ORCID Profile
0000-0002-0130-2401
Current Organisation
NIWA - The National Institute of Water and Atmospheric Research Ltd.
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Publisher: Wiley
Date: 14-07-2023
DOI: 10.1111/GCBB.13088
Abstract: The rapidly growing areal extent of oil palm ( Elaeis guineensis Jacq.) plantations and their high fertilizer input raises concerns about their role as substantial N 2 O sources. In this study, we present the first eddy covariance (EC) measurements of ecosystem‐scale N 2 O fluxes in an oil palm plantation and combine them with vented soil chamber measurements of point‐scale soil N 2 O fluxes. Based on EC measurements during the period August 2017 to April 2019, the studied oil palm plantation in the tropical lowlands of Jambi Province (Sumatra, Indonesia) is a high source of N 2 O, with average emission of 0.32 ± 0.003 g N 2 O‐N m −2 year −1 (149.85 ± 1.40 g CO 2 ‐equivalent m −2 year −1 ). Compared to the EC‐based N 2 O flux, average chamber‐based soil N 2 O fluxes (0.16 ± 0.047 g N 2 O‐N m −2 year −1 , 74.93 ± 23.41 g CO 2 ‐equivalent m −2 year −1 ) are significantly (~49%, p 0.05) lower, suggesting that important N 2 O pathways are not covered by the chamber measurements. Conventional chamber‐based N 2 O emission estimates from oil palm up‐scaled to ecosystem level might therefore be substantially underestimated. We show that the dynamic gas exchange of the oil palm canopy with the atmosphere and the oil palms' response to meteorological and soil conditions may play an important but yet widely unexplored role in the N 2 O budget of oil palm plantations. Diel pattern of N 2 O fluxes showed strong causal relationships with photosynthesis‐related variables, i.e. latent heat flux, incoming photosynthetically active radiation and gross primary productivity during day time, and ecosystem respiration and soil temperature during night time. At longer time scales ( days), soil temperature and water‐filled pore space gained importance on N 2 O flux variation. These results suggest a plant‐mediated N 2 O transport, providing important input for modelling approaches and strategies to mitigate the negative impact of N 2 O emissions from oil palm cultivation through appropriate site selection and management.
Publisher: Copernicus GmbH
Date: 28-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-7375
Abstract: & & Indonesia is one of the hotspots of land transformation from forest ecosystems toward oil palm and other cash-crop monocultures. Land-cover changes directly impact below-canopy microclimate, which are critical drivers for many ecological functions, such as greenhouse gas exchange and soil microbial activity. However, microclimatic variability below canopies, even within the same land-use type can be quite large due to structural heterogeneity, vegetation age or vitality, and differences in management practices.& & & & In this study, we focused on the assessment of microclimatic differences within the most common land-use types in tropical lowland Jambi province (Sumatra, Indonesia), using mini-meteorological stations. We used a rapid assessment approach in which we monitored below-canopy key meteorological parameters at a total of 120 different locations from June to November 2021, covering lowland tropical rainforest, oil palm monoculture, rubber monoculture and agroforestry systems, and fallow shrublands. We clustered the study region into 16 micro-regions, each with a radius of four kilometres. In each micro-region, an open-land area served as a reference meteorological location. Based on the gradients of meteorological parameters between below-canopy and open-land conditions we derived the site-specific impact of the respective land-use type on below-canopy microclimate. To further explore microclimatic characteristics of the different land-use types, we used airborne laserscanning (ALS) data available at a subset of 90 plots as well as information on age, management intensities and ownerships of plantations, distance between plantations and forests, and overall land cover distribution.& & & & Preliminary results show that forests and fallow shrublands are generally cooler, wetter and receive lower below-canopy radiation compared to agricultural systems and open land. Forests show a strong capacity to buffer high levels of open-land air temperature and atmospheric vapour pressure deficit (VPD) variability by, on average, 1.7& #176 C and 6.4 hPa, respectively, while oil palm showed very little buffering capacities (0.2& #176 C and 2.2 hPa). At a regional scale, mixed land-use systems tend to be slightly warmer (+0.36& #177 .18& #176 C) and drier (+1.47& #177 .52 hPa VPD) compared to forest-dominated land-use systems. Within the mixed land-use systems, forests tend to be drier (+1.05& #177 .41 hPa VPD) while below-canopy temperature remains similar (+0.38& #177 .34& #176 C) compared to forests in the forest-dominated land-use systems. Interception is an important component in the hydrology of the studied forest locations, with approx. 66% of precipitation being intercepted, while at fallow shrubland, rubber and oil palm locations, only 24, 25 and 17%, respectively, of precipitation was intercepted. Overall, our preliminary results show that there is high variability in meteorological conditions, even within the same micro-region or land-use type.& &
Publisher: Wiley
Date: 11-02-2022
DOI: 10.1111/GCB.16060
Abstract: Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km
Publisher: Springer Science and Business Media LLC
Date: 27-02-2020
DOI: 10.1038/S41467-020-14852-6
Abstract: 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 CO 2 , CH 4 and N 2 O fluxes in young and mature Indonesian oil palm plantations. CO 2 dominates the on-site GHG budgets. The young plantation is a carbon source (1012 ± 51 gC m −2 yr −1 ), the mature plantation a sink (−754 ± 38 gC m −2 yr −1 ). LCA considering the measured fluxes shows higher GHG emissions for palm-oil biodiesel than traditional LCA assuming carbon neutrality. Plantation rotation-cycle extension and earlier-yielding varieties potentially decrease GHG emissions. Due to the high emissions associated with forest conversion to oil palm, our results indicate that only biodiesel from second rotation-cycle plantations or plantations established on degraded land has the potential for pronounced GHG emission savings.
