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天然林资源是衡量区域生态环境状况的重要指标之一。分析天然林资源动态对提高其管理水平和促进区域可持续发展具有重要意义。通过对西南地区1949年以来天然林资源数据的挖掘和比较分析,结果表明:天然林发展可以1981年为界分为前后两个阶段,前阶段天然林面积和蓄积因木材消耗分别降低了26%和33%,后阶段在生态建设工程推动下两者分别增加了58%和42%,达到2008年的25.87×106hm2和31.84×108m3,恢复到了1949年的资源总量水平;但天然林整体质量提高缓慢,平均每hm2蓄积123 m3尚处历史低位;天然林年龄结构也不均衡,幼、中龄林的面积占天然林的58%,蓄积仅占30%,成、过熟林面积占28%,蓄积却占55%;目前天然林中公益林和商品林的面积比约7∶3,蓄积量比约8∶2;商品材采伐量在天然林保护(简称天保)工程实施初期锐减了80%,但在2008年又回升到了天保工程前,且总体增长趋势未变。经过10 a天保和退耕还林工程后,目前西南地区天然林总面积增长放缓,但单位面积的蓄积还很低,故建议天然林发展策略从增加天然林面积转向保持面积和提高整体质量。保持面积的关键是划定天然林面积红线和严格控制天然林采伐,提高整体质量的重点是调整商品林年龄结构,适当提高薪炭林和特用林面积比重,加强退化天然林的生态恢复和重建。
Natural forest resources is one of the important indicators to measure the status of regional ecological environment. Analyzing the dynamic changes of natural forest resources is of great significance to improving its management level and promoting regional sustainable development. Through the excavation and comparative analysis of the natural forest resources data in the southwest of China since 1949, the results show that the development of natural forests can be divided into two stages before and after 1981, with the natural forest area and the accumulated wood consumption reduced by 26% And 33% respectively. After the promotion of ecological construction projects in the latter stage, the two increased by 58% and 42% respectively, reaching 25.87 × 106hm2 and 31.84 × 108m3 in 2008, returning to the level of total resources in 1949. However, the overall quality of natural forests With an average of 123 m3 per hm2. The age structure of natural forests is not balanced. The area of young and middle-aged forests accounts for 58% of the natural forests, accounting for only 30% of the total. The area of over-mature forests accounts for 28% % Of the total area, accounting for 55% of the total area. At present, the area ratio of commonweal forest to commercial forest in natural forest is about 7: 3, and the stock volume is about 8: 2. The harvesting volume of commercial timber is sharply reduced in the initial stage of the implementation of natural forest protection 80%, but in 2008 rose back to the natural forest protection project, and the overall growth trend has not changed. After 10 days of Natural Forest Protection and the Project of Returning Farmland to Forests, the total area of natural forests in southwest China has been slowing down but the area per unit area is still low. Therefore, it is suggested that the natural forest development strategy should shift from increasing the area of natural forests to maintaining the area and improving the overall quality. The key to maintain the area is to define the red line of natural forest area and strictly control natural forest harvesting. The key point to improve the overall quality is to adjust the age structure of commercial forest, appropriately increase the area of firewood forest and special forest area, enhance the ecological restoration and reconstruction of degraded natural forest .