两种林龄文冠果叶N、P、K的季节变化及再吸收特征

Seasonal variation and resorption characteristics of leaf N,P,and K in two aged Xanthoceras sorbifolia plantations

以科尔沁沙地西南缘乌丹地区文冠果人工林为研究对象,分析了8年生和50年生文冠果叶片N、P、K含量的季节变化和再吸收效率。结果表明:2种林龄文冠果年生长周期内N、P、K含量均呈下降趋势,其中,5—6月和8—10月下降幅度较大,6—8月含量变化不大;8年生文冠果叶片凋落前后的N、P、K含量(衰落叶中N除外)均极显著>50年生文冠果(P<0.01)。8年生文冠果叶片养分再吸收效率表现为:N(50%)>P(32%)>K(30%),但50年生的则表现为K(63%)>P(62%)>N(48%);二者N再吸收效率差异不显著(P>0.05),而50年生文冠果叶片P、K再吸收效率极显著高于8年生文冠果(P<0.01)。50年生文冠果叶片再吸收效率高,反映其较高的养分保存能力和养分利用效率,能更好地适应贫瘠养分生境。

Taking the 8-and 50-year-old Xanthoceras sorbifolia plantations in Wudan area of southwestern Horqin Sandy Lands as test objects,this paper studied the seasonal variation and nutrient resorption efficiency of their leaf N,P,and K.Throughout the growth season,the leaf N,P,and K concentrations in the two plantations had a decreasing trend,with the decrement being larger from May to June and from August to October,but less from June to August.The nutrient concentrations in living and fallen leaves,except the N concentration in fallen leaves,were significantly （P0.01） higher in 8-year-old plantation than in 50-year-old plantation.The leaf nutrient resorption efficiency in 8-year-old plantation was in the order of N （50%） P （32%） K （30%）,while that in 50-year-old plantation was in the order of K （63%） P （62%） N （48%）.No significant difference （P0.05） was observed in the leaf N resorption efficiency between 8-year-old and 50-year-old plantations.However,the leaf P and K resorption efficiency in 50-year-old plantation was significantly higher than that in 8-year-old plantation （P0.01）.On the whole,the leaf nutrient resorption efficiency in 50-year-old plantation was higher than that in 8-year-old plantation,reflecting the higher leaf nutrient conservation capability and use efficiency in 50-year-old X.sorbifolia plantation,and the better adaptation capability of this plantation to nutrient-poor habitat.