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森林清查是森林经营方案的组成部分。森林清查为制订经营政策和策略提供所需的信息。在菲律宾,森林开发局根据国家森林资源清查规划指导森林清查。这个规划使用航空摄影和地面核实编制清查图和形成森林统计。用这种方法既费钱时间又长,往往是当清查工作完成的时候,示意图和一些统计数据已过时了。在1976年菲律宾着手进行了一个以卫星资料为根据的,用Image——100系统对卫星数据进行数字化分析的全国森林清查。结果表明森林面积比用以前数据的线性规划得到的森林统计值少。这次清查是由NRMC负责进行的,范围是很大的,只作工级分类用小比例尺地图表示。然而成本的费用,卫星数据明显地比航空相片便宜得多。使用卫星数据可以又快又经济地提供森林资源的概貌。可是它不能提供像航空相片一样详细的可辨认的信息。另一方面,使用航空相片可以详细地编制地图,但是这种方法是既费工又昂贵的。多阶抽样是一种尝试,用两种基本数据产
Forest inventory is an integral part of the forest management program. Forest inventories provide the information needed to develop business policies and strategies. In the Philippines, the Forest Development Authority directs forest inventories under the National Inventory of Forest Inventory Program. The plan uses aerial photography and ground verification to compile inventories and form forest statistics. It takes a lot of time and money in this way, often when the inventory is completed and the schematics and some statistics are outdated. In 1976, the Philippines conducted a national forest inventory based on satellite data that digitally analyzed satellite data using the Image - 100 system. The results show that the forest area is less than the forest statistics obtained from the linear programming of the previous data. This inventory is carried out by NRMC, the scope is very large, only the classification of work-level small scale map. However the cost of the satellite data is significantly cheaper than aerial photos. Using satellite data provides an overview of forest resources quickly and economically. However, it does not provide as detailed and identifiable information as an aerial photograph. On the other hand, the use of aerial photographs can be detailed in the preparation of the map, but this method is both laborious and expensive. Multistage sampling is an attempt to use two basic data sets