Rubber Cultivation Research Articles

Effects of rubber cultivation on biodiversity in the Mekong Region.

Abstract In the Mekong Region, the expansion of rubber plantations is a major threat to the remaining natural forests and has led to a considerable degradation of biodiversity. The shift from traditional agriculture to rubber cultivation additionally reduced landscape and agricultural system diversity and with this, the availability of potentially useful habitat types for species originating from natural forest. In most cases, monoculture rubber plantations showed to harbour less than half of the species richness in various plant and animal groups compared with natural forest, and often it was found or being assumed that many of these species are unable to exist permanently in rubber plantations. There is clear evidence that the existence natural forest area is essential for the conservation of large portions of native forest species in rubber-dominated landscapes. Alteration of rubber monoculture land use can only contribute effectively to species conservation if natural forest plots remain. Furthermore, suggested restoration concepts such as the conversion of rubber plantations into forest on marginal sites and land-sharing approaches are currently only vaguely described, and their contribution to the conservation of native forest species remains uncertain. In addition, modalities of stakeholder involvement, economic compensation and ecologically reasonable implementation of such measures are still unexplained. As an ecologically reasonable and economically feasible method to improve species diversity in rubber monoculture plantations, we suggest the promotion of natural undergrowth vegetation to enlarge suitable habitat structures in connection with natural forest. This can be reached through the cease of weeding and herbicide application and potentially through the cultivation of useful wild plants.

Ecosystem services and biodiversity of rubber plantations - a systematic review.

Abstract Humans benefit from ecosystems which provide free goods and services. The capacity of ecosystems to deliver such services is under constant stress since humans continue to alter the environment. Ecosystem service (ESS) approaches have the potential to pinpoint multiple benefits that humans derive from nature, including services without direct market value such as climate regulation, pollination and flood protection. Payments for Ecosystem Services (PES) schemes and land-use planning are two main fields of application that require reliable data about key ESSs provided by a given landscape. This review focuses on ESS studies on rubber ( Hevea brasiliensis ) cultivation and investigates whether the studies fulfil the mentioned requirements. We analysed 76 studies in respect to the regional origin, number of assessed ESSs by each study, distribution of ESSs concerning provisioning, regulating and maintenance, and cultural ESSs, and if the studies also included biodiversity. We found that there is still a huge gap between what topics scientists research (single or few ESSs that are easy to measure) and what information policymakers would need (results including multiple ESSs, ideally from different sections, which include less tangible ESSs such as cultural services). Of the analysed 76 publications only two fulfilled the requirements to inform policymakers, and even they were not truly interdisciplinary. The main challenge remains to develop interdisciplinary studies which require joint research or collaborative projects with sufficient funding to fulfil the required task.

LE DEVELOPPEMENT DE L’HEVEACULTURE LES MUTATIONS AGRICOLES ET SPATIO-FONCIERES A SONGON

The present article approaches the question of the expansion of the rubber cultivation in one pioneer area in Cote d’Ivoire. This culture introduced since the colonial period in the sub-prefecture of Songon transformed the landscape that was previously an important land reserve. She also transformed the local agricultural economy and unstructured customary tenure and generated at the autochthonous populations a new rapport with the earth.

Land suitability for sustainable rubber cultivation in Moneragala district

With respect to rainfall, the current rubber growing areas are suitable for rubber planting. However, the DS divisions, Kataragama, Tanamalwila and Siyambalanduwa are relatively drier. Nearly, 97 % of the land extent in the district has a mean annual temperature between 23 0 C to 27 0 C, which is desirable for rubber. Majority of the land area (67%) belongs to the elevation category below 200 m above mean sea level. Most of the lands belong to the slope category of less than 20% which is desirable and only 1% of the lands belong to greater than 45% slope. There is no limitation with respect to rockiness in the selected sites of Moneragala district. Water tables less than 1 m were not observed in any of the locations. The soil depth is found in the desirable range (>1 m). The pH levels are well within the desirable range of 4 to 6. Yet, the observed organic matter content (OMC) was found in the limiting range. The study identified the available lands, viz. barren lands, grasslands, shrub lands and under- utilized lands through GIS approach and nearly 6% (34,752 ha) of the identified land can be categorized under most suitable lands for cultivation of rubber in the Moneragala district. DOI: http://dx.doi.org/10.4038/jepsl.v3i1.7313 Journal of Environmental Professionals Sri Lanka, Vol. 3 No. 1 2014, 48-61

