Oil Palm Estate Research Articles

Juridical analysis of policy concerning oil palm estate management in Indonesia

The development of the palm oil industry (CPO) in Indonesia is often confronted by challenges coming from the international community, one of which is the rejection of Indonesian CPO exports declared by the European Union on the grounds of deforestation and land clearing, specifically forest burning, that are aimed to convert the forest areas to oil palm estates. In an attempt to clean such a bad name in palm oil industries in the world and to avert the label ‘unsustainable’ given by European Union, President Joko Widodo issued Presidential Instruction Number 8/2018. However, the implementation of the Presidential Instruction is not without hurdles like the absence of specific guidelines to help to implement the policy at the regional level and the lack of opportunities to involve civilians to guard this policy. Juridical analysis of the policy aimed to improve palm oil management and to hamper deforestation is, thus, required. With the normative-juridical method, this research is aimed to recommend the government to grow the potential of CPO-based biofuel in Indonesia and the application of a one-map policy over the potential of oil palm estates to allow the implementation of transparency principle in the structure of good governance. All these recommendations are mainly aimed to give more opportunities to the members of the public to have meaningful participation as well as sustainable and enviro-friendly in improving the management of palm oil cultivation.

Study of life cycle assessment in biodiesel production from crude palm oil and its benefits for the sustainability of oil palm industry in Aceh province Indonesia

LCA is a method used to quantificate impact especially environmental aspect from production of product. The environmental impact that can be calculated by LCA is very diverse, approximately 18 impacts, which called midpoint impact. The most commonly calculated impact is GWP, which is derived from GHG emissions. In Indonesia LCA began to develop and be used by govermnet or industry to calculate impact from their activities especially production of product. One of the industry that use LCA is palm oil industry. Indonesia palm oil is criticsm from both domestic and international level because of the environmental impact and unsustainable. However, production of biodiesel from CPO in Indonesia can reduced emission is 47 % if we compare to diesel fuel. Even though the source of the energy is considered as carbon neutral, the production path can emit various environmentally hazardous gasses. Scientific approach through Life Cycle Assessment can be used as a tool to assess this issue. Number of LCA study on Indonesian biodiesel production come up with different result. This difference could be due to data inconsistency and did not present the actual condition found in the field. According to those aforementioned situations, an effort to address this issue should be conducted by identifying and presenting actual condition of Indonesian palm oil estate. This study is aimed to analyze implementation of life cycle assessment for oil palm industry from oil palm cultivation to biodiesel combustion in vehicle (upstream to downstream) in Indonesia

Analysis of Oil Palm Tree Recognition using Drone-Based Remote Sensing Images

The oil palm tree, or scientifically called as Elaeis guineensis is native to West Africa, where it grows in the wild, transformed into a crop that later was introduced to Malaysian industry. The cultivation of oil palm improved rapidly under the agricultural sector causes degradation, particularly when the oil palm plantation goes uncontrolled. Tree plantation identification is very important for plantation management, environmental management, biodiversity monitoring and many other applications. Accurate inventories and monitoring oil palm estates can be a challenge and critical towards the plantation management and plant area expansion. Managing oil palm estate manually can almost be impossible, so do the tree counting. Manual field-based tree counting is time-consuming and high cost. Conventional method for tree counting can be carried out by manually marked on images or carry out field surveying using GPS to collect the positions of oil palm trees and display their position on image. Developing easier, simpler and cheaper method for tree counting is needed. The aim of this study is to analyse oil palm trees using drone-based remote sensing images. The algorithms used in this research study including Gray-Level Co-occurrence Matrix (GLCM), wavelet transform and template matching. The database of oil palm tree been developed with a total of 131 oil palm trees and 161 of non-oil palm trees have been collected. The window size of oil palm tree been analysed where 250 x 250 pixels which GLCM showed the best overall accuracy of 73.10% for both oil palm and non-oil palm. In this specific window, the oil palm crown can be covered and the result given is more accurate compared to other window sizes. The resulting analysis shows that wavelet transform algorithm gives the highest overall accuracy value which is 82.07%. The other eight statistic parameters can also used to modify the GLCM in order to observe the accuracy and identify which give the best classification accuracy. The availability and ubiquity of drone technologies with high resolution images and regular basis monitoring, new techniques in image and pattern recognition using drone-based remote sensing images let the idea of high accuracy oil palm tree detection become a reality.

