Articles

Impacts of climate variability on the spatio-temporal dynamics of plant formations in the forest-savannah transition zone: the case of the Lamto Scientific Reserve, Central Côte d’Ivoire

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Understanding climatic variability’s effects on land and biodiversity is vital for guiding sustainability, conservation, and climate impact predictions in fragile ecosystems like Côte d’Ivoire’s forest-savanna transition zone. This study aims to analyse the impact of climate variability on the spatio-temporal dynamics of land use in the Lamto Scientific Reserve. To do this, a set of monthly climate data covering the period from 1990 to 2022 was used, including indicators such as rainfall, maximum, minimum and average temperatures, drought and standardised rainfall indices. The study also involved the classification of Landsat images dating from 1990, 2002, 2012 and 2022, enabling changes in land use to be observed. The corresponding areas were correlated with the climatic variables using a Spearman correlation test. The results show a transition from savannah to denser tree cover in the reserve. In addition, an increase in rainfall, varying between 900 and 1687 mm, suggests that Lamto could be classified as a humid region. The analysis highlights the complex interactions between climate change, particularly high temperatures, and land-use dynamics. Gallery and semi-deciduous forests show resilience in the face of rising temperatures, favouring their expansion. On the other hand, pre-forest formations, such as open forests and wooded savannahs, are more affected by these temperatures, which hinders their development. Tree savannahs also show a certain resilience, while shrub savannahs and bare land are often associated with ecological degradation processes in response to high temperatures. Finally, although rainfall plays a role, its influence seems minor, suggesting that other environmental or climatic factors, such as watercourses or microclimate, play a more significant role in land use/land cover dynamics.

Influences of Historical and Anthropogenic Factors on the Dynamics of Reconstitution of Post-Cultivation Vegetation in the Sub-Sudanese Zone: The Case of the Department of Dianra, North-West Côte D’ivoire

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Prior knowledge of vegetation dynamics, including post-crop recovery dynamics, is necessary for rational and sustainable management of land assets. This study was initiated to assess the influence of historical and anthropogenic factors on post-cultivation reconstitution in the Dianra Department. To this end, information on the history and post-cultivation human activities was collected from farmers. The Phytoecological and dendrometric data were collected using the surface botanical method in the post-cultivation plots. In total, 105 plots of 400 m² were planted in post-cultivation plots between 1 and 32 years old. The influence of historical and anthropogenic factors was assessed using an Analysis of Covariance (ANCOVA), in which the functional traits of the species and the structural attributes of the plots were considered as the variables to be explained and the historical and anthropogenic factors as the explanatory variables. This analysis shows that post-cultivation reconstitution in the sub-Sudanese environment is subject to the influence of several factors, the most perceptible of which are: age, number of years of cultivation, grazed area, cultivation history, groundnut cultivation as the last crop, and cultivation technique by horse and cart. The age, groundnut cultivation as the last crop and the Open Forest/Wooded Savannah cultivation history favoured reconstitution. In contrast, a high number of years of cultivation, grazing and ploughing by horse and cart were unfavourable to reconstitution.

Influence of Rainfall and Water Deficit in the Efficiency of Potassium Fertilizer on the Productivity of Oil Palm (Elaeis Guineensis Jacq.), Grown in Southeastern Côte d’Ivoire

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In Côte d’Ivoire, palm oil occupies a preponderant position in agricultural production, in the economy, as well as consumer fats. Yield remains low, even with improved plant material being popularized whose productivity is estimated at more than 25 tons/ha/year. Trials have been set up in La Mé and Ehania (South-east Côte d’Ivoire), to help improve oil palm productivity, through a comparative study of the efficiency of potassium fertilization applied according to the locality. The experiments were conducted in Fisher blocks, including 5 treatments and 4 repetitions. The treatments included 5 doses of potassium fertilizer (T1, T2, T3, T4, T5) corresponding, respectively, to 1; 1.5; 2; 2.5; 3 kg KCl/tree/year. The results showed that the rainfall recorded in the locality of Ehania was significantly higher than that of La Mé. The average annual rainfall was 2000 mm of water in Ehania against, approximately, 1700 mm of water in La Mé. The yield and its components (weight of the bunch and number of bunches) were gradually improved according to the locality of cultivation by the different doses of fertilizer applied. This improvement was significantly higher on the Ehania plantation compared to that of La Mé. This improvement was approximately 30% and 27% compared to the standard dose of 1 kg KCl/tree/year, respectively, in Ehania and La Mé. It appears that the locality intervenes in the efficiency of potassium fertilizers, in the improvement of yield and its components. Rainfall appears, as, a main factor of productivity observed on the plot of the oil palm. Strict compliance with the choices of suitable areas, combined with reasoned potassium fertilization, will allow a better expression of the production potential of new oil palm plant material, currently being popularized.