Mature Oil Palm Research Articles

Hyperspectral remote sensing for assessment of chlorophyll sufficiency levels in mature oil palm (Elaeis guineensis) based on frond numbers: Analysis of decision tree and random forest

A common practice of chlorophyll (chl) determination has been using the chemical analysis that is destructive and time-consuming. A current prospective alternative method such hyperspectral remote sensing offers a non-destructive measurement of chl which provides a result in the rapid and real-time manner. Therefore, the ultimate aims of this study were to propose the chls (chl a, chl b, total chl content (TCC) and relative chl content (RCC)) sufficiency levels via Jenks Natural Breaks (JNB) classification and recommend the best subset of chl-sensitive wavelengths, frond number and classifier for classifying the chls according to the designated sufficiency levels via hyperspectral remote sensing platform. In order to achieve the objectives, an experiment was conducted on mature Tenera palm stands (12 and 15 years old) with N treatments varied from 0 to 2 kg. The Jenks Natural Breaks (JNB) classification was proposed to determine the chl sufficiency levels. Feature selection was carried out to select the chl-sensitive wavelengths while Decision Tree (DT) and Random Forest (RF) classifiers were used to classify the chl sufficiency levels using the selected wavelengths. Results from this study showed that the chl-sensitive wavelengths mostly belong to the red-edge region and importantly, they were frond age-dependent. Generally, the classification accuracy tended to decrease as frond gets older. The RF performed the best in discriminating the chl sufficiency levels with accuracy ranging from 92.79 to 98.77% compared to 56.30–90.48% achieved by DT. In the nutshell, the execution of frond 9 was more ideal than frond 17 for monitoring chl content of mature oil palm via remote sensing and RF portrayed promising insight in assessing chls content of mature oil palm.

Identifikasi Spesies Tanaman Penutup Tanah pada Perkebunan Kelapa Sawit Menghasilkan

The study aimed to identify the types of plants suitable for cover crops on mature oil palm. The study was started by conducting microclimate measurements and vegetation analysis in a mature oil palm ecosystem with plant subjects consisting of 5 years and 10 years old plants. The measurements and analysis were carried out in August 2018 to select suitable plant samples. The research was continued by planting 6 selected plants under the shade of 0, 25, 50, and 75% using nested design to determine the responses of plant samples to various levels of shading from September 2018 to April 2019 at the Cikaawang IPB Experimental Field. The results of microclimate analysis in 5-year-old mature oil palm in Jonggol shows the light intensity of 1094.7 lux with a temperature of 28.5 oC and humidity of 68.76%, while a 10-year-old mature oil palm in Cikabayan had a light intensity of 997.8 lux with a temperature of 32.5 oC and humidity of 87.25%. The species of Asystasia gangentica, Axonopus compressus, Borreria alata, and Ottochloa nodosa were the dominant plant vegetation in two ecosystems. Asystasia gangentica was able to grow and optimally cover the area at all shading levels, while Axonopus compressus, Borreria alata, and Ottochloa nodosa can only grow and cover the area optimally at 0% and 25% and 50% shade, respectively.
 Keywords: micro climate, response of plant species, vegetation analysis

THE EFFECTIVENESS OF FLUROKSIPIR MHE 480 g/l HERBICIDES AS CONTROLLING Chromolaena odorata (L.) WEEDS ON MATURE OIL PALM

Experiments have been carried out with the objective of knowing Fluroxypyr MHE 480 g/l against weeds Chromolaena odorata L on mature oil palm. Experiments conducted in the oil palm Sagala Herang District of Subang Regency in West Java. The experimental design used was a randomized block design with four replications and seven treatments were then tested further by Duncan test at 95% confidence level. Herbicide treatments were tested , namely herbicides Fluroxypyr MHE 480 g/l dose of 0.75 ml/l - , of 3.0 ml/l, manual weeding and no treatment ( control ). The research results show that the herbicide Fluroxypyr MHE 480 g/l with doses 1.5 ml / l effective and efficient pressing Chromolaena odorata weed growth of up to 12 weeks after application or three months after application. At all doses Herbicide Fluroxypyr MHE 480 g/l up to 3 MSA observations do not show symptoms of poisoning in mature oil palm

