Comparison Of Soil Properties Under Different Succession Series Of Tropical Lowland Rain Forest In Bawangling, Hainan Island

Tropical forest is an important part of the terrestrial ecosystem, and it is plays an important role in maintaining the global carbon cycle, biodiversity conservation, and climate regulation. However, the tropical forest has been decreased because of commercial logging, illegal logging, agricultural activities, the expansion of human habitat and other reasons in recent years. This article selects four different succession stages(15years of secondary forest,30years of secondary forest,60years of secondary forest and old growth forest) of tropical lowland rainforest in Bawangling, Hainan Island as the entry point of the study, in order to discover the difference of soil properties between different succession period. Our objective is to provide the basic data for the study area’s vegetation recovery, ecological construction and the forest management. The main results are as follows:(1)From the analysis of physical properties, during the succession course of tropical lowland rainforest, the soil porosity, water content, soil bulk density and soil mechanical composition has changed, in which, the soil porosity and water content have improved, soil mechanical composition has strongly changed, but the soil bulk density reveals no change.(2) From the analysis of chemical properties, during the succession course of tropical lowland rainforest, all the soil appear acidic, and the soil pH value increases firstly and then decreases; soil organic matter content increases firstly and then decreases; the content of soil total N and soil available N have also increase firstly a and then decrease; the content of soil total P continued decreased and the content of soil total P increase firstly a and then decrease; the content of soil total K and soil available K increase firstly a and then decrease. The analysis of variance showed that, in the process of succession of tropical lowland rainforest, the soil chemical indicators have significant changes.(3)During the succession course of tropical lowland rainforest, the relationship between soil nutrient have change. It means the succession course has a certain impact on the relationship between soil nutrient. It seems that the soil organic matter influence s soil nutrients more with the succession.(4) During the succession course of tropical lowland rainforest, the spatial correlation of15years of secondary forest,30years of secondary forest,60years of secondary forest have changed strongly, and the old growth forest changes moderately. The continuity of spaces of soil organic matter, soil total N,soil available N, soil total P, soil available P, soil total K,soil available K have changed too. The unobserved points were estimated and the map of spatial distribution was obtained using the Kriging interpolation. The results indicated that the spatial distribution of soil organic matter, soil total N,soil available N, soil total P,soil available P, soil total K,soil available K content at different scales was obviously different.(5) Based on the soil physical, chemical properties and the integrative evaluation index system, the variation characteristics of soil fertility at different succession stages of tropical lowland rainforest were evaluated. The ranking of soil fertilities are:30years of secondary forest>15years of secondary forest>60years of secondary forest>old growth forest.