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 2020-08-03 Cooperative journals: 《广西植物》
Abstract：为探讨观光木、山白兰和灰木莲 3 种木兰科植物对不同光环境的光合适应机制，该文以其幼苗为材料，设置透光率分别为 100% NS、72. 3% NS、48. 6% NS、24. 9% NS 的 4 种光照处理，测定其光合特性参数、生物量分配比例、叶绿素含量等数据，研究不同遮阴处理对其生长和光合作用的影响。结果表明：（1）过强或过弱的光照环境限制了幼苗株高及地径的生长，与全光照相比，72. 3% NS 有利于幼苗的形态生长。（2）随着遮阴程度的增加，观光木、山白兰和灰木莲幼苗的最大光合速率、光补偿点、光饱和点、暗呼吸速率、蒸腾速率逐渐降低，叶绿素含量增加，水分利用效率先升后降。（3）随着光强的减弱，观光木和山白兰地上部分的生物量积累增加，而灰木莲的根生物量积累增加。（4）观光木的比叶面积随着遮阴程度的增加而先增后减；灰木莲的比叶面积显著减小；山白兰的比叶面积差异不显著；观光木、山白兰和灰木莲对低光环境响应和适应的差异主要表现在生物量分配比例及叶的形态特征上。综上结果显示，72. 3% NS 最有利于幼苗的生长，观光木、山白兰和灰木莲在遮阴条件下可以通过降低 Pmax、LSP、LCP、Rd、Tr，增加叶绿素含量，适当调整生物量分配比例来增大光合能力。在中度遮阴时增加水分利用效率、株高、地径来增大光合能力。
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