Occurrence and Severity of Physiological Disorders of Oil Palm (Elaeis guineensis Jacq. L.) in Uganda

In Africa, oil palm is grown in 25 countries supported by corporate investors. In Uganda, commercial oil palm cultivation began in 2005 in Bugala Islands. Seedlings were imported from countries with established breeding programs. These seedlings were grown in areas with different environmental conditions which have resulted in a number of physiological disorders. The aim of this research was to determine the major physiological disorders in oil palm fruit bunches in Uganda. The study was carried out in the adaptive trials in Kagadi, Bugiri, Buvuma and Masaka Districts and in the different smallholder farmer blocks in Kalangala District. Data was collected on bunch rot, bunch failure and uneven ripening. Sampling was carried out in oil palm plantations above five years of age. Three fields were selected from each unit and three units from each block by the help of the Agricultural Extension Officers (AEOs). Palms were randomly sampled and assessed for presence of bunch rot, bunch failure and uneven ripening symptoms. The incidence was expressed as a percentage of the total number of palms sampled while the severity of bunch rot disease was scored on a scale of 0-4. From the results, the differences in bunch rot and bunch failure in adaptive trials were statistically significant as well as across seasons (P < 0.05). Uneven ripening was not statistically significant and severity of bunch rot in the different farmer blocks in Kalangala was statistically significant (P = 0.03). Uneven ripening was high across smallholder farmer blocks in Kalangala and was statistically significant (P = 0.05) even across seasons (P < 0.05). These results are important for sensitization of farmers on management of oil palm disorders and essential for guiding policy makers and investors as the oil palm industrial sector is being developed in Uganda. This study calls for determination of water deficit at the various ecological zones and its relationship to physiological disorders as a guide for further oil palm estate development.

Implementation of Life Cycle Assessment (LCA) for oil palm industry in Aceh Province, Indonesia

Life Cycle Assessment (LCA) is a holistic environmental accounting procedure which quantifies and evaluates all wastes discharged to the environmental and raw materials consumed throughout the entire life cycle, beginning with sourcing raw materials from the earth through manufacturing and distribution to consumer use and disposal. Currently, environmental consideration becomes the most important issue in application oil palm industry in Indonesia. Scientific approach through LCA can be used as a tool to assess this issue. LCA can be used to ensure that all environmental impacts has been considered for deciding action, calculating environmental impact that might occur, comparing process performance and developing data base for further research. In this regard, LCA can be used as a tool to support decision making on environmental improvement conducted by enterprise or government. Other advantage taken from LCA is that it can be used for in comparing and evaluating products which have similar functions or uses. The target of LCA is to compare the whole environmental damage caused by product or particular activity and then select one option which have the least damage risk. In Indonesian case, the data access that can be used in this LCA study is very limited. Number of LCA study on Indonesian biodiesel production come up with different result. This difference could be due to data inconsistency and did not present the actual condition found in the field. According to those aforementioned situations, an effort to address this issue should be conducted by identifying and presenting actual condition of Indonesian palm oil estate. In this research, LCA will be used to analyze the prospect of oil palm industry in Aceh province Indonesia based on sustainability and environmental impact. This study is aimed to analyze implementation of life cycle assessment for oil palm industry (upstream to downstream) in Aceh Province Indonesia.

The impact of fire in palm oil estate on the bird and butterfly species diversity: case study in RAJ Oil Palm Estate, South Sumatera

