Species composition and community characteristics of a 25 ha forest dynamics plot in deciduous broad-leaved forest, Qinling mountains, north-central China

Abstract

The deciduous broad-leaved forests in the warm temperate-subtropical transition zone of the Qinling Mountains are well preserved. The forests lie in the transition zone from warm temperate to subtropical forests and have a relatively complex community structure. Few studies have been conducted to investigate community structure based on a large-sized plot in this transitional region. This study analyzed species composition and community characteristics within a 25 ha plot, serving as the baseline information for monitoring long-term forest dynamics and diversity in the future. Based on the field protocol of the Center for Tropical Forest Science (CTFS) and the Chinese Forest Biodiversity Monitoring Network (CForBio), a 25 ha deciduous broad-leaved forest plot was established in the temperate-subtropical transition zone. All free standing trees with diameter at breast height (DBH) ≥ 1 cm were tagged, measured and identified to species. A total of 47,739 woody individuals with DBH≥ 1 cm belonging to 119 species, 66 genera and 36 families were identified. The families and genera of temperate floristic elements accounted for 41.18% and 60.00%, respectively and were the dominant flora in this plot. Fifty-one rare species accounted for 42.86% of the total individuals. Deciduous trees species were dominant accounting for 89.07% of the total species. The 20 species with importance values ≥ 1 contributed 70.35% and 57.41% to the total number of individuals and the total basal area, respectively. The three most abundant species were Quercus aliena var. acutiserrata in the canopy layer, Sorbus alnifolia in the sub-tree layer, and Quercus spinosa in the shrub layer. The mean DBH of all individuals in the plot was 8.61 cm, and the overall structure of DBH size class of all individuals generally shows an inverse “J” type which indicated successful regeneration. All the dominant species exhibited large-scale aggregated spatial distribution closely related to habitat preferences except for Populus purdomii.