从林业分类经营的空间分析看大兴安岭采伐政策

A View to Forest Harvest Policy from Multiple-class Management Spatial Analysis in Great Hing'an Mountains

大兴安岭是我国首批实施天然林保护工程的重点林区,1998年开始实施分类经营,区划为生态公益林区(禁伐区和限伐区)和商品林区。该区划是否反映自然条件,各区的经营措施是否有利于功能的发挥,尤其是商品林区能否承担现有的采伐任务,成为林业经营的焦点。论文对大兴安岭呼中林业局分类经营格局的空间分析显示,区划充分考虑了自然因素,对天然林的特征和分布与自然立地条件间关系的认识和划分合理。在此基础上重点分析了1989～2000年3种经营区内森林的数量和质量变化:商品林区开发以来一直是重点产林区,在1989年针叶林面积比例(41%)就小于该区域的原始状态(72%)、呼中林业局(47%)以及限伐区(54.9%)和禁伐区(47.8%),景观破碎化程度大于其它区域;至2000年针叶林面积比例继续降至27%,仍小于林业局(31%)、禁伐区(32%)和限伐区(39%),分布更加破碎化,质量愈加下降,中幼龄林、公顷蓄积小于80 m3/hm2和郁闭度小于0.6的森林面积比例已分别达84%、52%和73%,森林数量和质量仍为3个区域中最差,难以支持现有的计划产量。因此,该林业局需要继续缩减产量,近期不安排主伐,森林培育仍为主要目标。限伐区和禁伐区的针叶林比例相对较高,但也都低于40%,需继续分别实施抚育措施和严格的禁伐制度。论文空间定量化地分析了大兴安岭的采伐限额与实际植被状况的差距,对进一步改善林业政策具有重要的指导意义。

The natural forest reservation program started in Great Hing＇ an Mountains in 1998. Multiple-class forest management is considered as one of the important parts in the program. So itis essential to map scientifically managed forest into commercial or non-commercial（ harvest-limited area and harvest-banned area） area to incorporate non-timber values into timber production plans. Employing imagery data and historical data, we analyze the topographical factors and landscape pattern in non-harvest area, harvest-limited area and commercial area in the Great Hing＇ an Mountains, China. The result show the current management division is reasonable in terms of topgraphical factors. The commercial forest distributed in the accessible and lower area, the nonharvest forest is reversely in unaccessible and higher area. However, compared to harvest-limited forest with 54. 9% coniferous and harvest-banned forest with 47.8% coniferous forest, the less atea in coniferous forest （27%） and mature forest （20%） and more Iragmentation in coniferousforest pattern suggest a big harvest volume during 1989 -2000, even before 1989, in commercial forest. But, the forest is dominated by forest of mid-age, less than volumes 120 m^3/ha and less than canopy closure 0. 6. It also showed the current harvest quota is still larger than produc that commercial forest can provide. The planned annual harvest volume is supposed to be down; furthermore, the production-oriented harvest should be completely replaced by tending tion cut operation. Meanwhile, the limited tending operation should be implemented in non-commercial forests. The gap between harvest quota and real vegetation pattern based on spatial analyses will help policy makers and implementers to set and achieve the equal goals of timber production and forest sustainability.