Indian Brahmaputra Valley Offers Significant Potential for Cultivation of Rubber Trees under Changed Climate

In a warming world, species distribution models have become a useful tool for predicting plausible shifts of a species occurrence enforced by climate change. Using maximum entropy (Maxent) model, we analysed present and future distribution patterns of rubber tree (Hevea brasiliensis ) in two distinct bio-geographical regions of India: the Western Ghats having a good distribution of rubber plantations at present and the Brahmaputra valley, where rubber trees are recently being cultivated. The model-derived suitable regions of the Western Ghats and Brahmaputra valley provided good conformity with a satellite-derived rubber plantation distribution map. Annual range of temperature and mean temperature in the coldest months, temperature seasonality and rainfall in the warmest quarter would be the major decisive variables in the distribution of this species as revealed by the area under receiver operating curve. Interestingly, we predict that more areas will become suitable for rubber cultivation by the middle of the 21st century in the Brahmaputra valley, while some areas under current cultivation may become partially unsuitable for this species in the Western Ghats. This result can help planners in deriving a comprehensive rubber plantation policy for India considering the existing land-use scenarios.

An Assessment of Sediment and Nitrogen Input into the Upper Merbok Estuary, Kedah, Malaysia

The increased loss of nutrients via agricultural runoff has serious potential ecological and public health implications. This paper discusses water quality and nutrient inputs into Merbok river in Northern Malaysia. Merbok river stretches 35 km long with depth ranging from 3 to 15 m. Merbok catchment areas of $$440~\mathrm{{km}}^{2}$$ are made up of alluvium deposits overlying an extensive span of ferruginous shale and mudstone with a few scattered outcrops of granite and ferruginous sandstone/quartzite. In 2006, the Merbok catchment consisted of 25.2 % urban areas, 48.6 % agricultural areas, 20.8 % forests, 0.6 % livestock farming areas, and 4.8 % was covered by other types of land uses. As early as 1990s, Merbok river has been classified as a very polluted river in terms of the ammonium nitrogen (NH4-N) and suspended sediment concentrations (SS). The results of our monthly survey of water quality and nutrient contents, which was carried out every month from October 2011 to September 2012 at 12 sampling stations, suggested and confirmed the previous findings. Such findings affirmed that nearly 3 decades ago, SS and NH4-N were high in the river catchment. The average SS was high (35 mg/l) (Class II of Landerarbeitsgemeinschaft Wasser (LAWA), (1998) water quality standard), at the lower end of Merbok river (M2), while the highest SS of 106 mg/l was recorded at Puntar river, which is upper tributary of Bongkok river. This is due to land clearing in the oil palm plantation and for rubber cultivation observed during sampling period. The maximum recorded NH4-N concentrations observed in the upper Merbok river ranged from 1.97 to 3.98 mg/l along Bongkok river. Moreover, relatively high concentrations were recorded from other tributaries such as the Lalang river (3.10 mg/l); Getah river (3.13 mg/l) and Tok Pawang river (3.53 mg/l), which were all above the limit of 2.4 mg/l or Class IV of the LAWA classification. The trend of data has referred to excessively contaminated rivers of heavy pollution burden. In addition, it was found that the maximum nitrate concentrations were increasing from 8.33 mg/l at the upper Bongkok river (B1) peaking at Bongkok B4 (9.24 mg/l) and decreasing to 6.01 mg/l near the tidal limit of Merbok river (M1) and 5.65 mg/l at M2 in the Merbok estuary, all of which were LAWA class III of heavily-polluted water. Land use and human activities in the upper catchment contributed to such significant pollution burden in the river.

