培育措施对人工林樟子松木材力学性质的影响

研究了不同培育措施(初植密度、间伐强度、坡向、坡位)对人工林樟子松(Pinus sylvestris var.mongolica)木材的密度和力学性质(横纹抗弯强度、抗弯弹性模量、顺纹抗压强度、冲击韧性、端面硬度)的影响。初植密度(1.5m×1.0m,1.5m×2.0m和1.5m×2.5m)对木材密度和抗弯弹性模量有显著的影响。初植密度为1.5m×1.0m时,木材主要力学指标值最大。适当间伐可提高木材的抗弯弹性模量和顺纹抗压强度,但重度间伐则会降低木材的力学强度。坡向(阳坡和阴坡)对木材的抗弯弹性模量影响显著,阳坡高于阴坡。坡位(上坡位和下坡位)对除端面硬度外的木材力学性质指标影响都显著,各项力学指标值均是坡下高于坡上。表5参9。     

Strategy for implementing silvicultural practices in Japanese plantation forests to meet a carbon sequestration goal

The strategy for implementing silvicultural practices in Japanese plantation forests was examined to achieve a carbon uptake of 13.0 Mt-C year^–1, which was capped by the Marrakesh Accords, during the first commitment period, 2008–2012. The plantation forests that implemented silvicultural practices in the period 1990–2012 (FM plantation forests) were identified in compliance with the hypothesized identification rules, and carbon uptake in the forests was estimated using a simple model composed of simulation and optimization components on the assumption that whole plantation forest is classified into only two groups. Furthermore, parametric analysis was conducted to investigate the relationships among three factors: (1) the average annual harvesting volume (including thinning) in plantation forests during the first commitment period, (2) the total area of FM plantation forests in 2012, and (3) the average annual amount of carbon to be sequestered in FM plantation forests during the first commitment period. The results imply that young stands have to be prioritized in implementing silvicultural practices under any harvesting plan and carbon sequestration goal, and that FM plantation forests sequestered 8.0–10.5 (Mt-C year^–1) carbon in inverse proportion to the harvesting volume of 21.0–14.0 million m³ year^–1 (log volume), assuming that most of the plantation forests were incorporated into them.     

Dynamics of soil carbon in a beechwood chronosequence forest

Accurate estimates of forest soil organic matter (OM) are now crucial to predictions of global C cycling. This work addresses soil C stocks and dynamics throughout a managed beechwood chronosequence (28–197 years old, Normandy, France). Throughout this rotation, we investigated the variation patterns of (i) C stocks in soil and humic epipedon, (ii) macro-morphological characteristics of humic epipedon, and (iii) mass, C content and C-to-N ratio in physical fractions of humic epipedon. The fractions isolated were large debris (>2000 μm), coarse particular OM (cPOM, 200–2000 μm), fine particular OM (fPOM, 50–200 μm) and the mineral associated OM (MaOM, <50 μm).