Perceptions paysannes sur les services écosystémiques d’approvisionnement, la vulnérabilité et les stratégies de conservation de Diospyros mespiliformis Hochst en zone soudanienne du Tchad

Diospyros mespiliformis Hochst. est une espèce d’arbre à usage multiple des forêts tropicales sèches qui est encore exploitée à l’état sauvage et dont les pratiques sylviculturales ne sont pas documentées. La présente étude avait pour but d’appréhender les perceptions paysannes sur l’importance socio-économique, le niveau de vulnérabilité et la pratique de la culture de cette espèce dans la zone soudanienne du Tchad. L’approche méthodologique a consisté en des enquêtes réalisées auprès de 350 personnes réparties dans 10 villages, ainsi que des observations de terrain. Les résultats ont montré que D. mespiliformis est bien connu des populations locales (100 % des enquêtés) qui en font usage dans six catégories d’usage, avec un large consensus au niveau des utilisations médicinales (Cs = 0,96), alimentaires (Cs = 0,33), dans les constructions (Cs = 0,26) et comme bois d’énergie (Cs = 0,24). Par contre le consensus est resté faible pour l’utilisation dans l’artisanat (Cs = - 0,76) et comme bois d’œuvre (Cs = - 0,83). Selon 80,2 % des répondants, les revenus tirés de l’exploitation de cette ressource contribuent significativement à l’amélioration du bien-être des ménages. En dehors de la cueillette et du ramassage des fruits, toutes les autres méthodes de récolte citées par les répondants (écorçage, prélèvement des racines, effeuillage et abatage) sont destructives, mais seulement 17,7 % des répondants en sont conscients. Une tendance régressive de la dynamique du peuplement de l’espèce est perçue par la majorité (52 %) des répondants. Selon 83,5 % des enquêtés, les habitudes en matière de culture de cette espèce sont rares voire inexistantes, à cause des difficultés de germination des graines, de la rareté des graines et des conditions climatiques défavorables à la réussite du drageonnage. Les répondants dans la quasi-totalité (99 %) se sont déclarés prêts à adopter la pratique de la culture de la plante si les contraintes de régénération sont levées. Les résultats de cette étude indiquent clairement que D. mespiliformis serait une espèce propice à la domestication participative pour l’intensification du système agroforestier dans la zone soudanienne du Tchad. Diospyros mespiliformis Hochst. is a multipurpose tree species from tropical dry forests that is still exploited in the wild and whose silvicultural practices are not documented. The aim of this study was to understand the peasants’ perceptions on the socio-economic importance, the level of vulnerability and the cultivation practice of this species in the Sudanese zone of Chad. The methodological approach consisted of surveys carried out among 350 people in 10 villages, as well as field observations. The results showed that D. mespiliformis is well known to local populations (100% of respondents) who use it in six categories of use, with a broad consensus for use in medicine (Cs = 0.96), food (Cs = 0.33), constructions (Cs = 0.26) and as fuelwood (Cs = 0.24). On the other hand, the consensus remained weak for use in crafts (Cs = - 0.76) and as lumber (Cs = - 0.83). According to 80.2 % of respondents, income from the exploitation of this resource significantly contributes to improving household well-being. Apart from picking and collecting fruit, all other harvesting methods cited by respondents (debarking, root picking, leaf stripping and felling) are destructive, but only 17.7 % of respondents are aware of this. A regressive trend in the population dynamics of the species is perceived by the majority (52 %) of respondents. According to 83.5 % of respondents, the cultivation habits of this species are rare or even non-existent, because of poor seed germination, the scarcity of seeds and climatic conditions unfavorable to the success of suckering. Almost all respondents (99 %) declared themselves ready to adopt the practice of growing the plant if the regeneration constraints are lifted. The results of this study clearly indicate that D. mespiliformis would be an interesting species for participatory domestication for the intensification of the agro-forestry system in the Sudanese zone of Chad.

Optimization of a Whole-Stalk Operating System after Sugarcane Base Cutting

Leaf stripping and top breaking are the key procedures in whole-stalk sugarcane harvesting. In this study, a whole-stalk operating system after sugarcane base cutting was developed and tested to improve the leafy trash cleaning performance and adaptability of a whole-stalk harvester. A leaf shredding procedure was proposed before leaf stripping, and an anti-float top breaking device was developed for breaking cane tops. The rotational speeds of the leaf shredding (RL), leaf stripping (RS), and top breaking (RT) rollers were regarded as experimental factors, and the leafy trash content (including leaves, leaf sheaths, and tops in this study), top breaking rate, abrasion rate, and non-fracture rate of the middle or bottom parts were selected as indices. Central composite design combined with response surface methodology and comprehensive evaluation method were employed to conduct experiments and explore the interaction effects of factors on indices. The optimal operating parameters were nonlinearly optimized and determined to be RL of 512.9 rpm, RS of 418.8 rpm, and RT of 307.0 rpm. Under these conditions, the predicted values of leafy trash content, top breaking rate, abrasion rate, and non-fracture rate were 4.98%, 88.39%, 5.19%, and 96.21%, respectively. Verification experiments indicated that the observed values were in agreement with the predicted values. Results suggested that the leaf shredding device and anti-float top breaking device developed in this study were effective for improving the leafy trash cleaning performance and adaptability of the whole-stalk operating system, and there was a good potential for performance improvement of whole-stalk sugarcane harvesters. Keywords: Central composite design, Leaf shredding, Leaf stripping, Response surface methodology, Top breaking, Whole-stalk harvester.

Research on the Leaf-Stripping Device of Whole Stalk and Small-Scale Sugarcane Combine Harvester

This paper describes the sugarcane planting area in our country, and explains the present situation of mechanized harvest. It expounds the existing problems in the mechanized process of the sugarcane harvested region. In addition, it introduces the structure of the leaf-stripping device on the small-scale and whole stalk typical sugarcane harvester, analyzes the process leaves off in the sugarcane combine harvester,meanwhile it supplies a good design plan for the leaf-stripping device of sugarcane harvester.

Experimental Study on Leaf-Stripping Mechanism of Separating Machinery for Corn Stalk Skin Flesh Leaf

For deciding the structure and parameters of Skin flesh leaf separation machinery of Stems and leaves separation mechanism of corn stalk,the Skin flesh leaf separation machinery key mechanism—leaf-stripping mechanism was experimented in the paper by Self-designed leaf-stripping equipment. For optimization parameters in structure and motion of leaf-stripping mechanism,the experimental method of the three-factor quadratics rotary orthogonal combination was adopted, and two evaluation indexes were applied in the experiment. By carrying on the experiments, the suitable parameters in structure and motion were obtained as below, rotation speed of leaf-stripping roll was 921～1224rpm. leaf-stripping teeth plate clearance was 36.8～41.5mm. and moisture content of corn stalk was 44.9％~65％ .