Subjects: Biology >> Botany >> Applied botany submitted time 2024-02-07 Cooperative journals: 《广西植物》
Abstract： In order to understand the adaptation ability of Syzygium hancei seedlings to environmental factors in three different habitats under natural regeneration conditions. The present study collected the current year’s S. hancei seedlings as experimental materials that regenerated in naturally coastal environments of Guangxi, and then antioxidant enzyme activities, soluble sugar content, malondialdehyde content and photosynthetic pigments in leaves and roots were analysed. The results were as follows: (1) Variance analysis (ANOVA) was conducted on multiple environmental factors, which indicated light intensity was highly significant differences, soil surface temperature and water content were not significant differences between the three sample plots. (2) Various light density resulted in the changes of leaves and roots physiological characteristics of seedlings in different habitats. With the light density increasing, leaves’ superoxide dismutase (SOD) activity, soluble sugar (SS), malondialdehyde (MDA), and chlorophyll a/b contents, and roots’ peroxidase (POD) activity of seedlings were significantly higher in habitat B than in habitat A; while leaves’ POD activity, chlorophyll a , chlorophyll b and total chlorophyll contents, and roots’ SOD activity, SS and MDA contents were higher in habitat A than in habitat B. (3) With light intensity decreasing, seedlings that regenerated in habitat B represented significantly higher SOD activity and MDA content in leaves, and POD activity in roots than regenerated in habitat A; however, these seedlings that regenerated in habitat A represented significantly higher POD activity and SS content in leaves compare with regenerated in Habitat B; chlorophyll a , chlorophyll b, total chlorophyll,and SS contents, and roots’ MDA content were significantly higher in habitat A than in habitat B firstly, and then changed to Habitat B being significantly higher than Habitat A; chlorophyll a/b content and roots’ SOD activity were significantly higher in Habitat A firstly and then changed to Habitat A being significantly higher than Habitat B. (4) Comprehensive analyses show that the physiological and biochemical characteristics of all three habitats show different adaptation abilities, in the meanwhile, photoinhibition occurrs in habitat B that is with the lowest canopy density, hence, some manual adjusting practices are need to create a moderate light environment, and provide a suitable condition for promoting the natural regeneration of seedlings.
Subjects: Biology >> Botany >> Applied botany submitted time 2023-12-26 Cooperative journals: 《广西植物》
Abstract： The purpose of the study was to characterize the changes in soil microbial abundance and diversity and carbon utilization of Podocarpus macrophyllus by adding different levels of nitrogen (N), phosphorus (P) and potassium (K), to reveal the response of P. macrophyllus soil microorganisms to different nutrient levels of N, P and K and to provide a theoretical basis for fertilization and management of P. macrophyllus from the perspective of microorganisms. Using two-year old P. macrophyllus seedlings as the test species, the researchers controlled the gradient of N, P and K nutrient levels using the L9 orthogonal test in the potted soil. The dilution plate coating method and Biolog-ECO microplate method were used to explore the effects of different soil nutrient levels on the amount and community diversity of P. macrophyllus soil microorganisms and their utilization characteristics of six carbon sources. The results showed that the number of soil bacteria (P < 0.05) and actinomycetes (P < 0.001) decreased while the number of fungi (P < 0.001) and nitrogen-fixing bacteria (P < 0.01) increased significantly when different levels of N, P, and K were added. Additionally, the Pielou index (P < 0.001) of the soil microbial community decreased, and the Simpson index (P < 0.05) and McIntosh index (P < 0.001) increased with increasing N addition. This reduced the intensity of utilization of six carbon sources by soil microorganisms, especially the intensity of utilization of difficult carbon sources such as amines (P < 0.001), carboxylic acids (P < 0.001), polymers (P < 0.001) and other compounds (P < 0.001). The increase in P addition significantly reduced the Shannon index of soil microbial community (P < 0.05), while the increase in K addition significantly reduced the Shannon index (P < 0.05) and Pielou index (P < 0.05) of the soil microbial community and the intensity of utilization of two easily available carbon sources, carbohydrates (P < 0.001) and amino acids (P < 0.01), by the microbial community. In conclusion, N addition and K addition are the main factors affecting the functional diversity of soil microbial communities of P. macrophyllus. Attention should be paid to the cultivation of P. macrophyllus by applying fertilizer in small amounts and multiple times, reducing the addition of N and K, and appropriately increasing the addition of P to promote the growth of P. macrophyllus and its sustainable cultivation.