Empty Fruit Bunches as Potential Source for Biosilica Fertilizer for Oil Palm

In Indonesia, the development of oil palm plantations has been going on a pervasive way; they covered about 14.03 million hectares in 2017. This massive coverage of land might then generate a tremendous amount of biomass per year, both in the form of both solid and liquid wastes. The processing of fresh fruit bunches (FFB) in palm oil mill (POM) produces wastes that primarily in the form of empty fruit bunches (EFB), which is amounting of up to 25% (w/w) of FFB. It has been being indicated that EFB contains a considerable amount of silica (Si) which attracts the Indonesian Research Institute for Biotechnology and Bioindustry (IRIBB) to investigate the potential use of EFB as a source of bio-available Si, in the form of H4SiO4 (mono silicic acid, BioSilAc). The experiment was carried out at Sungai Mirah Minting Estate, PT Bumitama Gunajaya Agro-Central Kalimantan. The EFB material was obtained from POM and chopped into 2.5-5.0 cm in size. A four-week bio-decomposition process was employed by using bio-decomposers containing Trichoderma pseudokoningii, T. polysporum, and Phanerochaete chrysosporium. Chemical analyses of composted EFB were conducted before and 28-days after decomposer application. The presence of Si in the compost was observed by scanning electron microscopy (SEM). The effect of Si-containing EFB compost on the immature and mature oil palm was evaluated. Seven treatments, i.e. combination of EFB compost and BioSilAc application with reduced-dosages of NPK fertilisers were arranged in a random block design with three replicates. The results show that large quantities of silica bodies attached to the surface of EFB fibres and amounting to 0.44% soluble Si. The FFB data indicated that the application of 75% NPK + 500 kg composted EFB + 2 L BioSilAc/ha/year on a five-year-old plant resulted in higher yield than that obtained from 100% standard dosage of NPK. The study also revealed that the application of EFB compost reduced 50% of BioSilAc dosage.

A Study on Barn Owl Population (Tyto alba var. javanica) in Reducing Rat Attacks and Parthenocarpy in Oil Palm Fresh Fruit Bunches

In mature oil palms, rat attacks fruit bunches, causing significantly reduction in the potential yield and the quality of oil palm fruit bunches. Rat is also known to consume the post anthesis male flowers which act as the breeding sites for the eggs and larvae of Elaeidobius kamerunicus pollinator beetle. Indirectly, the pollinator beetle population can be reduced in high rat infestation area, affecting the pollination and increasing the percentage of parthenocarpic fruit bunches. The barn owl (Tyto alba var. javanica) is a rat biological control agent in the oil palm plantations. The study conducted at PT. Mustika Sembuluh in Central Borneo shows that barn owl (T. alba) population is significantly correlated with both rat attacks and parthenocarpic percentage of oil palm fruit bunches in oil palm plantation

Oil Palm (Elaeis guineensis) Mapping with Details: Smallholder versus Industrial Plantations and their Extent in Riau, Sumatra

Oil palm is rapidly expanding in Southeast Asia and represents one of the major drivers of deforestation in the region. This includes both industrial-scale and smallholder plantations, the management of which entails specific challenges, with either operational scale having its own particular social and environmental challenges. Although, past studies addressed the mapping of oil palm with remote sensing data, none of these studies considered the discrimination between industrial and smallholder plantations and, furthermore, between young and mature oil palm stands. This study assesses the feasibility of mapping oil palm plantations, by typology (industrial versus smallholder) and age (young versus mature), in the largest palm oil producing region of Indonesia (Riau province). The impact of using optical images (Sentinel-2) and radar scenes (Sentinel-1) in a Random Forest classification model was investigated. The classification model was implemented in a cloud computing system to map the oil palm plantations of Riau province. Our results show that the mapping of oil palm plantations by typology and age requires a set of optimal features, derived from optical and radar data, to obtain the best model performance (OA = 90.2% and kappa = 87.2%). These features are texture images that capture contextual information, such as the dense harvesting trail network in industrial plantations. The study also shows that the mapping of mature oil palm trees, without distinction between smallholder and industrial plantations, can be done with high accuracy using only Sentinel-1 data (OA = 93.5% and kappa = 86.9%) because of the characteristic backscatter response of palm-like trees in radar scenes. This means that researchers, certification bodies, and stakeholders can adequately detect mature oil palm stands over large regions without training complex classification models and with Sentinel-1 features as the only predictive variables. The results over Riau province show that smallholders represent 49.9% of total oil palm plantations, which is higher than reported in previous studies. This study is an important step towards a global map of oil palm plantations at different production scales and stand ages that can frequently be updated. Resulting insights would facilitate a more informed debate about optimizing land use for meeting global vegetable oil demands from oil palm and other oil crops.

