-->Special Column：Island Plants

Vegetation characteristics and plant diversity of Waimalangshan Island, Zhoushan

2017/4/7 11:47:50

The vegetation characteristics and the ɑ, β biodiversity of plant commnuties were investigated at the desert island of Waimalangshan Island, Zhoushan Archipelago, Zhejiang Province. In order to discuss the difference of vegetation characteristics and plant diversity between Waimalangshan Island and nearly mainland, we analyzed the vegetation characteristics, life form of island plants, geographical elements, similarity of six plant communities, the structure and diversity of community. Firstly, there were 55 species of seed plants belonging to 33 families 51 genera in Waimalangshan Island. The area of Waimalangshan Island is small, but there existed some autochthonal strand plants such as Heteropappus arenarius, Eurya emarginata, Rhaphiolepis umbellata, which had great development potentials in landscape use. Secondly, the tropical types of genera were distinct similar to nearly islands, Dongfushan Island and Dajinshan Island. The families of dominant species in communities were Theacea, Pinaceae Euphorbiaceae, nevertheless, it was different from the zonal vegetation's dominant families in island forest. The major life form was phanerophytes plants of island plants and the proportion in plant life form were lower than that in the life form of subtropical vegetation. Thirdly, the richness and structure of plant population were simple and contained less diversity than the nearly mainland due to small area and special circumstance. Margalef richness, Simpson diversity, Shannon-Wiener diversity, Pielou evenness of tree layers were higher than that of shrub's layer. The dominant species of tree and shrub's layer was single. Similarity of six plant communities were low ranging from different habitats because of high level of landscape fragmentation. Because of the difference of ecological adaptability and stage of plant succession, the plant population would take a long time to be climax community. Lastly, the proportion of introduced plants of Waimalangshan Island plants was 9.09%. Pinus thunbergii and Phyllostachys mannii which were introduced species for landscape use had a distinct dominance in plant communities for several decades. Native plants loss, introduced plants increased and native plants disappeared. It should be treated with caution that introduced plants may caused eco-disturb to native plants for competitive relationship in habitat fragmentation.

Flora of seed plants in Pingtan Island, Fujian and effects of exotic plants

YE Zhi-Yong — 2017/4/7 11:47:50

The flora were investigated and analyzed in Pingtan Island, Fujian Province. According to primarily statistics, there are 541 species of seed plants belonging to 369 genera of 127 families, including 330 species of native plants in 234 genera of 91 families and 211 species of exotic plants in 160 genera of 79 families. Compared to nearby mainland and coastal islands in China, the major characteristics of Pingtan Island flora were summarized as follows: Firstly, island plants species were poorer than continential plants. The quantity of single-species family was more than that of dominant families. The flora of species and genera in Pingtan Island was similar to that in Jiufeng Mountain and Chongming Island. The cluster analysis showed that the distribution type of genera flora in Pingtan Island was similar to Huboliao National Nature Reserve and Dajinshan Island. Secondly, 127 families were divided into twelve types and seven variants at family-level, 369 genera were divided into fourteen types and twelve variants at genus-level. Tropical elements take obvious advantages, part of subtropical elements, nevertheless there lack the relic plants. Thirdly, we conduct that part of native plants of Pingtan Island and continential plants were different. A number of plants were native strand plants, which showed typical coastal features. Lastly, the relationship between the flora of exotic plants and native plants had a very significant correlation. At the meantime, exotic plants had a great influence on Pingtan Island flora and distribution types.

Comparison of fungi in healthy and unhealthy leaves from three kinds of mangrove plants

2017/4/7 11:47:51

Mangrove may become unhealthy after infected by fungi. In order to compare the fungi in healthy and unhealthy leaves of mangrove plants, the healthy and unhealthy leaves of Excoecaria agallocha, Kandelia candel and Aegiceras corniculata were collected from Maowei Sea National Mangrove Reserve, including 82, 82 and 81 of them from healthy leaves, and 90, 86 and 90 from healthy leaves respectively. The fungi were isolated and purified from leaves and identified by morphological characters, then the DNA of fungi were extracted and analysed by RAPD and ITS sequence. After preliminary analysis, 157 strains of endophytic fungi were isolated, and they were classified into nineteen kinds through morphology and RAPD analysis. The nineteen strains of fungi were analysed by ITS sequence. The results showed that nineteen strains belonged to Ascomycetes, and the similarity between fifteen isolates and the existed ITS sequences in GenBank was more than 97%. Among them, the ITS sequences of four endophytic fungi shared less than 95% similarity with the ITS sequences available in GenBank, so they may belong to new species. Seven species of fungi were isolated from healthy leaves of Excoecaria agallocha, and five from unhealthy leaves, and the fungi of unhealthy leaves was included in the fungi from healthy leaves. One fungus was isolated from healthy leaves of Kandelia candel, and nine from unhealthy leaves, and the fungus of unhealthy leaves was included in the fungi from healthy leaves, and Dothiorella aegiceri was both isolated in healthy and unhealthy leaves; One fungus was isolated from healthy leaves of Aegiceras corniculata, and three from unhealthy leaves, and Dothiorella aegiceri was both isolated in healthy and unhealthy leaves too. Our result is interesting. Firstly, our research demonstrated that the discriminate between fungi pathogen and endophytic fungi was not very clear in some plants, because the endophytic fungi of Excoecaria agallocha developed into plants pathogens; secondly, we found that the pathological changes in Kandelia candel and Aegiceras corniculata was caused by external fungi pathogen, and this was followed by biting of insect on leaves, and the wound were in favor of infections of fungi pathogen.

