Economic evaluation of two management strategies of Acacia nilotica (L.) plantations along the Blue Nile south of Sennar Dam, Sudan

Abstract

This study was concerned with the plantations of Acacia nilotica grown for sawlog -to produce railway sleeper- production along the Blue Nile, South of Sennar dam, Sudan. The overall objective was to determine the best management strategy of the plantations that maximizes financial returns. Primary data was collected using standard work study techniques and inventory methods. Secondary data used included previous studies on yield tables and volume estimations. The study used the criterion of net present value (NPV) for determination of financial rotation, and for evaluating different management strategies. The research applied comparative statistics to assess relative stocking of existing stands. The research revealed that the operations of seed sowing and singling were the most expensive forest operations involving 5.8 and 7.8 mandays per feddan, respectively. Log transport was the most expensive sawmilling-related operation involving 36 mandays and 3 machine days per feddan. With the current conversion factor of state sawmills of about 40%, the technical rotation of stands of site index 22 to produce sawlogs large enough to yield the maximum of a single sleeper was estimated to be within a range of 25-36 years. That of stands of site index 25 to yield the maximum of two sleepers falls within the range 25-36 years. Stands of site index 28 are technically suitable to produce sawlogs large enough to yield the maximum of three sleepers within age range of 29-36 years. These results exclude stands of site index 16 and 19 from producing saw logs for sleeper production. A. nilotica stands under present management show low relative stocking and yield per feddan, low millable percentage of final cut (47%) and rotation age dropped to 25-27 years. The financial rotation was determined as 33 and 26 years when A. nilotica stands are managed for sawlog production under Foggie management strategy (FMS) and Jackson management strategy (JMS), respectively. Addition of capitalized net income from sawmilling operations for production of Sudan railways sleeper reveals that JMS is financially more attractive (95.1, 75.3 thousand Dinars) than FMS (88.3, 71.2 thousand Dinars) in more productive stands of site index 28 at both high and low levels of management, respectively. FMS is financially superior (29.2, 18.8 thousand Dinar) in less productive stands of site index 22 than JMS (25.1, 14.4 thousand Dinar) at both high and low levels of management, respectively. JMS and FMS applied to stands of site index 25 generated very close NPVs per feddan (59.0 & 59.2 thousand Dinar) at high level of management and low level of management (46.7 & 45.5 thousand Dinar). The use of taungya practice in establishment of A. nilotica stands, advancement of thinning in stands with better site qualities, and their combination improve their overall profitability relative to NPV of the system without them. A number of policy and practical implications of the findings of this research are evident, First, A. nilotica forests need to be reorganized on the basis of site index and sawlog production be concentrated on stands of site index 28 and 25 while stands of site index 16 and 19 be assigned for firewood production. Second, the system of A. nilotica forests should be treated as inseparable continuum of sawlog-sleeper production. Third, Jackson Management Strategy is financially more attractive and should be adopted for the treatment of stands of site indexes 28 and 25 managed for sleeper production .