The spatial footprint of the non-ferrous metal industry in Lubumbashi

in Tropicultura (in press)

In the south-eastern part of the Katanga Province (Democratic Republic of the Congo), high concentrations of copper and cobalt are found in the soils of the well-known “Copper Belt”. Due to the dominant ... [more ▼]

In the south-eastern part of the Katanga Province (Democratic Republic of the Congo), high concentrations of copper and cobalt are found in the soils of the well-known “Copper Belt”. Due to the dominant south-eastern winds, the metallurgic industry in Lubumbashi has been the source of spatially concentrated atmospheric deposits of non-ferrous metal particles and associated substances in a cone-shaped zone, situated north-west of the metal processing site. The existence of this zone has been evidenced using two different techniques: firstly, by means of landscape metric comparisons of the vegetation and bare soil patterns in two study areas, one inside the pollution cone and one outside; secondly, by means of the theory on city perception developed by Kevin Lynch. Higher fragmentation and lower vegetation presence were observed inside the pollution cone, reflecting the negative impact of atmospheric deposits. Those differences were higher for sites closer to the emission source. Lynch’s approach outlined the negative impact of diverse industrial plants on the perception by the local population. Six pollution districts and several contaminated paths, limits, nodes and polluting landmarks were identified. Citizens even recognize them as part of the collective image of the city. [less ▲]

Attempted cultivation of Jatropha curcas L. in the lower Senegal river valley: story of a failure

in Tropicultura (2012), 30(4), 204-208

With the objective of determining whether it would be possible to sustainably produce Jatropha curcas L. seeds on the marginal land situated close to the Senegal River, a 6-hectare pilot plantation was ... [more ▼]

With the objective of determining whether it would be possible to sustainably produce Jatropha curcas L. seeds on the marginal land situated close to the Senegal River, a 6-hectare pilot plantation was cultivated under drip irrigation between September 2007-November 2011, close to the village of Bokhol (Lat. 16°31’N, Long. 15°23’W). A series of tests were conducted on this plot, in order to identify the best cultivation methods for the area (date, density and method of planting, appropriate type of pruning, fertilisers to be applied, irrigation method, etc.). The average yields obtained at this site, after four years of cultivation (less than 500 kg.ha-1 of dry seed), using the best known production techniques, are significantly lower than anticipated, compared to the available figures for the irrigated cultivation of Jatropha in other parts of the world. The main causes of this failure are the plant’s limited useful vegetation period of six months per year, instead of twelve, and the scale of attacks by a soilborne vascular disease, which destroyed over 60% of the plantation within four years. [less ▲]

Insecticidal effect of Jatropha curcas oil on the aphid Aphis fabae (Hemiptera: Aphididae) and on the main insect pests associated with cowpeas (Vigna unguiculata) in Niger

in Tropicultura (2011), 29(4), 225-229

The insecticidal activity of Jatropha curcas has been evaluated on various crop pests. Oil concentrations of 0.5, 1, 2.5, 5, 10 and 15% were first tested on the black bean aphid (Aphis fabae Scop.) as ... [more ▼]

The insecticidal activity of Jatropha curcas has been evaluated on various crop pests. Oil concentrations of 0.5, 1, 2.5, 5, 10 and 15% were first tested on the black bean aphid (Aphis fabae Scop.) as part of an efficacy test conducted in the laboratory. During a second stage, the insecticidal efficacy of 5 and 7.5% oil concentrations was evaluated on the main pests infesting cowpea crops (Vigna unguiculata L.) as part of a field test conducted at the University of Niamey (Niger). The results obtained in the two tests demonstrate the biocidal effect of the treatments applied, which increases with the concentration. On the black bean aphid, the biocidal effect increases during the hours following the application of oil before reaching a peak after 4 days. On cowpeas, J. curcas oil concentrations of 5% and 7.5% make it possible to reduce the level of attack by aphids (Aphis craccivora) by 10 and 50% respectively compared to the control. A 50% and 75% fall in the number of thrips (Megalurothrips sjöstedti) and bugs (Anoplocnemis curvipes), respectively, can be observed under the same conditions. This treatment made it possible to greatly increase yields compared to the untreated control. [less ▲]

