Aiyen Tjoa

Aiyen Tjoa
Universitas Tadulako · Faculty of Agriculture

Doctor of Philosophy

About

72
Publications
23,540
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1,319
Citations

Publications

Publications (72)
Preprint
Effects of oil-palm (Elaeis guineensis Jacq.) management on silicon (Si) cycling under smallholder oil-palm plantations have hardly been investigated. As oil palms are Si accumulators, we hypothesized that management practices and topsoil erosion may cause Si losses and changes in spatial Si concentration patterns in topsoils under oil-palm cultiva...
Article
Full-text available
To secure high yield, tropical oil palm plantations are fertilized, and understory vegetation is controlled by chemical clearing with herbicides. These treatments cause a drastic turnover of soil microbes and cause loss of beneficial mycorrhizal fungi. Here, we tested if reduced fertilization and weeding instead of conventional treatments restored...
Article
Full-text available
The effects of land use and fire on ecosystem silicon (Si) cycling has been largely disregarded so far. We investigated the impacts of land use and fire on Si release from topsoils and litter of lowland rainforest and oil-palm plantations in Jambi Province, Indonesia. Lower concentrations of Si in amorphous silica (ASi) were found in oil-palm plantati...
Article
Full-text available
Mangroves are uniquely important ecosystems, for preserving biodiversity, sustaining livelihoods and mitigating against climate change. However they are degraded globally and are therefore a priority for ecosystem restoration. To date, the assessment of mangrove restoration outcomes is generally poor, and the limited studies that do exist are focus...
Article
Full-text available
Intensive management practices in large-scale oil palm plantations can slow down nutrient cycling and alter other soil functions. Thus, there is a need to reduce management intensity without sacrificing productivity. The aim of our study was to investigate the effect of management practices on gross rates of soil N cycling and soil fertility. In Ja...
Article
Cocoa (Theobroma cacao L.), a major commodity globally, depends on insects for pollination. However, the cocoa pollinator identity is largely unknown and there are important knowledge gaps regarding landscape and farm-level management driving pollinators. Here we analyzed flower visitation with two approaches to quantify how landscape and farm-leve...
Article
Full-text available
The high and relatively unexplored diversity of fungi present in the mangrove ecosystem represents a source of novel biotechnological importance. This study explored the potential of fungi isolated from the mangrove ecosystems to produce proteases and cellulases (commercially important enzymes) and their ability to inhibit pathogenic Vibrio species...
Article
Full-text available
At the oil palm landscape, conserving biodiversity and ecosystem processes can range from continuous adjacent forest remnant to tree patches (agroforestry) maintained within the oil palm landscape on steep slopes and riparian margins. The objective of the research was to analyze patched of tree planting inside monoculture oil palm plantation (agrof...
Article
Full-text available
The efficiency of the water transport system in trees sets physical limits to their productivity and water use. Although the coordination of carbon assimilation and hydraulic functions has long been documented, the mutual inter-relationships between wood anatomy, water use and productivity have not yet been jointly addressed in comprehensive field...
Article
Full-text available
Nutrient leaching in intensively managed oil palm plantations can diminish soil fertility and water quality. There is a need to reduce this environmental footprint without sacrificing yield. In a large-scale oil palm plantation in Acrisol soil, we quantified nutrient leaching using a full factorial experiment with two fertilization rates (260 kg N,...
Article
Increasing demand for cocoa and climate-related yield declines have sparked a multi-stakeholder debate on cocoa production strategies. Agrochemical inputs and pollination enhancement through hand pollination are two strategies to increase yields. Here, we test both strategies with field experiments in Indonesia. We show that even partial hand polli...
Article
The purpose of this study was to evaluate the plant growth performance of top grafted young cacao cultivated in various elevations. This research was conducted from January-August 2019 in South Sulawesi and Central Sulawesi. A total of 54 plants were taken randomly from 6 locations with 3 altitudes (<300, 300-600, >600 meter above sea level, as.)....
Article
Root and soil interactions will alter the biochemical status of the rhizosphere, the acquisition of nutrients and impacted to plant growth. The biochemical of the rhizosphere is strongly influenced by the agriculture input e.g. fertilizer, herbicides and farm management system. Application of fertilizers, their effects are robust and difficult tobe...
Preprint
Full-text available
