Regeneration characteristics and influencing factors of Abies fargesii forests in Shennongjia National Nature Reserve
神农架巴山冷杉群落更新特点及影响因素

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.