Seasonal nitrous oxide emissions from different land uses and their controlling factors in a tropical riparian ecosystem
Seasonal nitrous oxide emissions from different land uses and their controlling factors in a tropical riparian ecosystem
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DOI：
10.1016/j.agee.2012.05.008
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发表时间：
2012-09-01
影响因子：
6.6
通讯作者：
Limsakul, Atsamon
中科院分区：
文献类型：
--
作者：
Kachenchart, Boonlue;Jones, Davey L.;Limsakul, Atsamon
热带河岸生态系统提供的一项重要生态服务是减轻周围农业区的营养物污染（如硝酸盐）。然而，这种营养修复的负面影响可能是生态区也是一氧化二氮（N2 O）的主要排放源。我们假设，高无机氮，有机碳，和土壤水分含量在热带河岸生态系统中，通过快速硝化和反硝化过程增强N2 O的生产。因此，本研究的目的是量化的变化，在这样一个生态系统中，在泰国北方，特别强调（1）不同的土地利用（比较复制豆科植物造林面积与传统的玉米农业高利率的氮肥添加），和（2）时间方面（比较雨季和旱季）。我们的目标是量化N2 O排放，并确定控制这些排放的主要驱动因素。采用原位密闭箱法，豆科再造林区N2 O年平均排放量（3.3 kg N2 O-N ha（-1）y（-1））显著高于种植玉米的农业区（2.2 kg N2 O-N ha（-1）y（-1））。季节变化结果表明，丰水期N2 O通量速率高于枯水期。N2 O排放速率的变化与孔隙水、反硝化作用和微生物生物量碳密切相关，而与硝化作用关系不大。研究表明，在无机氮和土壤有机碳充足的情况下，WFPS对反硝化过程中N2 O的排放具有重要的控制作用。相比之下，热带河岸再造林的N2 O年排放量与温带河岸森林和其他生态系统的报告相似。虽然玉米农业区的N2 O排放量与河岸生态系统中种植的其他作物相当，但其N2 O通量高于非河岸带种植的作物。我们的结论是，位于热带河岸带的农业用地不代表一个主要的热点N2 O排放量，这并没有减少他们提供的生态系统服务的其他方面的积极效益。(C)2012爱思唯尔有限公司版权所有。
An important ecological service provided by tropical riparian ecosystems is the mitigation of nutrient pollution (e.g. nitrate) from surrounding agricultural areas. However, a negative impact of this nutrient remediation may be that the ecozone also functions as a major emitter of nitrous oxide (N2O). We hypothesized that the high inorganic nitrogen, organic carbon, and soil water content in tropical riparian ecosystems enhances N2O production through rapid nitrification and denitrification processes. This study was therefore designed to quantify the variability in N2O emissions in such an ecosystem in northern Thailand with specific emphasis on (1) different land uses (comparing replicate leguminous reforestation areas with conventional maize agriculture with high rates of nitrogen fertilizer addition), and (2) temporal aspects (comparing wet and dry seasons). Our aim was to quantify N2O emissions and to identify the major drivers controlling these emissions. Using in situ closed chambers the annual average emissions of N2O from the leguminous reforestation area (3.3 kg N2O-N ha(-1) y(-1)) was significantly higher than agricultural areas with maize (2.2 kg N2O-N ha(-1) y(-1))). The seasonal variation results indicated that the rate of N2O flux in the wet season was higher than in the dry season. The variations of N2O emission rates were strongly correlated with water filled pore space (WFPS), denitrification, and microbial biomass C, but not with nitrification. This study indicates that when inorganic N and soil organic C are sufficient, WFPS plays an important role in controlling N2O emissions from denitrification. Comparatively, annual N2O emissions from the tropical riparian reforestation were similar to that reported for temperate riparian forests and other ecosystems. Although the annual N2O emissions from the maize agricultural area were comparable to other crops cultivated in riparian ecosystems, it was higher than the N2O fluxes from crops grown in non-riparian zones. We conclude that agricultural lands located in tropical riparian zones do not represent a major hotspot of N2O emissions and that this does not diminish the positive benefits they provide in relation to other aspects of ecosystem service provision. (C) 2012 Elsevier B.V. All rights reserved.