秦岭华山松营养诊断与林地施肥

Nutrition diagnosis and fertilization of Pinus armandii forest in the Qinling Mountains,China

以陕西秦岭南坡华山松天然林为对象,采集华山松针叶、凋落物、土壤样品,测定全氮(TN)和全磷(TP)含量,开展华山松林木营养诊断,分析华山松林养分限制格局,研究促进华山松正常生长的施肥种类和施肥量,为林地精准施肥和科学培育华山松大径材提供支持。结果表明:华山松大径材率(胸径DBH>26 cm)为29.0%,具有成长为大径材潜力的华山松个体(18 cm<DBH≤26 cm)比率为60.6%。华山松针叶N、P含量分别为12.65和1.34 g·kg^(-1),N∶P为10.24(<14的林木生长不受限阈值);N、P回收效率分别为33.8%和48.0%。在0~10 cm土层,土壤与华山松针叶的N、P含量呈显著负相关,凋落物与土壤的N、P含量呈显著正相关,土壤N储量与华山松针叶N∶P呈显著二次函数关系。华山松正常生长受土壤N限制,在林地补充0.42 t N·hm^(-2)可解除华山松生长限制。为快速培育大径材,宜向林地内具有成长为大径材潜力的个体施0.16 t N·hm^(-2),按单位面积内林木个体生物量比例进行单株氮素分配。

We examined the contents of total nitrogen(TN)and total phosphorus(TP)in needle,litter,and soil of Pinus armandii forest on the southern slope of the Qinling Mountains in Shaanxi,China.We conducted nutrition diagnosis of P.armandii forest,analyzed nutrient limitation pattern,the fertilization types and amount to increase growth,to provide support for precision fertilization and scientific cultivation of big timber of P.armandii.The results showed that the proportion of big timber(DBH>26 cm)and individuals with the potential to grow into big timber(18 cm<DBH≤26 cm)was 29.0%and 60.6%,respectively.The needle N and P contents were 12.65 and 1.34 g·kg^(-1),respectively,and the N:P was 10.24(<14,unrestricted threshold of forest growth).The N and P resorption efficiency of needle was 33.8%and 48.0%,respectively.In 0-10 cm soil layer,soil N and P contents were significantly negatively correlated with that in the needle,but positively correlated with that in litter.The relationship between the needle N:P and soil N storage was expressed by a quadratic function.The growth of P.armandii was N limited,and an addition rate of 0.42 t N·hm^(-2)would ensure normal growth of all individual trees.We recommended the rate of 0.16 t N·hm^(-2)to the trees with the potential to grow into big timber to promote them to be big timber in a short period,allocating nitrogen to individual plants in proportion to the biomass of individual trees in the stand per unit area.