哀牢山多花山矾幼苗在森林及模拟森林光环境条件下的生长特征

Seedling growth of Symplocos ramosissima with manually controlled experimental conditions in the Ailaoshan Mountains, Yunnan Province

对云南省哀牢山常绿阔叶林优势树种多花山矾Symplocos ramosissima幼苗进行生境选择移栽研究,把多花山矾幼苗分别置于森林生境及人工遮阳生境中,测定其基径、株高、叶片数、比叶面积、根冠比、质量相对生长率、总生物量和存活率等生长参数,以掌握幼苗致死原因及更新特征,了解森林的演替动态。结果表明:多花山矾幼苗移栽到不同森林生境后,各生长参数均在林窗中心最大,林窗边缘次之,林冠下最小,比叶面积则相反。在人工遮阳生境中,多花山矾幼苗生长参数均随光照强度增加而增大,而比叶面积则随着光照强度增大而减小。在相近光照强度下,人工遮阳条件下多花山矾幼苗的各项生长参数均高于森林林窗生境,幼苗的生长比在自然森林生境中生长得更快。在1层(28.36%)和2层(8.10%)遮阳网条件下,多花山矾幼苗的生长参数在土壤含水量较高时最大,但在3层(2.37%)遮阳网条件下,在不同水分梯度处理中,多花山矾幼苗的生长参数没有规律。在1层遮阳网条件下,土壤含水量为20%(干旱胁迫)时,多花山矾幼苗的生长参数一般都较低。在一定光照强度范围内,多花山矾幼苗生长都随光照的增强逐渐加快,林窗中心对多花山矾幼苗生长最有利。土壤含水量也是影响幼苗生长的主要因素,干旱胁迫可以抑制幼苗的生长发育,较高的土壤含水量有利于幼苗的定居和生长,但在较低的光照条件下,幼苗生长对土壤水分梯度的响应不敏感。

It is very important to study the seedlings growth under the condition of moisture and light. To ob- serve the habitat preference of Symplocos ramosissima seedlings in the Ailaoshan Mountains, Yunnan Province, seedlings were transplanted in different environmental conditions. The basal stem diameter, height, leaf number, specific leaf area（SLA）, root shoot ratio, relative mass growth rate, total dry weight and survival rate of seedling were measured both in forest habitats （including understory, gap center, and gap edge） and artificially created shading conditions outside of the forest. Results of early growth showed higher values in gap center than in gap edge and the lowest under the forest canopy. Artificial shading experiments revealed a positive relationship to an increase in light intensity; whereas SLA decreased. Also, visible light intensity increased. With artificial shading even for similar light intensities, seedling growth was better than in forest habitats. At a light level of 28.36%, seedling growth was highest at 38.00% soil moisture content, and at an 8.10% light level it was best at 48.0% soil moisture content. Early growth at 2.4% light exhibited no pattern with soil moisture. At 20.00% soil moisture （drought stress） and 28.4% light, seedlings grew slowly. Thus, low soil moisture and drought stress can inhibit the growth of seedlings, but seedling growth of S. ramosissima at low light levels was not sensitive to the soil moisture gradient. [Ch, 3 tab. 23 ref.]