四合木自然更新和种子萌发适应性研究

发布时间：2018-04-20 18:09

本文选题：四合木 + 土壤种子库　；参考：《内蒙古农业大学》2017年硕士论文

【摘要】：四合木是鄂尔多斯高原特有的珍稀濒危植物,是第三纪古地中海孑遗植物,具有重要的学术研究价值。通过对四合木核心区土壤种子库特征的研究,探讨土壤种子库与种群更新之间的关系;通过对四合木不同种群的幼苗密度、林缘扩散距离、单株下幼苗分布密度和分布格局进行调查,分析其更新规律;通过研究不同土壤含水量和沙埋厚度对四合木种子萌发和出苗的影响,探讨其种子萌发适应性。研究结果如下:(1)四合木核心区种子库共观察到7种植物,隶属于6科7属,其中灌木1种、草本6种。密度随土层深度的增加而减小。土壤种子库与地上植被之间的综合相似性系数较低,从综合相似系数来看,利用土壤种子库恢复地面植被所能呈现的植物种类有限。(2)调查范围(20m×20m)内,四合木样地全年盛行西北风,幼苗的分布方向大致为东南东北西南方向,风向是影响幼苗分布方向的主导因素;乌家庙、桃司兔、低山和棋盘井种群的幼苗在整体上呈聚集分布,海南种群幼苗仅在5-7m尺度上表现出聚集分布,其他尺度(1-5m和7-10m)上均表现随机分布;在调查的5个样地内,空间关联性呈现出空间正关联和无关联2种类型,表明幼苗和成苗个体之间空间关系无影响,种群更新困难的原因不是由于种内竞争。(3)当覆沙厚度超过2cm时,四合木种子不出苗。根据不同土壤含水量和沙埋厚度的交互作用分析可知,土壤含水量和沙埋厚度对四合木种子的出苗率均有显著的影响(P0.05)。土壤含水量为20%沙埋厚度为0.5cm时,是四合木种子萌发和出苗的最适宜环境。
[Abstract]:Four wood is an endemic rare and endangered plant in the Ordos Plateau and is an ancient Mediterranean relict plant in the third period. It has important academic research value. Through the study of the characteristics of soil seed bank in the core area of the four wood core area, the relationship between the soil seed bank and the population regeneration is discussed. Through the seedling density of different species of four wood species and the spread of the forest edge The density and distribution pattern of seedling distribution under single plant were investigated, and the regularity of its regeneration was analyzed. The seed germination adaptability of four wood seeds was studied by studying the effect of different soil water content and sand burial thickness on Seed Germination and seedling emergence. The results were as follows: (1) the seed Bank of the four wood core core area was observed in 7 plants, belonging to 6 families and 7 genera. There are 1 species of shrubs and 6 herbs. The density decreases with the increase of soil depth. The comprehensive similarity coefficient between the soil seed bank and the aboveground vegetation is low. From the comprehensive similarity coefficient, the plant species can be limited by the restoration of ground vegetation by the soil seed bank. (2) the northwest wind is prevalent throughout the year of 20m x 20m. The direction of the distribution of the seedlings is approximately the south-east and south-west of the southeast, and the wind direction is the dominant factor affecting the direction of the seedling distribution. The seedlings of the Miao, the peach and the low mountain and the chessboard well are aggregated on the whole, and the seedlings of the Hainan population show the aggregation distribution on the 5-7m scale only, and the other scales (1-5m and 7-10m) are distributed randomly. In the 5 samples of the survey, spatial relevance and unrelated 2 types showed that the spatial relationship between the seedlings and the seedlings did not affect the spatial relationship. The reason for the difficulty of the population renewal was not due to intraspecific competition. (3) when the thickness of the sand covered more than 2cm, the four wood seeds were not seeded. The effect analysis shows that the soil moisture content and the sand burial thickness have significant influence on the seedling emergence rate of four wood seeds (P0.05). When the soil water content is 20% sand buried thickness is 0.5cm, it is the most suitable environment for the seed germination and emergence of the four wood seeds.

【学位授予单位】：内蒙古农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：Q948;Q945.34

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