RAJ oil palm is one of the oil plantation estates in South Sumatera that experienced land fires in 2018 with the burning estimated around 110 ha, and are believed to have a negative impact reducing on species diversity of birds and butterflies in the area. The study was conducted to identify and analyze the comparison of species diversity of birds and butterflies, loss and gain of the species in burnt and unburnt areas after one year of fire. Data collection was carried out in two types of land cover (grass and gelam) in pairs for burnt and unburnt lands after one year of fire. To inventory, the birds and butterfly species were done at the active time of animals, by using strip transect method, parallel in burnt and unburnt areas with a total of 3 repetitions in each type of land cover. The estimation of the impact was obtained by reckoning the loss and gain of birds and butterfly species from the burnt and unburnt area, the level of species richness, evenness, and similarity. The results showed that the total number of animal species found in both observation lines for each type of land cover (grass and gelam) for unburnt and burnt areas were 29 species of birds and 6 species of butterflies. Generally, it can be stated that the values of H and Dmg for birds were relatively greater in the burnt area compared to in the unburnt area. On the contrary, the values for butterflies were greater in the unburnt area than in the burnt area. The percentage of species loss for the bird was smaller than the gain in the burnt area compared to unburnt land, 24% of species loss and 28% of species gain in the grassland, and 14% of species loss and 33% of species gain in the gelam land. For butterflies, the percentage of species loss was relatively greater than the percentage of species gain due to fire, 67% for the species loss and 33% for the species gain.

Factors Affecting Employee Absenteeism in Oil Palm Estate

Employee absenteeism is one of the problems in oil palm plantation. This behavior leads to low productivity and high burdening business cost. This study aims to examine, analyze and explain the influence of stress, family issues, working environment and salary to employee absenteeism in oil palm estate. The primary data used in this study come from questionnaire on respondents’ stress, family issues, working environment, salary and employee absenteeism. From 90 people as the population, 73 respondents who met the criteria as a sample were chosen by using the Krejcie and Morgan table. The analytical method used is multiple linear regression analysis using SPSS Version 22. The results of this study indicate that there is a positive and significant influence simultaneously between stress, family issues and working environment on employee absenteeism. Family issues has the highest share and proportion 25.8% of the variation in employee absenteeism, so it needs special attention. Performance and productivity for estate workers are very crucial to ensure the estate’s operation runs smoothly. So, estate manager shall pay special attention to engage their workers.

Preface

The International Conference of Biomass and Bioenergy 2019 was successfully conducted by Surfactant and Bioenergy Research Center (SBRC), IPB University in cooperation with International Society of Biomass and Bioenergy (ISBB); Niigata University of International and Information Studies; Universiti Teknologi PETRONAS, Malaysia; Korea Institute of Energy Research, South Korea; College of Engineering, Villanova University, USA; Biomass Project Research Center, Hiroshima University, Japan; and was supported by The Indonesian Oil Palm Estate Fund (BPDP Sawit), PT. Bogor Life Science and Technology IPB, PT. Adev Natural Indonesia, Indonesian Biofuel Producers Association (APROBI), and IPB University, on 19-20 August 2019 in Bogor, Indonesia. This conference with the theme of Biomass and Bioenergy, A Pathway for Sustainable Development Goals was the fourth international scientific conference on biomass and bioenergy in Indonesia. This conference is conducted annually to raise current global issues in biomass and bioenergy fields.The committee accepted 45 of over 54 papers which were presented in the conference and the selected papers are published in this ICBB 2019 proceedings. These papers were classified into the following groups:1. Production Technology of Bioenergy,2. Biomaterial and Biochemical,3. Feedstock, Business, Environment.List of Reviewers of International Conference of Biomass and Bioenergy 2019 are available in this pdf.

Towards Sustainable Oil Palm Plantation Management: Effects of Plantation Age and Soil Parent Material

This study was conducted to generate information required to guide plantation management in relation to replanting on soils derived from different parent materials. Six oil palm estates in coastal lowlands of southwest Cameroon were considered. Oil palm yield data (in t⋅ha−1 of fresh fruit bunch, FFB) and corresponding age of palms (in years after planting, YAP) were obtained for the various estates. In all the estates, average yields were ⋅FFB⋅ha−1 and highly variable. Plantation age, solely, explained between 20% - 58% of the variation in yield. The highest average yields (11.5 t⋅FFB⋅ha−1) were obtained in plantations aged between 9 and 18 YAP and the lowest (4.66 t⋅FFB⋅ha−1) were obtained in old plantations (>23 YAP). Plantations located on volcanic parent materials generally had higher yields compared to those established on sedimentary parent materials. In order to intensify production and increase yields while conserving the environment, one important measure to consider is the replacement of aged palms, and the recommended optimal replanting age in coastal plains of southwest Cameroon should be at most 23 YAP. Estimated mean yields, if aged palms are replanted on time, can increase by 43% - 65%. Additionally, site-specific nutrient management options should be considered in plantation intensification programs.