Short Communication: Analysis of weed vegetation in immature and mature oil palm plantations

Abstract. Satriawan H, Fuady Z. 2019. Analysis of weed vegetation in immature and mature oil palm plantations. Biodiversitas 20: 3292-3298. The species of weeds which grow and dominate in palm oil areas depend on location, local climate, and the light received. This research aimed to determine the diversity of weeds in the planting of palm oil with a different age grown in 2012, 2013, 2014 and 2016. The sample slots measured uniformly at 1 m x 1 m totaling 25 plots. Vegetation analysis was conducted to the density (D), relative density (RD), frequency (F), relative frequency (RF), important value index (IVI), Summed Dominance Ratio (SDR), and Species Diversity Index (H’). Weed composition includes 21 families with 36 species, with the total number of each individual during the year of palm oil planting was 3540, 3148, 3731, and 2910. The relative density value of the highest weeds in the planting year group in 2012 and 2013 were Asystasia intrusa (20.22% and 21.05%), in 2014 were Eleusine indica (23.93%) and 2016 were Cynodon dactylon with 24. 49%. The importance value of weeds in four groups in planting year of oil palm was also in line with the relative density value. These were A. intrusa in 2012 and 2013, amounting to 27.41 and 27.95 and in 2014 and 2016, totaling to 23.72 and 37.64 was E. indica and C. dactylon. The value of the highest species diversity of 6.85 was found in the year 2014, followed by 2012 with 5.88.

Resilience of ecological functions to drought in an oil palm agroecosystem

Oil palm is a major habitat in the tropics. It is highly productive and contributes substantially to the economies of producing countries, but its expansion has caused widespread deforestation, with negative consequences for biodiversity. Such biodiversity losses may have substantial impacts on ecosystem functions within oil palm and resilience of functions to changing rainfall patterns, with impacts on yield. However, although the direct effects of water deficit on yield have been studied, little work has investigated ecosystem processes within plantations or the resilience of functions to changing rainfall. We conducted ecosystem function experiments within mature oil palm at the Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Programme site in Sumatra, Indonesia. We measured rates of leaf litter decomposition, seed removal, mealworm predation, and herbivory at multiple time points spanning the 2015–2016 El Niño - Southern Oscillation (ENSO) event that caused widespread drought within Southeast Asia. We found that mealworm predation, seed removal, and decomposition rates were high, whilst herbivory levels were low, indicating a healthy ecosystem with high levels of pest control and organic matter breakdown. Exclusion tests showed that the presence of invertebrates was associated with higher levels of seed removal and decomposition and the presence of vertebrates with higher predation. All functions were relatively robust to changes in rainfall. Yet, whilst seed removal and herbivory did not alter with rainfall, decomposition and predation showed more complex effects, with levels of both processes increasing with current rainfall levels when rainfall in preceding time periods was low. This suggests that both processes are resilient to change and able to recover following drought. Our results indicate that the ecosystem processes measured within oil palm plantations are healthy and resilient to changing rainfall patterns. This is hopeful and suggests that the crop may be fairly robust to future changes in precipitation.

Soil erosion in disturbed forests and agricultural plantations in tropical undulating terrain: in situ measurement using a laser erosion bridge method

Abstract The rapid growth of agricultural plantations and climatic extremes has raised concerns pertaining to enhanced soil erosion. Soil erosion studies are still relatively limited in Malaysia. In this study, soil erosion in four sites such as high conservation value forests (HCVFs), logged forest (LF), mature oil palm (MOP), and mature rubber (MR) within the Kelantan River Basin was measured. A total of 3,207 measurements were conducted via the Modified Laser Erosion Bridge in all sites over 1 year. Results of soil erosion are 87.63, 25.45, 8.44, and 5.90 t ha−1 yr−1 for the HCVF, LF, MOP and MR, respectively – classified as very severe (HCVF), very high (LF), moderate (MP) and slight (MR) according to the Indian condition classification. Steep slope gradient (significant positive correlation to erosion) and logging are the main factors attributed to the high erosion rates. This is to be further explored in the future and more detailed studies should be conducted on the HCVF and LF areas, respectively. Mitigation measures and sustainable agricultural practices should be planned to control and reduce soil erosion.

