Subjects: Biology >> Botany >> Applied botany submitted time 2022-06-29 Cooperative journals: 《广西植物》
Abstract： Lianas are one of the components in maintaining forest diversity. However, the over-increase of lianas in tropical and subtropical forests, especially in secondary forests is threatening the restoration and healthy development of forests. Few domestic researches have paid attention to the phenomenon and make a comprehensive evaluation on the mechanism of the over-increase of lianas and negative effects on forests. In this paper, we reviewed and summarized the related researches on mechanisms and ecological consequences of the over-increase of lianas both at home and abroad with the purpose of offering reference for forest management and forest ecological restoration. Based on the relevant studies we hold the opinions: (1) The increase of lianas can be corelated with drought severity, elevated atmospheric CO2, increased natural disturbance (gaps) and forest fragments. Lianas possess the advantages of rapid growth, strong reproductive capacity and phenotypic plasticity, and high resource use efficiency under the altered environment. Thus, the favorable environment and inherent advantages can contribute to the increase of lianas. (2) Lianas compete with trees by means of shading stress, nutrient and water competition and mechanical loading, abrasion, and strangulation, which all may increase the mortality of trees. (3) Empirical evidence shows that the over-increase of lianas can negatively affect the tree growth recruitment, reproduction, and survival; at community level, lianas can alter tree community composition and decrease community diversity; at ecosystem level, lianas have the potential to ramify forest ecosystem function by decreasing carbon storage and altering carbon, nutrient, and water cycling. We recommend that future studies should be aimed at the correlations between population dynamic of liana species and environmental changes, the effect of forest disturbance on the growth of lianas, responses of lianas to the environmental changes and the adaption mechanisms, comprehensive evaluation on the ecological consequences of the increase of lianas by means of long-term dynamic monitoring plots and controlling experiments. It is also essential to find appropriate management and control strategies of the over-increase of lianas. We suggest that paying more attentions to the increase of lianas and the potential negative effects in secondary forest.
Subjects: Biology >> Botany >> Applied botany submitted time 2021-12-19 Cooperative journals: 《广西植物》
Abstract： The plant nuclear DNA content (2C-value) and ploidy level are important botanical characteristics which are powerful evidences for studies on population evolution, biosystematics and ecology. In order to determine the nuclear DNA content and ploidy level of Enkianthus Lour. from China, and to explore the difference of nuclear DNA content between interspecies and intraspecies. Here, we collected 60 samples from 23 populations as experimental materials, representing all six species of Enkianthus in subtropical areas of China. We used Oryza sativa L. spp. japonica variety 'Nipponbare' as an internal standard to determine their nuclear DNA Content by flow cytometry, and then the ploidy level was examined by referencing the 2C-value of a diploid species of E. serrulatus. In addition, the ploidy level was further verified by using traditional chromosome tableting technology. The results were as follows: (1) The mean nuclear DNA content of Enkianthus species in China ranged from 1.77 pg to 5.62 pg. (2) Four species in E. Sect. Enkianthus: E. quinqueflorus, E. serrulatus, E. serotinus and E. perulatus were diploid (2n=2x=22), and two species in E. Sect. Racemus: E. chinensis and E. deflexus were tetraploid or hexaploid. (3) For diploid species, the nuclear DNA content showed significant differences between interspecies and intraspecies (P<0.05), but there were no significant difference in tetraploid and hexaploid species (P>0.05). The results of this study will lay a certain foundation for the future researches on phylogenetics, biogeography, domestication and genetic breeding of Enkianthus.
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