ObjectiveTopography is an important factor leading to the heterogeneity of plant community structure. In order to know the difference of community structure and species diversity of woody plants in karst forest at different topographic sites, studies were carried out in woody plant communities of Maolan Natural Reserve, Guizhou Province of southwestern China. Studies about topographic difference of community structure and species diversity of Maolan karst forest had great significance to reveal the mechanism of species maintenance in karst forest.
MethodCommunity survey method was used to analyse plant community structure. The species diversity of tree and shrub layers at different topography sites (funnel, hillside and valley) was analyzed using Margalef diversity index(D), Pielou evenness index(J), Simpson dominance index(M) and Shannon-Wiener diversity index(H).
ResultThe results showed that: (1) There were 81 species of woody plants in valley forest and they belong to 39 families and 63 genera; there were 80 species of woody plants in funnel forest and they belong to 39 families and 61 genera; there were 69 species of woody plants in hillside forest and they belong to 35 families and 58 genera; in the research area, species floristic composition of valley forest was the most complex, that of funnel forest was the second and floristic composition of hillside forest was the simplest. The dominant species in three topography sites mainly belong to Lauraceae, Rosaceae, Anacardiaceae and Cornaceae plant. The PCA ordination results of 30 plots reflected the relationship between the community type and the environmental gradient, and the main environmental factors affecting the diversity of the species were light, water and soil. (2) The important value of Litsea verticillata was the highest in the tree layer and it was the dominant species of community. The important values of Cyclobalanopsis glauca, Cornus japonica var. chinensis and Cladrastis platycarpa were lower than that of Litsea verticillata, and they were the sub-dominant species of the arbor layer of the community. Pittosporum crispulum was the dominant species of shrub layer. (3)The main life form composition of woody plant at different topography sites was mesophanerophyte and microphanerophyte, and megaphanerophyte was the least. Microphanerophyte was the dominant life form in the hillside forest and mesophanerophyte was the dominant life form in funnel and valley forest. (4)Among three topography sites, species diversity indexes of the arbor layer were valley > funnel > hillside, but species diversity indexes of the shrub layer were valley > hillside > funnel.
ConclusionAmong three kinds of topographic sites, species floristic composition and species diversity of valley forest were the most complex and the most abundant, the dominant species were Litsea verticillata and Pittosporum crispulum, woody plant life forms were phaenerophytes and microphanerophytes in valley forest. Light, moisture and soil are the main environmental factors affecting the community distribution pattern at different terrain sites.