Nutrient leaching in intensively managed oil palm plantations can diminish soil fertility and water quality. There is a need to reduce this environmental footprint without sacrificing yield. We quantified nutrient leaching in a large-scale oil palm plantation on Acrisol soil with factorial treatment combinations of two fertilization rates (260 N, 5...
Article
Nickel hyperaccumulators are plants that can absorb a large amount of Ni in their tissues. Nickel hyperaccumulators have a strong potential to be used as bioindicators in mineral explorations. Previous studies show that analysis of magnetic susceptibility has a potential to accelerate the screening of Ni hyperaccumulators. In this study, we investi...
Article
Full-text available
Land-use transitions can enhance the livelihoods of smallholder farmers but potential economic-ecological trade-offs remain poorly understood. Here, we present an interdisciplinary study of the environmental, social and economic consequences of land-use transitions in a tropical smallholder landscape on Sumatra, Indonesia. We find widespread biodiv...
Article
Full-text available
The potential of palm-oil biofuels to reduce greenhouse gas (GHG) emissions compared with fossil fuels is increasingly questioned. So far, no measurement-based GHG budgets were available, and plantation age was ignored in Life Cycle Analyses (LCA). Here, we conduct LCA based on measured CO2, CH4 and N2O fluxes in young and mature Indonesian oil pal...
Article
Inclusion of ecosystem-based approaches in the governmental masterplan for tsunami mitigation in Palu, Indonesia may make the city a rare case study for ecological disaster risk reduction in tropical biodiversity hotspots. Such case studies are a key pillar of the United Nations (UN) Sendai Framework to protect coastal societies globally.
Article
Full-text available
Aim Massive biota mixing due to plate‐tectonic movement has shaped the biogeography of Malesia and during the colonization process, Asian plant lineages have presumably been more successful than their Australian counterparts. We aim to gain a deeper understanding of this colonization asymmetry and its underlying mechanisms by analysing how species...
Article
Full-text available
Oil palm plantations are intensively managed agricultural systems that increasingly dominate certain tropical regions. Oil palm monocultures have been criticized because of their reduced biodiversity compared to the forests they historically replaced, and because of their negative impact on soils, water, and climate. We experimentally test whether...
Article
Input such as fertilizer highly affects the root response, and can change the root morphology and architecture, which will have an impact on the nutrient uptake and biomass production. This research investigates changes in root architecture and morphology, nitrogen uptake and biomass production of the Noko rattan seed in the treatment of inorganic...
Poster
Full-text available
Cocoa (Theobroma cacao L.) is a cross-pollinated plant that is dependent on insect pollination. Despite this plant-pollinator dependency and the large economic value of cocoa, there are still important knowledge gaps in the identity of flower visitors, plantation management to enhance their habitats, and overall potential of pollination services to...
Article
Full-text available
The original version of this Article contained an error in the third sentence of the abstract and incorrectly read "Here, using long-term plot monitoring records of up to half a century, we find that intact forests in Borneo gained 0.43 Mg C ha-1 year-1 (95% CI 0.14-0.72, mean period 1988-2010) above-ground live biomass", rather than the correct "H...
Article
Full-text available
Background and Aims To increase yield, cacao is planted increasingly in unshaded monocultures, replacing a more traditional cultivation under shade. We investigated how shade tree cover and species diversity affect the root system and its dynamics. Methods In a replicated study in Sulawesi (Indonesia), we studied the fine and coarse root system do...
Book
Full-text available
This book is based on close and multi-year communication between ecologists and local cacao farmers and can therefore serve as a valuable tool to build a bridge of communications between farmers and scientists about ecosystems, biodiversity and land use strategies. As described in the book, birds and bats can make an economically beneficial contrib...
Article
Full-text available
Less than half of anthropogenic carbon dioxide emissions remain in the atmosphere. While carbon balance models imply large carbon uptake in tropical forests, direct on-the-ground observations are still lacking in Southeast Asia. Here, using long-term plot monitoring records of up to half a century, we find that intact forests in Borneo gained 0.43...
Article
Explaining the diversity and distribution of tree taxa in the isolated tropical mountain forests (TMF) of the Malesian archipelago remains one of the great challenges of tropical biogeographical research. We investigated tree diversity, endemism and community composition in 13 plots of 0.24 ha between 700 and 2400 m in the TMF of Central Sulawesi’s...
Article
Full-text available
