Muara Enim, Indonesia
Muara Enim, Indonesia

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Mori T.,Kyoto University | Ohta S.,Kyoto University | Ishizuka S.,Japan Forestry and Forest Products Research Institute | Konda R.,Kyoto University | And 3 more authors.
Biology and Fertility of Soils | Year: 2013

An incubation experiment was conducted to examine the effects of phosphorus (P) addition with and without ammonium, nitrate, or glucose on N2O and NO emissions from soil taken under Acacia mangium plantation and incubated at 100 % water-filled pore space (WFPS). Additions of NO3 -stimulated the N2O and NO emissions while NH4 +did not, showing that denitrification was the main process of N2O and NO production in the study condition. When NO3 -was added with P significantly (P < 0. 05) increased N2O emissions regardless of the ratio of the added nitrogen and carbon, suggesting that P addition stimulated denitrification activity. The activation of denitrification by P addition is possibly attributed to two mechanisms: (1) the added-P stimulated denitrification by relieving P shortage for denitrifying bacteria and (2) the added-P stimulated activity of heterotrophic soil microflora with increased O2 consumption promoting the development of anaerobic conditions with stimulation of denitrification. © 2012 Springer-Verlag.

Mori T.,Kyoto University | Ohta S.,Kyoto University | Ishizuka S.,Japan Forestry and Forest Products Research Institute | Konda R.,Kyoto University | And 8 more authors.
Forest Ecology and Management | Year: 2013

A 2-year-long monitoring experiment was conducted to determine the effects of phosphorus (P) addition on nitrous oxide (N2O) emission, methane (CH4) uptake and carbon (C) sequestration and decomposition in a newly established Acacia mangium plantation in South Sumatra, Indonesia. We established three large plots and prepared six control sub-plots and four sub-plots with P added in each large plot. Gas emissions were measured using a chamber method. We also measured selected physical and chemical parameters for soil, fresh leaves, litter layers, and the aboveground biomass of Acacia trees. Mean daily N2O flux was reduced (0.42mgN m-2 day-1) by P addition. The reduction in N2O emissions resulting from P addition was likely to be due to the stimulation of root uptake of soil N and water, as suggested by the soil N and WFPS dynamics and correlations with N2O fluxes. P addition significantly increased (25.6Mgha-1 20months-1) the Acacia biomass, contributing to an increase (46.9Mg CO2-e ha-1) in C sequestration. P addition also stimulated soil C decomposition. Soil total C (TC) decreased significantly (0.14kgCm-2) in the second year of P addition; CO2 emissions from soil were also stimulated (0.29g C m-2 day-1) by P addition. P addition reduced (0.15mgC m-2 day-1) CH4 uptake significantly, although the difference was small. © 2013 Elsevier B.V.

Mori T.,Kyoto University | Ohta S.,Kyoto University | Ishizuka S.,Japan Forestry and Forest Products Research Institute | Konda R.,Kyoto University | And 2 more authors.
Biology and Fertility of Soils | Year: 2014

We examined the effects of phosphorus (P) fertilization on N2O emissions from an Acacia mangium plantation in Indonesia. We focused on the roles of microbial and plant root activities using a trenching method to prepare root-excluded and root-including plots. In root-excluded plots, P application did not change the amount of N2O emissions. By contrast, in root-including plots, P application significantly reduced N2O emissions (from 71.1 ± 20.2 to 19.3 ± 5.1 mg N m-2 106 days-1). Lower total P, Bray-2 P, and Bio-P (microbial P determined by chloroform fumigation extraction method) contents in the soils of root-including plots as compared to root-excluded plots a few days after P application shows that acacia trees absorbed P fertilizer rapidly. This rapid P uptake probably relieved the P limitation of acacia and might have consistently increased root N uptake. This interpretation is supported by lower inorganic N content in P-applied soils (the average of three sampling times is 8.9 and 11.3 μg N g soil-1 in P-applied soils and soils without P application, respectively), which in turn decreased N2O emissions. Our study suggests that P fertilizer suppresses N2O emissions from tropical leguminous forest plantations. © 2013 Springer-Verlag Berlin Heidelberg.

