滇中高原云南松养分的回流及利用特征研究

Characteristics of the Retranslocation and Use of the Nutrient of Pinus Yunnanensis in Middle Yunnan Plateau

养分的回流与利用是树木保持营养、提高适应能力的最重要策略之一,对于土壤养分贫瘠地区树木的生长具有非常重要的意义.云南松对贫瘠低P土壤环境具有很强的适应能力.以滇中高原玉溪磨盘山区域内立地条件一致的3个不同林龄（15、30和45a）云南松（Pinus yunnanensis）林为对象,采用“微波消解-ICP-AES”法和碱解扩散法对其针叶中N、P、K、Mg、Ca和Fe等6种养分元素的含量、养分回流及利用效率特征进行了分析,从养分循环利用角度探讨云南松对贫瘠低P环境的适应机制.结果表明,（1）云南松对养分元素的吸收存储与其利用效率呈一定的负相关关系,在针叶中含量高、吸收储存能力强的元素其利用效率相对较低,反之,其利用效率相对较高.针叶中Ca和N的含量都较高,其利用效率均较低,而P和Fe（微量元素）含量均较低,其利用效率却较高.N与Fe的含量之间存在显著负相关（r=-0.994,P=0.005）.（2）不同林龄凋落叶中Ca、Fe的含量均大于鲜叶,Ca、Fe在落叶中出现明显富集,富集率随林龄增加而降低;除45年生云南松Mg有回流（6.6%）外,15年生和30年生均出现少量富集,其利用效率随林龄增加而降低.（3）不同林龄针叶中N、P和K均出现明显的回流,回流率与其利用效率之间呈现出一定的正相关关系;不同林龄N和K的回流率均高于30%,P的回流率（8.71%-61.49%）和利用效率（2028.64-4179.20g·g^-1）较高且随林龄的增加均不断提高,这是云南松对贫瘠低P环境适应的一种重要机制,研究进一步验证了云南松是低P贫瘠环境中的优良造林树种.

Nutrient retranslocation and utilization is one of the most important strategies for trees to maintain nutrition and improve the adaptability, which has important significance for the growth of trees in barren soil. It is prominent for Pinus yunnanensis to adapt to the soil which is barren and insufficient in P. Characteristics of nutrient （including N, P, K, Ca, Mg and Fe） content, nutrient retranslocation and use efficiency in needles of Yunnan pine （Pinus yunnanensis） at different forest ages （15, 30 and 45 a） and with the identical growth conditions, in Yuxi Mopan Mountain area, Middle Yunnan Plateau were analyzed by ICP-AES with microwave digestion and alkali N-proliferation methods. The analysis on the adaptability mechanisms of Pinus yunnanensis against the soil which is barren and insufficient in P is conducted from the perspective of the cyclic utilization of the nutrient and the results thereof show that, （1） The negative correlation between the absorption and content of the nutrient and the corresponding usage efficiency regarding Pinus yunnanensis exists. The element outstanding in content and absorption is weak in respect of its usage efficiency, and vice versa. For example, Ca and N in needles has the lower use efficiency but higher content, while Fe （trace element） has the lower content but higher use efficiency, and there is a significant negative correlation between the concentration of N and Fe （P〈0.01）; （2） The nutrient content of Ca and Fe in fallen needles at different forest ages are greater than that of in fresh needles, appearing obviously accumulation in fallen needles, and the accumulation rate decreasing with the increase of forest age. The nutrient Mg has retranslocated only in 45 a Yunnan Pine （6.6%）, in 15 and 30 a forest showing few accumulation and it’s use efficiency decreases with the increase of forest age; （3） Nutrients N, P and K are significantly retranslocated at different ages and the retranslocation rate and use efficiency shows a positive correlation; The retranslocation rate of N and K at different ages are greater than 30%. The nutrient P retranslocation rate （8.71%-61.49%） and use efficiency （2028.64-4179.20 g·g^-1） are great and increases with the increase of forest age. All of these are the very important mechanisms for Yunnan pine to adapt to soil environment barren and lacking in P and these also further show that Yunnan pine is a fine afforestation tree species in the soil environment barren and lacking in P.