千岛湖片段化生境中木本植物种子雨基本特征及其影响因子

为探究片段化生境中木本植物种子雨的基本特征,该研究根据2015—2020年(研究期间)在千岛湖样岛上的植物群落长期监测样地内每月收集的种子雨数据,采用Kruskal-Wallis检验对木本植物的种子雨密度进行年际差异分析,对不同传播方式物种的种子雨密度进行月份间差异性分析,并利用线性混合效应模型,探究岛屿空间特征(岛屿面积、距最近岛屿的距离、距大陆的距离)以及气候因子(0 ℃以上积温、降水量)对木本植物以及不同传播方式物种的种子雨密度的影响。结果表明:(1)2015—2020年6年间,在29个样岛用240个收集器共收集到877 178粒木本植物的成熟种子,属于26科40属52种。(2)动物传播是木本植物主要的种子传播方式,不同传播方式物种的种子雨时间动态存在较大差异。(3)木本植物的种子雨年密度与岛屿面积和年积温呈显著正相关,与年降水量呈显著负相关。(4)自主传播物种的种子雨月密度与距最近岛屿的距离呈显著正相关,而动物传播物种的种子雨月密度则与距大陆的距离呈显著正相关,风力传播物种的种子雨月密度与月积温呈极显著正相关。综上表明,生境片段化通过岛屿空间特征影响了木本植物种子雨的时间动态。

Basic characteristics and influencing factors of seed rain of woody plant in fragmented habitats in the Thousand Island Lake

Seed rain can affect species composition, forest community diversity, and plant population and community renewal. Studying the characteristics of seed rain is of great significance for in-depth research on regeneration strategies and restoration of plant population. In order to explore the basic characteristics of seed rain in fragmented habitats, this study used monthly seed rain data collected from 2015 to 2020, and used the Kruskal-Wallis test to analyze the annual difference of the seed rain density of woody plant, and to analyze the monthly difference of the seed rain density of species with different dispersal syndromes. Then we used linear mixed-effect models to test the relationships among island spatial attributes(i. e., island area, the distance to the mainland, and the distance to the nearest island), climatic factors(i. e., accumulated temperature above 0 degrees, precipitation)and seed rain density of woody plant and species with different dispersal syndromes. The results were as follows:(1)During the six years of 2015-2020, a total of 877 178 mature seeds of woody plant were collected from 240 seed traps in 29 study islands, belonging to 26 families, 40 genera and 52 species.(2)Zoochory was the major dispersal syndrome in the Thousand Island Lake, there were great differences in the temporal dynamics of seed rain in different dispersal syndromes.(3)The annual density of seed rain of woody plant was significantly positively correlated with island area and annual accumulated temperature, and significantly negatively correlated with annual precipitation.(4)The monthly density of seed rain of autochory was significantly positively correlated with the distance to the nearest island, while that of zoochory was significantly positively correlated with the distance to the mainland, and that of anemochory was significantly positively correlated with the monthly accumulated temperature. In conclusion, habitat fragmentation affect the temporal dynamics of the seed rain of woody plant through island spatial attributes.