神农架巴山冷杉群落更新特点及影响因素

采用样方法对神农架自然保护区巴山冷杉群落更新特性、环境因子对其更新的影响进行了研究.研究表明:(1)林窗更新是巴山冷杉群落重要的更新方式,以红桦为代表的阔叶树种和巴山冷杉等耐荫树种在林窗内外均存在更新差异;(2)巴山冷杉在林窗更新中具有最大优势,3a以下的巴山冷杉幼苗数量占45.7%,随着年龄的增加下降明显,7a以上的幼树数量只占6.3%;(3)用SPSS将影响巴山冷杉更新的四类环境因子进行主成分分析表明,林窗面积、坡向、林窗微环境、乔灌草盖度依次是影响巴山冷杉幼苗生长和分布的主要因子;(4)林窗微环境因子的相关分析表明,在不同的生活史阶段,更新影响因子重要性不同,光照水平和土壤水分分别对幼苗和幼树的生长具有显著影响;(5)坡向和密度的相关分析表明在北坡巴山冷杉更新幼苗数量丰富,灌草层是巴山冷杉更新过程的潜在障碍.

Regeneration characteristics and influencing factors of Abies fargesii forests in Shennongjia National Nature Reserve

Community regeneration and the environmental causes of Abies fargesii forests in Shennongjia National Nature Reserve were studied by sampling plot method. Results showed that (1) forest gap regeneration was an important pathway for regeneration of Abies fargesii communities, and broad\|leaved species such as Betula albo\|sinensis Burk. and shade\|tolerant species such as Abies fargesii in gaps differed from those under canopies in their regeneration characteristics; (2) Abies fargesii was most predominant in the early gap regeneration but gradually displaced by other species with time, and accounted for 45.7% of the seedlings below age 3 and 6.3% of the saplings older than 7 years; (3) principal component analysis of four types of environmental factors by SPSS indicated that the controlling factors of growth and distribution of Abies fargesii seedlings were ranked in the order of gap area, slope aspect, gap micro\|environment, and tree\|shrub\|herb cover; (4) correlation analysis of the gap micro\|environment suggested varying controlling factors of Abies fargesii regeneration with developmental stages, and that irradiance and soil water were the most influential factors on growth of seedlings and saplings; (5) correlation analysis of slope aspect and population density showed that Abies fargesii seedings were more abundant on the northern slope, and the shrub\|herb layer was a potential barrier in the process of Abies fargesii regeneration.