Spatial zoning of microbial functions and plant-soil nitrogen dynamics across a riparian area in an extensively grazed livestock system
Spatial zoning of microbial functions and plant-soil nitrogen dynamics across a riparian area in an extensively grazed livestock system
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DOI：
10.1016/j.soilbio.2018.02.004
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发表时间：
2018-05
影响因子：
9.7
通讯作者：
L. L. Sosa-L.;H. Glanville;M. Marshall;A. P. Williams;Maïder Abadie;I. Clark;A. Blaud;Davey L. Jones
中科院分区：
文献类型：
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作者：
L. L. Sosa-L.;H. Glanville;M. Marshall;A. P. Williams;Maïder Abadie;I. Clark;A. Blaud;Davey L. Jones
人类活动显著改变了全球生物地球化学氮循环，导致淡水富营养化、生物多样性丧失和温室气体排放增加等重大环境问题。陆地和水生生态系统之间的河岸界面中的土壤可以阻止过量的氮进入淡水（例如通过植物吸收、微生物转化和反硝化）。尽管这些过程在集约化管理的农业生态系统中有很好的记录，但我们对半自然系统中河岸氮去除的理解仍然很差。我们的目的是评估一个绵羊放牧的河岸地区土壤微生物群落（PLFA）的空间分区、氮循环基因丰度（古细菌和细菌oa、nifH、nirK、nirS、nosZ）、氮处理速率和植物氮吸收。正如预期的那样，不同河岸样带的土壤性质差异很大，靠近河流的土壤有机质、NH4+、碳(C)和氮含量显著降低（<10 m）。此外，沿样带还发现不同的微生物群落结构。固氮丰度（nifH）随着离河距离的增加而增加（bbb10 m），而氨氧化古菌（AOA）丰度随着离河距离的增加而增加。N2O的排放速率受C的限制，在较小程度上受N的限制，靠近河流的排放较大。植物对尿素来源的氮素的吸收率很高（约占土壤中添加氮素的55-70%），但30-65%的氮素可能因反硝化或淋滤而损失。恢复百分比还表明，植物和微生物氮去除过程的空间格局在河岸带不同。我们的研究为控制半自然河岸生态系统氮循环空间变异性的潜在机制提供了新的见解。
Anthropogenic activities have significantly altered global biogeochemical nitrogen (N) cycling leading to major environmental problems such as freshwater eutrophication, biodiversity loss and enhanced greenhouse gas emissions. The soils in the riparian interface between terrestrial and aquatic ecosystems may prevent excess N from entering freshwaters (e.g. via plant uptake, microbial transformations and denitrification). Although these processes are well documented in intensively managed agroecosystems, our understanding of riparian N removal in semi-natural systems remains poor. Our aim was to assess the spatial zoning of soil microbial communities (PLFA), N cycling gene abundance (archaeal and bacterialamoA,nifH,nirK,nirS,nosZ), N processing rates and plant N uptake across an extensively sheep grazed riparian area. As expected, soil properties differed greatly across the riparian transect, with significant decreases in organic matter, NH4+, carbon (C) and N content closest to the river (<10 m). In addition, different microbial community structures were found along the transect. The abundance of N fixation (nifH) increased with distance from the river (>10 m), while ammonia oxidising archaea (AOA) increased in abundance towards the river. N2O emissions rates were limited by C and to a lesser extent by N with greater emissions close to the river. Plant uptake of urea-derived15N was high (ca. 55–70% of that added to the soil) but 30–65% of the N was potentially lost by denitrification or leaching. Percentage recovered also suggests that the spatial patterning of plant and microbial N removal processes are different across the riparian zone. Our study provides novel insights into the underlying mechanisms controlling the spatial variability of N cycling in semi-natural riparian ecosystems.