Search

In this paper, we take secondary forest, orchard, and woodland soils of rubber in different planting years as a research subject and analyze the influence of different land use on soil organic matter. The results show that land use has significant influence on soil organic matter components (p orchard> rubber plantation. These differences are mainly due to the litter under different tillage quantity, quality and variety of management measures. While orchards and rubber plantation have used different tillage method, as a plantation by human, it was greatly influenced by human.

Exploring the distribution of soil pH and nutrients are significant to the sustainable development of tropical agricultural growth. Taking Longjiang Farm in Hainan province as the research plot, and exploring the distribution characteristics of soil nutrients in study area by applying the GIS spatial analysis tools. The results indicated that the soil is acidic and the contents of soil nutrients are varied significantly in research area. The spatial distributions of available Ca, available Mg, available Cu and available Zn were mainly determined by the distributions of soil parent materials. The contents of soil organic matters and total N are escalated gradually from north to south in study area. The spatial analysis tools can be applied to explore the distribution of soil nutrients in areas, which is significant to the regional agricultural planning.

The development of rubber industry depends on the sustainable management of rubber plantation. To evaluate the environmental effects of planting Hevea brasiliensis on a subsystem of tropical forest ecosystem, the variation of soil fertility and carbon sequestration under rubber plantation within 30-year life period were investigated in Hainan Island. Results showed that (1) with the increase of stand age of rubber plantation, soil fertility decreased all along. From 1954 to 1995, soil organic matter, total N, available K and available P decreased by 48.2%, 54.1%, 56.7% and 64.1%, respectively. (2) If the complete return of litters was considered without additional fertilizer application to the soil of the rubber plantations, the consumption periods for P, N, K, Mg were only 825 years, 329 years, 94 years and 65 years, respectively. To improve soil fertility is essential for rubber plantation development. (3) The C sequestration of rubber trees per hectare accounts for 272.08 t within 30-year life period and 57.91% of them was fixed in litters. In comparison with C sequestration by rain forest (234.305 t/hm2) and by secondary rain forest (150.203 t/hm2), rubber forest has more potentials for C fixation. On the base of above results, the following measures would benefit the maintenance of soil fertility and the development of rubber industry, including applying fertilizer to maintain the balance of soil nutrients, intercropping leguminous plant to improve soil fertility, reducing the collection of litters, optimizing soil properties to improve element P availability such as applying CaCO3. The information gathered from the study can be used as baseline data for the sustainable management of rubber plantation elsewhere.

The impacts of economic forest on global environmental change (GEC) are one of the hot issues in environmental study. Based on the 3-year observation data and 40-year climate data, GEC and analysis of the hydrological dynamic characteristics of rubber plantations and estimate of the water balance in the rubber plantations in Hainan Island were made. The results showed that the rainfall intercepted by the canopy of the plantations accounted for 11.45% of the annual rainfall, the total runoff for 23.71%, the total evaporation and transpiration for 63.24%, the soil moisture storage for 1.6%. Analysis of the 40-year rainfall data in the 19 counties of Hainan Island during 1951-1990 showed that the large-scale substitution of the natural vegetation with the rubber plantations had no significant effect on the local rainfall in Hainan Island. The main reasons are (1) 80% of the rainfall in Hainan is brought by typhoons; (2) the proportion of 11.6% rubber plantations in total forest coverage in Hainan is not enough to influence the local rainfall in Hainan Island; and (3) although the rubber plantation is artificial vegetation, it has the similar function to the tropical rain forest. Analysis of the total water resource and total GDP of Hainan in 1997 showed that the economic benefit resulted from the water resource was 1.0 RMB Yuan/m3. The value of hydrological of the rubber plantation in Hainan was 113.9 million RMB Yuan/3 when compared with the tropical rain forest. The paper reaches conclusion that the hydrological eco-service function of rubber plantation has been enhanced after transformed from natural vegetation, which includes the natural service and powerful social service.