作　　者： ; ; ; ; ; ;

机构地区： 中国科学院生态环境研究中心城市与区域生态国家重点实验室

出　　处： 《生态学报》 2013年第19期6163-6172,共10页

摘　　要： 于2012年4月—2013年4月调查了广西珍珠湾地区贝克喜盐草(Halophila beccarii Ascherson)种群的基本属性及土壤种子库储量。结果表明,不同月份间该种群的面积、覆盖率、直立茎密度、生物量、繁殖器官密度等属性差异明显,均呈现先增大后减小再增大的趋势;各个属性出现峰值的日期有所不同,面积、覆盖度、地下生物量和总生物量的最高峰值出现在10月底,而直立茎密度和地上生物量峰值最高峰值出现在8月初。贝克喜盐草珍珠湾种群有明显雌蕊先熟现象,雌花发育高峰期(8月初,5404朵/m2)早于雄花发育高峰期(8月底,2189朵/m2)。而果实高峰期(4125个/m2)为10月份。地上与地下生物量之比值(1.95—0.53)随种群的发育而逐渐减小,基于此比值可判断贝克喜盐草种群所处的发育阶段。在生长高峰期,贝克喜盐草种群有较大的分布面积(21.4 hm2)、较高的覆盖度(55%)、直立茎密度(21602茎/m2)及生物量(70.583 g/m2干重)。贝克喜盐草果实含种子为1—4粒(平均为2.22粒);1月、3月和4月土壤种子库密度分别为5749、5652、2728粒/m2,3—4月期间土壤种子库种子损失率高达104粒m-2d-1。尽管贝克喜盐草有较高的种子产量(10月份,9158粒/m2)和较快的生长速度,但由于土壤种子库中种子损失严重且种子萌发率较低以及人为干扰对其生境的强烈干扰等因素,因此可能会对次年的种群更新产生较大的负面影响。 Halophila beccarii Ascherson is one of two species in the oldest lineage of seagrasses, and belongs to the family Hydrocharitaceae. It is a small submerged creeper, found in the upper intertidal zone, and grows on mud or muddy sand substrates in estuarine and coastal areas. This species has been recorded to be at the coastlines of East Asia, Southeast Asia, Central Asia, Kenya and Tanzania. Global population trends indicate this species is declining, although it is fast growing and may recover quickly from disturbance. However, it also has a narrow, restricted depth range that coincides with the intertidal zone, an area subject to much anthropogenic disturbance. This species was listed as ‘Vulnerable’ by the International Union for Conservation of Nature under criterion B2. H. beccarii occupies a very limited area in China and it is threatened by many forms of disturbance. Very little ecological information has been reported from China or subtropical regions globally for this species, and existing ecological studies are restricted to tropical regions in Southeast Asia or South Asia. The lack of basic ecological information on H. beccarii in China affects our understanding of the mechanisms underlying its decline, and thus hinders efforts to conserve and manage this threatened seagrass species. To examine temporal variation in the area, percent cover, above-ground/below-ground biomass, shoot density, reproductive organ density and the sediment seed banks of H. beccarii in Pearl Bay, Guangxi, samples were taken and surveys were carried out from April 2012 to April 2013 at roughly one-month intervals. Our results indicate that the area, percent cover, shoot density, biomass and reproductive organs density of H. beccarii in Pearl Bay vary greatly at different stages of population development over an annual cycle. Generally, all population parameters initially increased from April 2012, until they reached a peak value and then decreased. It seems the growth dynamics of the population followed ＂n＂ patterns with

关 键 词： 濒危海草 物候 贝克喜盐草 土壤种子库 种群发育

领　　域： [生物学]