木榄母树下2种红树植物幼苗生长特征研究

Growth Feature of Seedlings of Two Mangroves Under Mother Trees of Bruguiera gymnorrhiza

在广西北仑河口珍珠港内进行木榄母树下栽植木榄 (Bruguiera gymnorrhiza)和红海榄 (Rhizophorastylosa )幼苗试验。选取 3棵母树 ,分别以每棵母树为中心 ,在东、西、南、北方向上 ,离母树 5 .0 m距离内按每 0 .5 m栽植 2条胚轴。以 1月、 4月、 7月、 10月为冬、春、夏、秋季代表月 ,测定母树下幼苗的实生高、基径、叶数及分枝等生长指标 ,结果表明 :木榄的平均成活率随时间的推移呈下降趋势 ,栽植 1年后的成活率为 6 7.0 % ,2年后的平均保存率为 48.9% ,夏季的成活率较春季的高 3.7% ;红海榄幼苗成活率总的呈下降趋势 ,造林 1年后成活率为 5 8.3% ,2年后的保存率为 42 .0 %。木榄母树下 3.0 m～ 5 .0 m和 3.5 m～ 4.5 m的距离分别为木榄幼苗和红海榄幼苗的适宜生长范围。 2种幼苗生长的季节动态均表现为主茎生长高峰期在夏季 ,基径生长高峰期在秋季。红海榄苗前 3年的生长量和生长速度均高于木榄苗 ,在苗期生物量构成中红海榄分配给叶的份额逐年增加 。

The seedling growth trial of B gymnorrhiza and Rhizophora stylosa under mother trees of B gymnorrhiza was conducted in Zhenzhu Harbor,Beilun Estuary,Guangxi. Three mother trees were employed. Two hypocotyls were planted every 0 5 m in east, west, south ,north directions within 5 0 m with mother tree as a centre. Height, basal diameter, leaves and branches of seedlings were determined in Jan., Apr., Jul. and Oct. which stood for spring, summer, autumn and winter respectively. The survival rate of seedlings of B. gymnorrhiza was 67 0% one year after planted, and dropped to 48 9% one more year, and was 3 7% higher in summer than in spring. The survival rate of seedlings of Rh stylosa was 58 3% one year after planted, and dropped to 42 0% one more year. The favor growth area was found from 3 0 m to 5 0 m for seedlings of B gymnorrhiza and 3 5 m to 4 5 m for Rh stylosa.The main stem of these two species had fastest growth in summer, and the basal diameter in autumn. The biomass and growth speed of Rh stylosa were higher than B gymnorrhiza in the first three years. The contribution of leaves of Rh stylosa to the whole biomass increased yearly in seedling stage, but decreased in B gymnorrhiza. The survey indicated that natural habitats of mangrove plants were favored to their seedlings.