Modelling of forest decluttering technology along with estimation of deadwood amount

Abstract

A technology has been proposed for cleaning the forest from deadwood along with an evaluation of its total amount on the site (CFD). The basis of the deadwood quantitative evaluation is the linear intersection sampling (LIS). Within the CFD framework technology, the paper considers the technique of harvesting deadwood using a portable winch with a cable length from 40 to 120 m. A mathematical model has been developed of both the technological process and deadwood estimation. In the model, a number of sites were considered accounting for 50 to 150pcs of deadwood / ha. The results of simulation experiments have showed that the required number of sampling lines decreases in a power-law dependence with an increase in the amount of deadwood on the site and the length of the winch cable (sampling line). For the accuracy index P = 20%, the required number of sampling lines is within the range of 10-70 pcs / ha. Errors between the true values of the deadwood amount on the strip and its estimates did not exceed 7% in absolute value. At the same time, the deviation of the estimates depends neither on the amount of deadwood on the strip nor the length of the winch cable (sampling line). Errors in estimating the mean deadwood length for a sample made from the pieces that crossed sampling lines did not exceed 3%. The estimation procedure impact on the deadwood harvesting productivity proved to be negligible. The drop in performance does not exceed 1%. The impact of the amount of deadwood on the productivity on the site can be considered insignificant. With an increase in the length of the winch cable, a noticeable decrease in productivity is observed. Thus, with an increase in the length of the cable from 40 m to 120 m, productivity drops by 40%. This is due to the fact that the technology in question assumes piece skidding of deadwood. In this case, the time it takes to unwind the cable to a greater distance exceeds the time for the skid relocation. However, should the technology change, for example, in case of using a more powerful winch and skidding several trees at the same time, the situation may change.