对广西北海大冠沙两种生长型(矮型:成熟林树高〈1.5m;过渡型:成熟林树高1.5—2m)的红树植物白骨壤(Avicennia marina)成熟叶和衰老叶的N、P含量、N:P比及内吸收率进行研究.结果表明:(1)两种生长型白骨壤成熟叶具有较高的N含量,分别为(20.45±1.10)mg/g和(22.25±1.12)mg/g;V含量分别为(1.42±0.03)mg/g和(1.31±0.03)mg/g;叶片衰老过程中,N、P含量明显下降;(2)叶片衰老过程中,N:P有增加的趋势;两种生长型成熟叶的N:P分别为14.41±0.85和16.97±0.86,显示两种生长型白骨壤均为N、P共同限制;(3)两种生长型白骨壤的N、P内吸收率在60%以上,内吸收率的高低与生长型没有明显关系.
Nitrogen and phosphorus concentrations, N: P ratio and nutrient resorption efficiency of leaves during senescence for two growth forms ( a dwarf form with tree height of below 1.5 m, and a transition form with tree height from 1.5 m to 2 m at maturity) of Avicennia marina were studied at Daguansha,Beihai,Guangxi. The results showed as follows: ( 1 )Mature leaves had the relatively high N concentration,with (20.45 ± 1.10) mg/g for dwarf form and (22.25 ± 1.12) mg/g for transition form; P concentration of mature leaves was ( 1.42 ±0.03) mg/g for dwarf form and ( 1.31±0.03) mg/g for transition form,respectively; N and P concentrations decreased with leaf senescence. (2) N: P ratio increased with leaf senescence, N: P ratio of two growth forms was 14.41 ± 0.85 and 16.97± 0.86, respectively. (3) Resorption efficiency of N or P was above 60% , and there was no significant effect of growth form on resorption efficiency.