CO2 balance on oil palm agrosystem in Sumatra, Indonesia

The high demand and advantage of palm oil as vegetable oil for food and cosmetic products, and more recently for biofuels have led to the development of area dedicated to this crop, especially in South East Asia, and to some extent in South America and in Africa. In South Asia, where the highest production is recorded in Indonesia, the development of oil palm plantations has often been done at the expense of forests, causing changes in the atmospheric carbon dioxide (CO2) balance due to the land use changes and agricultural management practices. Several studies have emphasized the importance of quantifying the oil palm contribution to the global carbon budget. A Long-term spatial and temporal measurement during its 25-30 years of life-cycle is needed to provide an accurate CO2 balance assessment. One of the advanced methods is to directly measure CO2 fluxes across a relatively large area using a micrometeorological approach based on eddy covariance principles. This method can estimate time series of Net Ecosystem CO2 Exchange (NEE), Gross Primary Production (GPP) and ecosystem respiration (Reco) which are useful to assess carbon balance over an oil palm plantation. For that purpose, a flux tower of 25 m height, fully equipped with micrometeorological instruments, has been installed in 2011 in the center of a 90-ha plot of mature palms planted in Riau Province (Sumatra, Indonesia). The average oil palm canopies height was 18 m with an annual average air temperature of 26°C, 80% air humidity and a 2,500 mm average annual precipitation. The atmospheric conditions, seasonal variations and air pollutants such as haze, heavily influenced the CO2 flux measurement. During this 6 year of study, the mature oil palm agro-system acted as a carbon sink that assimilates CO2 from the atmosphere between 36 to 40 t CO2 ha−1 y−1 as NEE. This result was the balance between emission assimilation of 209 t CO2 ha−1 y−1 (GPP) and release back to the atmosphere of between 138 and 173 t CO2 ha−1 y−1 through respiration (Reco). These variations on the CO2 fluxes were mainly caused by seasonal patterns with a significant contribution of wet and dry days.

Understory Vegetation in Oil Palm Plantations Promotes Leopard Cat Activity, but Does Not Affect Rats or Rat Damage

The expansion of oil palm (Elaeis guineensis) plantations is a primary cause of land-use change and biodiversity loss in Southeast Asia. This has led to an increasing demand for the development of more sustainable agricultural management practices in plantations, such as Integrated Pest Management. Although populations of carnivorous mammals show declines when forest is converted to oil palm, some species, such as Leopard Cats (Prionailurus bengalensis) have been found to persist. They are often encouraged by plantation managers for their conservation value, and as agents of pest control to manage rat populations. Despite this, little is known about whether they reduce pest rat numbers, or whether plantation management affects how they use the oil palm habitat. This study was based at the Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Programme in mature oil palm plantations in Riau, Sumatra, where there are three management strategies altering understory vegetation structure. We quantified Leopard Cat activity, invasive rat abundance and rat damage using camera traps, live traps, and visual estimates respectively. We collected data over a four-year period, before and after the management strategies were applied. We recorded three species of wild mammals (Leopard Cats, Common Palm Civets, and Wild Pig) within the plantations, of which Leopard Cats made up 82% of the total number of observations. We found that Leopard Cat habitat use was higher with increased understory vegetation, but that there was no effect of the vegetation treatments on rat abundance or rat damage. There was also a trend for reduced rat abundance with increased Leopard Cat activity. These results show that management practices can significantly affect Leopard Cat habitat use, with potential benefits for pest control. They also highlight the value of large-scale long-term manipulative experiments for developing more sustainable management practices in oil palm.

