福建连江县5个无居民海岛种子植物区系及地理分布研究

Seed Plant Flora and Distribution on Five Uninhabited Islands in Lianjiang,Fujian Province

本研究采取样线法和样方法调查相结合的技术路线,对连江5个无居民海岛的植物资源现状进行详细踏勘,根据所获得的实地调研数据以及对文献资料的查阅,运用植物区系地理学,对研究地的种子植物区系物种组成、科-属的分布区类型、分布生境类型等进行统计整理,与不同地区无居民海岛种子植物属的相似性系数和属的地理成分进行对比,并探讨5个无居民海岛之间维管束植物物种相似度以及与岛屿空间特征参数的关系。结果表明:(1)连江5个无居民海岛共有野生种子植物190种,隶属于64科165属;该种子植物区系的数量优势科为菊科、禾本科,大科、较大科、属种优势明显,寡种科、仅含1种的科数量多。生活型以草本(55.94%)和灌木(23.27%)居多,乔木和藤本数量不占优势,分别仅占13.86%和6.93%。(2)区系组成繁杂多样,在科、属水平上均以热带分布类型为首要,分别为90.24%、68.03%,其中泛热带分布分别占科、属的75.62%、36.05%,科级的温带类型只有9.76%,属级占31.97%,热带类型科-属与温带类型科-属的R/T值分别为9.25和2.13,表明连江5个无居民海岛种子植物区系主体为热带、亚热带成分,与其亚热带地理特点相符,呈热带至亚热带过渡特征。(3)地缘关系上,将连江5个无居民海岛与中国从南往北4个不同地区无居民海岛种子植物区系对比,连江5个无居民海岛种子植物区系在属相似性上与纬度相近的平潭6个无居民海岛最相似,属相似性系数为71.32%。连江5个无居民海岛属的R/T值为2.13,低于厦门近岸海域无居民海岛(4.23)和平潭6个无居民海岛(2.58),高于浙江沿海5个无居民海岛(1.11)和渤海区9个无居民海岛(0.66),温带分布型所占比例随着纬度增大呈现逐渐递增的趋势,热带分布型占比在缩小,体现了海岛植物区系地理成分的纬向分异性,R/T值越大,热带性质越强。(4)物种相似性上,5个无居民海岛间植物物种相似度较低,岛屿空间特征参数的相关性分析表明,无居民海岛相似性受岛屿边缘效应和生境多样性二者的影响。总体上,连江5个无居民海岛种子植物区系植物种类多样,古老植物丰富,呈热带、亚热带过渡性质,与其泛北极植物区与古热带植物区过渡地带的地理特征相符。

Five uninhabited islands in Lianjiang was researched in detail to plant resources by the methods of surveying typical sampling plots and transect lines.According to field investigation data and literature review,statistical analysis of the species composition of seed plants,distribution area types and ecological types by using floristic geography prin-ciple,then compared with the similarity coefficients of genura and geographic composition of the genura of seed plants in different regions,and explored the similarity of vascular plant species among the five uninhabited islands and the relationship with island spatial characteristics.The wild seed plants represented by 190 species,belonging to 165 genera in 64 families.The dominant families were Compositae and Poaceae.It was obvious that the plurimotypic families and larger families in terms of the numbers of genura and species in a dominant position,meanwhile in terms of the numbers of families,dominated by oligotypic families and monotypic families.Herbaceous(55.94%)and shrubs(23.27%)pre-ponderated in the life form,trees and vines were at a disadvantage in terms of number,only accounted for 13.86%and 6.93%respectively.The floristic composition was intricate and varied,and in terms of tropical distribution type,with a high proportion of the family and genus levels,accounted for 90.24%and 68.03%respectively,among them the pan-tropical species accounted for 75.62%and 36.05%respectively,the temperate component only accounted for 9.76%and 31.97%respectively,the R/T values of tropical to temperate family was 9.25 while of genus was 2.13,showing that seed plant flora in the five uninhabited islands were of tropical and sub-tropical types,consistent with the subtropical geography of the islands,transitional from tropical to subtropical.In terms of geographical relationship,compared with the seed flora of four regions from south to north in China,the flora was closely related to six uninhabited islands in Pingtan with similar latitudes,the similarity coefficients of genura was 71.32%.The R/T value of five uninhabited is-lands in Lianjiang was 2.13,which was lower than that of the uninhabited islands in the nearshore Xiamen(4.23)and the six uninhabited islands in Pingtan(2.58),and higher than that of the five nonresidential coastal islands in Zhejiang(1.11)and the nine uninhabited islands in the Bohai Sea area(0.66).With the increase of latitude,there was a growing tendency on the temperate component at genus-level,while the tropical component was contrary to the former,and the larger the R/T value,the stronger the tropical nature.In terms of flora similarity,the similarities of species between each of the five uninhabited islands in Lianjiang were low,correlation analysis showed that similarity of vascular plant spe-cies among different islands was influenced by island edge and habitat diversity.As a whole,the plant species of the seed flora were diverse with a tropical and subtropical transitional nature,ancient plants were abundant,it was consis-tent with its geographic characteristics of the transition zone between the pan-arctic and palaeotropial flora.