Characteristics and maturity level analysis of four communities in Ehuangzhang tropical monsoon forests of northern edge

To analyze the community characteristics of tropical monsoon forests with different succession stages, four different plant communities named A, B, C, and D were investigated in this study, respectively, in a typical monsoon forest of Ehuangzhang in Yangchun, Guangdong Province. The species composition, biodiversity and spatial structure were analyzed, their maturity levels’ differences were detemined, succession direction was predicted, and suggestions for optimization were put forward. The results were as follows: (1) The forest layers of the four communities were single. Small diameter at breast height (DBH) class trees and lower forest dominated these communities, owning 1-3 obvious dominant species. (2) The Shannon-Wiener index ranged from 2.72 to 3.74, Simpson index from 0.90 to 0.97, and Pielou evenness index from 0.74 to 0.89, suggesting that their diversity characteristics were significant differences. (3) Their dominance ranged from 0.49 to 0.51, uniform angle from 0.56 to 0.61, mingling from 0.54 to 0.83, forest spatial structure index from 60.57 to 71.44, forest spatial structure distance from 53.15 to 68.53. (4) The analysis of community basic characteristics, diversity characteristics and spatial structural characteristics indicated that the maturity levels in all community ranked D > A > C > B. In conclusion, four communities are currently in the pre- or mid-term succession stages and the development space of DBH and tree height is large. The four communities are in the moderate growth state. All trees show a slight aggregated distribution, and the tree species are moderately, strongly or very strongly mingling. Besides, there is a distance in spatial structure between four communities and ideal forest with the development of maturity levels. The four communities continue to succession with intolerant tree species as the main dominant tree species, and gradually and preliminarily have the typical vegetation characteristics of the district forest climax community. With the development of maturity levels, the four communities’ biodiversity and mingling will increase, the spatial structure will be optimized and the stability will be enhanced. The results of this study provide scientific basis for community construction mechanism and forest structure optimization. In the future, Ehuangzhang tropical monsoon forests should be more regulated and protected, while the ecology of vegetation and biodiversity conservation in the area should be widely monitored and studied in depth.