Effects of Understory Vegetation Management on Plant Communities in Oil Palm Plantations in Sumatra, Indonesia

Oil palm plantations have expanded rapidly in recent decades, and are causing substantial impacts on tropical habitats and biodiversity. However, owing to its long lifespan (25-30 years), oil palm forms a much more varied and structurally-complex habitat than many other crops. This can include abundant understory vegetation and also epiphytes on palm trunks. However, the diversity of this plantation vegetation has been poorly studied, and there has been little consideration of the impacts of common plantation vegetation management practices on plant communities. We conducted a long-term vegetation management experiment that forms part of the Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Programme in Riau, Indonesia. We manipulated herbicide and manual cutting regimes within mature oil palm plantations to create three different understory complexity treatments (Reduced, Normal, and Enhanced vegetation) across replicated sets of plots. Plant communities were surveyed before and after experimental understory vegetation treatments began in three different microhabitats: within the middle of the plantation block (core), on the road edge (edge) and on oil palm trunks (trunk). Part of the sampling was also conducted during a drought event. We recorded 120 plant species, which comprised a mixture of native, non-native, ‘beneficial’, and ‘problem’ species. We found substantial variation in plant communities between edge, core, and trunk microhabitats, indicating high levels of heterogeneity within the plantation. There were significant effects of varying understory treatment within both core and edge microhabitats, but no spillover of impacts into the trunk microhabitat. We also observed substantial impacts of drought on plant communities, with declines in either biomass, percentage cover, or richness seen across core, edge, and trunk microhabitats during low-rainfall periods. Our findings highlight the diversity of plant communities that can be supported within oil palm plantations, and the substantial impacts that management decisions, and also drought, can have on them. Given the role that diverse plant communities can have in supporting species in other groups, this is likely to have a significant impact on the wider plantation biodiversity. We suggest that plantation management strategies give greater consideration to within-plantation understory plant communities and choose more wildlife-friendly options where possible.

KEANEKARAGAMAN SPESIES HERPETOFAUNA PADA BERBAGAI TIPE TUTUPAN LAHAN DI LANSEKAP PERKEBUNAN SAWIT: Studi Kasus di PT. BLP Central Borneo

The expansion of oil palm plantations in Indonesia is often blamed as the drivers of natural resource destruction and decrease the tropical biodiversity. Herpetofauna is one of biodiversity on oil palm plantation, but information about its species diversity is still limited. This research was aims to reveal the variation of diversity of Herpetofauna on oil palm landscape in central Borneo. Field inventory was conducted on seven types of land cover i.e. young oil palm, mature oil palm, old oil palm, High Conservation Value area, secondary forest, shrubs, and smallholder plantation. We used Visual Encounter Method to invent Herpetofauna spesies on all land cover type. This study reveal that the diversity of Herpetofauna species in PT BLP varies by land cover type. The land cover types of HCV and Secondary Forest have the largest number of species (12 species). Secondary Forest is the type of land cover with the highest abundance among other types of land cover, followed by old oil palm plantations. The oil palm plantations lanscape with different type of land cover can be part of the habitat for several Herpetofauna species and managed for sustainable oilpalm scheme.

Isolation and amplification DNA of Elaeis guineensis from Bangun Bandar Plantation, North Sumatra

Elaeis guineensis is the primary commodity that supports the economy of Indonesian country. Lately, several reported diseases of oil palm caused by fungi, have declined in the quality of oil palm plantation also caused the death of several mature oil palm plants. The disease damages roots or tree trunk tissue is known as Basal Stem Rot (BSR). The present study aimed to report explains of the PCR and UV-tex method for detecting Ganoderma in mature palm plants. PCR can detect disease and primer EgMT used to produce various sizes of PCR products. Each sample has different brightness amplification depending on the reaction of the plant to the BSR fungus. The primer is expected to be suitable for detecting Ganoderma fungus in dura, pisifera and tenera oil palm mature plants. The length of the DNA fragment is visible with UV-1D after being irradiated with UV light. DNA amplification ranged from a value of 10,526-114,289 bp. The type of dura plant detected by amplified BSR disease was 34,211-114,289 bp. On the other hand, pisifera is only 21,053 bp and tenera 10,526-104,844 bp.

Effects of Replanting and Retention of Mature Oil Palm Riparian Buffers on Ecosystem Functioning in Oil Palm Plantations