Intensive rubber cultivation degrades soil nematode communities in Xishuangbanna, southwest China

Fifty years after the introduction, rubber monoculture now covers more than 400,000 ha of previously tropical seasonal rainforest, representing 20% of the land in Xishuangbanna, southwest China. However, little is known about effects of this widespread rubber monoculture on soil ecosystems. Here, we used soil nematodes as indicator species to assess effects of different rubber plantation types on soil ecosystems. Four land-use types (rubber monoculture, rubber and tea mixture, rubber polyculture and natural forest) at three sites were selected to compare soil nematode communities. Nematode communities were significantly different among the four land-use types. Natural forest had highest nematode abundance and taxa richness, followed by rubber polyculture, rubber and tea mixture and rubber monoculture. Compared to natural forest, rubber monoculture after 15–20 years reduced nematode taxa richness by as much as 33%. This was accompanied by reduced soil C and N, indicating loss of soil nutrients and ecological functioning. Nematode ecological indices (H′, MI and PPI) suggested a common pattern that natural forest was the most stable and undisturbed ecosystem, followed by rubber polyculture, rubber and tea mixture and rubber monoculture. Nematode trophic groups and SI indicated that food-web structures changed from complex in natural forest to much more simple in rubber monoculture. Finally, based on our results, two protective measures have been proposed to local government and farmers for rubber plantation and management in Xishuangbanna: 1. plant various cash crops such as tea, coffee, and cocoa into rubber monocultures; 2. decrease the management intensity and adjust strategies to restore surface vegetation, and ultimately convert rubber monoculture to rubber polyculture.

Trunk Injection Method for Introducing Chemical Formulations in to Rubber Trees

Natural Rubber is an important commodity to the economy of Sri Lanka. This industry makesexport earnings, sustain the livelihood of over thousands of people, supplement thousands ofhectares to the forest cover and provide many other socio-economic and ecological benefits.The economically important diseases are regarded as a major constraint for achievingpotential productivity levels of rubber cultivations. Hence management of these diseasesprovides economic benefits to rubber growers. The most popular method of disease control ischemical control. There are various chemical application techniques and spray applications,soil drenching, dusting or broadcasting are popular methods. Based on the age, type of thedisease or the prevailing weather conditions, the application technology needs to be changed.These conventional technologies have many health and environmental drawbacks. Therefore,economical and environmental friendly chemical application techniques have becomeimportant. The present study was aimed at investigating the trunk injection method forintroducing chemical formulations into trees. Several types of potential injectors are availableand the chemjet injectors described by Guest et al., (1994) was used throughout theexperiments. These injectors [Chemjet Trading (Pvt) Ltd, Australia] contain 20ml of thesolution and have a working pressure of 1 – 1.5 bars facilitating the formulation into the treesthrough drilled holes. The injection process was tested at Dartonfield Estate, on the Heveabrasiliensis clone RRIC 121. The average girth at the tested plants was 89 cm. Two analysesviz. 45, 60 to a depth of 4 cm from the outer bark was done. The uptake rates weredetermined using 8% tebuconazole in aqueous solutions. Uptake of the fungicide was slightlyhigher in deep injected method compared to shallow injection. The two angles tested againstthe liquid uptake too were not significantly different from each other. No interaction wasobserved among the injection angle and the depth of injection on the liquid uptake. More than70% of the trees had uptaken the entire 20ml injected volume within 48 hrs of injection.Trunk diameter had no effect on the uptaking process. The results obtained proved thepossibility of injecting liquids / chemical solutions into rubber trees. Trunk injection requireslow volumes of chemicals resulting in reduced cost in chemical applications. Minimumwastage of chemicals could be achieved together with reducing the impact of hazardouschemicals on the environment. Compared to the currently practiced chemical applicationmethods into trees, this application technique has many advantages.

