施肥对三江平原丘陵区长白落叶松人工林中龄林单木树冠特征影响

Effects of Fertilization on Crown Characteristics of Individual Trees in Middle Aged Larix Olgensis Plantation in Hilly Region of Sanjiang Plain

以三江平原丘陵区佳木斯市孟家岗林场间伐后长白落叶松(Larix olgensis Henry)人工林中龄林为对象,实施4种处理:施氮肥(施纯氮250kg/hm^(2))、施氮磷肥(施纯氮250kg/hm^(2)+纯磷50kg/hm^(2))、施氮磷钾肥(施纯氮250kg/hm^(2)+纯磷50kg/hm^(2)+纯钾30kg/hm^(2))和对照(不施肥),研究施肥后不同时期胸径与冠幅、树高与冠长间的关系,评价落叶松冠长率对间伐后施肥的响应。结果表明:施肥后不同时期落叶松胸径与冠幅、树高与冠长间均呈幂函数增长趋势;施肥3年后、4年后、5年后的冠长率(冠长/树高)分别为0.1899—0.2030(平均为0.1986)、0.2282—0.2642(平均为0.2428)、0.2851—0.2976(平均为0.2920),低于对照林分相同时期的冠长率(3年后:0.2010;4年后:0.2822;5年后:0.3006)。施肥能够缓慢促进间伐后落叶松的冠幅和冠长的增长,施肥对落叶松树干生长的促进作用应该更多来自于施肥后针叶的高效光合作用。

The middle aged Larix olgensis Henry plantation after thinning in Mengjiagang Forest Farm was selected to fertilization.After thinning in October 2012,the 4 treatments were established in July 2015:nirtogen fertilizer(N,250kg/hm^(2)),nitrogen+phosphorus fertilizer(NP,nitrogen 250 kg/hm^(2)+phosphorus 50 kg/hm^(2)),nitrogen+phosphorus+potassium fertilizer(NPK,nitrogen 250kg/hm^(2)+phosphorus 50kg/hm^(2)+potassium 30kg/hm^(2))and control(no fertilizer).Fertilization after 3 years,4 years and 5 years,the relationship between DBH and crown width,tree height and crown length,and the response of crown length ratio(crown length/tree height)to fertilization after thinning were evaluated.The results showed that:after fertilization,the relationship between DBH and crown width,tree height and crown length of larch showed a power function increasing trend.The crown length ratio after 3,4 and 5 years of fertilization were 0.1899-0.2030(mean 0.1986),0.2282-0.2642(mean 0.2428)and 0.2851-0.2976(mean 0.2920),respectively,which were lower than that of the control stand at the same period(3 years later:0.2010;4 years later:0.2822;5 years later:0.3006).Fertilization can slowly promote the growth of larch crown width and crown length after thinning,and the promotion effect of fertilization on larch trunk growth should be more due to the high efficient photosynthesis of needles.