Subjects: Biology >> Botany >> Applied botany submitted time 2023-07-26 Cooperative journals: 《广西植物》
Abstract： Shiwandashan is one of the hotspots of biodiversity in Guangxi, and its main vegetation type is the mountain evergreen broad-leaved forest. In order to understand the current community status and the development status of dominant species population structure of mountainous evergreen broad-leaved forests in the region; This study was conducted in a fixed monitoring sample plot of 1 hm2 established within the evergreen broad-leaved forest community in the Shiwandashan. Woody plants with a diameter at breast height ≥ 1 cm in the sample plot community were used as the research object to analyze their species composition, diameter class structure, tree height structure, and the spatial distribution pattern of dominant species using the g(r) function. The results indicate that: (1) There are 153 species of woody plants with a diameter at breast height ≥ 1 cm in the community, belonging to 52 families and 108 genera. The individual density of the sample plot community is 7 517 plants/hm2; The dominant species in the community are Clethra delavayi, Schima argentea, Hartia villosa, Castanopsis hystrix, Engelhardtia roxburghiana, Ardisia quinquegona, Itea chinensis, Symplocos adenophylla, Eurya subintegra, Ilex pubescens; But the dominant position of dominant species is not obvious. (2) The overall average diameter at breast height of the community is 5.51 cm, and the distribution of diameter class and tree height is approximately an inverted "J" shape. The diameter class distribution of dominant species is mostly an inverted "J" or "L" shape, and the community has a large number of small and medium-sized diameter class standing trees, indicating a strong self-renewal ability of the community. (3) Dominant species coexist stably in the community; The dominant species exhibit aggregated distribution in the sample plot, but there are differences in the location of aggregated distribution among dominant species. Overall, the community is currently in a good state of renewal, with the existence of dominant species in the top level community. However, the community has certain secondary characteristics and has not yet reached a stable top level community state. The dominant species can coexist stably and have the potential to inherit towards a stable top level community. Therefore, it is necessary to continue to strengthen management and promote the renewal and survival of the evergreen broad-leaved forest community in the Shiwandashan areas.
Subjects: Biology >> Botany >> Applied botany submitted time 2023-05-21 Cooperative journals: 《广西植物》
Abstract： To investigate the effect of exogenous nitric oxide (NO) on aluminum tolerance of eucalyptus seedlings under aluminum stress. In this study, sodium nitroproside (SNP) was used as exogenous NO donor in four kinds of eucalyptus seedlings (Eucalyptus grandis, E. urophylla, E. tereticornis, E. urophylla×E. grandis). The effects of different concentrations of NO (0, 50, 100, 200, 400, 800 μmol·L-1) on the physiological indices of ROS, antioxidant enzyme activities and the contents of organic osmotic regulatory substances of Eucalyptus seedlings under 120 mg·L-1 aluminum stress were studied, and the differences of aluminum resistance of four eucalyptus species under NO treatment were compared. The results show that: (1) The addition of exogenous NO (50 μmol·L-1 ≤ NO≤ 200 μmol·L-1) under aluminum stress can promote the contents of soluble sugar and soluble protein, the activities of antioxidant enzymes (SOD, POD, CAT, APX), the removal of ROS in the body, the reduction of MDA accumulation, and the improvement of aluminum resistance. However, under high concentration of NO(≥ 800 μmol·L-1), the activity of antioxidant enzymes and the content of osmotic regulatory substances decreased in eucalyptus seedlings, showing stress response. (2) Nitric oxide significantly improved the aluminum tolerance of sensitive eucalypts, but not significantly improved the aluminum tolerance of tolerant eucalypts. Finally, the aluminum resistance of the four eucalypts tended to be consistent under the action of NO. (3) SOD, MDA, CAT, O2-, soluble protein and soluble sugar can be used as key indicators to evaluate the aluminum tolerance of eucalyptus. This study provided a scientific reference for the selection of aluminum tolerance germplasm resources of eucalyptus, and laid a foundation for further understanding of the mechanism of NO regulating the difference of aluminum tolerance between Eucalyptus species.
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