Biodiv Sci ›› 2021, Vol. 29 ›› Issue (11): 1461-1469.DOI: 10.17520/biods.2021150

• Original Papers:Plant Diversity • Previous Articles     Next Articles

Population structure of Cycas hainanensis and its relationship with forest canopy density

Erhuan Wu1, Donghai Li2,*(), Xiaobo Yang2,*(), Yongling Zuo2, Long Li2, Peichun Zhang2, Lin Chen2, Lujia Tian2, Chendi Li2   

  1. 1 School of Life and Pharmaceutical Sciences, Hainan University, Haikou 570228
    2 School of Ecology and Environment, Hainan University, Haikou 570228
  • Received:2021-04-22 Accepted:2021-09-02 Online:2021-11-20 Published:2021-11-23
  • Contact: Donghai Li,Xiaobo Yang

Abstract:

Aim Cycas hainanensis, an ancient species of Cycas, is a top priority plant species in China and is also classified as endangered by the International Union for Conservation of Nature (IUCN) Red List. We aim to study the relationship between population structure and forest canopy density of C. hainanensis in the Baomeiling Provincial Nature Reserve of Changjiang County, Hainan Province.
Methods After an investigation of the C. hainanensis population and its community by utilizing the sample survey, we analyzed community characteristics including structure and species diversity, and population characteristics such as age structure, survival curve, spatial patterns, and population density. We also studied the relationship between C. hainanensis and forest canopy density.
Results The vertical structure of the community of C. hainanensis was divided into two tree layers, shrub layer and herb layer. The species diversity index of the community was high and the community species composition was rich. The distribution of C. hainanensiswas uneven in all quadrats and formed clusters in the undergrowth as well as the forest edge at an elevation of 500 m. The population dynamics belonged to growth type, and the population renewal ability is strong. The population survival curve of C. hainanensistended to the Deevey-II type. The population mortality increased with age, which indicated that the population of C. hainanensis was in a state of stable growth. The population viability decreased with the growth and development of individual specimens. The spatial distribution pattern of C. hainanensis population conformed to clumped distribution, and the degree of aggregation was positively correlated with an increase of forest canopy density. A curve estimation demonstrates that the density of C. hainanensisseedlings and saplings increased significantly in the study area where forest canopy density was 36.11%-58.33%.
Conclusions In conclusion, the C. hainanensispopulation in the Baomeiling Provincal Nature Preserve of Changjiang County is in a stable growth state and preferred to grow in a forest environment with an elevation of approximately 500 m and forest canopy density of 35%-60%.

Key words: Cycas hainanensis, community structure, population structure, survival curve, distribution pattern