外来红树植物无瓣海桑引种及其生态影响

无瓣海桑是我国首个从国外引进并大面积推广种植的红树植物,生长快,适应性强,已成为华南沿海红树林恢复造林的主要树种。但近年来无瓣海桑引种已引起较大争论,焦点是无瓣海桑是否会对乡土红树植物生长产生不利影响,是否会造成生态入侵,是否应限制推广种植。根据引种以来的研究成果,对无瓣海桑的生态适应性、种植技术、生产力与物质循环、生态影响等四个方面的引种研究进行综述;分析无瓣海桑引种对乡土红树植物生长的影响和生态入侵可能性,对无瓣海桑引种造林提出建议。指出今后无瓣海桑引种的的研究重点为:无瓣海桑引种的生态监测与入侵评估;对滩涂水生生物的影响;与乡土红树植物优化配置的混交种植技术;无瓣海桑的资源化利用。     

深圳福田无瓣海桑与海桑人工林鸟类群落研究及生态评价

报道深圳福田无瓣海桑+海桑人工林和天然红树林鸟类群落的组成特征、密度、相似性、生物多样性等方面的调查研究结果。并通过比较的方法,从鸟类群落学的角度,对无瓣海桑+海桑人工林的生态功能进行了初步分析和评价。认为从目前情况看,无瓣海桑和海桑作为深圳沿海人工造林的主要引进树种,对原有红树林生态系统的结构和功能暂时没有不利影响,对尽快恢复和发展红树林地的面积,提高原有红树林生态系统的生物多样性具有积极的作用。建议①必须采取有效措施防止生态的入侵;②在大面积种植无瓣海桑+海桑人工林时应间种适当面积的当地红树树种。     

中国杯萼海桑遗传多样性的ISSR研究

杯萼海桑(Sonneratia alba J.Smith.)是海桑科红树植物,在我国分布于海南岛的东海岸.本文采用简单序列霞复区间扩增(ISSR)分子标记技术对分布于海南岛的杯萼海桑的4个天然居群和东寨港红树林自然保护区引种的一人工居群共100个个体进行了遗传变异分析.11个引物共扩增出133条带,其中103条具多态性,多态位点百分率为77.44%.在居群水平上相对较低,多态位点百分率为51.88%～65.41%,平均为57.74%.期望杂合度、香农信息指数在物种水平上分别为0.227 1和0.348 9;在居群水平上分别为0.1 83 7和0.227 5.依据Gst值,杯萼海桑绝大多数遗传变异发生在居群内的个体间(81.02%),18.98%的遗传变异发生在居群间.AMOVA分析也表明了类似的遗传结构.居群间平均遗传一致度为0.934 2.依据Nei(1972)的遗传距离对不同居群进行UPGMA聚类,将居群分为两组,来自三亚(SY)和陵水(LS)的居群聚为一类;东寨港引种栽培的人工居群(DZ)和琼海(QH)、文昌(WC)的居群聚为另一类.Mantel检验表明,遗传距离与地理距离呈极显著相关.     

盐度对无瓣海桑幼苗的生长和某些生理生态特性的影响

本文研究了盐度（０‰～５０‰）对无瓣海桑幼苗生长的影响。盐度对无瓣海桑幼苗长叶数、茎长、植株鲜重、主根长、根系鲜重等方面起抑制作用;随盐度的提高,无瓣海桑幼苗成活率下降;但盐度对无瓣海桑幼苗叶片面积存在一个低盐（０‰～１０‰）促进、高盐（１５‰～４０‰）抑制的过程;盐度对叶绿素含量的影响总趋势是随盐度提高,低盐时叶绿素含量下降,而当盐度超过１０‰时上升。因此认为：１）无瓣海桑幼苗在无盐存在下,也可     

人工湿地污水处理系统3种红树植物生理生态特性

研究了淡水条件下潜流型人工湿地污水处理系统中红树植物海桑、桐花树和木榄的生理生态特性。一年后,海桑、桐花树和木榄株高增长量分别为134、32cm和21cm,基径增长量分别为18.2、14.3mm和12.9mm,生物量增长量分别为747、113g/株和55g/株,表明海桑生长最快,桐花树次之,木榄最慢。从2004年1月至12月,海桑、桐花树和木榄各项生理指标的平均值分别为:叶片总叶绿素含量1.91、1.26、0.91mg/gFW,叶绿素a含量1.44、0.93、0.64mg/gFW,叶绿素b含量0.5、0.34、0.17mg/gFW,净光合速率9.67、6.39、3.57μmolCO2/(m2·s),蒸腾速率54、38、24mmolH2O/(m2·s),气孔导度285、222、110mmolH2O/(m2·s),电解质渗出率10.2、12.9、13.5%和SOD活性447、396、386U/gFW。结果表明光合作用和水分代谢海桑>桐花树>木榄,植物受伤害程度海桑<桐花树≈木榄。另外,3种红树植物全年的生理生态特征的变化规律基本相似,4～10月份生长较快,大部分生理指标维持高水平,1～3月份和11～12月份由于温度较低,生长比较慢,大部分生理指标处于较低水平。综合比较一年来人工湿地中3种红树植物的各项生理生态特征,结果显示海桑好于桐花树,桐花树好于木榄。     