Oil palm plantations are a major agricultural land use in Southeast Asia. In the coming decades large areas of mature oil palm will be cleared and replanted. To inform more sustainable long-term production in this globally important crop, it is crucial we understand how replanting impacts ecosystem functions and services. We investigated whether several production-relevant ecosystems functions (dung removal, soil mesofauna feeding activity, herbivory, herbivore predation, and seed predation), and the simultaneous delivery of all functions (ecosystem multifunctionality), vary between recently-replanted oil palm (1-4 yr) and mature oil palm (23-30 yr) areas. Following new in-country and Roundtable on Sustainable Palm Oil (RSPO) guidelines, riparian buffers of mature oil palm, in which subsequent natural regrowth is allowed, are being preserved during the replanting cycle in plantations that lack natural forest reserves. We investigated whether or not mature oil palm riparian buffers maintain levels of ecosystem functioning beneficial for palm oil production. Only one function (herbivory) differed between mature and replanted areas, with higher levels of herbivory found in recently replanted oil palm. There was no difference in ecosystem multifunctionality between mature and recently-replanted oil palm. Mature oil palm riparian buffers were found to be valuable for maintaining lower levels of herbivory than recently-replanted oil palm. However, no other functions, nor ecosystem multifunctionality, differed between the mature oil palm riparian buffers and recently-replanted oil palm. The results of this study suggest that replanting has limited impacts on the ecosystem functions we considered. Furthermore, they suggest mature oil palm riparian buffers do not have negative impacts on production-relevant ecosystem functions in oil palm landscapes.

GHG emission under different cropping systems in some Histosols of Malaysia

Oil palm is the fastest expanding equatorial crop, and is one of the biggest threats to carbon-rich tropical peatlands in Malaysia. Smallholder plantations cover a vast area of peatlands in Peninsular Malaysia and follow varied cropping systems. Here we analyse the impacts of specific crops and the effects of proximity to such crops, upon GHG emissions from the soil, and the soil microbial community phenotype. We found that only mature oil palm plants in 1st generation oil palm mono-cropping potentially had significant autotrophic contributions to total CO2 emissions with 33.5% increase in locations closer to mature oil palm stems. The sampling locations closer to younger oil palms and other crops did not significantly increase total CO2 emissions. CH4 emissions were significantly greater for sampling locations near plants with adventitious root system such as yam and pineapple crops. However CH4 emissions were very low in comparison to CO2 emissions, and their contribution to carbon loss was limited in these sites. Surface peat microbial community structure was unaffected by proximity to different crops within each cropping system, possibly due to a lack of influence of rhizosphere in the surface peat layers (0–5 cm). The results suggest that most of the total CO2 emissions from these agro-ecosystems contribute to C loss due to microbial decomposition of the peat soil, unlike greater autotrophic contributions to total emissions in forested peatlands reported in other studies. Hence without appropriate above-ground vegetation or hydrology conducive to peat formation, ancient carbon stored in these peatlands is gradually lost into the atmosphere via greater heterotrophic respiration under agricultural management on such peat-based ecosystems.

From peat swamp forest to oil palm plantations: The stability of tropical peatland carbon

Accurate assessment of tropical peatland carbon dynamics is important to (a) determine the size of the active carbon pool, (b) estimate the scale of transfers of peat-derived greenhouse gases (GHGs) to the atmosphere resulting from land use change, and (c) support carbon emissions reduction policies. To date, information on the quality of tropical peatland organic matter and its sensitivity to increases in global temperatures is limited, particularly in the context of land conversion. The aim of this work is therefore to determine peat quality and temperature response of potential GHG emissions under flooded conditions from tropical peatland sites. Whilst reflecting the process of conversion from forest to oil palm plantation. Four land use types that represent the stages of conversion from peat swamp forest to oil palm were chosen: (i) secondary ‘forest’, (ii) recently ‘drained’ but not cleared forest (iii) cleared and recently planted ‘young oil palm’ plantation and (iv) ‘mature oil palm’ plantation. Overall, surface peat carbon was more labile than deeper peats. The largest labile pool was measured at forest sites. In the later stages of land conversion, the labile carbon had been lost and the relative abundance of recalcitrant organic material increased. Potential GHG fluxes were greatest in surface peats compared to deeper peats and declined as labile carbon was depleted following land conversion. Higher temperatures resulted in higher potential GHG emissions at all stages of conversion, but the magnitude of the temperature response depended on organic matter lability. For CO2 fluxes, the temperature response was most pronounced at forest sites. This reflects the greater peat lability at this land use. In contrast, for CH4 emissions, there were increased emissions both at forest and converted land types with higher temperatures. This suggests that increasing temperatures in response to climate warming may drive higher CH4 emissions from sites dominated by degraded organic matter. Collectively, this study demonstrates that during conversion from peat swamp forest to oil palm plantation, the enhanced decomposition and reduced litter input rates is reflected eventually in reduced potential gross CO2 emissions from peat. Nonetheless higher temperature resulting from climate warming may maintain high GHG emissions at plantation sites.