Smallholder-dominated agricultural mosaic landscapes are highlighted as model production systems that deliver both economic and ecological goods in tropical agricultural landscapes, but trade-offs underlying current land-use dynamics are poorly known. Here, using the most comprehensive quan-tification of land-use change and associated bundles of ec...
Data
Primer pair sequences for plants, bacteria, and archaea
Data
Supplementary Figures 1 - 9, Supplementary Tables 1 - 5, Supplementary Note 1 and Supplementary References
Article
Full-text available
Tropical lowland rainforests are increasingly threatened by the expansion of agriculture and the extraction of natural resources. In Jambi Province, Indonesia, the interdisciplinary EFForTS project focuses on the ecological and socio-economic dimensions of rainforest conversion to jungle rubber agroforests and monoculture plantations of rubber and...
Article
Full-text available
One of the main drivers of tropical forest loss is their conversion to oil palm, soy or cacao plantations with low biodiversity and greatly reduced carbon storage. Southeast Asian cacao plantations are often established under shade tree cover, but are later converted to non-shaded monocultures to avoid resource competition. We compared three co-occ...
Data
Above- and belowground biomass stocks. Above- and belowground biomass stocks and the shoot:root ratio of the nine study sites of the three cultivation systems in the Kulawi valley (means per plot). Only for the group ‘all’ fine root data is included. (PDF)
Data
Net primary production (NPP). Components of annual net primary production (NPP) (in Mg ha-1 yr-1) of the nine study sites of the three cultivation systems in the Kulawi valley (means per plot). Note that coarse root biomass production includes production of root stocks as well. (PDF)
Data
Above- and belowground carbon stocks. Above- and belowground carbon stocks and the shoot:root carbon ratio of the nine study sites of the three cultivation systems in the Kulawi valley (means per plot). Only for the group ‘all’ fine root data is included. (PDF)
Data
Carbon pools in net primary production (NPP). Associated carbon pools (in Mg C ha-1 yr-1) in annual net primary production (NPP) of the nine study sites of the three cultivation systems in the Kulawi valley (means per plot). Note that coarse root biomass production includes production of root stocks as well. (PDF)
Data
Declaration to copyright of Fig 1. (PDF)
Data
Aboveground stand structural properties. Aboveground stand structural properties of the nine study sites of the three cultivation systems in the Kulawi valley (means per plot). (PDF)
Article
Full-text available
Accumulation of Aluminium (Al) at concentrations far above 1,000 mg kg-1 in aboveground plant tissues of Arbor aluminosa (Symplocos) species is the main reason why traditional Indonesian weavers rely on their leaves and bark as a mordant for dyeing textile. Recently, Symplocos species have become a flagship species for the conservation efforts of w...
Data
The dataset including all elemental concentrations measured with microwave-plasm atomic emission spectrometry (MP-AES) and soil pH values at three montane rainforest sites in Central Sulawesi. (XLSX)
Data
Leaves of Symplocos odoratissima showing signs of herbivory in a montane rainforest at the Dali field site in Central Sulawesi. (TIFF)
Data
Elemental concentrations of different organs and developmental stages of leaves for three Symplocos species from three montane rainforest sites in Central Sulawesi. (DOCX)
Article
Tropical agroforests are diverse systems where several predator groups shape animal communities and plant–arthropod interactions. Ants, birds and bats in particular can reduce herbivore numbers and thereby increase crop yield. However, the relative importance of these groups, whether they interact, and how this interaction is affected by management...
Article
Full-text available
Expansion of palm oil and rubber production, for which global demand is increasing, causes rapid deforestation in Sumatra, Indonesia, and is expected to continue in the next decades. Our study aimed to (1) quantify changes in soil CO2 and CH4 fluxes with land-use change and (2) determine their controlling factors. In Jambi Province, Sumatra, we sel...
Article
Full-text available
Rapid deforestation in Sumatra, Indonesia is presently occurring due to the expansion of palm oil and rubber production, fueled by an increasing global demand. Our study aimed to assess changes in soil-N cycling rates with conversion of forest to oil palm (Elaeis guineensis) and rubber (Hevea brasiliensis) plantations. In Jambi Province, Sumatra, I...
Data
Soil clay contents from 0.5 m down to 2-m depth. (PDF)
Data
Plantation age, tree species and vegetation characteristics. (PDF)
Article
Full-text available
Expansion of palm oil and rubber production, for which global demand is increasing, causes rapid deforestation in Sumatra, Indonesia and is expected to continue in the next decades. Our study aimed to (1) quantify changes in soil CO2 and CH4 fluxes with land-use change, and (2) determine their controlling factors. In Jambi Province, Sumatra, we sel...