福建北部属中亚热带湿润常绿阔叶林区。位于北纬25°50′—28°22′,东经116°28′—119°22′。年平均温度17.8-20.2℃,绝对最高温度38.9—41.4℃,绝对最低温度-5.8—-9.0℃。年雨量1500—2300毫米。年平均霜期70天左右,最长连续出现霜日9—11天。闽北这个山岭地带,自西北向东南成阶梯状倾斜降落,大部为丘陵山地红壤。该区的自然生物气候构成了适宜发展果树的辽阔地带。近十年来,闽北山区群众积极贯彻“以粮为纲,全面发展”的方针,陆续发展了数万亩柑桔,产量不断增加,已成为福建柑桔生产的重要基地。他们利用广阔的低丘山地发展柑 Fujian is a subtropical humid evergreen broad-leaved forest in the north. Located at latitude 25o 50’-28o 22 ’and longitude 116o 28’-119o 22’ east. The annual average temperature of 17.8-20.2 ℃, the absolute maximum temperature of 38.9-41.4 ℃, the absolute minimum temperature -5.8--9.0 ℃. Annual rainfall 1500-2300 mm. The average annual frost period is about 70 days, the longest continuous frost day 9-11 days. The northern part of this mountainous area stretches steeply from northwest to southeast, mostly in the hilly red soil. The natural biological climate of the area constitutes a vast area suitable for the development of fruit trees. In the past ten years, the masses in the mountainous areas of northern Fujian have actively implemented the policy of “taking grain as the key link and all-round development” and successively developed tens of thousands of mu of citrus with an increasing output. It has become an important base for citrus production in Fujian. They make use of the vast hilly area to develop the citrus