Value chain analysis for green productivity improvement in the natural rubber supply chain: a case study

The main objective of this research was to map and to analyze green productivity of a natural rubber supply chain and formulate scenarios for increasing its green productivity level. The case studies were conducted in private enterprises engaged in natural rubber plantation and processing. Material flow analysis was performed using the green material flow map to analyze the seven sources of green wastes. The best strategy for green productivity improvement was determined by using the Analytic Hierarchy Process (AHP). The performance of green productivity improvement strategies was then assessed as future GPI (Green Productivity Index) and compared with current GPI. Results of this research have shown that the natural rubber cultivation combined with latex production improvement and waste minimization was the best green productivity improvement strategy. The best selected strategy for the production process was reusing the processing water.

Ecological Governance of Rubber in Xishuangbanna, China

In recent years, the Xishuangbanna Tropical Botanic Garden (XTBG) and the Xishuangbanna prefecture government have woken up to the environmental threat that extensive monoculture rubber cultivation poses in this tropical site in southern Yunnan. In response, XTBG has become a centre of knowledge production on how to restore some ethnic minority farmers' rubber fields to natural forest. As is common globally, the plan relies on mainstream ecology and leaves out farmers' experience and opinions. Curiously, in the 1980s and 1990s XTBG was a centre of human ecology research on farmers' knowledge about managing ecosystems and protecting biodiversity. This paper traces the transformation in the values, actors, institutional configurations, and epistemic communities that enabled farmers' experiences to be central to knowledge production and inscription across surrounding landscapes in the 1980s and 1990s, only to be disparaged and ignored in the production of knowledge and landscapes in the 2000s. Farmers who once taught XTBG scientists the names of species and how to survive on them during the Cultural Revolution are now excluded from determining how to restore those same species to the hills around them. Our analysis suggests possible pathways for ecological knowledge to be generated as well as lost.

Adopsi Teknologi Budi Daya dan Strategi Pengembangan Perkebunan Karet Rakyat di Kecamatan Teweh Tengah Kabupaten Barito Utara

Although Indonesia has the largest rubber plantation in the world, the productivity is still very low. About 85% of the plantation belongs to the majority of farmers whose adoption level of cultivation technology is still low. This study aimed to determine the internal and external characteristics that greatly affect the level of farmers' adoption of technology in rubber cultivation to come up with the formulation of development strategy in the management of rubber plantation in Teweh Tengah Sub-district, Barito Utara regency. Processing and data analysis was done by analysis of descriptive and inferential statistics using the percentage distribution tables, Chi-square statistical analysis, correspondence analysis and logit analysis. Descriptively, the technology adoption rate of rubber farmers was categorized as 54% low, 40% moderate and 6% high. A Chi-Square test showed a correlation between the level of adoption by gender, age, course/training, Information Seeking activities of cultivation technology, Extension Support, Farmer Group Support, and Government support. The analysis result of Logit Method of Stepwise showed that there were two characteristics of internal and external variables that influenced the adoption rate of rubber cultivation technology: Support of Farmer Groups and Activities of Seeking for Cultivation Technology Information. A strategy for the development of rubber plantation Management should be based on growth, strengthening and development of farmer groups. The support of farmer groups can foster the process of increasing the information and skills for farmers. Development strategy included establishment and institutional development. improvement and development of information for farmer groups.Key words: Logit Regression, Rubber Plantation, Technology Adoption, farmer group

