ABSTRACT

Poplar plantations have been widely practiced in the coastal area of the Caspian Sea in northern Iran. In this research, soil compaction following logging operations carried out by wheeled cable skidder was investigated in two poplar plantations with different characteristics including moist soil and dry soil. The soil gravimetric moisture content (MC) in the dry site ranged from 13% to 14.4%, while in the moist site it ranged from 30.5% to 34.6%. The mineral soil samples were collected from the skid trails in both sites. The impact of skidding operations on soil layers (soil depth, SD) was examined by measuring rut depth (RD), penetration resistance (PR), bulk density (BD), and total porosity (TP) at five traffic intensities (TI). Results indicated that MC and TI had a significant effect on RD, PR, BD, and TP; however, SD had a significant effect on PR and BD. The values of BD were significantly higher in the moist site than in the dry site, while the values of PR and TP were significantly higher in the dry site than in the moist site. The RD in the moist site (11.7 cm) was 1.65 times more than RD in the dry site (7.1 cm) after one pass where a pass was defined as one empty and one loaded trip over a spot. The differences between BD after 10 and 15 passes were not significant on the dry site, but significant in the moist site. We concluded that skidding operations should be conducted when soil conditions are dry.

摘要

杨树种植园已在伊朗北部里海沿岸地区广泛种植。在这项研究中，在两个具有不同特性的杨树人工林中，包括潮湿土壤和干燥土壤，调查了轮式电缆集材机伐木作业后的土壤压实。干地土壤重量含水量（MC）为 13% 至 14.4%，而潮湿地为 30.5% 至 34.6%。矿质土壤样品是从两个站点的滑道收集的。通过在五种交通强度 (TI) 下测量车辙深度 (RD)、穿透阻力 (PR)、容重 (BD) 和总孔隙度 (TP)，来检查打滑作业对土壤层（土壤深度，SD）的影响。结果表明，MC和TI对RD、PR、BD和TP有显着影响；然而，SD对PR和BD有显着影响。BD 值在潮湿地显着高于干燥地，而 PR 和 TP 值在干燥地显着高于潮湿地。一次通过后，潮湿场地（11.7 厘米）的 RD 是干燥场地（7.1 厘米）的 RD 的 1.65 倍，其中一次通过定义为一次空载和一次装载行程。10 次和 15 次后 BD 之间的差异在干燥场地不显着，但在潮湿场地显着。我们得出的结论是，应在土壤条件干燥时进行打滑作业。在干燥场地（7.1 厘米）的 RD 是 RD 的 65 倍，其中一次通过定义为一次空载和一次装载行程。10 次和 15 次后 BD 之间的差异在干燥场地不显着，但在潮湿场地显着。我们得出的结论是，应在土壤条件干燥时进行打滑作业。在干燥场地（7.1 厘米）的 RD 是 RD 的 65 倍，其中一次通过定义为一次空载和一次装载行程。10 次和 15 次后 BD 之间的差异在干燥场地不显着，但在潮湿场地显着。我们得出的结论是，应在土壤条件干燥时进行打滑作业。