Hydrological eco-service of rubber plantations in Hainan Island and its effect on local economic development

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/m 3 The value of hydrological of the rubber plantation in Hainan was 113 9 million RMB Yuan/a 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.

Assessment of the Influence of Oil Palm and Rubber Plantations in Tropical Peat Swamp Soils Using Microbial Diversity and Activity Analysis

In this study, tropical peat swamp soils from Giam Siak Kecil-Bukit Batu Biosphere Reserve (GSKBB) in Indonesia was evaluated to assess the impact of oil palm and rubber plantations on this unique organic soil through comparisons with soils from a natural forest using a polyphasic approach (chemical and molecular microbial assays). Changes in the ammonium, nitrate and phosphate concentration were observed in soils converted to agricultural use. Soil enzyme activities in plantation soils showed reduced β-glucosidase, cellobiohydrolase and acid phosphatase activities (50% - 55% decrease). PCR-DGGE based analysis showed that the soil bacterial community from agricultural soils exhibited the lowest similarity amongst the different microbial groups (fungi and Archaea) evaluated (34% similarity to the natural forest soil). Shannon Diversity index values showed that generally the conversion of tropical peatland natural forest to rubber plantation resulted in a greater impact on microbial diversity (ANOVA p < 0.05). Overall, this study indicated substantial shifts in the soil microbial activity and diversity upon conversion of natural peatland forest to agriculture, with a greater change being observed under rubber plantation compared to oil palm plantation. These findings provided important data for future peatland management by relating changes in the soil microbial community and activities associated to agricultural practices carried out on peatland.

Preliminary Study on the Effect of Different Ecological Cultivation Modes on the Water Stability of Soil Aggregates in Rubber Based Agroforestry Systems

Rubber trees (Hevea brasiliensis Müll. Arg.) have been commercially cultivated for a century and a half in Asia, particularly in China, and they constitute a common element of plantation ecosystems in tropical regions. Soil health is fundamental to the sustainable development of rubber plantations. The objective of the study is to explore the influence of different complex ecological cultivation modes on the stability of soil aggregates in rubber based agroforestry systems. In this study, the ecological cultivation mode of rubber—Alpinia oxyphylla plantation, the ecological cultivation mode of rubber—Phrynium hainanense plantations, the ecological cultivation mode of rubber—Homalium ceylanicum plantations and monoculture rubber plantations were selected, and the particle size distribution of soil aggregates and their water stability characteristics were analyzed. The soil depth of 0 - 20 cm and 20 - 40 cm was collected for four cultivation modes. Soil was divided into 6 particle levels > 20 cm. soil was divided into 6 particle levels > 5 mm, 2 - 5 mm, 1 - 2 mm, 0.5 - 1 mm, 0.25 - 0.5 mm, and 0.053 - 0.25 mm according to the wet sieve method. The particle size proportion and water stability of soil aggregates were determined by the wet sieve method. The particle size proportion and water stability of soil aggregates under different ecological cultivation modes were analyzed. The results showed that under different ecological cultivation modes in the shallow soil layer (0 - 20 cm), the rubber—Alpinia oxyphylla plantation and the rubber—Phrynium hainanense plantation promoted the development of dominant soil aggregates towards larger size classes, whereas the situation is the opposite for rubber—Homalium ceylanicum plantation. In soil layer (20 - 40 cm), the ecological cultivation mode of rubber—Phrynium hainanense plantation developed the dominant radial level of soil aggregates to the diameter level of large aggregates. Rubber—Alpinia oxyphylla plantation and rubber—Homalium ceylanicum plantation, three indicators, including the water-stable aggregate content R0.25 (>0.25 mm water-stable aggregates), mean weight diameter (MWD), and geometric mean diameter (GMD), were all lower than those in the rubber monoculture mode. However, in the rubber—Phrynium hainanense plantation, the water-stable aggregate content R0.25, mean weight diameter, and geometric mean diameter were higher than in the rubber monoculture mode, although these differences did not reach statistical significance.

REGIONAL GEOCHEMISTRY OF RUBBER PLANTATION IN HAINAN ISLAND,CHINA

Hainan Island is located in the northern periphery of the tropical world.The environment is suitable for a number of tropical economic crops.The content of soil organic matter under rubber plantation is around 10- 20 g kg-1.Cu,Zn,Mn,As,Mg,Ca and K in the soil profile reflect the parent material and the intensive weathering and leaching in the area.Copper has noticeably accumulated in the lower horizon,whereas the concentrations of Ca,Mg and K.in rubber trees are 0.5- 4.9,2.2- 4.3 and 4.6-10.2 g kg-1respectively.These three elements are mostly distributed in the plant roots and are particularly required during the development of new leaves early in the season.