Comparison between different selection methods of rubber trees

The purpose of this study was to compare estimates of genetic gain using three different selection methods (between and within, combined selection and Multi-Effect Index) for the cultivation of rubber trees (Hevea brasiliensis), analyzing the variables rubber yield and the annual girth growth, evaluated at three locations. The population and consisted of 22 open pollinate progenies from different regions of rubber cultivation in the State of São Paulo (Jaú, Pindorama and Votuporanga). The experiment was arranged in a randomized block design with 6 replications, 10 plants per plot and spacing of 2m×2m. The individual narrow-sense heritability (hˆr2) and heritability of progeny means (hˆmp2) were mean and high, respectively, for all variables at the three sites, indicating little environmental influence on the variables. The within and between selection method proved more promising in Jaú, while at the other locations, gains were higher by the Multi-Effect Index, with genetic gain of over 100%. The combined selection obtained medium gains, in some cases very close to those of the Multi-Effect Index. The multi-effect selection index can increase the genetic gains, maximizing selection and enabling a reduction in the breeding cycle of the species.

Tree Diversity Mediates the Distribution of Longhorn Beetles (Coleoptera: Cerambycidae) in a Changing Tropical Landscape (Southern Yunnan, SW China)

Longhorn beetles (Coleoptera : Cerambycidae) have been used to identify sites of high biological diversity and conservation value in cultivated landscapes, but were rarely studied in changing landscapes of humid tropics. This study was conducted in a region of southern Yunnan, China, which was dominated by natural rainforest until 30 years ago, but is successively transformed into commercial rubber monoculture plantations since that time. The objectives were to investigate longhorn beetle species diversity and distribution in the major land use types of this landscape and to estimate the effects of an expected expansion of rubber plantations on the longhorn beetle assemblages. The results showed that tree species diversity (181 species in total) and longhorn beetle diversity (220 species in total) were closely related with no significant differences between the tree and longhorn beetles assemblages shown by similarity distance analysis. There was a highly positive relationship between the estimated species richness of longhorn beetles and the number of tree species. Individual numbers of longhorn beetles and trees were also highly positive related at the sampling sites. Non-metric multidimensional scaling revealed that the degree of canopy coverage, succession age and tree diversity explained 78.5% of the total variation in longhorn beetle assemblage composition. Natural forest sites had significantly higher numbers of species and individuals than any other type of habitat. Although young rubber plantations bear the highest longhorn beetle diversity outside forests (half of the total number of longhorn beetle species recorded in total), they can not provide permanent habitats for most of these species, because they develop into closed canopy plantations with less suitable habitat conditions. Therefore, along with an expected expansion of rubber cultivation which largely proceeds at the expense of forest areas, the habitat conditions for longhorn beetles in this region might decrease dramatically in future.

Small-Scale Rubber Planting for Enhancement of People's Livelihoods: A Comparative Study in Three South Asian Countries

South Asian upland cultivators are transitioning from subsistence production to commercial production using mainly small-scale rubber cultivation, which helps this transition and reduces poverty. This study, conducted October 2007 through February 2009, examines how small-scale rubber planting enhances people's livelihoods. Data were gathered from Bangladesh, India, and Sri Lanka. We found differences in rubber tree stock, growth, management, and livelihood impact. Plantations in India and Sri Lanka were doing well, while Bangladesh tree stock was low. Strong institutional support, proper silvicultural practices, funding for plantation maintenance, and participant awareness of benefits contributed to satisfactory plantation conditions in India and Sri Lanka, where participants realized good earnings from tapping, while Bangladeshi participants earned little. Because monoculture rubber plantations present risks, participants should practice mixed cropping. Rubber agroforestry can be the best alternative to monoculture rubber plantations because it reconciles economic and sustainable uses of natural resources, and biodiversity conservation.

