Subjects: Biology >> Botany >> Applied botany submitted time 2024-05-07 Cooperative journals: 《广西植物》
Abstract： Seedling is the most important stage during the life history of plant and plays a critical role in the forest regeneration. We studied the species composition seasonal dynamics and spatial distribution of tree seedlings in the 20 hm 2 Ailaosha n forest dynamics plot . The forest dynamics plot was built in a mid mountain moist evergreen broad leaved forest in the Ailaoshan. Within the 20 hm 2 plot, we established 450 seedling quadrats of size 1 m × 1 m . We investigated the species composition, seas onal recruitment, seasonal mortality and spatial distribution of tree seedlings for four years ( from 2019 to 2022). The results were as follows: 1 We recorded a total of 2 928 seedlings of 58 species belonging to 42 genera and 26 families. There were 817 recruits of 47 species and 1 181 dead seedlings of 50 species. (2) The i mportance val u e s of tree seedlings varied among different tree species across years . Symplocos ramosissima and Machilus bombycina were t he dominant species, with importan ce values con sistently in the top 2 in four years while the importan ce value of the pioneer species Viburnum cyclindricum decline d continuously (3) W e didn't find significant differences in species richness, average species richness in a quadrat, species diversity S hannon Wiener index, Simpson index) index), abundance, recruits, recruitment rate, mortality and mortality rate of tree seedlings between different seasons. 4 The majority of species exhibited restricted distribution within the plot, wh ile only a few species di splayed a broader distribution across the plot. Topography was found to determine the distribution and diversity of tree seedlings with higher species richness, density and diversity (Shannon Wiener index and Simpson index) in the flat topography compared to the ridge and valley of the plot . T hese findings suggest that we don't find significant differences in community composition, recruitment and mortality of tree seedlings between different seasons. Topography influences the spatial distribution and diver sity of tree seedlings. The present study reveals the dynamics of recruitment and mortality of tree seedlings and provide the theoretical basis for biodiversity conservation and forest management.
Subjects: Biology >> Botany >> Applied botany submitted time 2020-08-03 Cooperative journals: 《广西植物》
Abstract：附生植物是热带亚热带森林生态系统中物种多样性极高且极其脆弱敏感的生物类群之一。光照被认为是促进附生植物由陆生类群演化而来并决定其生长和分布的关键因素。然而由于接近林冠和规范性采样的限制，附生植物与光照的关系仍亟待阐述。为揭示附生植物对光强变化的响应和适应策略，该研究以亚热带常绿阔叶林6 种附生植物（林冠层木本：鼠李叶花楸、毛棉杜鹃；林冠层草本：狭瓣贝母兰、毛唇独蒜兰；树干区草本：点花黄精、距药姜）为对象，对其在4 个光处理梯度下生长的叶片气孔特征及其可塑性进行了对比分析。结果表明：（1）2 种附生小乔木的气孔面积（SA）、气孔密度（SD）、潜在气孔导度指数（PCI）和表皮细胞密度（ECD）均对光强改变显著响应。2 种附生兰科植物的SA 最大而SD 最小；附生乔木叶片SD 和ECD 的光响应趋势与陆生植物更相似，而附生草本则出现种间差异。（2）6 种附生植物的气孔、表皮细胞特性及其表型可塑性，在草本-木本、常绿-落叶植物、林冠-树干区之间，均无明显差别。（3）附生植物气孔特性和表皮细胞平均可塑性指数均低于陆生植物。研究结果表明了亚热带常绿阔叶林中附生植物对于光环境变化的适应性相对较弱。不同的附生植物可以通过不同程度地增加叶片SD 和ECD 来适应高光强生境，并通过对SD 和SA 的双重调节以增大潜在光合能力从而应对低光胁迫。
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