Publisher: Copernicus GmbH
Date: 31-07-2019
Abstract: Abstract. The El Niño–Southern Oscillation (ENSO) in 2015 was one of the strongest observed in almost 20 years and set the stage for a severe drought and the emergence of widespread fires and related smoke emission over large parts of Southeast Asia. In the tropical lowlands of Sumatra, which were heavily affected by the drought and haze, large areas of tropical rainforest have been converted into oil palm (Elaeis guineensis Jacq.) plantations during the past decades. In this study, we investigate the impact of drought and smoke haze on the net ecosystem CO2 exchange, evapotranspiration, yield and surface energy budget in a commercial oil palm plantation in Jambi province (Sumatra, Indonesia) by using micrometeorological measurements, the eddy covariance method, yield data and a multiple linear regression model (MLRM). With the MLRM we identify the contribution of meteorological and environmental parameters to the net ecosystem CO2 exchange. During the initial part of the drought, when incoming shortwave radiation was elevated, net CO2 uptake increased by 50 % despite a decrease in upper-layer soil moisture by 35 %, an increase in air temperature by 10 % and a tripling of atmospheric vapour pressure deficit. Emerging smoke haze decreased incoming solar radiation by 35 % compared to non-drought conditions and diffuse radiation almost became the sole shortwave radiation flux for 2 months, resulting in a strong decrease in net CO2 uptake by 86 %. Haze conditions resulted in a complete pause of oil palm net carbon accumulation for about 1.5 months and contributed to a decline in oil palm yield by 35 %. With respect to a projected pronounced drying trend over the western Pacific during a future El Niño, our model showed that an increase in drought may stimulate net CO2 uptake, while more severe smoke haze, in combination with drought, can lead to pronounced losses in productivity and net CO2 uptake, highlighting the importance of fire prevention.
Publisher: Copernicus GmbH
Date: 03-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-1777
Abstract: & & The global population growth and changes in human lifestyle and consumption patterns put immense pressure on the limited freshwater resources in the world. Aiming at sustainable use and equitable allocation of the water resources, it becomes crucial to know the water appropriation for the production of different commodities and consumer goods. These days, oil palm (& em& Elaeis guineensis& /em& ) is one of the highest-demanded crops around the globe since the oil of its fruits and kernel is widely used as biofuel and major ingredients in food and cosmetic industries. Given this massive demand, the areas under oil palm cultivation in the tropics have continuously been expanding in the last decades, particularly in Indonesia. With the oil palm boom, not only bio ersity loss, and carbon dioxide emissions from deforestation have been increasing, but also the consumptions of blue and green water resources are of concern.& & & & & In this ongoing research, the concept of water footprint (WF) is employed to quantify the green and blue water use of oil palm production in the Bajubang district, Batanghari regency, Jambi province, Sumatra, Indonesia. This is one of the first studies that uses field-measured data of evapotranspiration (ET) from oil palm plantations in different growth stages over seven years for the purpose of WF assessment, compared to the available literature where ET was estimated using modelling approaches. The multi-year measurements were conducted using the eddy covariance technique, which continuously measures water vapor (H& sub& & /sub& O) fluxes at the ecosystem level over the plantation. Based on these measurements, specifically, the WF assessment is performed on a product basis during the plantation life cycle, per area and time unit, for the oil palm fruit yield and oil palm derived products (palm oil, palm-oil biodiesel). Besides the crop water consumption at the plantation (i.e. ET) as the core element, other water consumptions in the products& #8217 processing chain are included in the WF assessment. Preliminary results indicate a WF of 2440 m& sup& & /sup& t& sup& -1& /sup& for palm oil and 65 m& sup& & /sup& GJ& sup& -1& /sup& for palm-oil biodiesel. This is about 50% lower than the global average estimates. Local WF account of oil palm products has a critical contribution to product transparency while being useful for comparative purposes. Contrasting the WFs of products serving the same function (e.g., palm oil biodiesel, soybean biodiesel) is of essential importance, aiming at conscious product choices in a world of freshwater scarcity.& & & & Keywords: water footprint, oil palm, palm oil, Indonesia, eddy covariance, evapotranspiration& &