Effect of free range poultry system on land use efficiency and floral diversity in Rubber plantations

Plantation crops like rubber were traditionally grown in monocultures to avoid any risk on theirproductivity. However, with the smallholder farmers being involved in rubber cultivation, the idea offarming system evolved with the maximizing the overall land productivity and diversifying the incomesources in order to meet the need ofthe resource poor. At present, rubber based intercropping systemswith other economically beneficial crops are recommended and being practised to some extentparticularly in smallholdings. However, no successful attempts were taken on livestock integration tothe rubber system. With the understanding of practical limitations in incorporating ruminants to thesystem, the present study was commenced as a preliminary investigation to assess the effectivenessof free range poultry with respect to productivity and its effects on floral diversity under rubber.Based on the experience in coconut based poultry systems in Sri Lanka, a strain developed as abackcross of the hybrid between CPRS (Central Poultry Research Station) Brown and indigenouswith indigenous, was used in this study expecting desired characteristics of both types. i.e., high levelof egg production and adaptability to the environment. The trial began with 30 birds in a mature rubberclearing of the Rubber Research Institute of Sri Lanka. Information on egg production, the effectpoultry on weed growth and its diversity were recorded together with visual observations on birds'behavior.Average egg production was 8 eggs per bird per month. This value has dropped to 3 when themajority of birds were in moulting, However, in some months, it has gone up to 14. Some birds wereki lied by predators and even unsuccessful attacks affected the egg production. Birds showed poorbrooding characters with that attempts taken to hatch eggs were failed. Poultry feeds had to besupplied (SOg layer ration per bird) to maintain the continuous egg production. Birds always used tofeed on the area close human dwelling. Dominance of the floral species under rubber was changedwith the incorporation of poultry. Although Adiantum latifolium was dominant throughout the study.Summed Dominance Ratio (SDR) of Paspalam conjugatum and Syngonium podophyllum declinedwith the poultry integration. Measures to be taken to improve the poultry system were also identified.

Swidden, rubber and carbon: Can REDD+ work for people and the environment in Montane Mainland Southeast Asia?

Swidden (also called shifting cultivation) has long been the dominant farming system in Montane Mainland Southeast Asia (MMSEA). Today the ecological bounty of this region is threatened by the expansion of settled agriculture, including the proliferation of rubber plantations. In the current conception of REDD+, landscapes involving swidden qualify almost automatically for replacement by other land-use systems because swiddens are perceived to be degraded and inefficient with regard to carbon sequestration. However, swiddening in some cases may be carbon-neutral or even carbon positive, compared with some other types of land-use systems. In this paper we describe how agricultural policies and institutions have affected land use in the region over the last several decades and the impact these policies have had on the livelihoods of swiddeners and other smallholders. We also explore whether incentivizing transitions away from swiddening to the cultivation of rubber will directly or reliably produce carbon gains. We argue that because government policies affect how land is used, they also influence carbon emissions, farmer livelihoods, environmental services, and a host of other variables. A deeper and more systematic analysis of the multiple consequences of these policies is consequently necessary for the design of successful REDD+ policies in MMSEA, and other areas of the developing world. REDD+ policies should be structured not so much to ‘hold the forest boundary’ but to influence the types of land-use changes that are occurring so that they support both sustainable livelihoods and environmental services, including (but not limited to) carbon.

Systemic Impact Evaluation: A Methodology for Complex Agricultural Development Projects. The Case of a Contract Farming Project in Guinea

This article presents a mixed-method approach used to analyse the impact of a complex agricultural development project, the SOGUIPAH (Guinean Oil Palms and Rubber Company) project designed to promote oil palm and rubber cultivation in Guinea. At farm level, the combination of a farming system analysis and an economic analysis with a counterfactual scenario enables us to quantify impact on the farmers’ income and to account for related impact heterogeneity. These comparisons reveal a somewhat limited impact of the project as a whole, though with a considerable heterogeneity across the types of farm households it reaches.