Moderating the Effects of Company Value’s Determinants of Oil Palm Estate Companies

The goals of this study are to test and obtain the empirical evidences of the impacts of capital structure, firm growth, and profitability on firm value with dividend policy as moderator. This study uses the data from quarterly financial statements, annual reports, sustainability reports, and other reports of oil palm plantation companies listed in the Indonesian Stock Exchange (IDX) in the years of 2009 - 2017. There are only 5 companies from the 16 companies listed that meet the given criteria for the analysis. The research results confirm that the negative and highly significant influence of capital structure on the company value during the instable global economy pointed out by the downward trend sales price of crude palm oil (CPO) can be mitigated to be positive and significant by increasing the dividend payment consistently toward the optimal stage. The weakly significant indirect impact of capital structure on the firm value through the company growth can also be leveraged into significant by implementing the same approach. This approach can also leverage the insignificant impact of company growth on the company value into significant. Taking into account the marginal benefits and costs of using the long term bank loan or bond in financing the company operation becomes more and more decisive as a result of the long investment period. The company growth’s stimulation on the profitability is not responded by the investors and makes the influence of the profitability on the company value negative and highly significant. The company growth and profitability mediate the direct effect of capital structure on the company value weakly significantly and the both function as partial mediation. The company growth does not mediate the direct influence of capital structure on the profitability and the profitability does not mediate the direct effect of company growth on the company value.

Soil and transport factors in potential distribution systems for biofertilisers derived from palm oil mill residues in Malaysia

Oil palm provides an important source of edible oils and fats, accounting for >30% of total global production and >55% of the international trade in these foodstuffs. The palms produce fresh fruit bunches, comprising several hundreds of small fruitlets, which are compressed and steamed to extract the oil. Soil nutrients in oil palm estates become depleted after decades of heavy harvesting and require fertilisers. Liquid palm oil mill effluent, solid empty fruit bunches and other residues can have deleterious environmental impacts and require careful management.The problems of residue disposal and soil nutrient impoverishment can be linked and managed by composting the oil palm mill residues and distributing the biofertiliser produced back to the plantation. Using case studies from West Malaysia we present an early stage practical tool for the planning of the distribution component of such a cycle. The computer-based tool uses multiple field-based and remote sensing data sources to integrate the effects of local soil conditions, transport distances, environmental protection and management priorities and then models customised distribution plans. The tool operates at plantation level and can be augmented with detailed local data, but the approach is extensible and potentially applicable to regional or national planning.

Do oil palm impacts on species richness negatively affect the local livelihoods?

Land use conversion is the leading cause of biodiversity changes, and biodiversity is often used as an indicator of sustainability. A great number of scholars and public, in general, have often associated biodiversity loss, such as species richness, with unsustainable oil palm plantations. Similarly, oil palm expansions were also associated with negative impacts on the local people’s livelihoods. Seldom in discussions on oil palms sustainability, do they take into consideration the perceived biodiversity changes from social points of view. This study seeks to determine the local people’s perceptions of the changes in species richness due to land conversion into oil palm plantations and how they have affected the local livelihoods. Household surveys were conducted using direct observation, literature study, and in-depth structured interview to 373 respondents from various ethnicities including indigenous people in 15 villages around 6 oil palm estates in North Sumatera, Riau, and West Kalimantan, whom were selected based on convenience sampling. Respondents were stratified into indigenous people, migrants, and estate’s workers. A five-point Likert Scale was employed to identify people’s perceptions while recollection technique was used to identify biodiversity loss. Results of the study revealed that there were varied perceptions related to the impacts of oil palms expansions on species richness from social perspectives. The species had different ecological and social values, depended on the benefits that people attach to the species. Although, as many as 16 wildlife and 15 plant species loss were recalled following the plantations’ development, these losses provided little contributions to the current livelihood strategies. The locals appeared to be responsive to better economic opportunities and willingness to shift the livelihood system for improved incomes. These results suggested that species richness might not always be the best indicator of plantation sustainability, as sustainability other than approached from ecology, must also have social and economic dimensions.

