volume: 34, issue: 1
volume: 41, issue: 1
Several rehabilitation treatments have been applied to mitigate runoff and sediment in machine trafficked areas following logging operations, while the knowledge on the consequence of these remediation techniques on the recovery of soil properties remains scarce. The objective of the study was to determine the effect of different rehabilitation treatments including sawdust mulch (SM), water diversion structure (WDS), untreated/bare trail (U), and undisturbed or control area (UND) on the recovery of soil chemical properties over a six-year period after machine-induced compaction occurred on three longitudinal trail gradients (10, 20, and 30 %).In each treatment, the following soil properties were measured: litter thickness, pH, EC, soil organic C, total N, and available P, K, Ca, and Mg. Five sampling plots (with 10 m length and 4 m width) were positioned in each trail gradient classes and three of these plots were randomly considered for soil sampling.The results demonstrate that litter thickness differed among the three treatments, with the highest amount present on the UND area and lowest on the U treatment. Meanwhile, the highest pH (6.75), EC (0.21 Ds m−1), N (0.27 %), available P (14.61 mg kg−1), available K (123.5 mg kg−1), available Ca (135.1 mg kg−1), and available Mg (42.1 mg kg−1) and the lowest C (1.21 %) and C/N ratio (7.83 %) were found on the SM with gradient of 10 % compared to other gradient classes on SM, WDS and, U treatments. The recovery value of litter depth, pH, EC, C, N, C/N ratio, and available nutrients (P, K, Ca, and Mg) were higher on the SM than the WDS at the gradient of 10 %, while significantly higher levels of these variables were measured under WDS installed on trail gradients of 30 % and 20 % when compared with the same gradients on SM. Results of the study revealed that soil chemical properties showed some evidence of recovery following SM and WDS rehabilitation treatments compared to U, although these properties did not fully recover within 6 years as compared to UND area
volume: 41, issue:
Ground-based skidding operations can lead to soil compaction and displacement, which could cause negative effects on forest soil. Hence, some efforts such as forestry best management practices (BMPs) must be implemented in the prone area to mitigate these possible impacts. Several materials and treatments have been adopted to suppress these adverse effects by increasing the ground cover. However, the effects of mulch treatments on runoff and sediment yield are inconclusive with a diverse range of effectiveness. For these reasons, in this research mulch treatments were tested as to determine how the application of organic mulch amendments such as straw and leaf litter and contour-felled logs would alleviate the runoff and sediment yield on machine operating trails and ensure successful hillslope stabilization. The aims of the study were to analyse and compare the effectiveness of leaf litter (LM) and straw mulch (SM) rate and different distances of contour-felled logs (CFL) to mitigate the runoff and sediment yield, and examine the impact of rainfall intensity on effectiveness of litter mulch, straw mulch, and contour-felled logs. Totally, 30 bounded runoff plots in the machine operating trails and four treatments including litter mulch (LMR1: 0.62, LMR2: 1.24, and LMR3: 1.86 kg m-2), straw mulch (SMR1: 0.45, SMR2: 0.92, and SMR3: 1.34 kg m-2), contour-felled logs (CFL10: 10, CFL20: 20, and CFL30: 30 m), and untreated area were established in triplicate with 4 m width and 100 m length. During the study period, the runoff and sediment yield in the untreated trails (U) were 2.36 mm and 11.84 g m-2. Straw (from 41.5 to 60.6%) and litter mulch (from 38.1 to 55.1%), and contour-felled logs treatments (from 70.8 to 88.1%) significantly decreased the runoff, compared to U treatment. Results show that mulch treatments with three different levels of Litter Mulch Rate, LMR1, LMR2, and LMR3 decreased mean sediment by 46.6, 64.0 and 71.8%, in the treatments with three different levels of Straw Mulch Rate, SMR1, SMR2, and SMR3 decreased mean sediment by 42.9, 62.1, and 69.9%, and in the treatments with three different distances of Contour-Felled Logs, CFL10, CFL20, and CFL30 decreased mean sediment by 90.6, 94.7 and 88.3% comparing to U, respectively. The relationships of the runoff and sediment responses to increasing mulching rate of litter and straw followed as negative logarithmic curves, but the decreasing-increasing trends were observed in runoff and sediment yield as the distance between contour-felled logs increased from 10 to 30 m. Polynomial regression equations were developed for predicting the runoff and sediment yield as a function of the application rate of litter and straw mulch and the distance between contour-felled logs, and rainfall intensity. We concluded that contour-felled logs treatment was more effective than both litter and straw mulch to mitigate the runoff, runoff coefficient, and sediment yield on machine operating trails. As a management measure, it could be possible to propose that the contour-felled logs with a distance of 20 m be prescribed to protect the machine operating trails from the negative effects of surface waterflow.