森林资源连续清查体系的优化改进近年来一直受到关注。针对天津市森林资源的分布特点,基于历次森林资源清查结果及相关资料,对天津市的森林资源连续清查抽样设计方案进行了优化改进,并用2017年的具体实施结果对优化改进方案进行了分析论证。结果表明:1条500 m长的“L”形样线对森林面积的抽样效率大体相当于3个0.066 7hm²(1亩)大小的方形样地;全市森林面积和活立木蓄积的抽样精度均达到了国家技术规定要求的90%以上,山区和平原区2个副总体的森林面积和森林蓄积抽样精度分别达到85%和80%以上。通过分析研究得出以下结论:样线调查是平原区开展森林资源调查的有效方式;分层抽样是提高森林资源连续清查效率的高效方法;天津市抽样设计方案的优化改进满足了精度要求,达到了预期效果。

Optimizing and improving National Continuous Forest Inventory System is an important concern in recent years.According to the distribution characteristics of forest resources in Tianjin and previous Continuous Forest Inventories (CFI) results,the sampling design of CFI in Tianjin was optimized and improved,and the optimal sampling design was verified and analyzed using the implementation results in 2017.The results showed that one 500m sample line was similar to three 0.066 7 hm² (1 Chinese mu) sample plots on sampling efficiency for estimation of forest area,the sampling precisions of forest area and growing stock volume were more than 90% as specified in national technical regulation,and those of forest area and forest volume in two sub-populations,i.e.,mountainous and plain areas,were more than 85% and 80% respectively.Finally,it is concluded that sample line based survey is an effective way to conduct CFI in plain area,stratified sampling is a highly effective method to improve the efficiency of CFI,and the optimization and improvement on sampling design of CFI in Tianjin have met the precision demands and achieved the expected results.