广西英罗港红树植物种群的分布

The Population Distribution of Mangrove at Yingluogang of Guangxi,China

用生态样带和连续取样方法研究了广西英罗港红树植物种群的分布 ,结果表明 :在 36 0 m长的生态样带中 ,从内滩海堤到外滩 (无红树林的光滩 ) ,土壤的机械组成、养分和盐分含量均存在明显的梯度变化 ,0～ 2 0 cm土壤的有机质、全氮、水解氮、全磷、速效磷、全盐分别是 1 .1 1 %～ 6 .6 7% ,0 .0 2 1 %～ 0 .1 36 % ,4 1 .6～ 2 0 3.7mg/kg,0 .0 0 87%～ 0 .0 30 9% ,2 .78～ 1 4 .32 mg/kg和 1 0 .2 0‰～ 31 .1 2‰ ;土壤砂粒、粉粒和粘粒分别是 5 7.3%～ 89.6 % ,8.1 %～ 2 9.0 %和 2 .3%～1 3.7% ,除土壤砂粒含量与距离呈正相关外 ,其它测定因子均表现为负相关关系。随着与海堤距离的加大 ,红树植物种群的分布出现明显的差异。在距岸 2 4 0～ 34 0 m的滩面 ,以桐花树种群的重要值最高 ,其重要值指数变化在 91 .6 6～ 1 75 .0 2之间 ,向陆地演进 ,其种群的重要值逐渐减少 ;在 4 0～ 2 30 m,红海榄种群占居明显优势 ,其重要值指数为 1 1 0 .6 6～2 6 4 .86 ;在距岸 0～ 30 m的海滩 ,以木榄种群占优势 ,其重要值指数为 2 1 3.1 6～ 2 5 0 .5 3;白骨壤种群和秋茄种群的重要值都较低 ,这主要是它们的种群密度低所致。红树植物种群的分布表现为典型的过渡替代的交错分布 ,从海堤到外滩 。

The spatial distributions of mangrove populations were studied at Yingluogang of Guangxi,China,by continuous sampling along 360m long strips.The main results are as follows:(1)The soil texture,nutrients and salt content vary remarkably along the sampling strip,from the inner seawall to the outer bare beach where no mangrove occurs.The values of organic matter,total nitrogen,hydrolysable nitrogen,total phosphorus,available phosphorus and total salt are 1.11%～6.67%,0.021%～0.136%,41.6～203.7mg/kg,0.0087%～0.0309%,2.78～14.32mg/kg and 10.20‰～31.12‰,respectively.(2)The contents of sand,slit and clay in the soils are 57.3%～89.6%,8.1%～29.0% and 2.3%～13.7%,respectively.The sand content increases along the strip from the inner seawall to outer bare beach,while the other soil traits change in the opposite direction.(3)The distribution pattern of Mangrove population veried obviously along the sampling strip.At the interval between 240m and 340m away from the seashore, A.corniculatum population has the highest IV(Important Value) with a range from 91.66 to 175.02 and thereafter its IV decreases gradually as it distributes in the direction towards lang. R.stylosa population becomes dominant at the interval between 40 and 230m away from seashore with the highest IV ranging from 110.66 to 264.86. B.gymnorrhiza population dominates at the range of 0-30 m away from seashore with the IV varying from 213.16 to 250.53,while A.marina and K.candel populations have a relatively low IV as a result of their low populaton density.Mangrove populations distribute in a transitional mosaic pattern from the seawall to the outer beach,with the following sequence of occurrence: B.gymnorrhiza,R.stylosa,A.corniculatum, and A.marina. This distribution pattern is the result of continuous succession processes.(4).Integrated environment gradient analysis illustrates the distribution peak value of A.marina and A.corniculatum populations are both 1,while K.candel,R.stylosa and B.gymnorrhiza populations are 2.5,7 and 10,respectively.This suggests that A.Marina and A.corniculatum are pioneer populations during ecological succession, B.gymnorrhizais is a latesuccession population,and while K.candel and R.stylosais are intermediate-stage populations.(5).The regression model based on the relatonship between mangrove and its environmental factors was established,showing a good representation of the spatial distribution pattern of mangrove populations.It is found that the strip and continue sampling methods are suitable for investigating spatial distribution and ecological succession of mangrove populations.