陕西省秦岭林区桦树林产汁量调查

采用样地桦树半封闭钻孔采计法对陕西省秦岭林区的桦树林产汁量进行了调查，结果表明，陕西省秦岭林区的桦树林产计期为4月上旬至5月上旬；旺汁期平均单株桦树日产汁量为8．6kg；平均每公顷桦树林年产汁量约为51t以上，与其他部份桦树汁产区比较属于桦树计高产林区。陕西省秦岭林区约有桦树林161000hm2，年蓄积桦树汁资源约在8211000t以上，合理开发利用，将会产生良好的经济效益。

An investigation of the output of birch juice in the Qinling Mountains of Shaanxi Province

The result of the investigation on output of birch juice in the Qinling Mountains shows that birch trees produce birch juice from early April to early May, in a high output period, a birch tree produces 8. 6 kg of birch juice per day on average; 1 hm2 of birch grove produces more than 51 t of birch juice per year. There are 161 000 hm2 of birch groves in the Qinling Mountains of Shaanxi Province, which store more than 8 211000t of birch juice.