An alternative view of deforestation in Central Africa based on a Boserupian framework

in Tropicultura (2011), 29(4), 250-254

Evaluation de la contamination de la chaîne trophique par les éléments traces (Cu, Co, Zn, Pb, Cd, U, V et As) dans le bassin de la Lufira supérieure (katanga/RD Congo)

in Tropicultura (2010), 28(4), 246-252

Désertification des parcours arides au Maroc

in Tropicultura (2010), 28(2), 107-114

Rangeland or natural arid pastures of Morocco are ecosystems where there is a natural or seminatural vegetation composed of steppes, shrubs and grassland. They cover about 82% of the Moroccan arid lands ... [more ▼]

Rangeland or natural arid pastures of Morocco are ecosystems where there is a natural or seminatural vegetation composed of steppes, shrubs and grassland. They cover about 82% of the Moroccan arid lands. These areas represent livelihoods for thousands of people and protect the country from desertification. Despite the importance of the rangelands and the threat of desertification, it is surprising that up to date there is no comprehensive assessment of their condition and their evolution, hindering any plan for desertification alleviation. However, the available information on selected pilot areas shows that these rangelands are threatened by desertification. It’s associated with biodiversity loss and contributes to climate change. The leading causes of land degradation are the human actions combined with climate. The establishment of a comprehensive surveillance system based on remote sensing, biophysics and socio-economic data must be envisaged to provide policymakers with an operational tool adapted to the spatio-temporal monitoring of desertification. [less ▲]

Determination of a Suitable Protocol for Indigenous Oilseed Cucurbits Plant Regeneration

in Tropicultura (2010), 28(4), 217-225

The present work was carried out to establish rapid in vitro propagation of the indigenous oilseed Citrullus lanatus. Efficiency of 3 protocols for seed decontamination was investigated. High level of ... [more ▼]

The present work was carried out to establish rapid in vitro propagation of the indigenous oilseed Citrullus lanatus. Efficiency of 3 protocols for seed decontamination was investigated. High level of seed sterilization was obtained after removing seed coat and soaking the seeds in 1.6 % sodium hypochlorite with a drop of Tween 20. Shoot tips, single node and cotyledon explants of 3 morphotypes have been screened for adventitious shoot formation in tissue culture. Best response in termis of multiple shoot induction was obtained from cotyledon proximal part with hypocotyl segmenet on Murashige and Skoog medium supplemented with 1 mg/l 6-Benzylaminopurine, 30 g/l sucrose and 8 g/l agar. After 3 weeks of culture, 90% of cotyledon proximal parts induced shoot. An average of 12.6 shoots per explants and a mean shoot length of 8 mm were obtained after multiplication stage. Shoot induction appeared to be strongly influenced by genotype and explant type. The percentage of shoot induction from cotyledon proximal parts ranged from 23.3% to 64.0% according to the genotype. Efficient rooting was achieved on half-solid MS medium containing 0.1 mg/l 1-Naphthaleneactic acid or without growth regulator. Acclimatised plantlets were transferred to greenhouse where they grew and flowered like seeded plantlets. [less ▲]

Envahissement des cuvettes par apports éoliens: processus, impacts et moyens de lutte

in Tropicultura (2008), 26

Les enjeux socio-économiques autour de l’agroforesterie villageoise à Aguié (Niger)

in Tropicultura (2008), 26(3), 141-149

Gestion participative du sanctuaire de gorilles de plaine de l’Ouest (Gorilla gorilla gorilla) de Lossi en République du Congo-

in Tropicultura (2007), 25(1), 44-50

The gorilla sanctuary of Lossi experiments the synergy between scientific research and nature conservation. Three partners are involved in a management participative process. These partners include the ... [more ▼]

The gorilla sanctuary of Lossi experiments the synergy between scientific research and nature conservation. Three partners are involved in a management participative process. These partners include the Republic of Congo, the local community of Lossi and the European programme on the forest ecosystems in Central Africa. An investigation was carried out on the sanctuary of Lossi in 2003, in order to study in situ the effects generated by the participative management and to identify the constraints linked to the participative approach. The work of primatologists allowed the habituation of the gorillas to the human presence and opened eyesight tourism of western lowland gorillas. A camp for tourists and the access road to the sanctuary have been constructed. The tourism generated jobs in favour of the local population which is also a take-partner of contracts on road repairing. The income from the tourism allowed the construction of a health centre. However, the works of researchers and tourism activities failed during the outbreaks of the Ebola hemorrhagic fever and during the three civil war episodes. The consolidation and the long term of this process of co-management of natural resources of Lossi remains the establishment of a management that should include conservation, rural development and scientific research, with equitably in the distribution of gain between the partnerses. [less ▲]