Production Rates of Mechanized Tree Felling Operations at Sao-Hill Forest Plantation, Tanzania

With the advancement of technology in forest operations, utilization of advanced machines in timber harvesting has been increasing in the last decades. However, in order to understand their contribution in harvesting operations, it is important to quantify their production rates. The findings will assist the development of timber harvesting plans. Therefore, this study was conducted at Sao-Hill Forest Plantation in Tanzania to determine time consumption and production rates of whole tree harvesting system using feller buncher. Regression models for predicting time consumption and production rates were also developed. The results showed that average productive felling time was 0.7 minutes per tree and production rates was 32.6 m3/h respectively. The production rates varied among tree size classes. For trees with diameter at breast height (dbh) of 10-19.9 the average production rates was 19.07 m3/h while for dbh class of 30-39.9 the production rate was 75.48 m3/h. Time consumption and production rates models were having Adjusted-R2 of 50% and 56 % respectively. Their relative root mean square errors (RMSEr), computed based on the predictions from 10 - fold across validation results, were 28.69% and 45.37%, respectively. Applicability of the models should be limited within the ranges from which they have been developed

Modelling Above Ground Biomass Using Sentinel 2 and Planet Scope Data in Dense Tropical Montane Forests of Tanzania

Forest biomass estimation using field -based inventories at a large scale is challenging and generally entails large uncertainty in tropical regions. In this study, we investigated the performance of Sentinel 2 and Planet Scope data for above ground biomass (AGB) modelling, in the tropical rainforest of Tanzania. A total of 296 field inventory plots were measured across the west Usambara mountain forests. The results showed that, Sentinel 2-based model fitted using GLMs had better performance (cvRMSEr = 67.00 % and pseudo-R2= 20%) as compared to Planet Scope-based models (cvRMSEr = 72.1 % and pseudo-R2= 5.2%). Overall GLMs resulted into models with less prediction errors in contrast to random forest when using Sentinel 2 data. However, for the Planet Scope, there was marginal improvement when using random forest (cvRMSEr = 72.0%). Models that incorporated texture variables produced better prediction accuracy as compared to those with band values and indices only. The study has shown that, Sentinel 2 and Planet Scope remotely sensed data can be used to develop cost-effective method for AGB estimation in tropical rainforests of Tanzania

Aboveground biomass and carbon stock of Usambara tropical rainforests in Tanzania

Forest Above ground biomass (AGB) and carbon stock (AGC) estimation is important for carbon budget accounting, sustainable forest management as well as for understanding the role of forest ecosystem in the climate change mitigation. In the recent decade, there has been a growing global interest on quantifying AGB and AGC in the tropical countries. However, the information on AGB and AGC at local and subnational scales in most of the tropical forests is scattered and not consolidated. In this study, we reviewed the existing information on AGB and AGC for tropical rainforests of northern Tanzania. We used both data published in the peer-reviewed literature and data from unpublished sources provided by various sources. Our results showed that, there are three types of data sources and methods used for estimation of AGB and AGC. These included, field, geographical information system and remote sensing. Of all the methods, field based method was applied to a large extent. The average reported minimum values of AGB and AGC are 177.00 Mg ha-1 and 88.5 Mg ha-1, and the maximum average values are 872 Mg ha-1 and 436 Mg ha-1 respectively. Overall, the average values of AGB and AGC in the Usambara tropical mountain forests (UTMFs) are 351.08 Mg ha-1 and 175.54 Mg ha-1 respectively. Forest structure parameters, particularly tree sizes and number of tree stems, were the major structure parameters reported to affect the amount of AGB and AGC. To conclude, the study revealed that there is a progressive trend in the estimation of AGB and AGC in the UTMFs. However, more update and effective forest survey data and methods are needed particularly in west Usambara mountain forests block

Modeling Productivity and Costs of Mechanized Tree Length Skidding Operations

Skidding operation constitute the entire process of moving felled trees from the stump site to the roadside landing. This operation normally bears substantial amount of the mill delivery costs. Thus, detailed information on productivity and cost is important for planning of cost-effective skidding operation. This study was conducted at Sao hill Forest plantation to quantify productivity and costs of tree length skidding operations. Continuous time study technique using snap-back method was used for time recording. Costs data were obtained from Mufindi Paper Mill logging department. Productivity and costs modeling, were performed using Microsoft excel. The analysis, showed that; the average productivity of the grapple skidder using tree length (TL) ranges between 398.423 m3/hr at a distance of 10 m and 49.862 m3/hr at a distance of 80 m. On the costs analysis, the unit skidding costs tends to increase with an increase of skidding distance (m) from 512.197 TZS/m3 at a distance of 10 m to 4,092.675 TZS/m3 at a distance of 80 m. Based on these findings it is recommended that variables distance and volume are the core factors to consider during planning to enhance efficient and costs effective skidding operation

Lumber Recovery and Production Rates of Small-Scale Mobile Sawmilling Industries in Northern Tanzania

This study was carried out to quantify technical efficiency of mobile sawmills by determining the lumber recovery rates and production rates of two mobile sawmills namely as Wood-Mizer (band saw machine) and Ding-dong (circular saw machine). The study was conducted in Lushoto district, located in the Northern part of Tanzania. The results indicated that Wood-Mizer had lumber recovery of 51.3% and production rate of 0.64m3/hr., while Ding-dong had lumber recovery rate of 35.2%, and production rate 0.86m3/hr. Generally, results have shown that both sawmills have reasonable lumber recovery rates and production rates irrespective of the differences between the two, however Wood-Mizer had great conversion efficiency compared to the Ding-dong machine. Considering the reduced supply of saw logs for sustainable forest management, a machine with high conversion efficiency is highly encouraged than machine with high speed of production, thus Wood-Mizer stands to have more chances of applications as compared to Ding-dong machine which had relatively higher production rates. However, we encourage further studies to be conducted with diverse sets of factors associated with economic aspects as well as tree species to have more baseline information on the performance of these two mobile sawmilling machineries

Height-Diameter Allometry for Tree Species in Tanzania Mainland

Article ID 4832849201

Optimal Rotation Age of Pinus patula in Government Forest Plantations in Tanzania

A study to determine the optimal rotation age of Pinus patula was conducted in five forest plantations in Tanzania, i.e., Kawetire, Kiwira, North Kilimanjaro, West Kilimanjaro and Meru. Growth and yield, and mechanical properties data were collected from compartments representing age from 5 to 25 years. In addition, revenues and management costs data were collected for the purpose of determining the economic rotation age. For the purpose of determining the optimal rotation age based on growth and yield, the following basic models were developed: 1) site index curves model, 2) height-D model, 3) Single tree volume model, 4) Basal area growth model 5) stand volume model, 6) mortality model, and 7) simulation of thinning. Analysis of Variance (ANOVA) was carried out to ascertain whether the wood properties vary across age classes. Economic analysis of rotation age data involved computation of Net Present Value (NPV). Growth and yield data revealed irrespective of site class, P. patula can be harvested at age of 18 years while mechanical wood properties show that harvesting ages range between 16 and 21 years. Based on NPV, the optimal age was 16 years. Therefore, it is recommended P. patula be harvested at age of 18 years irrespective of site class