Effect of different habitat types on abundance and biting times of Anopheles balabacensis Baisas (Diptera: Culicidae) in Kudat district of Sabah, Malaysia

BackgroundWe investigated the effect of five common habitat types on the diversity and abundance of Anopheles spp. and on the biting rate and time of Anopheles balabacensis (currently the only known vector for Plasmodium knowlesi in Sabah) at Paradason village, Kudat, Sabah. The habitats were forest edge, playground area, longhouse, oil palm plantation and shrub-bushes area. Sampling of Anopheles was done monthly using the human landing catch method in all habitat types for 14 months (October 2013 to December 2014, excluding June 2014). The Anopheles species were morphologically identified and subjected to PCR assay for the detection of Plasmodium parasites. Generalised linear mixed models (GLMM) were applied to test the variation in abundance and biting rates of An. balabacensis in different habitat types.ResultsA total of 1599 Anopheles specimens were collected in the village, of which about 90% were An. balabacensis. Anopheles balabacensis was present throughout the year and was the dominant Anopheles species in all habitat types. The shrub bushes habitat had the highest Anopheles species diversity while forest edge had the greatest number of Anopheles individuals caught. GLMM analysis indicated that An. balabacensis abundance was not affected by the type of habitats, and it was more active during the early and late night compared to predawn and dawn. PCR assay showed that 1.61% of the tested An. balabacensis were positive for malaria parasites, most of which were caught in oil palm estates and infected with one to two Plasmodium species.ConclusionsThe identification of infected vectors in a range of habitats, including agricultural and farming areas, illustrates the potential for humans to be exposed to P. knowlesi outside forested areas. This finding contributes to a growing body of evidence implicating environmental changes due to deforestation, expansion of agricultural and farming areas, and development of human settlements near to forest fringes in the emergence of P. knowlesi in Sabah.

Glyphosate resistance of Eleusine indica populations from North Sumatra, Indonesia

Abstract. Tampubolon K, Purba E, Basyuni M, Hanafiah DS. 2019. Glyphosate resistance of Eleusine indica populations from North Sumatra, Indonesia. Biodiversitas 20: 1910-1916. Controlling of Eleusine indica populations in oil palm plantations using a similar mode of action of herbicide may cause resistant weed. Overall E. indica populations from oil palm plantations in North Sumatra, Indonesia have never been reported to be glyphosate-resistant. This research was aimed to determine the survival percentage and to classify the resistance of E. indica to glyphosate from oil palm plantations in 11 districts in North Sumatra Province. The research was conducted in the Weed Research Center Field Laboratory, Faculty of Agriculture, Universitas Sumatera Utara from October 2016 to August 2017. This research was arranged in a Randomized Block Design with the glyphosate-treatment using a recommended dose of two l ha-1 and three replications. The ESU0 population was collected in the soccer field of Politeknik Negeri Medan (Medan city) was used as a check, and has never been exposed to the herbicide. Parameters were analyzed using one-way ANOVA, and the means were compared using DMRT at a probability level of 5%. The results showed that 276 (65.56%) of 421 populations were classified as glyphosate-resistant, 88 populations (20.90%) were classified as glyphosate-resistant developing, and 57 populations (13.54%) were classified as glyphosate-susceptible. The highest range of dry weight of glyphosate-resistant E. indica populations were found in 5 districts including South Labuhanbatu District followed by the Serdang Bedagai, Simalungun, Asahan, and North Labuhanbatu Districts. The observed resistance level and dry weight range in the present study indicated the failure in controlling E. indica due to continued use of glyphosate and the potency of E. indica distribution into other oil palm estates due to its high biomass production capability.

Territorializing effects of global standards: What is at stake in the case of ‘sustainable’ palm oil?