Young and mature oil palm tree detection and counting using convolutional neural network deep learning method

ABSTRACTDetection and counting of oil palm are important in oil palm plantation management. In this article, we use a deep learning approach to predict and count oil palms in satellite imagery. Previous oil palm detections commonly focus on detecting oil palm trees that do not have overlapping crowns. Besides this, there is a lack of research that builds separate detection system for young and mature oil palm, utilizing deep learning approach for oil palm detection and combining geographic information system (GIS) with deep learning approach. This research attempts to fill this gap by utilizing two different convolution neural networks (CNNs) to detect young and mature oil palm separately and uses GIS during data processing and result storage process. The initial architecture developed is based on a CNN called LeNet. The training process reduces loss using adaptive gradient algorithm with a mini batch of size 20 for all the training sets used. Then, we exported prediction results to GIS software and created oil palm prediction map for mature and young oil palm. Based on the proposed method, the overall accuracies for young and mature oil palm are 95.11% and 92.96%, respectively. Overall, the classifier performs well on previously unseen datasets, and is able to accurately detect oil palm from background, including plant shadows and other plants.

Growth and nutrient balance of Asystasia gangetica (L.) T. Anderson as cover crop for mature oil palm (Elaeis guineensis Jacq.) plantations

Nutrient recycling and mineral balance are important factors affecting nutrient budgets in oil palm (Elaeis guineensis Jacq.) plantations. The nutrient budget includes processes such as plant uptake, removal by harvesting, accumulation or storage in the standing plant, and recycling through decomposition of cover crop Asystasia gangetica (L.) T. Anderson can be utilized as cover crops in mature oil palm plantations with appropriate management. This study aimed to examine the growth of A. gangetica in 17 yr old oil palm plantations with different populations, understanding the contribution of A. gangetica to improve available nutrient in the plantation on the nutrient balance, and to study its role as cover crop in the mature oil palm plantation. The experiment was conducted in an experiment field of 17 yr old of mature oil palm at Bogor, Indonesia. Results showed that A. gangetica can be used as cover crops in mature oil palm plantations because it meets several conditions such as rapidly covering the land (11 wk after planting), and able to increase the available N, P, K as much as 18.49%, 9.20%, 38.36%, respectively, based on the nutrient balance with the optimum population is 1 000 000 plants ha-1.

EFEKTIVITAS FLUBENDIAMIDA DALAM PENGENDALIAN ULAT API Setothosea asigna Van Eecke, ULAT KANTUNG Metisa plana Walker, DAN PENGGEREK TANDAN Tirathaba rufivena Walker SERTA PENGARUHNYA TERHADAP AKTIVITAS KUMBANG PENYERBUK Elaeidobius kamerunicus Faust.EFEKTI

Flubendiamida merupakan insektisida baru yang memiliki selektivitas tinggi terhadap serangga dari kelompok Lepidoptera. Penelitian dilakukan untuk melihat pengaruh aplikasi flubendiamida terhadap tingkat mortalitas ulat api S. asigna, ulat kantung M. plana, dan penggerek tandan T. rufivena pada tanaman kelapa sawit menghasilkan. Dampak aplikasi flubendiamida terhadap aktivitas serangga penyerbuk E. kamerunicus juga turut diamati pada penelitian ini. Aplikasi flubendiamida dilakukan secara langsung pada tajuk atau tandan buah yang terserang hama dengan dosis 0, 50, 100, 150, dan 200 mL/ha. Sementara itu, untuk melihat pengaruhnya terhadap kunjungan serangga penyerbuk, flubendiamida diaplikasikan secara langsung pada tandan bunga jantan yang sedang mekar dengan dosis 150 mL. Hasil pengujian menunjukkan bahwa tingkat mortalitas ketiga ulat meningkat seiring dengan pertambahan dosis aplikasi. Flubendiamida pada dosis aplikasi 150-200 mL/ha efektif untuk mengendalikan ulat api dan ulat kantong, sedangkan untuk penggerek tandan pada dosis 200 mL/ha. Aplikasi flubendiamida tidak menyebabkan efek negatif terhadap kunjungan dan perkembangbiakan kumbang E. kamerunicus pada bunga jantan kelapa sawit.