深圳福田海桑+无瓣海桑自然林的空间结构分析

采用位置指数(CE)、混交指数(DM)、分异指数(T)以及Ripley’sK方程,探讨了深圳福田红树林保护区海桑+无瓣海桑自然林的空间结构特征。海桑、无瓣海桑、秋茄和桐花树种群都呈现集群分布;海桑-无瓣海桑、海桑-秋茄、海桑-桐花树、桐花树-无瓣海桑以及秋茄-桐花树之间在空间分布上呈现负关联,秋茄-无瓣海桑之间呈现正关联,但这些关联都不显著。海桑和秋茄与其它树种属于中度混交,而无瓣海桑和桐花树与其它树种的混交程度相对较弱。海桑和无瓣海桑个体之间的胸围差异明显,而其它树种个体之间的胸围差异中等。海桑个体之间的树高差异明显,而其它树种个体之间的树高差异中等。采用的空间指数和空间统计技术有效地描述了树种的空间属性。     

深圳福田无瓣海桑与海桑人工林鸟类群落研究及生态评价

报道深圳福田无瓣海桑＋海桑人工林和天然林树林鸟类群落的组成特征、密度、相似性、生物多样性等方面的调查研究结果。并通过比较的方法,从鸟类群落学的角度,对无瓣海桑＋海桑人工林的生态功能进行了初步分析和评价。认为：从目前情况看,无瓣海桑和海桑作为深圳沿海人工造林的主要引进树种,对原有红树林生态系统的结构和功能暂时没有不利影响,对尽快恢复和发展红树林地的面积,提高原有红树林生态系统的生物多样性具有积极的作用。建议：①必须采取有效措施防止生态的入侵;②在大面积种植无瓣海桑＋海桑人工林时间种适当面积的当地红树树种。     

Environmental Effects of Canopy Gap Formation in High-Rainfall Mangrove Forests1

This study investigated the importance of gap formation in mangrove swamps on the island of Kosrae, Federated States of Micronesia, in order to understand better both natural processes of forest development and the effects of harvesting trees for firewood in these wetlands. Measurements were concentrated in seven plots located near four rivers: three in fringe zones and four in basin zones. Each plot was a cluster of five points and covered an area of ca 1.3 ha. From every point in each of the seven plots, the nearest canopy gap ≥10 m² was located; 25 of the 35 gaps were formed by harvesting. Porewater salinity was significantly higher under the canopy in fringe mangrove forests than in basin mangrove forests. Although gaps were small (mean gap size = 158 m²; median gap size = 92 m²), soil temperatures were significantly higher in gaps of both zones. Soil redox potential was significantly lower and porewater salinity significantly higher in the gaps than under the canopy in the basin zone only. Higher porewater salinity may be attributed to high evaporation rates from the soil and high transpiration rates from trees surrounding gaps. There were significantly more seedlings in gaps than under the canopy only in the fringe zones. Although gap formation alters the soil environment of Kosraean mangrove swamps, high freshwater input may buffer these effects in basin mangrove swamps by reducing porewater salinity. Current harvesting rates do not appear to be changing canopy species composition, but large gaps, especially in mangrove forests in more arid areas, may lead to major changes.     

A review of mangrove rehabilitation in the Philippines: successes,failures and future prospects

From half a million hectares at the turn of the century, Philippine mangroves have declined to only 120,000 ha while fish/shrimp culture ponds have increased to 232,000 ha. Mangrove replanting programs have thus been popular, from community initiatives (1930s–1950s) to government-sponsored projects (1970s) to large-scale international development assistance programs (1980s to present). Planting costs escalated from less than US$100 to over $500/ha, with half of the latter amount allocated to administration, supervision and project management. Despite heavy funds for massive rehabilitation of mangrove forests over the last two decades, the long-term survival rates of mangroves are generally low at 10–20%. Poor survival can be mainly traced to two factors: inappropriate species and site selection. The favored but unsuitable Rhizophora are planted in sandy substrates of exposed coastlines instead of the natural colonizers Avicennia and Sonneratia. More significantly, planting sites are generally in the lower intertidal to subtidal zones where mangroves do not thrive rather than the optimal middle to upper intertidal levels, for a simple reason. Such ideal sites have long been converted to brackishwater fishponds whereas the former are open access areas with no ownership problems. The issue of pond ownership may be complex and difficult, but such should not outweigh ecological requirements: mangroves should be planted where fishponds are, not on seagrass beds and tidal flats where they never existed. This paper reviews eight mangrove initiatives in the Philippines and evaluates the biophysical and institutional factors behind success or failure. The authors recommend specific protocols (among them pushing for a 4:1 mangrove to pond ratio recommended for a healthy ecosystem) and wider policy directions to make mangrove rehabilitation in the country more effective.