Taxonomic and phylogenetic diversity of vascular plants at Ma'anling volcano urban park in tropical Haikou, China: Reponses to soil properties

Abstract

Anthropogenic processes and socio-economic factors play important roles in shaping plant diversity in urban parks. To investigate how plant diversity of Ma' anling urban volcano park in Hainan Province, China respond to these factors, we carried out a field investigation on the taxonomic and phylogenetic diversity of vascular plants and soil properties in this area. We found 284 species of vascular plants belonging to 88 families and 241 genera, which included 194 native species, 23 invasive species, 31 naturalized species, 40 cultivars, and 4 rare / endangered plant species. Tree composition and richness significantly varied between different vegetation formations (plantation, secondary forest, and abandoned land). Plant species richness and community composition were significantly affected by elevation (El), soil water content (WC), total soil nitrogen (TN) and soil organic matter (SOM). There were significant diversity differences between plantations and abandoned lands, but not between the plantations and secondary forests. The flora in the study site was tropical in nature, characterized by pantropic distributions. Compared to adjacent areas, floristic composition in the study site was most similar to that of Guangdong, followed by that of Vietnam. Our study revealed the diversity patterns of volcanic plants and provided the basis for future planning of plant conservation, such as preserving plant species, maintaining plant habitats, and coordinating plant management in this region.

Fig 1. A general overview of Ma’anling volcano park (study site), at Haikou, Hainan Province, China.

The grid consisted of 100 quadrats. The length of each quadrat is 1 km.

Fig 2. The percentage of plant distribution types at the family and generic levels.

1. Pantropic distribution 2. Tropical Asia and tropical America disjuncted distribution3.Old world tropics distribution 4.TropicalAsia to tropical Australasia distribution 5.Tropical Asia to tropical Africa distribution 6.Tropical Asia (Indo-Malesia) distribution 7.North temperate distribution 8. East Asia and north America disjuncted distribution 9. Center Asia distribution 10. East Asia distribution 11. Tropical Africa and tropical America disjuncted distribution.

Fig 3. Plant diversity indices of different life forms in different land use types.

Error bars were constructed with one standard deviation of the means. Here, d refers to Berger-Parker index, He refers to Shannon index, Je refers to Pielou evenness index. Different letters represented significant differences at p = 0.05 among the three different vegetation types.

Fig 4. Phylogenetic diversity indices for different vegetation types.

Error bars were constructed with one standard deviation of the means. PD refers to phylogenetic diversity. Ntaxa refers to the number of species. MPD refers to mean phylogenetic distance. MNTD refers to mean nearest taxon distance. Different letters represented significant differences at p = 0.05 among three different vegetation types.

Fig 5. Scatter plots of net relatedness index (NRI), nearest taxon index (NTI), Shannon index (He), Beger-parker index (d), phylogenetic diversity (PD), number of taxa (ntaxa, the number of species) and soil physic-chemical properties.

The dependent variable include: taxonomic and phylogenetic diversity(d, He, Je, PD, ntaxa, NRI, NTI) of different life forms(tree, shrub, herb, all species). The independent variables include: WC, TN and SOM. Single factor regression analysis were established.