A Study on Construction and Dynamics of a Tropical Coast Plant Community with Multiple Native Tree Species as Windbreak on Hainan Island

In the Casuarina equisetifolia plantation as coast windbreak, the native tree species were planted in 2 patterns, i.e. plots with single native tree species and plot with multiple native tree species, the survival rate and growth of native tree species and the environmental factors were observed continuously and the comparative analysis of the growth of native plants in the 2 planting patterns was conducted. The results showed that most of the native tree species planted in the Casuarina equisetifolia coast windbreak could survive to form mixed forest. After 5 years' growth, the survival rates of Scaevola sericea and Pandanus tectorius were the highest (48.89%) among the 7 native tree species, and then Pongamia pinnata (42.22%) , while Calophyllum inophyllum was the lowest (13.33%). The average plant height and base diameter of plants in mixed plots with multi-species increased from 75.2 cm and 1.3 cm to 185.4 cm and 5.1 cm respectively. Among the 4 arbor species, the growth increament of Pongamia pinnata was the largest, and then Calophyllum inophyllum and Hibiscus tiliaceus, while the growth increment of Ficus microcarpa was relatively small. Among the 3 shrub species, the growth increment of S. sericea was largest and then Clerodendrum inerme and the last Pandanus tectorius. The average relative growth increment and photosynthetic intensity of Pongamia pinnata and F. microcarpa were larger in mixed plot with multi-species than in mixed plots with single species. In both types of plots, all the growth parameters of Pongamia pinnata were larger than those of F. microcarpa. In this study, the soil water contents and soil pH values increased significantly. The native tree species grow well in the mixed forest and have improved the soil environment apparently. The native tree species could be employed to construct mixed forest with multi-species as coast windbreak.