关键词: 森林动态监测样地, 常绿与落叶阔叶混交林, 区系特征, 径级结构, 点格局分析

Abstract: Mixed evergreen and deciduous broadleaf forest in Shennongjia is the most well-preserved zonal forest in the world at the same latitude. The study of its species composition and community structure can provide scientific support for the protection management and sustainable management of this type of forest. This study surveys the floristic characteristics, species composition, diameter class structure and spatial distribution of dominant species within mixed evergreen and deciduous broadleaf forest of Shennongjia. The results showed that there were 5550 individuals of woody plants with DBH ≥ 1 cm, belonging to 110 species, 73 genera and 44 families. At the level of family, the floristic composition was primarily represented by both tropical (47.73%) and temperate (43.18%) elements. At the level of genera, the floristic composition was primarily represented by both tropical (24.66%) and temperate (69.86%) elements. The basal area and importance value of evergreen tree species were 11.63 m² (24.46%) and 39.93%, respectively. The basal area and importance value of deciduous tree species were 35.91 m² (75.54%) and 60.07%, respectively. The two species with the largest important values were Fagus engleriana and Rhododendron hypoglaucum, which were the co-constructive species of the community. The canopy density of the tree layer was 0.86, the height of the first sub-layer was ≥ 15 m, and the dominant species were Fagus engleriana and Quercus serrata. The height of the second sub-layer was 5~15 m, and the dominant species were Fagus engleriana and Rhododendron hypoglaucum. The average height of shrub layer was 1.8 m, the average coverage was 49.4 %, and the dominant species were Indocalamus latifolius and Fargesia dracocephala. The average height of the herb layer was 0.2 m, the average coverage was 11.6 %, and the dominant species were Carex lanceolata var. subpediformis and Epimedium franchetii. The size class structure of the whole community, Fagus engleriana and Quercus oxyodon showed a reverse "J" shape, the size class structure of Rhododendron hypoglaucum was normal distribution shape, and the size class structure of Quercus serrata and Carpinus fargesiana was waved shape. Rhododendron hypoglaucum and Quercus oxyodon were aggregated distribution on the whole scale, Fagus engleriana, Quercus serrata and Carpinus fargesiana showed aggregated distribution on different scales, and different species showed different habitat preferences. In conclusion, the community belongs to Fagus engleriana Seem. + Rhododendron hypoglaucum Hemsl. community, which is a representative mixed evergreen and deciduous broadleaf forest in Shennongjia area. It has good regeneration ability and is in a stable recovery period after disturbance.

Key words: forest dynamic monitoring plot, mixed evergreen and deciduous broadleaf forest, floristic characteristics, size class structure, point pattern analysis