Variation of soil fertility and carbon sequestration by planting Hevea brasiliensis in Hainan Island, China

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/hm^2） and by secondary rain forest （150.203 t/hm^2）, 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.

Lost in transition： Forest transition and natural forest loss in tropical China

The term forest transition refers to a change in forest cover over a given area from a period of net forest area loss to a period of net gain. Whether transitioning from deforestation to reforestation can lead to improved ecosystem services, depends on the quality and characteristics of the newly established forest cover. Using publicly available data, we examine forest transition in two regions of tropical China: Hainan Island and Xishuangbanna. We found that the overall increase of forest cover in both areas during the1980 s was due to an increase in plantation forests rather than to increases in the area covered by natural forest. We also found a time lag between the increase in overall forest cover and an increase in natural forest. On Hainan Island, natural forest continued to decline beyond the point in time when overall forest cover had started to increase, and only began to recover ten years after the turning point in 1978. In Xishuangbanna, where the transition point occurred ten years later, the decline of natural forest cover is still going on. These divergent trends underlying forest transition are concealed by the continued practice to apply the term "forest" broadly, without distinguishing between natural forests and planted forests.Due to the use of undiscriminating terminology, the loss of natural forest may go unnoticed, increasing the risk of plantation forests displacing natural forests in the course of forest transition. Our findings are important for programs related to forest management and ecosystem services improvement, including reforestation and Payments for Ecosystem Services programs.

Effects of the type of forest alteration on gross nitrogen mineralization in soils of southern India

Change in land-use practices can result in major shifts in the cycling of various elements,particularly nitrogen(N),which is prone to anthropogenic perturbations.For quantifying these shifts,accurate measurements of rates of biogeochemical transformations of N are needed.We used the(^(15)N) isotope dilution technique to understand the effects of the types of forest alteration on(N) transformation rates by comparing gross N mineralization and ammonium(NH_(4)^(+)) consumption rates in soils of a managed forest,an unmanaged forest,and a rubber plantation in Kerala,India.Overall,nitrate(NO_3~-) dominated soils of the managed and unmanaged forests,whereas soils in the rubber plantation showed relatively higher NH_(4)^(+) concentration.Total N(TN) and total organic carbon(TOC) concentrations were the highest under the rubber canopy(TN:1.49±0.02 mg N g^(-1);TOC:7.96±0.86 mg C g^(-1)).In soils of all three forest types,gross N mineralization rates were higher compared to NH_(4)^(+) consumption rates.Despite high TN and TOC concentrations,the rates of gross N mineralization and NH_(4)^(+) consumption were considerably lower in the rubber plantation(mineralization:1.08±0.08 mg N kg^(-1)d^(-1);consumption:0.85±0.09 mg N kg^(-1) d^(-)) compared to the managed(mineralization:3.71±0.35 mg N kg^(-1) d^(-1);consumption:2.20±1.41 mg N kg^(-1) d^(-1)) and unmanaged(mineralization:2.20±1.07 mg N kg^(-1) d^(-1);consumption:1.39±0.27 mg N kg^(-1) d^(-1)) forests.The lower NH_(4)^(+) consumption rates in the rubber plantation led to significantly higher(p<0.05) residence time of NH_(4)^(+)(~4 days) compared to the managed and unmanaged forests(<2 days),possibly contributing to acidification of rubber soils(pH~4.8).These results together suggest that replacement of naturally grown forests with a mono-cropped plantation such as rubber negatively impact rates of N transformation processes in tropical soils and imply that change in tree species composition of naturally grown forests can adversely affect soil microbial activity.We recommend intercropping these plantations with commercial crops to maintain soil microbial diversity and biogeochemical cycling for sustainable forest management.

Dormancy-inducing factors of rubber litter beetle, Luprops tristis （Coleoptera： Tenebrionidae）

The effect of photoperiod, temperature, humidity, rainfall and moisture were examined on the annual migration ofLuprops tristis （Fabricius, 1801） （Coleoptera： Tenebrionidae） from rubber plantations to shelters, and the induction of 9 months dormancy thereafter. Results confirm the role of rainfall-mediated wetness from summer showers as the cue that induces dormancy in Luprops tristis and provide further proof to the function and significance of moisture in diapause induction in tropical insects. Other factors did not have any significant independent effect on migration and dormancy induction. Reserve food accumulation by teneral adults well ahead of the onset of adverse conditions and the non-return of beetles to the field in short-term favorable conditions strongly indicate that Luprops tristis has evolved the ability to ＂predict＂ and avoid adverse conditions and the inheritance of dormancy-regulating factors from the parent generation.

