In Southeast Asia, oil palm (OP) plantations have largely replaced tropical forests. The impact of this shift in land use on greenhouse gas (GHG) fluxes remains highly uncertain, mainly due to a relatively small pool of available data. The aim of this study is to quantify differences of nitrous oxide (N₂O) and methane (CH₄) fluxes as well as soil carbon dioxide (CO₂) respiration rates from logged forests, oil palm plantations of different ages, and an adjacent small riparian area. Nitrous oxide fluxes are the focus of this study, as these emissions are expected to increase significantly due to the nitrogen (N) fertilizer application in the plantations. This study was conducted in the SAFE (Stability of Altered Forest Ecosystems) landscape in Malaysian Borneo (Sabah) with measurements every 2 months over a 2-year period. GHG fluxes were measured by static chambers together with key soil physicochemical parameters and microbial biodiversity. At all sites, N₂O fluxes were spatially and temporally highly variable. On average the largest fluxes (incl. 95 % CI) were measured from OP plantations (45.1 (24.0–78.5) µg m⁻² h⁻¹ N₂O-N), slightly smaller fluxes from the riparian area (29.4 (2.8–84.7) µg m⁻² h⁻¹ N₂O-N), and the smallest fluxes from logged forests (16.0 (4.0–36.3) µg m⁻² h⁻¹ N₂O-N). Methane fluxes were generally small (mean ± SD): −2.6 ± 17.2 µg CH₄-C m⁻² h⁻¹ for OP and 1.3 ± 12.6 µg CH₄-C m⁻² h⁻¹ for riparian, with the range of measured CH₄ fluxes being largest in logged forests (2.2 ± 48.3 µg CH₄-C m⁻² h⁻¹). Soil respiration rates were larger from riparian areas (157.7 ± 106 mg m⁻² h⁻¹ CO₂-C) and logged forests (137.4 ± 95 mg m⁻² h⁻¹ CO₂-C) than OP plantations (93.3 ± 70 mg m⁻² h⁻¹ CO₂-C) as a result of larger amounts of decomposing leaf litter. Microbial communities were distinctly different between the different land-use types and sites. Bacterial communities were linked to soil pH, and fungal and eukaryotic communities were linked to land use. Despite measuring a large number of environmental parameters, mixed models could only explain up to 17 % of the variance of measured fluxes for N₂O, 3 % of CH₄, and 25 % of soil respiration. Scaling up measured N₂O fluxes to Sabah using land areas for forest and OP resulted in emissions increasing from 7.6 Mt (95 % confidence interval, −3.0–22.3 Mt) yr⁻¹ in 1973 to 11.4 Mt (0.2–28.6 Mt) yr⁻¹ in 2015 due to the increasing area of forest converted to OP plantations over the last ∼ 40 years.

中文翻译：

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矿物土壤上热带森林和油棕人工林温室气体通量的比较

在东南亚，油棕（OP）种植园已大大取代了热带森林。土地用途的这种变化对温室气体通量的影响仍然高度不确定，这主要是由于可用数据量相对较小。这项研究的目的是量化一氧化二氮（N ₂ O）和甲烷（CH ₄）通量以及土壤二氧化碳（CO ₂）从原木森林，不同年龄的油棕种植园以及邻近的小河岸地区呼吸的速率。一氧化二氮通量是本研究的重点，因为由于人工林中施用了氮肥，这些排放有望显着增加。这项研究是在马来西亚婆罗洲（沙巴州）的SAFE（森林生态系统改变的稳定性）景观中进行的，每2个月进行一次为期2年的测量。温室内的温室气体通量与关键的土壤理化参数和微生物多样性一起被测量。在所有站点，N ₂ O通量在空间和时间上都是高度可变的。平均而言，在OP人工林中测得的最大通量（包括95％CI）（45.1（24.0–78.5）  µ g m ^-2  h^-1  Ñ ₂ O-N）中，从河岸面积稍小通量（29.4（2.8-84.7）  μ克米^-2  ħ ^-1  Ñ ₂ O-N），并从记录的森林的最小通量（16.0（4.0-36.3）  μ克间^{- 2}  h ^-1  N ₂ O-N）。甲烷通量通常很小（平均值 ±  SD）： - OP为2.6  ±  17.2  µg CH ₄ -C m ^-2  h ^-1， CH ₄ -1.3 ±  12.6  µg CH ₄ -C m ^-2  h ^-1对于河岸，在伐木森林中测得的CH ₄通量范围最大（2.2  ±  48.3  µg CH ₄ -C m ^-2  h ^-1）。与沿岸人工林（93.3 ±  70 ）相比，沿岸地区（157.7 ±  106 mg m ^-2  h ^-1  CO ₂ -C）和伐木森林（137.4  ±  95 mg m ^-2  h ^-1  CO ₂ -C）的 土壤呼吸速率更大。 毫克米^-2 小时^-1  CO ₂-C）由于大量分解的枯枝落叶。不同土地利用类型和地点之间的微生物群落明显不同。细菌群落与土壤pH值相关，而真菌和真核生物群落与土地利用相关。尽管测量了大量的环境参数，但是混合模型只能解释N ₂ O，CH _4的3％和土壤呼吸的25％的通量变化的17％。扩大测定Ñ _2个使用陆地地区森林和OPö通量沙巴导致排放从7.6 MT（95％置信区间，增加 - 3.0-22.3万吨）年^-1在1973年至11.4公吨（0.2-28.6万吨）年^-1在2015年，由于森林面积增加转换为OP种植园在过去 〜  40年。