不同密度对长序榆苗期生长的影响

对长序榆播种苗不同育苗密度的苗高、地径、叶面积系数和生物量进行系统观测 ,研究了密度效应的变化趋势。根据叶面积系数和群体生物量提出了理想的生物学密度 ,用逐步聚类法划分了苗木分级标准 ,结合苗木产量和质量综合评定 ,确定了中亚热带地区的一般圃地条件和经营管理水平下 ,长序榆 1年生播种苗密度以 45～ 6 0万株·hm-2 较为适宜。

Influence of the Different Densities on the Growth of Ulmus elongata Seedlings

The change tendency towards the density effect was studied,based on systematically observing the height,collar diameter,leaf area coefficent and biomass of different densities of Ulmus elongata sowing seedlings.In the light of leaf area coefficients and the population biomass,the ideal biological density was put forward.The gradual cluster analysis was adopted to divide the grading standard of seedlings.In combination with the comprehensive evaluation of seedling quality and quantity,the relatively appropriate density of one year old seedlings of U.elongata was determined to be 450,000～600,000 plants per hm in the middle subtropical area under the common nursery conditions and management level.