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After decades of drought in the Sahel, several studies have reported a ‘(re)greening’ of the area. However, most of these studies were based on large scale climatological or remotely sensed observations, with little or no ground truthing. The aim of this study was to assess the local perceptions of the distribution of socio‐economically important tree species in the Sub‐Sahel of Burkina Faso. Semi‐structured interviews were performed with 87 groups of informants from 20 villages belonging to three ethnic groups (Mossi, Fulani and Samo). Univariate and multivariate statistics were used to compare perceptions between the targeted ethnic groups. According to the locals, more than 80 per cent of the 90 listed species were declining, with over 40 per cent identified as threatened, including numerous plants of great economic value. Increasing species were mostly drought‐tolerant plants such as Balanites aegyptiaca. A few species were listed as locally extinct. Gender and age did not significantly affect local knowledge, whereas ethnicity did. The major causes of species decline were identified to be drought, deforestation and bushfires. In all ethnic groups, informants observed a southward shift in species distribution. Local perceptions suggest a general decline in woody vegetation. Thus, the alleged (re)greening in the Sahel might not have reversed the degradation of woody species in the area. Data derived from local ecological knowledge were consistent with that of many ecological studies, suggesting the reliability of people's knowledge for obtaining ecological data. Information from this study can be used as baseline for conservation of species identified as threatened. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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T. K. Sop J. Oldeland U. Schmiedel I. Ouedraogo A. Thiombiano 《Land Degradation \u0026amp; Development》2011,22(6):519-529
In developing countries many people depend on woody resources for their livelihoods. Monitoring human impact on the populations of socio‐economically important species is therefore important for the conservation of vulnerable plants. In order to assess and compare the population structure and regeneration patterns of three multipurpose species, namely Acacia seyal Del., Balanites aegyptiaca Delile and Pterocarpus lucens Lepr. in four ethnic areas of the sub‐Sahel of Burkina Faso (Samo, Gourmantché, Fulani and Mossi), we used the size‐class distribution method (SCD) (Condit et al., 1998 ). Diameter at breast height (Dbh) of adult individuals of each species were sampled on 1000 m2 (20 m × 50 m) plots in each ethnic domain. Recorded Dbhs were distributed among eight size‐classes of 5 cm intervals. For each species, the slope of the regression of the SCD was considered to be an indicator of the population structure. Seedlings and saplings were recorded on five nested 25 m2 plots and fell into five height classes of 0·5 m intervals. The target species had significant (p < 0·001) negative SCD slopes with an inverse J‐shape distribution in all ethnic areas; indicating stable populations with good regeneration. Kruskal–Wallis test for the SCDs of A. seyal, B. aegyptiaca and P. lucens did not differ significantly among the ethnic areas (p > 0·1). This suggests that the dynamics of each of the three species is similar across ethnic domains and the sub‐Sahel. Data from P. lucens depicted an apparent stable population structure which contrasted with our field observations, perception of local people and previous studies. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Tene Kwetche Sop Francois Wenemi Kagambèga Ronald Bellefontaine Ute Schmiedel Adjima Thiombiano 《Agroforestry Systems》2012,86(3):387-399
The aim of this study was to evaluate the effect of organic amendment on the germination and growth patterns of Jatropha curcas L. on completely barren and degraded land in the Sahelian area of Burkina Faso. Prior to the field trials, laboratory germination tests were undertaken to explore the impact of different pre-treatments on germination of Jatropha seeds. Seeds soaked in water for 24?h had the highest mean rate of germination (86%) while seeds that were pre-treated with sulphuric acid did not germinate. The results of the field experiment showed that plant growth and biomass development were significantly enhanced by organic amendment compared to the control. With direct seeding, 20% of the plants treated with organic manure survived after 2?years, while all seedlings of the control plot perished. In the plantations, 30% of the untreated seedlings remained alive whereas only 5% of the plants survived with amendment. The trials in unfenced plots were decimated by livestock grazing and trampling 2?months after the beginning of the experiment. This emphasizes the need to protect Jatropha plants at an early stage of their development from roaming animals. Organic amendment attracted humivorous termites, which were destructive to the seedlings. The use of pesticides may be necessary to control this problem. When directly seeded, plants of the control plots demonstrated poor growth and became rapidly diseased, further accelerating their decline. The low survival rates (5–30%) and meagre seedling performance, even for the amended plots, may be an indication that Jatropha is unsuited to severely degraded lands like the zippelé, and cannot be expected to give good yields and the claimed environmental and socio-economic benefits. However, we recommend that the performance of Jatropha on the zippelé should be further tested with other soil and water conservation techniques (half-moon, tillage, etc.) that have been shown to enhance crop production and yield on degraded lands in the Sahelo-Sudanian zone of West Africa. The impact of seed provenance on the outcome of this study is unknown. Therefore, further experiments should embrace seeds from different sources, including genotypes that are more adapted to dry conditions and might therefore show improved performance. 相似文献
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A thinning experiment stand at Avoca, Ballinvalley, on the east coast of the Republic of Ireland was used to test a developed methodology aimed at monitoring drought stress, based on the analysis of growth rings obtained by coring. The stand incorporated six plots representing three thinning regimes (light, moderate and heavy) and was planted in the spring of 1943 on a brown earth soil. Radial growth (early- and latewood) was measured for the purpose of this study. A multidisciplinary approach was used to assess historic tree response to climate: specifically, the application of statistical tools such as principal component and canonical correlation analysis to dendrochronology, stable isotopes, ring density proxy, blue reflectance and forest biometrics. Results showed that radial growth was a good proxy for monitoring changes to moisture deficit, while maximum density and blue reflectance were appropriate for assessing changes in accumulated temperature for the growing season. Rainfall also influenced radial growth changes but not significantly, and was a major factor in stable carbon and oxygen discrimination, mostly in the latewood formation phase. Stable oxygen isotope analysis was more accurate than radial growth analysis in drought detection, as it helped detect drought signals in both early- and latewood while radial growth analysis only detected the drought signal in earlywood. Many studies have shown that tree rings provide vital information for marking past climatic events. This work provides a methodology to better identify and understand how commonly measured tree proxies relate to environmental parameters, and can best be used to characterize and pinpoint drought events (variously described using parameters such as like moisture deficit, accumulated temperature, rainfall and potential evaporation). 相似文献
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