Post-Harvest Evaluation of Soil Physical Properties and Natural Regeneration Growth in Steep-Slope Terrains

Abstract

Protection of forest soils during harvesting operations is necessary to reduce damage and accelerate recovery time. The current study aims to evaluate soil physical properties, natural regeneration, and its recovery process in treatments including slope gradient, traffic intensity and skid trail after long periods of time, after ceasing the timber harvesting operations. The most recent skidding operations within each 5 years recovery period were studied for a chronosequence of 20 years. Soil samples were taken in abandoned skid trails and data were recorded on naturally regenerated species and density. The results revealed that most soil disturbances occurred on the slopes >20%, as well as the highest levels of traffic intensity. Bulk density and penetration resistance were still higher than the control area, with a significant difference between them, while total porosity was partially recovered. Twenty years after the skidding operation, soil bulk density and penetration resistance were 13.2% and 23.7% higher than the control area, while total porosity was 9.78% lower the than value of the control area. Seedlings of 50–150 cm and >150 cm in height on skid trails had significantly lower density than those in the control. The number of seedlings per m2 was less than the control area in all skid trails and for all height classes. The proportion of seedlings present in low traffic intensity was higher than in medium and high traffic intensities. The findings confirmed that full recovery rates are lengthy, and more time than 20 years is required to fully recover, especially with regards to penetration resistance.

Soil Recovery Assessment after Timber Harvesting Based on the Sustainable Forest Operation (SFO) Perspective in Iranian Temperate Forests

“…Over the years after the skidding operation, the soil physical properties improve from the three-year-old trail to the 25-year-old trail, although there are significant differences with the control area. The results show that 25 years after the skidding operations, the BD, PR, and MIP were 8.4%, 27.4%, and 50.44% greater, respectively, and the TP, MP, and SM, which were 1.96%, 17.1%, and 4.58% lower than the undisturbed area, respectively. The results of this study are consistent with the results of the study by Ezzati et al [50], which reported that, 20 years after skidding operations, under high traffic intensity and gentle slope class (<20%), the bulk density was 35-42% higher and the total porosity and macroporosity were 18-24% and 19-28% lower than the undisturbed area, respectively.…”

“…The change in the physical properties of the soil under the influence of skidding has been confirmed by other researchers, including Tavankar et al [63], Ezzati et al [50], Jourgholami at al. [32], Picchio et al [9], and Sohrabi et al [27]. The highest soil changes were obtained for high traffic intensity and slope, three years after the skidding operation.…”

“…The average load volume and number of logs for each skidding cycle by the Timberjack skidder were 3.8 m 3 and 2, respectively. The motivation behind this research was to gain a retrospective view of the research conducted by Ezzati et al [50] and Sohrabi et al [27] in the Hyrcanian forest, who claimed that the recovery of soil physical properties can be lengthy. However, this research did not investigate the recovery of the chemical and biological properties of the soil in responses to soil compaction over the time, which is one of the most interesting ideas developed in the current research.…”

Earthworms as an Ecological Indicator of Soil Recovery after Mechanized Logging Operations in Mixed Beech Forests

“…Due to the development, increase in size and weight of operating machines and their associated accessories in combination with the intensity of logging operations, especially in high humidity conditions, machine traffic in forest stands [7,[10][11][12] produces soil disturbance with drastically negative consequences. Soil disturbances caused by ground-based mechanized forest operations are usually considered as soil compaction (increase in soil bulk density) and soil displacement (lateral and longitudinal displacement of soil caused by the machine running gear), commonly referred to as rutting [7,[13][14][15][16][17].…”

Regeneration of Belowground Properties and Nutrient Pools in Soil after Compaction: Response to the Reforestation with Native Tree Species in the Hyrcanian Forest

“…Furthermore, soil compaction imposed by heavy machines during logging operations may dramatically affect the balancing and regulation of forest productivity process by demolishing soil structure and impairing soil physical properties [5]. Consequently, this phenomena lead to reduce the porosity in soil volume [6,7], decrease the connectivity of pore spaces [8,9], increase soil bulk density and strength [10,11], and reduce water infiltration and gas exchange [12,13], with consequent negative influences on soil macro-and micro-organisms (e.g., earthworms and microarthropods) [7,9], and elongation of root systems [14] and, ultimately, reducing tree and seedlings growth [15,16].…”