Understory vegetation community structure and diversity in low-value lichee (Litchi chinensis Sonn.) plantation in Dongguan of South China

Using field survey from an abandoned lichee (Litchi chinensis Sonn.) plantation in Dalingshan, Dongguan City, the community structure, diversity and niche characteristics of understory vegetation were analyzed. The field survey recorded 102 understory plant species, which belonged to 50 families and 85 genera. Thirteen ferns species of the vegetation mosaic belonged to 9 families and 9 genera; 65 dicotyledons belonged to 31 families and 52 genera; and 24 monocots belonged to 10 families and 24 genera. Shrubs and tree seedlings dominated the understory vegetation. There was no significant difference in species abundance between the shrub and herbaceous layers. No significant difference was also noted in the indices of species richness, evenness, Shannon-Wiener, and Simpson between the shrub and herbaceous layers. The dominant plant species included 8 shrubs (e.g., Raphiolepis indica), 7 herbs (e.g., Dicranopteris dichotoma) and 5 vines (e.g., Mussaunda pubescens). Niches breadth and niche overlaps were 0.909~1.450 and 0.567~0.955 for the main shrub layer, and 0.945~1.566 and 0.270~0.984 for the main herbaceous layer, respectively. The study revealed rich species of natural recruitment in the understory vegetation of lichee plantation. This was characterized by subtropical floristic elements with a complex structure. In view of the findings, it was suggested that in the transitional stage of Dongguan lichee industry, lichee plantation ceased to operate due to adverse stand conditions. Hence understory vegetation should be maintained or transformed into an ecological forest, which could help sustain the development of Dongguan lichee industry.