不同林龄杉木针叶大量元素转移特征

为探究不同林龄杉木成熟叶与衰老叶之间大量元素的转移规律,选择中国亚热带地区8、14、21、46年生杉木,测定其成熟叶和衰老叶中N、P、K、Ca、Mg含量。结果表明:不同林龄杉木成熟叶中养分含量差异显著(Mg除外),但未表现出有规律的变化,衰老叶中N、K、Mg含量不受林龄的影响。不同林龄杉木针叶大量元素平均转移率表现为REK>REP>REN>REMg>RECa,其中,Ca表现为负转移,不同林龄杉木针叶N、K、Mg转移率无显著差异。在杉木成熟叶中,P、K、Ca、Mg含量与其转移率存在极显著的线性正相关,杉木衰老叶片中营养元素均与其转移率存在负相关。研究表明:杉木通过将大量元素从衰老叶片转移到成熟叶片,从而减少养分损失,这种机制不随林龄增加而衰退。

Needles macronutrient concentrations and retranslocation characteristics in Chinese fir plantations of different ages

To study the retranslocation efficiency between mature and senescing needles, the needle macronutrient concentrations (N, P, K, Ca, Mg) were measured in four Chinese fir plantations with various ages (8, 14, 21, 46 years old, respectively) in subtropical China. The results showed that the nutrient concentrations( without Mg) of mature needles differed significantly among different ages of Chinese fir, and did not show regular rule. However, the concentrations of N, K, Mg did not fluctuate significantly among senescing needle with tree ages. The retranslocation efficiency of these five macronutrients in Chinese fir with different ages were presented on an order of REK>REP>REN>REMg>RECa , and Ca element was transferred from mature to senescing needles. The translocation efficiency of N, K, Mg did not varied significantly among different ages of Chinese fir. A significantly positive correla-tionship between P, K, Ca, Mg in the mature needle and retranslocation efficiency were found by using regression analysis while the macronutrient in senescing needle were negative correlated with retranslocation efficiency. In conclusion, our results suggested that mobilization of macronutrient from senescing to mature needle may represent a survival strategy adapted to Chinese fir with different ages, and this characteristic did not change with the increase of forest age.