Global private sustainability standards in agriculture today govern a range of commodities produced in the tropics. Our study analyses the most well-established of these standards, namely the Roundtable on Sustainable Palm Oil (RSPO). We show how, far from being a market device restricted to re-organising global markets in palm oil, RSPO standardisation has wider consequences spatially re-distributing power with territorial effects. Territorialisation occurs through two processes: a strategic and operational process linked to the fabrication and application of procedural rules; a socio-technological process linked to the valorisation of managerial approaches to sustainability. Over time, these twin processes have institutionalised a transnational political space of action with territorial properties. These include: new frontiers of political authority de-bordering national jurisdiction (geographically connecting local scale oil palm estates and plantations with a transversal global supply chain stretching from producing to consuming countries); historical connection; internal coherence and imposition of managerial practices and discourses, including managerial constructions of interdependencies between people, nature and artefacts; prime beneficiaries (large southeast Asian growers, international environmental NGOs and (mainly) European downstream firms); marginalised people (independent smallholders and communities in Malaysia and Indonesia). In this manner, RSPO reinforces its political power and authority over a managerial form of sustainability of palm oil production through territorialising it. Ultimately, this transnational political space of action comes into interaction (and, potentially, conflict) with other political spaces of action and territorial projects as pursued by local people, other NGOs or Malaysian and Indonesian state governments.

An Empirical Study on Infield Collection system in Oil Palm Estate: A Case Study

Shortage of workforce either local or foreign in oil palm plantation especially harvesting is a well-known fact. This investigation compares three different infield FFB collection method namely: [1] manual (wheelbarrow) with harvesting pole, [2] Mini Tractor With Grabber (MTG) with harvesting pole and [3] mini tractor without grabber (MTWG) with SmartCUT (motorized cutter). A field study of this integrated FFB harvesting and evacuation was governed at Sabah oil palm estate. The total area for this case study was 3000 ha with oil palm age about 10 to 14 years. Through this study, the harvester’s productivity (t/manday) means for MTG, MTWG and manual are 1.35, 0.93 and 0.54 mt respectively. The MTG has a higher output per machine and is highly significant compared to MTWG with SmartCUT. The benefit cost ratio (BCR) are RM4.33 for MTG, RM3.24 for MTWG with SmartCUT and RM2.73 for using manual. Nevertheless MTG has the highest BCR, it has to be tested with other cost benefit analysis. From this findings of study, I would recommend MTG as one of the mechanization for infield collection.

Negatives Impact Faced by Oil Palm Estate Management in managing Foreign Workers: A Case Study

This paper investigates the negatives impact of foreign labour on oil palm estates through a case study of Kota Tinggi Johor, a state where foreign labour immigration has played a key role in palm oil growth over the past three decades. Data were collected through a structured interview and survey. The questionnaires were delegated to employer’s representatives in Kota Tinggi Johor who have direct contacts with foreign workers. There were 97 sets of questionnaires completed and analyzed through the structured interviews. The main negative impacts induced by foreign workers are absenteeism, sexual harassment, alcoholism, discipline and criminal. Absenteeism and alcoholism factors showed significance difference towards estate management perspectives (P<0.05). This case study proves that there are still others factors influencing the negative impacts, social factors is not the only reason to affect. It must also being supported with economy and political factors in order to asses and control this challenges.

Riparian reserves help protect forest bird communities in oil palm dominated landscapes

Abstract Conversion of forest to oil palm agriculture is a significant and ongoing threat to tropical biodiversity. Despite this, little is known about the value of riparian reserves in oil palm and how these conservation set‐asides might best be managed to maintain biodiversity. We characterized bird communities of 28 sites in an oil palm‐forest mosaic in Sabah, Malaysia using 6,104 encounters from 840 point counts. Sites included oil palm riparian reserves of various vegetation quality and reserve widths, which were compared to oil palm streams without a riparian reserve as well as riparian and nonriparian control areas in continuous logged forest. Riparian reserves, oil palm waterways, and control sites in riparian and nonriparian forest supported distinct avifaunal communities. Riparian reserve width, forest quality, and amount of forest cover were the strongest predictors of bird species richness. For forest‐dependent species, each of these predictors had a stronger effect size when compared with all species. On average, reserves held 31% of all species and 30% of forest specialists, whereas riparian forest controls averaged 32% of all species, but 38% of forest species. Riparian reserves with &gt;40 m of natural vegetation on each bank supported similar bird diversity to riparian forest control habitats found in continuous forest. However, to support equivalent numbers of forest‐dependent species and species of conservation concern, reserves would need to be at least 100‐m wide on each bank. The largest numbers of species were found in riparian reserves with above‐ground carbon densities exceeding 75 tC/ha, highlighting the importance of forest quality, as well as width, in supporting riparian bird communities. Synthesis and applications. If designed and protected appropriately, riparian reserves in oil palm estates support diverse bird communities, including many species of conservation concern. This can be achieved by designating large reserves (80–200 m total width). But, to maximize species numbers, forest disturbance should also be minimized prior to conversion as well as during plantation operations.