Publisher: MDPI AG
Date: 18-03-2021
DOI: 10.3390/F12030359
Abstract: Rainforest conversion to woody croplands impacts the carbon cycle via ecophysiological processes such as photosynthesis and autotrophic respiration. Changes in the carbon cycle associated with land-use change can be estimated through Land Surface Models (LSMs). The accuracy of carbon flux estimation in carbon fluxes associated with land-use change has been attributed to uncertainties in the model parameters affecting photosynthetic activity, which is a function of both carboxylation capacity (Vcmax) and electron transport capacity (Jmax). In order to reduce such uncertainties for common tropical woody crops and trees, in this study we measured Vcmax25 (Vcmax standardized to 25 °C), Jmax25 (Jmax standardized to 25 °C) and light-saturated photosynthetic capacity (Amax) of Elaeis guineensis Jacq. (oil palm), Hevea brasiliensis (rubber tree), and two native tree species, Eusideroxylon zwageri and Alstonia scholaris, in a converted landscape in Jambi province (Sumatra, Indonesia) at smallholder plantations. We considered three plantations a monoculture rubber, a monoculture oil palm, and an agroforestry system (jungle rubber plantation), where rubber trees coexist with some native trees. We performed measurements on leaves at the lower part of the canopy, and used a scaling method based on exponential function to scale up photosynthetic capacity related traits to the top of the canopy. At the lower part of the canopy, we found (i) high Vcmax25 values for H. brasiliensis from monoculture rubber plantation and jungle rubber plantation that was linked to a high area-based leaf nitrogen content, and (ii) low value of Amax for E. guineensis from oil palm plantation that was due to a low value of Vcmax25 and a high value of dark respiration. At the top of the canopy, Amax varied much more than Vcmax25 among different land-use types. We found that photosynthetic capacity declined fastest from the top to the lower part of the canopy in oil palm plantations. We demonstrate that photosynthetic capacity related traits measured at the lower part of the canopy can be successfully scaled up to the top of the canopy. We thus provide helpful new data that can be used to constrain LSMs that simulate land-use change related to rubber and oil palm expansion.
Publisher: MDPI AG
Date: 24-01-2022
DOI: 10.3390/LAND11020183
Abstract: Rubber plantations are an economically viable land-use type that occupies large swathes of land in Southeast Asia that have undergone conversion from native forest to intensive plantation forestry. Such land-use change has a strong impact on carbon, energy, and water fluxes in ecosystems, and uncertainties exist in the modeling of future land-use change impacts on these fluxes due to the scarcity of measured data and poor representation of key biogeochemical processes. In this current modeling effort, we utilized the Community Land Model Version 5 (CLM5) to simulate a rubber plant functional type (PFT) by comparing the baseline parameter values of tropical evergreen PFT and tropical deciduous PFT with a newly developed rubber PFT (focused on the parameterization and modification of phenology and allocation processes) based on site-level observations of a rubber clone in Indonesia. We found that the baseline tropical evergreen and baseline tropical deciduous functions and parameterizations in CLM5 poorly simulate the leaf area index, carbon dynamics, and water fluxes of rubber plantations. The newly developed rubber PFT and parametrizations (CLM-rubber) showed that daylength could be used as a universal trigger for defoliation and refoliation of rubber plantations. CLM-rubber was able to predict seasonal patterns of latex yield reasonably well, despite highly variable tapping periods across Southeast Asia. Further, model comparisons indicated that CLM-rubber can simulate carbon and energy fluxes similar to the existing rubber model simulations available in the literature. Our modeling results indicate that CLM-rubber can be applied in Southeast Asia to examine variations in carbon and water fluxes for rubber plantations and assess how rubber-related land-use changes in the tropics feedback to climate through carbon and water cycling.
Location: New Zealand
No related grants have been discovered for Christian Stiegler.