Dos Santos Silayo | Sokoine University of Agriculture (original) (raw)
Papers by Dos Santos Silayo
Models to assist management of lowland forests in Tanzania are in most cases lacking. Using a sam... more Models to assist management of lowland forests in Tanzania are in most cases lacking. Using a sample of 60 trees which
were destructively harvested from both dry and wet lowland forests of Dindili in Morogoro Region (30 trees) and Rondo in
Lindi Region (30 trees), respectively, this study developed site specific and general models for estimating total tree volume and aboveground biomass. Specifically the study developed (i) height-diameter (ht-dbh) models for trees found in the two sites, (ii) total, merchantable, and branches volume models, and (iii) total and sectional aboveground biomass models of trees found in the two study sites. The findings show that site specific ht-dbh model appears to be suitable in estimating tree height since the tree
allometry was found to differ significantly between studied forests.The developed general volume models yielded unbiased mean
prediction error and hence can adequately be applied to estimate tree volume in dry and wet lowland forests in Tanzania. General aboveground biomassmodel appears to yield biased estimates; hence, it is not suitable when accurate results are required. In this case, site specific biomass allometric models are recommended. Biomass allometric models which include basic wood density are highly recommended for improved estimates accuracy when such information is available.
Timber harvesting in Tanzania still uses semi-mechanized and labour–intensive logging systems. Ma... more Timber harvesting in Tanzania still uses semi-mechanized and labour–intensive logging systems. Manual or semi-mechanised logging operations by using hand tools are more favoured due to cheap labour availability. These tools are operated by locally recruited crews characterized by low levels of skill and literacy. This study was designed to assess tree cutting crews using two man crosscut saws and develop productivity and production cost models in a learning by doing experiment. The experiments were designed in clear felling operations. Three experiments were set where each crew category was studied using time study and work sampling techniques that involved studying crews before training, after training and after the break at an interval of three months. Descriptive statistics and modelling was performed for each crews‟ performance. Specific crew‟s productivity and cost models have been developed reflecting necessary and unnecessary delay times. The results showed that there is an increase in production rate of the crews after training with a subsequent fall in production rates as the crews resumed cutting after the break. Results showed that there was an average of 40% production increase after training and about 23% production fall after the break for all crew categories. Further the production costs were relatively lower after training as compared to other experiments in the study. Generally, the unit cost of operations observed in the three experiments was mostly affected by labour costs. This is because labour cost accounted about 94% of the hourly costs. This means that since crosscut saw used two people, then any increase in labour charges will linearly affect the unit cost of production at a significant level. This study has demonstrated the importance of training tree cutting productivity and production costs. On the job training of the crews is therefore recommended despite their experience for improved productivity at reduced costs.
Agriculture is the primary driver of deforestation and degradation. This makes addressing defores... more Agriculture is the primary driver of deforestation and degradation. This makes addressing deforesting and
degrading agricultural practices highly pertinent in the REDD+ planning and implementation. REDD+ interventions
target to mitigate deforestation and degradation by addressing underlying drivers such agricultural expansion into
forestland. In tropical Africa, encroachment of forests in search of fertile virgin land has been a common practice.
Inevitably, the REDD+ processes will impact on the local livelihoods in different ways – positive and negative. The
local-level land use plans promoted under REDD+ are likely to alter how much land a farmer would access and where.
Different groups of the poor will be affected differently. Land use alterations will impact on the local food security
and food systems at large. In view of such impacts, compensations are made integral of REDD+ programming and
delivery. REDD+ projects promote agricultural intensification practices such as conservation agriculture in order to
attain higher food production per unit land while mitigating deforestation and degradation. As REDD+ concept is
being piloted in the country, we have limited understanding of the livelihood implications of REDD+ interventions.
Furthermore, local-scale economic viability of measures used to address drivers of deforestation and degradation
such as agricultural expansion is empirically not well understood. This paper is a modest attempt to illuminate the
livelihood implications of REDD+ interventions and estimate the economic viability of agricultural intensification
practices in the REDD+ pilot area in Kilosa district, Tanzania.
Integrating ecological concerns with the daily operations of logging crews has been an area of in... more Integrating ecological concerns with the daily operations of logging crews has been an area of interest in ensuring for sustainable environmental management in forestry. Learning curves have been found to be a useful tool in scheduling harvesting operations for better performance in the sector. This study was conducted to establish learning curves and forgetting factors of two-man crosscut saw operators in tree harvesting operations in Tanzania. Experienced and inexperienced operators were studied before training, after training and after the break at an interval of three months during clear felling operations. The results for the learning rate were somewhat different between crew category and across experiments. For example, start-up operators had about 67% and 57% higher learning rate as compared to experience operator when studied for the first time and after training. Results on the forgetting function showed some levels of knowledge depreciation for both crews as could be reflected by their productivity levels. For example the experienced crew had a forgetting factor of 9.4% while the start-up crew had 19% forgetting factor. Therefore, training is imperative for the logging crews to realise high performance at reduced environmental damage such as forest soils disturbances and increased logging residues that may arise from improper logging practises.