Konda R.,Kyoto University | Ohta S.,Kyoto University | Ishizuka S.,Japan Forestry and Forest Products Research Institute | Heriyanto J.,PT. Musi Hutan Persada | Wicaksono A.,PT. Musi Hutan Persada
Soil Biology and Biochemistry | Year: 2010

We evaluated the spatial structures of nitrous oxide (N2O), carbon dioxide (CO2), and methane (CH4) fluxes in an Acacia mangium plantation stand in Sumatra, Indonesia, in drier (August) and wetter (March) seasons. A 60×100-m plot was established in an A. mangium plantation that included different topographical elements of the upper plateau, lower plateau, upper slope and foot slope. The plot was divided into 10×10-m grids and gas fluxes and soil properties were measured at 77 grid points at 10-m intervals within the plot. Spatial structures of the gas fluxes and soil properties were identified using geostatistical analyses. Averaged N2O and CO2 fluxes in the wetter season (1.85mgNm-2d-1 and 4.29gCm-2d-1, respectively) were significantly higher than those in the drier season (0.55mgNm-2d-1 and 2.73gCm-2d-1, respectively) and averaged CH4 uptake rates in the drier season (-0.62mgCm-2d-1) were higher than those in the wetter season (-0.24mgCm-2d-1). These values of N2O fluxes in A. mangium soils were higher than those reported for natural forest soils in Sumatra, while CO2 and CH4 fluxes were in the range of fluxes reported for natural forest soils. Seasonal differences in these gas fluxes appears to be controlled by soil water content and substrate availability due to differing precipitation and mineralization of litter between seasons. N2O fluxes had strong spatial dependence with a range of about 18m in both the drier and wetter seasons. Topography was associated with the N2O fluxes in the wetter season with higher and lower fluxes on the foot slope and on the upper plateau, respectively, via controlling the anaerobic-aerobic conditions in the soils. In the drier season, however, we could not find obvious topographic influences on the spatial patterns of N2O fluxes and they may have depended on litter amount distribution. CO2 fluxes had no spatial dependence in both seasons, but the topographic influence was significant in the drier season with lowest fluxes on the foot slope, while there was no significant difference between topographic positions in the wetter season. The distributions of litter amount and soil organic matter were possibly associated with CO2 fluxes through their effects on microbial activities and fine root distribution in this A. mangium plantation. © 2010 Elsevier Ltd.

Hagiwara Y.,Kyoto University | Osono T.,Kyoto University | Ohta S.,Kyoto University | Wicaksono A.,P.T. Musi Hutan Persada | Hardjono A.,P.T. Musi Hutan Persada
Journal of Forest Research | Year: 2011

Colonization of leaf litter by ligninolytic fungi and relationships between mass loss and chemical qualities of surface leaf litter were examined in Acacia mangium plantations and adjacent secondary forests in southern Sumatra Island, Indonesia. Leaves were collected from eight A. mangium plantations of different ages and three secondary forests. Partly decomposed leaves beneath the surface leaf litter were used to measure the bleached area which indicated colonization by ligninolytic fungi. Surface leaf litter was used to measure initial chemical content and subjected to the pure culture decomposition test. The bleached area was greater in secondary forests than in A. mangium plantations. Nitrogen content was higher in all the A. mangium plantations than in the secondary forests, and acid unhydrolyzable residue (AUR) content was generally higher in the A. mangium plantations than in the secondary forests. The bleached area of leaf litter was negatively correlated with nitrogen content of surface leaf litter at all sites, indicating an inhibition of the colonization by ligninolytic fungi of leaves with higher nitrogen content. In a pure culture decomposition test inoculating a ligninolytic fungus to surface leaf litter, mass loss of leaves was negatively correlated with AUR content of surface leaf litter. Mass loss of leaves and AUR was not significantly related to nitrogen content. These results suggested that higher nitrogen content in A. mangium leaf litter had a negative effect by colonization of ligninolytic fungi, but the effect of high N in A. mangium leaf litter on the decomposition of leaf litter and AUR remained unsolved. © 2011 The Japanese Forest Society and Springer.

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