资源环境科技发展态势分析平台

Forest thinning to protect the soil and improve hydrologic function is used to alter stand structure and increase residual tree growth. However, little is known about how surface and belowground wood decomposition (ie., soil process changes) respond to aboveground vegetation manipulation. We determined mass loss of three species of wood stakes (loblolly pine (Pinus taeda L.), trembling aspen (Populus tremuloides Michx.), and Chinese pine (Pinus tabuliformis Corriere)) placed horizontally on the soil surface and vertically in the mineral soil after thinning a Chinese pine plantation in northern China. Restoration thinning treatments consisted of three levels of overstory removal (30%, 41% and 53% of the standing biomass) plus an unthinned control. Stakes were extracted every 12 months for 2years, and then at 6 month intervals until the end of the study (3.5 years). Surface stake mass loss was significantly greater (9.0%) in the 30% overstory removal treatment than the control, but overall mass loss at the soil surface was very low ( < 10%) after 3.5 years. In the mineral soil, aspen stake mass loss was greater than either Chinese or loblolly pine stakes, which had similar mass loss. In addition, mass loss was greatest in the 41% overstory removal plots. Stakes of all species decomposed faster deeper in the mineral soil than near the soil surface, but they were not affected by changes in soil N, OM, and pH after thinning. Overall, thinning this Chinese pine stand had little impact on surface and belowground wood stake decomposition.