Theses and Dissertations Collection

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Browsing Theses and Dissertations Collection by Subject "Agroforestry"

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    Basic density and strength properties of grevillea robusta cunn. and cordia afrjcana lam. grown in agroforestry in Moshi, Kilimanjaro, Tanzania.
    (Sokoine University of Agriculture, 1999) Mosha, Simon John
    Basic density and some strength properties of wood from Grevillea robusta Cunn. and Cordia africana Lam. grown in agroforestry in Moshi, Kilimanjaro region were studied with an overall objective of assessing the quality of these agroforestry tree species. The specific objectives were to conduct survey of end uses of the wood from G.robusta and C.ajricana grown in agroforestry, to determine tree characters such as tree form, branching habit and crown size, basic density and its variation within and between these tree species, some strength properties (Modulus of elasticity, Modulus of rupture, Work to maximum load, Total work, compression, shear and cleavage) and their variation within and between these tree species and the relationship between basic density and the strength properties for the two species. Sampling and data collected were done using standard methods according to Lavers (1969). Data analysis were done using both qualitative statistics and computer statistical analysis programme (SAS). The main results were as follows: the current end uses for these species were construction, furniture, fuelwood, shade for coffee, fodder, poles, tool handles, amenity, utensils and medicine. trees of C. africana had larger crown size and diameter at breast height (dbh) than G. robusta. Trees of G. robusta had longer and more straight bole (9.5 m) than that of the former (5.5 m). G .robusta also had slightly larger proportion of heartwood (65%) than C. africana (64%). Average basic density for G. robusta and C. africana were 0.48 g/cm3 and 0.37 •5 g/cm respectively. Basic density showed significant difference between sites, species, trees and within trees. Average strength property values for G .robusta and C. africana were; Modulus of elasticity (4988.0 N/mm2 and 4711.3 N/mm2) Modulus of rupture (47.85 N/mm2 and 47.46 N/mm2), Work to maximum load 0.07 mmN/mm3 and 0.06 mmN/mmJ, total work (0.11 mmN/mm3 and 0.10 mmN/mm3) respectively. Other strength properties were Compression (30.8 N/mm2 and 27.11 N/mm2), Shear (8.37 N/mm2 and 7.34 N/mm2) and Cleavage (16.29 N/mm and 12.35 N/mm) respectively. For all strength properties studied, there were significant differences between the two species, site, trees and within trees of the same species. G. robusta was found to be stronger than C. africana. For both species, trees from the lower altitude zone were stronger than those at higher altitude zone. It is recommended that, wood from G. robusta should be used where high strength is required. C. africana trees are suitable for shade due to their larger crown size. Denser and stronger timber should be selected from the low altitude zone.
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    Comparison of productivity, cost and energy expenditure when sawing on pitsawing and portable platforms In agroforestry farms in Kilimanjaro
    (Sokoine University of Agriculture, 2011) Rurangwa, Felix Anvers
    Although future increase in timber supply in many countries is expected to come from agroforestry, the problem of on farm timber sawing, physical strain on sawyers caused by “Pitsawing” has to be addressed, to increase timber sawing productivity. This study was aimed at analyzing the productivity and energy expenditure by sawyers when using Traditional Pitsawing Platforms (PSP) and Portable Steel Log Sawing Platforms (PLSP) in agroforestry farms in Kiruweni and Nduweni villages in South Kilimanjaro. Pitsawing productivity data was obtained using time studies of the pitsawing operations on the respective platforms and data on energy expenditure was obtained through heart rate measurements using heart rate monitor. Results indicated that the site preparation production rate, using PSP, was 0.1m 3 /h and the structure assembling production rate, using PLSP, was 2.9m 3 /h. The skidding production rate, using PSP, was 3.5m 3 /h and the production rate, using PLSP, was 11.9m 3 /h. Loading productivity improved from 4.97m 3 /h, using PSP, to 7.27m 3 /h, using PLSP. Productivity of sawing work element improved from 0.055m 3 /h, using PSP, to 0.057m 3 /h, using PLSP. In sawing, Energy Expenditure (EE) was 12.69kJ/min and 12.4 kJ/min using PSP and PLSP respectively. During pit excavation/structure assembling, EE was 14.05kJ/min, using PSP, and 2.61kJ/min using PLSP. The physical workload was classified as unduly heavy for PSP and light for PLSP. For the skidding work element, the EE decreased from 5.88kJ/min, using PLSP to 4.48kJ/min, using PSP. For the loading work element, the EE was decreased from 5.20kJ/min, using PSP to 3.55kJ/min, using PLSP. The sawing cost was TAS 205 320/m 3 , using PSP and TAS165 350/m 3 , using PLSP. In conclusion, PLSP is a technically more appropriate technology for reducing EE and sawing costs as well as increasing productivity during timber harvesting in agroforestry farms.