Combined effects of mowing and shading on growth and survival of Spartina alterniflora

2017/4/7 11:47:51

Spartina alterniflora, native to the Atlantic and Gulf coasts of North America, has invaded many estuaries and coasts of the world. Due to its well-developed rhizomes, seedlings usually emerged even the above-ground parts were cleared. So ensuring the death of rhizome is critical to control the weed. We examined the growth and survival rate of both above-ground parts and rhizome of S. alterniflora under only mowing and mowing+shading treatments in Guangxi Zhuang Autonomous Region, China. The results were as follows:(1)Plant height and biomass were significantly reduced at early stage after just mowing in May(P<0.05), while all above-ground growth characters increased during the following six months and were closed to the control group in November(P>0.05). However, rhizome survival rate showed contrary trend to the growth characters of above-ground parts.(2)Comparing to control and only mowing groups, the mowing+shading treatment restrained plant growth and resulted in death obviously. And the restraining effect was positively correlated with shading degree.(3)The light transmittances of mowing+single layer shading net, mowing+double layers shading net and mowing+triple layers shading net were 15.27%, 2.29% and 0.31% respectively, and rhizome survival rate were 3.68%, 2.09% and 1.70% in November respectively. Above-ground parts were all dead at November in mowing+single layer shading treatment, while they were all dead at July in mowing+double layers shading treatment and mowing+triple layers shading treatment. Considering the cost, lasting time and efficiency, we suggest that sowing plus single-layer shading treatment could be an effective method of controlling S. alterniflora in Guangxi Zhuang Autonomous Region.

Diversity of cultivated marine bacteria and antibacterial activity of endophytic bacterial in Rhizophora stylosa

2017/4/7 11:47:51

Rhizophora stylosa is an evergreen tree with prop roots, and a common tree found in tropical coastal mangrove forests, widely distributed in tropical coastal mudflats. As a typical representative of the mangrove, R. stylosa has rich endophytic diversity with little research. The study objects of R. stylosa were collected from Shankou National Nature Reserve, Guangxi, China. From stem, root, leaf and other tissues, seventeen endophytes were isolated with the dilution coating method and the three-wire method. We Observed their morphological characteristics, 16S rRNA and Venny Chart were utilized to analyze the diversity of their endogenous bacterial. Depending on the results of diversity analysis, we could find that these strains have different morphological characteristics and they could classified into three doors, seven genera, five families and eight species. Further analysis showed that endophytic bacteria groups of R.stylosa root, stem, leaf and other organizations vary different, only one same genus was Mangrovibacter plantisponsor. Micromonospora and Mangrovibacter genus were its dominant bacteria, the proportion was 29.4% and 17.6%, respectively. Among them, the most endophytic bacteria within the root, the proportion was 47.1%. Seventeen strains belong to three doors, wherein the most number of bacteria were Proteobacteria, accounting for 52.9%, then Actinomycetes door accounted for 41.2%. In those isolated strains, three strains of bacterial species with the full-length 16S rRNA gene similarity less than 97%, may be possible new genera or new genus and had potential research value. Vibrio parahaemolyticus was a zoonotic bacteria caused some damage to uman health, severe cases even death. To test anti Vibrio parahaemolyticus activity of the crude extract of strains isolated, we used filter paper method, and the results indicated that three strains(H003, H009, H013, 5 mg·mL^-1)had a strong antibacterial activity against Vibrio parahaemolyticus, their inhibition zone could reach(8.4±0.07),(8.2±0.07), and(8.3±0.14)mm, respectively. Endophytic bacteria of Rhizophora stylosa were genetically diverse and most of them showed strong inhibition effect against Vibrio parahaemolyticus. The results provides the essential material basis for the further study of its chemical diversity and utilization of resources.