Densidade ótima de estradas aplicada ao transporte de toras curtas em florestas plantadas

Abstract

To guarantee the factory supply, adequate planning of operations is necessary, especially for forest roads. Optimal road density, linked to the use of geotechnologies and forest productivity, is a crucial parameter for decision making. With this, the objective of this work was to define the critical points for the transport of wood, together with the density of the current scenario of the roads, in addition to determining the optimal density of forest roads in different scenarios of individual average volume of the forest and combinations proposed freight vehicles. The study area is in Ribas do Rio Pardo city, Mato Grosso do Sul state. Initially, using geoprocessing tools, we proceeded with the analysis of the classification of the roads and the determination of critical points for the transport of wood for each type of vehicular load combinations, being they two-train, three-train and six-train, associated with their limitations in terms of slope, above 12%, above 8% and above 5%, respectively. Subsequently, the optimal road density was generated by minimizing the sum of total costs for the nine different individual average volume scenarios (0.15, 0.20 and 0.25 m³.tree-1 ), correlated to different load vehicular combinations (two-train, three-train and six-train). To analyze the wood storage capacity on forest roads, it was necessary to calculate the volume of wood per linear meter, based on standard pile dimensions used in the company. After this stage, the minimum and maximum size of the plots was also obtained, based on the optimal density of roads. With all the proposal, it was possible to verify that 0.9% of the roads in the area are located on slopes above 12%, that is, a critical point for two-train traffic. 3.3% of the roads are at critical points, with a slope greater than 8%, for the movement of three-train and 17.3% of the roads are in places considered critical (decline > 5%) for the movement of six-train. It was observed that the current density of roads in the area is 52.72 m.ha-1 . The variation in the optimal density obtained in the evaluated scenarios was 19.57 and 27.61 m.ha-1 , corresponding to the average volume scenario 0.15 m³.tree-1 associated with the six- train and the individual average volume scenario 0, 25 m³.tree-1 related to the two-train, respectively. Scenarios with average individual volume of 0.15 m³.tree-1 , associated with two-train and three-train, assumed optimal density values of 25.57 and 23.68 m.ha-1 , respectively. The individual average volume scenarios 0.20 m³.tree-1 related to two-train, three-train and six-train, presented 26.16, 24.46 and 20.45 m.ha-1 of optimal density. The average individual volume 0.25 m³.tree-1 , connected to three-train and sixtrain, respectively, had optimal density of 26.91 and 22.06 m.ha-1 . The scenarios studied did not present restrictions regarding the wood storage capacity in the optimal scenarios, except for the six-train scenario with an average individual volume of 0.25 m³.tree-1 . As for the ideal sizes of plots, a variation between 18 and 51 ha can be seen, corresponding to the two-train scenarios with an average volume of 0.15 m³.tree-1 and the six-train with an average volume of 0.25 m³.tree-1 . The tools proposed in this study reached the expected expectations. The study of critical points, linked to the type of vehicular load combinations, showed efficiency in terms of mapping points of attention. The calculation of the optimal road density was efficient as a tool to reduce operational costs, analyzing the influence of individual average volume and different vehicular load combinations. The research proposes and recommends low-cost and easy-to-apply methodologies for forest manager decision-making.