable in montane meadow communities.
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Wild edible trees are expected to play a significant role in the crop diversification programs and agroforestry development in Africa. In the present study, the diversity of wild food species and socio-economical factors that support farmers' choice for the species used in these systems were assessed. A number of selected sites in each of the 3 climatic zones of Benin were surveyed. Data were collected through a field exploration and a semi-structured survey among 435 selected households throughout the country, using a questionnaire. The most culturally important species ranked by locals were determined for each climatic zone and the relations between the targeted species in traditional agroforestry systems and the reasons which support peasants' choices were described through a Principal Component Analysis. A total of 43 wild edible trees were found in the traditional agroforestry systems of Benin during the survey. Traditional agroforestry systems in the Guineo-Congolian zone turned out to be the most diversified with 29 species followed by the Sudanian zone with 22 species and Sudano-Guinean zone with 16 species. The most culturally important wild edible trees in traditional agroforestry systems in the Guineo-Congolian zone were different from those identified in Sudanian and Sudano-Guinean zones. Three main reasons that support peasants' ambition to conserve or to grow wild edible trees in their field were: their contribution to food, their use in traditional medicine and ceremonies and the farmers' perception of their availability in natural vegetation.
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A fire-mediated recruitment bottleneck provides a possible explanation for the coexistence of trees and grasses in mesic savannas. The key element of this hypothesis is that saplings are particularly vulnerable to fire because they are small enough to be top-killed by grass fires, but unlike juveniles, they take several years to recover their original size. This limits the number of recruits into the adult size classes. Thus savanna vegetation may be maintained by a feedback whereby fire restricts the density of adult trees and allows a grass layer to develop, which provides fuel for subsequent fires. Here, we use results from a landscape-scale fire experiment in tropical Australia, to explore the possible existence of a recruitment bottleneck. This experiment compared tree recruitment and survival over 4 y under regimes of no fire, annual early and annual late dry-season fire. Stem mortality decreased with increasing stem height in the fire treatments but not in the unburnt treatment. Tree recruitment was 76-84% lower in the fire treatments than the unburnt treatment. Such fire-induced stem loss of saplings and reduced recruitment to the canopy layer in this eucalypt savanna are consistent with the predictions of the fire-mediated recruitment bottleneck hypothesis.
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There is a growing commercialization of non-timber forest products (NTFPs) as a means of livelihood by rural communities throughout the developing world. This often occurs in the absence of any clear understanding of or guidelines regarding sustainable yields and ecological impacts, which may undermine the success of NTFP enterprises, especially from arid regions. This paper reports on the use of size class profiles and three quantitative indices to examine population profiles of five potentially useful tree species used as NTFPs in the semiarid lowveld of South Africa. We also contrast the population densities of the five tree species in 2003 with data from 1992. Low stem densities and population profiles indicated that three of the five species would preclude the establishment of NTFP enterprises based on their products. The other two species seem to have sufficient densities for some harvesting to take place, within an adaptive management framework. However, the longitudinal data indicated that the density of both these species had significantly declined over an eleven-year period, highlighting the need for appropriate management institutions. Additionally, the proportion of mature stems cut, and the degree of cutting per stem, had increased for all five species over the eleven years. The three quantitative indices of population stability were not correlated with one another, and hence provided a useful suite of measures sensitive to different aspects of size class profiles and their interpretation. Copyright © 2005 John Wiley & Sons, Ltd.
Article
The phenology of seven indigenous tree species was investigated in a dry Afromontane forest of Ethiopia over two years. About 210 mature trees were monitored for leaf fall, leaf flush, flowering and fruiting. The different phenophase events were correlated with climate variables and circular statistics was employed to test for seasonality. Leaf fall and leaf flush peaked during the long dry season. Leaf fall significantly correlated with mean monthly temperatures. Flowering was predominantly annual and seasonal. Most species flowered during the dry season between November and May. Flowering was temporally discordant among the species, which is interpreted as a kind of adaptation avoiding interspecific overlap and thus competition for pollinators. Unlike flowering, fruiting was less seasonal and trees bore fruits over extended periods of the year. Following flowering, fruiting peaked later in the dry season or the beginning of the rainy season. Both flowering and fruiting phenology of the study species were strongly influenced by temperature and rainfall. However, leaf phenology was influenced by temperature.
Article
Non-timber forest products (NTFPs) strongly contribute to livelihood security in the semi-arid tropics. There is increasing concern about the population status of NTFP-providing trees and therefore a need for their sustainable use. Thus, this study examines the impact of land-use type on the multipurpose baobab tree (Adansonia digitata L.) in Burkina Faso, combined with rates and patterns of bark- and leaf-harvesting, and their impact on fruit production. We compared stands in a protected area (W National Park of Burkina Faso) with those of surrounding communal area (fallows, croplands and villages) to obtain an indication on the status of the baobab population, to assess its harvesting tolerance and to estimate to what extent their actual use is sustainable. Our results reveal that land-use type has an impact on the population structure of the baobab. The size class distribution curve of park stands was inverse J-shape which indicates good rejuvenation, while the curve of fallows, croplands and villages stands was bell-shaped, indicating a lack of recruitment. However, a high number of seedlings were recorded in villages. Nearly all baobabs were pruned and debarked in villages, croplands and fallows while half of the individuals were harvested in the park. Most of the trees were pruned and debarked moderately. Debarking and pruning were slightly size specific. Pruning in interaction with tree-size had a significant impact on fruit production. In contrast, debarking had no effect on fruit production. We conclude that despite the land-use impact and the intense harvesting, baobabs are still well preserved in the communal area due to their longevity, extremely low adult mortality rates and traditional management practices. However, land-use intensifications may lead to increasing pressure on baobab populations in the future. Therefore, adapted management strategies are needed to guarantee the persistence of this important species and to avoid a shortage of baobab products.Research highlights▶ Population structure of A. digitata differed between park and its surrounding area. ▶ Pruning and debarking was slightly size specific. ▶ Pruning had an effect on reproductive performances of A. digitata. ▶ No significant effects were found for debarking or combined debarking and pruning. ▶ Despite the strong harvesting, baobabs are still well preserved.