武夷山不同海拔梯度黄山松叶片养分含量及其再吸收效率

Foliar nutrients and their resorption efficiencies of Pinu shwangshanensis along an elevation gradient of Wuyi Mountains in Jiangxi

氮、磷在植物的生长和代谢过程中具有关键作用,是陆地生态系统生产力的主要限制因素。植物克服氮、磷元素对生长限制的一个重要策略就是从凋落前的凋落叶中进行养分再吸收。选取武夷山国家自然保护区不同海拔黄山松的成熟叶与凋落叶,测定其C、N、P含量,分析N/P及N、P养分再吸收效率随海拔梯度的变化特征。结果显示:(1)黄山松成熟叶全氮、全磷含量变化范围分别是14.94~21.45 mg·g^(-1)与0.86~1.51 mg·g^(-1),凋落叶全氮、全磷含量变化范围分别是4.73~7.17 mg·g^(-1)与0.16~0.30 mg·g^(-1);(2)成熟叶片N/P随海拔升高而显著降低,凋落叶片N/P则随海拔升高呈指数递增趋势;(3)成熟叶N/P与土壤N/P显著正相关,而凋落叶N/P则随土壤N/P的升高指数降低;(4)叶片N、P再吸收效率随海拔升高呈先降低后升高的趋势,且各海拔叶片P再吸收效率显著大于N再吸收效率。表明黄山松具有较高的N、P元素的再吸收效率,而且相对于N、P元素是该区域黄山松养分循环的关键因素。

Nutrient resorption, one of the important mechanisms for nutrient conservation in plant species, plays an important role in litter decomposition and ecosystem nutrient cycling. To investigate the nutrient resorp- tion characteristics of Pinus hwangshanensis W.Y.Hsia along different mountain elevations, the N and P contents in foliage and fresh litter of P. hwangshanensis growing in five elevational sites of Wuyi Mountains in Jiangxi Province were determined. The results showed as follows： （1） the foliage N content in P. Hwangshanensis ranged from 14.94 to 21.45 mg.g1 and the foliage P content ranged from 0.86 mg.g-1 to 1.51 mg.gl; （2） in the fresh litter, N and P contents ranged from 4.73 to 7.17 mg.gq and from 0.16 to 0.30 mg.g-1, respectively; （3） the foliage N/P ratio was negatively correlated with elevations （P〈0.05）. The fresh litter N/P ratio showed an exponential relation to elevations （P〈0.01）. The foliage N/P was positively correlated with the soil N/P （P〈0.05）, whereas the fresh litter N/P was exponential declined with soil N/P （P〈0.01）. The trend of N resorption efficiency and P resorption efficiency was high-low-high along the elevation gradients. P resorption efficiency was uniformly higher than N resorption efficiency, suggesting that P may play an important role in litter decomposition and nutrient cycling at different elevations of Wuyi Mountains.