哀牢山中山湿性常绿阔叶林树种幼苗群落对季节和地形的响应(附录)

Response of seedling community to season and topography in mid-mountain moist evergreen broad-leaved forest in Ailaoshan, Yunnan

关键词:  哀牢山, 森林更新, 物种组成, 季节动态, 幼苗分布

Key words:  Ailaoshan, forest regeneration, species composition, seasonal dynamics, seedling distribution

摘要:

幼苗期是植物发育过程中最重要的阶段,也是森林自然更新的关键时期。为探究哀牢山中山湿性常绿阔叶林树种幼苗组成、季节动态及其空间分布,该研究以20 hm²监测样地为平台,通过对样地内450个1 m × 1 m样方连续4年(2019—2022年)的调查,分析树种幼苗的组成、新增和死亡季节动态、空间分布等。结果表明:(1)累计调查幼苗58种,2 928株,分属于26科42属。其中,新增幼苗817株,新增物种47种; 死亡幼苗1 181株,死亡物种50种。(2)幼苗重要值在不同树种和年际间表现出较大的差异,多花山矾(Symplocos ramosissima)和黄心树(Machilus bombycina)的幼苗始终是优势种,重要值始终在前2位,而先锋种水红木(Viburnum cylindricum)重要值则持续下降。(3)未监测到幼苗物种丰富度、样方平均幼苗物种丰富度和物种多样性(Shannon-Wiener指数和Simpson指数)、幼苗数量、新增幼苗数量、幼苗新增率、死亡幼苗数量和幼苗死亡率的季节性差异。(4)多数幼苗物种的空间分布范围较窄,仅有少数树种幼苗在整个样地广泛分布。平地地形中的样方幼苗物种丰富度、幼苗密度和物种多样性(Shannon-Wiener指数和Simpson指数)显著高于山脊和沟谷地形。综上认为,哀牢山中山湿性常绿阔叶林中季节对树种幼苗组成、新增和死亡的影响不大,地形决定树种幼苗的分布和多样性。该研究结果揭示了树种幼苗新增和死亡的动态变化,为生物多样性保护和森林经营管理提供了理论依据。

Abstract:

Seedling stage is the most important stage of plant development and plays a critical role in the forest regeneration. Species composition, seasonal dynamics and spatial distribution of the tree seedlings in the 20 hm² Ailaoshan forest dynamic plot were studied. The forest dynamic plot was built in a mid-mountain moist evergreen broad-leaved forest in Ailaoshan. Within the plot, 450 seedling quadrats of size 1 m × 1 m were established. Species composition, seasonal recruitment, seasonal mortality and spatial distribution of tree seedlings were investigated for four years(from 2019 to 2022). The results were as follows:(1)A total of 2 928 seedlings of 58 species were recorded, belonging to 42 genera and 26 families. There were 817 recruits of 47 species and 1 181 dead seedlings of 50 species.(2)The importance values of tree seedlings varied among different tree species across years. Symplocos ramosissima and Machilus bombycina were the dominant species, with importance values consistently in the Top 2 in four years, while the importance value of the pioneer species Viburnum cyclindricum declined continuously.(3)Significant differences in species richness, average seedling species richness in quadrat, species diversity(Shannon-Wiener index, Simpson index), seedling number, recruits, recruitment rate, mortality and mortality rate of tree seedlings were not found between different seasons.(4)The majority of species exhibited restricted distribution within the plot, only a few species displayed a broader distribution across the plot. Tree seedlings had 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. In conclusion, there are not significant differences in species composition, recruitment and mortality of tree seedlings between different seasons. Topography influences the spatial distribution and diversity of tree seedlings. The study reveals the dynamics of recruitment and mortality of tree seedlings, and provides the theoretical reference for biodiversity conservation and forest management.