University of Khartoum

Comparative Study on Application of Volume Tables and Tariff equations for Selected Tree Species in Sudan

Comparative Study on Application of Volume Tables and Tariff equations for Selected Tree Species in Sudan

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Title: Comparative Study on Application of Volume Tables and Tariff equations for Selected Tree Species in Sudan
Author: Hassan Abdullah, Esmat
Abstract: The main problems facing forest resource Assessment in the Sudan are the inadequacy of the methods of biomass estimation and the inability to produce reliable forecasts of production in addition to the lack of accurate statistics on forest products. The need for sound techniques and methodologies for volume estimates is vital to forest inventory at local or national levels. The available systems for volume estimation; standard volume tables and tariff system need to be tested under various situations related to area extent, species limitations, ages and size classes. Standard volume tables are based on an assumption of an average form factor along the entire limits of volume table; this constitutes a source of inherited error in volume table approach. The tariff system is assumed to overcome the inherited error and other limitations of the volume table as a result of incorporation of form factor variable in tariff equations derivation. The main objective of this study is to compare between the volume tables and tariff systems application for volume estimation using statistical procedure and the actual volumes as reference volume. The latter was calculated by the form factor method. Other objectives are to check upon the universality of tariff system, in relation to the limitations of standard volume tables (areas, species and ages), size classes, in addition to creation of relationships between the tariff values and other measurable tree parameters, to facilitate tariff values prediction. The study was carried out on three tree species, Acacia nilotica in plantation along the Blue Nile and Rahad riverine forests, Acacia seyal in natural stands at Okalma forest reserve in rain fed sector of Sennar state and Eucalyptus camaldulensis in plantation at Abugeli of the Blue Nile riverine forest. Statistical analysis was performed with JMP statistical software by SAS. For comparison between results of different volume estimating systems, effects of geographical areas, species type, and age on Volume Comparison Index (VCI) for both systems. Scatter plots, regression techniques were used to determine the effects of different systems on the Volume Comparison Index xi and relationship between different parameters, values and treatments as related to different systems. The results indicate that there is no significant variation between volume values estimated by tariff system, and the actual volume values (form factor method) for each of the three species while there are significant variations in volume values estimated by standard volume equation system as compared to the other two systems. The results indicated that, the general tariff system is consistently more accurate than the standard volume table, although the latter is species specific. The present study indicated that, form factor is a function of diameter at breast height (dbh) and height. Therefore, errors associated with the standard volume equations are due to the incorrect assumption of a constant form factor over the range of size-classes parameters of the standard volume equations. The application of the volume tables is constrained by inherited limitations to the site or locality, species type ages and size classes. Further to that, volume tables are characterized by inherited source of error even though applied for the species for which it is constructed. The application of the tariff system, overcome the error and limitations associated with the standard volume table as it incorporates form factor as a variable in tariff equations, indicating the universality of the system as it is simple and more accurate than the standard volume table under different conditions and species. The study provided evidence that the tariff system is a stand development measure as it is based on tariff numbers or form height classes which are characterized by increasing trend with age. Due to the strong relationship between top height and the tariff number, top height is the most convenient and suitable tree/stand parameter to be used for the determination of tariff numbers and in tariff system application. The study recommended that tariff system should replace the volume table in all biomass estimation in Sudan.
Description: 106 Pages
URI: http://khartoumspace.uofk.edu/handle/123456789/9269
Date: 2015-04-22


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