Rainwater Interception Pattern of a Regenerated Secondary Tropical Forest and Oil Palm (Elaeis guineensis Jacq.) Canopies in Bintulu, Sarawak

Regenerated secondary tropical forest that resulted from logging activity and transforming of forest into oil palm (Elaeis guineesis Jacq.) estate are expected to influence the magnitude of rainfall water fraction under these plant canopies. In depth information and knowledge regarding interception pattern of rainwater are still very much lacking, especially under these canopies in tropical region. Thus, the objective of this study was to evaluate the amount of rainwater passing the regenerated secondary tropical forest and oil palm canopies, which currently cover 14.7% of the total land area in Malaysia. Three sampling sites were established, which consisted of a regenerated secondary tropical forest (RSTF), productive oil palm plantation (POP) and non-productive oil palm area (NPOP). The computed throughfall (Tfd) for RSTF, POP and NPOP were 77.2%, 91.1% and 87.4%, respectively. The stemflow (Sfd) was worked out as 0.5% (RSTF), 0.7% (POP) and 0.4% (NPOP) of gross rainfall during the study period. The findings revealed that 22.3%, 8.2% and 12.2% were intercepted by RSTF, POP and NPOP canopies, respectively and evaporated back to the atmosphere. The measured Tfd, Sfd and evaporation (Ei) were different among the three study sites even within the local environment and thus, suggesting the findings to be influenced by 1) canopy structures and trunk morphology; 2) installation of sampling material; 3) species and age of tree or trunk; and 4) local meteorological condition. The study recommends extra caution should be considered during the installation of sampling material, especially for Sfd measurement to avoid leakage and improve the accuracy of Ei values. This is important because the portion of rainwater intercepted by these canopies is a significant component, which is vital for managing forest resources, oil palm estate, as well as catchment area for sustainable clean water resources.Keywords: Interception loss, oil palm, rainfall, regenerated secondary tropical forest, Sarawak

Using Bayesian networks to predict future yield functions with data from commercial oil palm plantations: A proof of concept analysis

Bayesian networks were used to predict yield functions from three commercial oil palm estates. The networks were trained using a range of environmental, agronomic and management data routinely collected during plantation management. The Bayesian networks predicted fruit yield (FFB), average weight of fruit bunches (ABW) and average bunch number per hectare (BUNCH_HA). Comparing the predictions of most probable yield against observed data showed the Bayesian networks were highly accurate, with r2 values between 0.6 and 0.9. Predictions for attaining specific yield targets exceeded 75% accuracy for the FFB, 85% for the BUNCH_HA, and 90% for the ABW function. Supplementary analysis compared the precision of the Bayesian networks with artificial neural networks (ANNs), and demonstrated that the Bayesian networks gave equivalent or superior accuracy for every test. The utility of the networks were demonstrated by predicting the probability of achieving above average yield functions for each block across the three estates using a set of hypothetical rainfall and fertiliser input scenarios during the year prior to harvest. For the majority of blocks, the probability of exceeding the yield target depended on the level of fertiliser and rainfall inputs received, indicating that production from these blocks is greatly influenced by prior rainfall and fertilizer. However, some blocks in favourable areas showed a very high probability of exceeding the mean yields at all rainfall and fertiliser inputs, while a number of other blocks showed a consistently low probability of achieving the same productivity; production from these blocks will be resistant to the effects of historic rainfall and fertiliser inputs. The ability of Bayesian networks to represent future yield expectations will greatly assist managers under pressure to improve the economic and environmental sustainability of plantations. The demonstration that machine learning can extract important insight from complex datasets will have broad application in the analysis of big data collected from oil palm as well as other agricultural industries.