日本落叶松近熟林施肥效应

就日本落叶松30年生近熟林不同施肥处理对生长量的影响进行了研究，方差分析结果表明，不同施肥处理对林木生长效应的影响均不显著，然而施肥对近熟林生长仍有一定的影响，起增产效应的主要因素是氮肥；随着施用量的增加，生长量增加，但施肥量过大，生长量却有下降的趋势，连续3a施肥与隔年2次施肥相比，既未出现增产效果，又增加了投入成本；施肥后2－3a增长量最大，以后将林龄的增加而逐渐消失。本试验施肥处理中，A2B1C1、A3B1C2、A2B2C1和A1B1C1肥效最佳，施肥后第2年经济效益与不施肥（CK）相比，每公顷分别增加了1987．84、1394．57、1302．55和1074．40元产值，投入产出比分别达到2．64、1．60、2．01和2．14。内部收益率分别达0．33、0．13、0．22和0．24。即合理施肥、及时主伐是有一定效应的。

Fertilization Effect and Benefit of Near - mature - forest Plantations of Larix kaempferi

In this paper, the effects on increment of different fertilization treatments for 30 - year - old trees of Larix kaempferi were studied. The results from variances analysis show that the effect differences of different treatments on growth arent significant. But fertilization have some effect on the increment of near - mature - forest, the main factor of increasing incre-ment is N fertilizer. The increment of the stands increased along with the increasing fertilizer quantity, but it would decline when fertilizer quantity were too much. Fertilization of 3 - year continuous couldnt increase growth and would cost much comparing with fertilization of 2 times every other year. The increment of the stands reached the highest after 2-3 years of fertilization and then declined with the increasing of stands age. In the tests, the effect of the treatment of A2B1C1, A3B1C2, A2B2C1 and A1B1C1 were the best, which the economy benefit in the second year after fertilization increased 1987.84, 1 394.57, 1 302.55 and 1 074.40 yuan per hacter respectively than that of no fertilization. The ratio of the input to the output reached 2. 64, 1.60, 2. O1and 2. 14. The IRR value reached 0. 33 , 0. 13 , 0. 22 and 0. 24 respectively. It is effective by proper fertilization and timely cutting.