Rubber plantation and its relationship with topographical factors in the border region of China, Laos and Myanmar

Rubber plantation is the major land use type in Southeast Asia. Monitoring the spa- tial-temporal pattern of rubber plantation is significant for regional land resource development, eco-environmental protection, and maintaining border security. With remote sensing tech- nologies, we analyzed the rubber distribution pattern and spatial-temporal dynamic; with GIS and a newly proposed index of Planted Intensity （PI）, we further quantified the impacts and limits of topographical factors on rubber plantation in the border region of China, Laos and Myanmar （BRCLM） between 1980 and 2010. The results showed that： （1） As the dominant land use type in this border region, the acreage of rubber plantation was 6014 km2 in 2010, accounting for 8.17% of the total area. Viewing from the rubber plantation structure, the ratio of mature- （〉10 year） and young rubber plantation （〈 10 year） was 5：7. （2） From 1980 to 2010, rubber plantation expanded significantly in BRCLM, from 705 km2 to 6014 km2, nearly nine times. The distribution characteristics of rubber plantation varied from concentrated toward dispersed, from border inside to outside, and expanded further in all directions with Jinghong City as the center. （3） Restricted by the topographical factors, more than 4/5 proportion of rubber plantation concentrated in the appropriate elevation gradients between 600 and 1000 m, rarely occurred in elevations beyond 1200 m in BRCLM. Nearly 2/3 of rubber plantation concentrated on slopes of 8^-25~, rarely distributed on slopes above 35~. Rubber plantation was primarily distributed in south and east aspects, relatively few in north and west aspects. Rubber planted intensity displayed the similar distribution trend. （4） Comparative studies of rubber plantation in different countries showed that there was a remarkable increase in area at higher elevations and steeper slopes in China, while there were large appropriate topog- raphical gradients for rubber plantation in Laos and Myanmar which benefited China for rubber trans-boundary expansion. （5） Rubber plantation in BRCLM will definitely expend cross borders of China to the territories of Laos and Myanmar, and the continuous expansion in the border region of China will be inevitable.

Contrasting responseS of hoverflies and wild bees to habitat structure and land use change in a tropical landscape （southern Yunnan, SW China）

The response of insects to monoculture plantations has mainly proceeded at the expense of natural forest areas, and is an outstanding and important issue in ecology and conservation biology, with pollination services declined around the world. In this study, species richness and distribution of hoverfly and wild bee communities were investigated in a changing tropical landscape in southern Yunnan, south-west China by Malaise traps periodically from 2008 to 2009. Species were recorded from the traditional land use types （natural forest, grassland, shrubland and rice field fallows）, and from recently established rubber plantations of different ages. Hoverflies （total 53 species） were most common in young successional stages of vegetation, including rice field fallow and shrubland. Species richness was highest in rice field fallows and lowest in forests and showed a highly significant relationship with the number of forb species and ground vegetation cover. In contrast, the highest richness of wild bees （total 44 species） was recorded from the natural forest sites, which showed a discrete bee community composition compared to the remaining habitat types. There was no significant relationship between the bee species richness and the environmental variables, including the numbers of different plant life forms, coverage of canopy and ground vegetation, successional age of vegetation and land use type. At the landscape scale, open land use systems, including young rubber plantations, are assumed to increase the species richness of hoverflies; however, this might decrease wild bee diversity. The present land use change by rubber cultivation can be expected to have negative impacts on the native wild bee communities.

Forest land use change at Trans-Boundary Laos-China Biodiversity Conservation Area

This paper analyzed forest land use change in Trans-Boundary Laos-China Biodiversity Conservation Area which is called Namha National Biodiversity Conservation Areas （Namha NBCAs）, with 1992 and 2002 TM （ETM）. Based on GIS and statistical methods, the intensity, state index of land use change and transfer matrix were used to study spatio-temporal land use change in the region. The results showed that the area of forest land decreased greatly, also the area of bamboo and grassland decreased. The other way round, the area of unstocked forest, slash and burn and rice paddy land increased. As a whole, the intensity of forest land change was higher, but others were lower. From the transfer matrix, most of the forest land changed into unstocked forest and urban area, some to slash and burn The grassland and bamboo were mainly transferred to forest and unstocked forest. The unstocked forest land mostly came from forest land and grassland. It was showed there were three main causes of the land use change namely： opium poppy cultivation, rubber plantation and also ecotourism activities and finally some policies were developed in order to address the land use change in the study areas.