CARBON AND NUTRIENT CYCLING THROUGH FINE ROOTS IN RUBBER (HEVEA BRASILIENSIS) PLANTATIONS IN INDIA

SUMMARYUnderstanding the growth dynamics of fine roots and their contribution to soil organic carbon and nutrient pools is crucial for estimating ecosystem carbon and nutrient cycling and how these are influenced by climate change. Rubber is cultivated in more than 10 million hectare globally and the area under rubber cultivation is fast expanding due to socio-economic reasons, apart from the importance given to this species for eco-restoration of degraded lands. An experiment was conducted to quantify fine root production, fine root turnover and carbon and nutrient cycling through fine roots in rubber plantations with different soil nutrient status and rainfall pattern. Fine root production was estimated by sequential coring and ingrowth core methods. Fine root decomposition was determined by the litter bag technique. Carbon and nutrient contents in fine roots were determined and their turnover was computed. Fine root biomass in the top 0–7.5-cm soil layer showed significant seasonal fluctuation and the fluctuations were particularly wide during the transition period from the dry season to the rainy season. Fine root production estimated by the different methods was significantly higher at the lower fertility site and during the higher soil moisture stress year. Fine root turnover ranged from 1.04 to 2.29 year−1. Root carbon and nutrient status showed seasonal variation and lower status was observed during the rainy season. The annual recycling of C, N, P, K, Ca and Mg through fine roots ranged from 590 to 1758, 30 to 85, 3 to 12, 13 to 31, 11 to 35 and 6 to 13 kg ha−1, respectively. Substantial quantities of carbon and nutrients were recycled annually in rubber plantations through fine roots. When soil moisture and nutrient stress were more severe, fine root production, turnover and carbon and nutrient recycling through fine roots were higher.

Cross‐border rubber cultivation between China and Laos: Regionalization by Akha and Tai rubber farmers

This paper is a multi‐sited ethnography of cross‐border rubber cultivation between China and Laos. Smallholder minority rubber farmers from Xishuangbanna (China) have forged successful informal share‐cropping arrangements to grow rubber trees on the land of relatives and friends in neighbouring Laos. By becoming rich and entrepreneurial rural citizens, Akha and Tai farmers have also, in their own eyes, raised their own ‘quality’ (suzhi) and see themselves as ‘modern’. By examining various meanings of ‘modern’ in China, and contrasting the rubber farmers' experience with Jacob Eyferth's notion of rural ‘deskilling’, this paper shows how through learning to plant, cultivate and tap rubber, these farmers have taken on the discipline and technical knowledge of ‘modern’ workers and become ‘skilled’. By rising in ‘quality’, minority farmers on China's periphery challenge the entrenched binaries of urban/rural, modern/backward, prosperous/poor and Han/minority nationality. Xishuangbanna minority farmers acknowledge that they are also ‘backward’ in the Chinese social hierarchy, but their extension of rubber cultivation to kin and others in Laos has confirmed their modernity as dispensers of development, technical know‐how and ‘superior’ Chinese culture to Lao farmers who are ‘backward and poor’. In contrast to large state rubber farms that have failed to establish rubber plantations in northern Laos, minority farmers have created regionalization.

Greenhouse gas emissions and carbon stock changes in rubber tree plantations in Thailand from 1990 to 2004

Abstract Rubber trees provide a variety of raw materials to manufacturing industries. Evaluating the environmental impacts throughout the life cycle of the trees is therefore important. In this study, the carbon stock and greenhouse gas emission profile throughout the complete cropping cycle of rubber plantations was estimated. The amount of biomass carbon stocks per hectare were estimated using a logistic growth model, expressed as 142.47/(1 + 13.31e −0.19 t ), where t is rubber age. Using this model, we found that carbon stocks in rubber tree plantations were continuously increasing until the rubber trees reached an age of 22–25 years. On average, the carbon stock in the 25 years of a rubber tree biomass was about 128.4 t C ha −1 . Although the carbon stock in latex also increased in a similar way to that of rubber trees, it was much less than that in the biomass of the rubber trees. Based on calculations involving Thailand's total rubber planting area (with various ages of rubber trees), the yearly average carbon stock change was the net increase of 1.71 Mt C y −1 . On the other hand the yearly average greenhouse gas emission from cultivation of rubber tree was 0.32 Mt C-e y −1 . Compared to the increment of biomass carbon, the carbon emissions from rubber cultivation activities, mainly from fertilizer and herbicide application, were relatively small.