Abstract:

Objective: This study aims to investigate the medium to long term effects of ice storm disturbance on natural evergreen broad-leaved forests, and to clarify the differences in community characteristics, stand spatial structure, and community stability between ice-damaged forests after 13 years of ice storm disturbance and undisturbed in northern Guangdong Province, China. Method: One 1 hm² permanent plot affected by the 2008 ice storm was established in Maozifeng (northern Nanxiong), and a comparable 1 hm² undisturbed control plot was established in Qingzhangshan (southern Nanxiong). All trees with a diameter at breast height (DBH) ≥1 cm were recorded and measured, including species identity, DBH, tree height, and spatial coordinates. Comparative analysis was conducted on the differences in species composition, biodiversity indices, DBH, and height class distributions between the two plots. The neighborhood-based spatial structural unit method was used to analyze the stand spatial structure, including the uniform angle index, neighborhood comparison, and mingling. The Godron method was used to analyze community stability. Result: The two plots affected and unaffected by ice disasters represented typical subtropical evergreen broad-leaved forests dominated by Fagaceae species. In the ice-damaged plot, the three dominant species (by importance value) were Castanopsis fargesii, C. carlesii, and C. faberi, whereas in the undisturbed plot they were C. faberi, Schima superba, and Quercus glauca. The number of small-diameter trees (DBH 1–4 cm) in the ice-damaged plot (2 668 individuals) was much higher than that in the undisturbed plot (681 individuals), while the numbers of medium-diameter trees (DBH 4–30 cm) and large-diameter trees (DBH >30 cm) were similar between the two plots. The mean uniform angle index of trees in the large sample plots affected and unaffected by ice disasters was 0.56 and 0.62, respectively, indicating that random distribution was the predominant spatial pattern in both plots, although some populations in the ice-damaged plot showed a tendency toward aggregated distribution. Mean neighborhood comparison values (0.51 and 0.49, respectively) suggested weak size differentiation and relatively stable stand structures. The mean mingling was higher in the ice-damaged plot (0.79) than in the undisturbed plot (0.62), indicating stronger interspecific mixing following disturbance. Community stability in the ice-damaged plot remained lower than that of an ideal stable forest, whereas the undisturbed plot closely approximated the stability of an ideal forest community. Conclusion: Ice storm disturbance has pronounced and lasting effects on community characteristics, stand spatial structure, and community stability of evergreen broad-leaved forests in northern Guangdong. Even 13 years after the ice storm, the disturbed forest still exhibits a high proportion of small trees, elevated stand density, partial aggregation of tree populations, and reduced community stability. These results indicate that ice storm disturbance exerts long-term influences on subtropical evergreen broad-leaved forests, and that post-disturbance forest recovery is a prolonged and dynamic process.

Key words: community stability, evergreen broad-leaved forest, uniform angle index, neighborhood comparison, mingling