A study was carried out to assess the effect of training and job interruptions on logging crews’ ... more A study was carried out to assess the effect of training and job interruptions on logging crews’ safety during tree cutting using chainsaw and two-man cross cut saws. For each cutting method, experienced and inexperienced/start up crews were studied before training, after training and after break using time study techniques for nine months at intervals of three months. Results show that crews seldom use safety gears. Inexperienced crews suffered more health risks than experienced crews. Most of occupational risks encountered by chainsaw operators’ start up crew were from falling objects (mostly dead branches and pods), falling trees, walking between trees with a running chainsaw as well as walking carelessly on logs and felled trees during bucking. Experienced two-man cross cut saw operators committed fewer risks with about 37% fewer injuries compared to inexperienced crew. Chainsaw operators suffered relatively more injuries compared to two-man cross cut saw operators. However, after training, there were significant improvements in both methods, especially for the start-up crews. There was decreased level of safety consciousness with increased accidents and or risks after the break for both crew categories with start-up crews suffering more injuries. On resuming operations after the break, start-up crews seemed to adhere to safety rules more than the experienced ones. It can be concluded that provision of appropriate safety gears as well as delivery of on job training are important measures for improved performance and lowering accidents and injuries to logging crews.
Timber harvesting in Tanzania uses semi-mechanized and labour – intensive logging systems. Manual... more Timber harvesting in Tanzania uses semi-mechanized and labour – intensive logging systems. Manual or semi-mechanized logging operations by using hand tools are more favoured due to cheap labour availability. For example, tree cutting is done manually using two-man crosscut saws, axes or chainsaws. This study was conducted at Sokoine University of Agriculture Training Forest to assess the effect of training and job interruptions for chainsaw operators during tree cutting operations in softwood plantation forests in Tanzania. Tree cutting operations using experienced and inexperienced chainsaw operators were studied in three experiments; before training, after training and after the break. Time study and work sampling techniques were used for data collection. Descriptive statistics and modeling was performed for each crews’ performance. Results show that generally, experienced crew spends lesser time in cutting as compared to inexperienced crews. However, start up chainsaw crew spent 32% higher time for preparation before tree felling. However, the crew showed significant improvement after training unlike the experienced one. The analysis of the delay times start up crew was had a significant proportion of the delay times during the first engagement which decreased substantially in the other two experiments. Generally, there was an improvement of the cutting time after training for all crew categories with decrease after the break. This observation signifies that job interruptions impact the productivity of the crews. Therefore, on job training on resumption of the operations may significantly improve crews’ productivity, safety as well as ensuring product quality.
Models to assist management of lowland forests in Tanzania are in most cases lacking. Using a sam... more Models to assist management of lowland forests in Tanzania are in most cases lacking. Using a sample of 60 trees which
were destructively harvested from both dry and wet lowland forests of Dindili in Morogoro Region (30 trees) and Rondo in
Lindi Region (30 trees), respectively, this study developed site specific and general models for estimating total tree volume and aboveground biomass. Specifically the study developed (i) height-diameter (ht-dbh) models for trees found in the two sites, (ii) total, merchantable, and branches volume models, and (iii) total and sectional aboveground biomass models of trees found in the two study sites. The findings show that site specific ht-dbh model appears to be suitable in estimating tree height since the tree
allometry was found to differ significantly between studied forests.The developed general volume models yielded unbiased mean
prediction error and hence can adequately be applied to estimate tree volume in dry and wet lowland forests in Tanzania. General aboveground biomassmodel appears to yield biased estimates; hence, it is not suitable when accurate results are required. In this case, site specific biomass allometric models are recommended. Biomass allometric models which include basic wood density are highly recommended for improved estimates accuracy when such information is available.
Timber harvesting in Tanzania still uses semi-mechanized and labour–intensive logging systems. Ma... more Timber harvesting in Tanzania still uses semi-mechanized and labour–intensive logging systems. Manual or semi-mechanised logging operations by using hand tools are more favoured due to cheap labour availability. These tools are operated by locally recruited crews characterized by low levels of skill and literacy. This study was designed to assess tree cutting crews using two man crosscut saws and develop productivity and production cost models in a learning by doing experiment. The experiments were designed in clear felling operations. Three experiments were set where each crew category was studied using time study and work sampling techniques that involved studying crews before training, after training and after the break at an interval of three months. Descriptive statistics and modelling was performed for each crews‟ performance. Specific crew‟s productivity and cost models have been developed reflecting necessary and unnecessary delay times. The results showed that there is an increase in production rate of the crews after training with a subsequent fall in production rates as the crews resumed cutting after the break. Results showed that there was an average of 40% production increase after training and about 23% production fall after the break for all crew categories. Further the production costs were relatively lower after training as compared to other experiments in the study. Generally, the unit cost of operations observed in the three experiments was mostly affected by labour costs. This is because labour cost accounted about 94% of the hourly costs. This means that since crosscut saw used two people, then any increase in labour charges will linearly affect the unit cost of production at a significant level. This study has demonstrated the importance of training tree cutting productivity and production costs. On the job training of the crews is therefore recommended despite their experience for improved productivity at reduced costs.