Subjects: Biology >> Botany >> Applied botany submitted time 2023-12-24 Cooperative journals: 《广西植物》
Abstract： Exploring the stoichiometric characteristics of understory plants’ leaves and soil in different forest types in Maoershan can reveal the adaptation strategies of understory plants in Maoershan, and provide data support for forest management. In this paper, coniferous and broad-leaved mixed forest (ZK), evergreen broad-leaved secondary forest (CLC) and evergreen broad-leaved forest (CL) in Maoershan were selected as three forest types, the leaf stoichiometry of main plants in herb layer and shrub layer, and the soil stoichiometry under three forest types were measured and analyzed. The results were as follows: (1) There was no significant difference in leaf C and N contents between herb layer and shrub layer, but P and K contents in herb layer were extremely significantly higher than that in shrub layer, and N∶P was significantly lower than that in shrub layer. Plants in herb layer was more likely to be restricted by N, plants in shrub layer was more likely to be restricted by P and the utilization efficiency of N and P were higher. There was no significant difference in leaf stoichiometry of plants in shrub layer among different forest types, but there were significant differences in leaf N content, C∶N, C∶P of plants in herb layer among different forest types. Plants in herb layer of coniferous and broad-leaved mixed forest had higher nutrient use efficiency. (2) The soil C and N contents of the three forest types showed that CL > CLC > ZK, and there were extremely significant differences among the three forest types. The soil P content of coniferous and broad-leaved mixed forest was the highest, while that of C∶P and N ∶ P was the lowest. (3) Soil in coniferous and broad-leaved mixed forest significantly affected some leaf stoichiometry of plants in herb layer and shrub layer, while the other two forest types had no significant effect on underforest plants. To sum up, there are significant or extremely significant differences in soil stoichiometry among different forest types in Maoershan. The nutrient requirements and environmental adaptation strategies of plants in herb layer and shrub layer are different. The soil of coniferous and broad-leaved mixed forest has a strong influence on the leaf stoichiometry of understory plants, and the soil with low decomposition efficiency of organic matter in this forest type, and the soil is limited by N due to the low decomposition efficiency of organic matter, so the management of N in the mixed forest should be strengthened.
Subjects: Biology >> Botany >> Applied botany submitted time 2023-09-20 Cooperative journals: 《广西植物》
Abstract： The spatial structure evolution of forests in karst areas is a key scientific issue in global forest research. In order to explore the dynamics of spatial structure in karst evergreen and deciduous broad-leaved forests, a study was conducted in the Guolin National Nature Reserve, focusing on a fixed monitoring plot of 2 hm2. Based on data from three surveys conducted in 2007, 2012, and 2017, the dynamics of community spatial structure were analyzed using the spatial structure parameters: individual distribution index (Wi), mixing degree (Mi), and size-number ratio (Ui). The results were as foloows: (1) The univariate distribution of spatial structure parameters revealed that the forest structure gradually shifted towards a slightly clumped distribution state as the stand age increased between 2007 and 2017. The mixing degree was at a level of strong mixing and showed a tendency towards extreme mixing. In terms of the size-number ratio, the stand exhibited a moderate state, shifting towards subdominance as the stand grew. (2) The study of spatial structure for different diameter classes of trees showed that the angle scale, size-number ratio, and mixing degree of trees in diameter classes 1~15 cm gradually increased with stand growth. As the diameter class increased, the values of the size-number ratio showed a decreasing trend while the mixing degree showed an increasing trend. (3) The study of spatial structure for dominant tree species revealed that, during the ten-year period from 2007 to 2017, all five dominant tree species groups exhibited a slightly clumped distribution. The size-number ratio showed a tendency towards subdominance and a moderate distribution state, while the mixing level was at a high degree and gradually shifted towards extreme mixing. The study concludes that the karst evergreen and deciduous broad-leaved forest in Guolin currently exhibits a slightly clumped distribution, a strong degree of mixing, and a tendency towards subdominance. The community is relatively stable, the stand regeneration is in good condition, and the forest is gradually transitioning towards a climax community. The analysis of the dynamic changes in vegetation structure in karst evergreen and deciduous broad-leaved forests is of great significance for predicting the future development and changes of forests.
Subjects: Biology >> Botany >> Applied botany submitted time 2021-12-19 Cooperative journals: 《广西植物》
Abstract： In order to explore the influence of gravel content of soil on the growth and root of the rare and endangered plant Handeliodendron bodinieri seedlings, one month age of H. bodinieri seedlings were used as materials and five pot experiments with different soil gravel contents (0% (CK), 20%, 40%, 60% and 80%) were carried out and the most suitable soil gravel content for the growth of H. bodinieri seedlings were selected. The results were as follows: (1) The gravel content of soil were highly significant influence on the growth of H. bodinieri seedlings. Seedling height and ground diameter of relative growth rate, leaf area, seedling quality index, biomass (root, leaf and whole plant) and root-shoot ratio were all maximum when gravel content was 40%. (2) The gravel content of soil had a very significant influence on root morphology of H. bodinieri seedlings. The total root length and root surface area all reached the maximum when gravel content was 40%. However, the root average diameter decreased with the increase of the gravel content, and the minimum root average diameter was the gravel content of soil of 80%. (3) The gravel content of soil had no obvious influence on root topological architecture and fractal characteristic of H. bodinieri seedlings, but were very significant influence on root average link length and root forks numbers. Root topological index (TI), modified topological index (qa, qb) all tended to be 1 in every treatment, so the branching pattern of the roots of H. bodinieri seedlings was close to fishtail branching in different gravel contents of soil. The root average link length increased first and then decreased with the increase of gravel content, and reached the maximum at 40% gravel content. The root forks number of H. bodinieri seedlings showed a gradually decreasing growth trend with the increase of gravel content. (4) According to the results of comprehensive evaluation of the seedlings growth, root morphology and architecture , the H. bodinieri seedlings had the best growth status in the gravel content of soil of 40%. Therefore, adding a suitable amount of gravel in the soil can promote the growth of H. bodinieri seedlings. The seedling growth status and seedings quality index were the best under the treatment of gravel content of 40%. The gravel content of 40% is the most suitable for the growth of H. bodinieri seedlings.
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