关键词: 中亚热带, 动态监测样地, 生物多样性, 植物区系, 重要值, 群落结构

Abstract

Aims: The deciduous broad-leaved forest in Shennongjia is a typical ecosystem that is well preserved on the northern edges of the middle subtropical zone. In order to explore underlying mechanisms of species diversity maintenance and forest dynamics in a mid-subtropical mountain region, a 25 ha forest dynamics plot of deciduous broad-leaved forest was constructed on the southern slope of Shennongjia in 2022, following the protocol of the Forest Global Earth Observatory (ForestGEO) and the Chinese Forest Biodiversity Monitoring Network (CForBio). The establishment of this plot had complemented the forest dynamics monitoring network in China.  

Methods: Based on the survey data of all woody plants (omitting bamboo and vines) with diameter at breast height (DBH) ≥ 1 cm, the plot was analyzed based on community composition, plant flora, and community structure. All of these individuals had been subjected to species identification, DBH measurement and coordinate measurement.

Results: Results suggested that the plot, characterized by an elevation difference of 334 m, accommodated 61,054 surviving individuals (total 97,664 individuals including branches) belonging to 149 species (including varieties), 79 genera and 44 families of woody plants. There were 28 evergreen and 121 deciduous tree species, respectively, and 44 (29.5%) rare species (< 1 ind./ha) were recorded in the plot. Individuals with sprouts accounted for 26.8% of the total population, while species with sprouts accounted for 93.3% of the total number of the plot. The plot had typical transitional characteristics from the middle subtropical zone to the north subtropical zone, dominated by both tropical families (43.2%, 19 families) and north temperate genera (44.3%, 35 genera). The canopy layer was dominated by Quercus aliena var. acutiserrata and Fagus engleriana, with importance values of 7.5% and 6.6%. The average DBH of trees species was 7.71 cm, and individuals with DBH ≤ 10 cm were dominant (76.7%). The size class distribution of dominant species mainly showed both an inverted “J” type and a normal distribution type.

Conclusion: Shennongjia mid-subtropical montane deciduous broad-leaved forest is rich in species diversity and diverse in flora, compared to plots at similar latitudes. The community structure is stable, with a high root sprouting ratio and successful regeneration.

Key words: middle subtropical zone, forest dynamic plot, biodiversity, fora, importance value, community structure