Agriculture is the primary driver of deforestation and degradation. This makes addressing defores... more Agriculture is the primary driver of deforestation and degradation. This makes addressing deforesting and
degrading agricultural practices highly pertinent in the REDD+ planning and implementation. REDD+ interventions
target to mitigate deforestation and degradation by addressing underlying drivers such agricultural expansion into
forestland. In tropical Africa, encroachment of forests in search of fertile virgin land has been a common practice.
Inevitably, the REDD+ processes will impact on the local livelihoods in different ways – positive and negative. The
local-level land use plans promoted under REDD+ are likely to alter how much land a farmer would access and where.
Different groups of the poor will be affected differently. Land use alterations will impact on the local food security
and food systems at large. In view of such impacts, compensations are made integral of REDD+ programming and
delivery. REDD+ projects promote agricultural intensification practices such as conservation agriculture in order to
attain higher food production per unit land while mitigating deforestation and degradation. As REDD+ concept is
being piloted in the country, we have limited understanding of the livelihood implications of REDD+ interventions.
Furthermore, local-scale economic viability of measures used to address drivers of deforestation and degradation
such as agricultural expansion is empirically not well understood. This paper is a modest attempt to illuminate the
livelihood implications of REDD+ interventions and estimate the economic viability of agricultural intensification
practices in the REDD+ pilot area in Kilosa district, Tanzania.
Integrating ecological concerns with the daily operations of logging crews has been an area of in... more Integrating ecological concerns with the daily operations of logging crews has been an area of interest in ensuring for sustainable environmental management in forestry. Learning curves have been found to be a useful tool in scheduling harvesting operations for better performance in the sector. This study was conducted to establish learning curves and forgetting factors of two-man crosscut saw operators in tree harvesting operations in Tanzania. Experienced and inexperienced operators were studied before training, after training and after the break at an interval of three months during clear felling operations. The results for the learning rate were somewhat different between crew category and across experiments. For example, start-up operators had about 67% and 57% higher learning rate as compared to experience operator when studied for the first time and after training. Results on the forgetting function showed some levels of knowledge depreciation for both crews as could be reflected by their productivity levels. For example the experienced crew had a forgetting factor of 9.4% while the start-up crew had 19% forgetting factor. Therefore, training is imperative for the logging crews to realise high performance at reduced environmental damage such as forest soils disturbances and increased logging residues that may arise from improper logging practises.
A study was carried out to assess the effect of training and job interruptions on logging crews’ ... more A study was carried out to assess the effect of training and job interruptions on logging crews’ safety during tree cutting using chainsaw and two-man cross cut saws. For each cutting method, experienced and inexperienced/start up crews were studied before training, after training and after break using time study techniques for nine months at intervals of three months. Results show that crews seldom use safety gears. Inexperienced crews suffered more health risks than experienced crews. Most of occupational risks encountered by chainsaw operators’ start up crew were from falling objects (mostly dead branches and pods), falling trees, walking between trees with a running chainsaw as well as walking carelessly on logs and felled trees during bucking. Experienced two-man cross cut saw operators committed fewer risks with about 37% fewer injuries compared to inexperienced crew. Chainsaw operators suffered relatively more injuries compared to two-man cross cut saw operators. However, after training, there were significant improvements in both methods, especially for the start-up crews. There was decreased level of safety consciousness with increased accidents and or risks after the break for both crew categories with start-up crews suffering more injuries. On resuming operations after the break, start-up crews seemed to adhere to safety rules more than the experienced ones. It can be concluded that provision of appropriate safety gears as well as delivery of on job training are important measures for improved performance and lowering accidents and injuries to logging crews.
Timber harvesting in Tanzania uses semi-mechanized and labour – intensive logging systems. Manual... more Timber harvesting in Tanzania uses semi-mechanized and labour – intensive logging systems. Manual or semi-mechanized logging operations by using hand tools are more favoured due to cheap labour availability. For example, tree cutting is done manually using two-man crosscut saws, axes or chainsaws. This study was conducted at Sokoine University of Agriculture Training Forest to assess the effect of training and job interruptions for chainsaw operators during tree cutting operations in softwood plantation forests in Tanzania. Tree cutting operations using experienced and inexperienced chainsaw operators were studied in three experiments; before training, after training and after the break. Time study and work sampling techniques were used for data collection. Descriptive statistics and modeling was performed for each crews’ performance. Results show that generally, experienced crew spends lesser time in cutting as compared to inexperienced crews. However, start up chainsaw crew spent 32% higher time for preparation before tree felling. However, the crew showed significant improvement after training unlike the experienced one. The analysis of the delay times start up crew was had a significant proportion of the delay times during the first engagement which decreased substantially in the other two experiments. Generally, there was an improvement of the cutting time after training for all crew categories with decrease after the break. This observation signifies that job interruptions impact the productivity of the crews. Therefore, on job training on resumption of the operations may significantly improve crews’ productivity, safety as well as ensuring product quality.