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首页> 外文期刊>Plant and Soil >Regulation of nitrogen fixation from free-living organisms in soil and leaf litter of two tropical forests of the Guiana shield
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Regulation of nitrogen fixation from free-living organisms in soil and leaf litter of two tropical forests of the Guiana shield

机译：圭亚那盾牌两种热带森林土壤和叶片灌注器中氮固定的调节

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Background and aims Biological fixation of atmospheric nitrogen (N-2) is the main pathway for introducing N into unmanaged ecosystems. While recent estimates suggest that free-living N fixation (FLNF) accounts for the majority of N fixed in mature tropical forests, the controls governing this process are not completely understood. The aim of this study was to quantify FLNF rates and determine its drivers in two tropical pristine forests of French Guiana. Methods We used the acetylene reduction assay to measure FLNF rates at two sites, in two seasons and along three topographical positions, and used regression analyses to identify which edaphic explanatory variables, including carbon (C), nitrogen (N), phosphorus (P) and molybdenum (Mo) content, pH, water and available N and P, explained most of the variation in FLNF rates. Results Overall, FLNF rates were lower than measured in tropical systems elsewhere. In soils seasonal variability was small and FLNF rates differed among topographies at only one site. Water, P and pH explained 24% of the variation. In leaf litter, FLNF rates differed seasonally, without site or topographical differences. Water, C, N and P explained 46% of the observed variation. We found no regulatory role of Mo at our sites. Conclusions Rates of FLNF were low in primary rainforest on poor soils on the Guiana shield. Water was the most important rate-regulating factor and FLNF increased with increasing P, but decreased with increasing N. Our results support the general assumption that N fixation in tropical lowland forests is limited by P availability.
机译：背景和旨在大气氮（N-2）的生物固定是将n导入非托管生态系统的主要途径。虽然最近的估计表明，自由生活的N固定（FLNF）占大多数N固定在成熟的热带森林中的大部分，管理该过程的控制并不完全理解。本研究的目的是量化FLNF速率，并确定法国圭亚那的两个热带原始森林中的司机。方法采用乙炔还原测定来测量两个位点的FLNF速率，在两个季节和沿三个地形位置，并使用回归分析来确定哪种辅助解释变量，包括碳（C），氮（N），磷（P）和钼（Mo）含量，pH，水和可用N和P，解释了FLNF率的大部分变化。结果总体而言，FLNF率低于其他地方的热带系统中的测量。在土壤中，季节性变异性小，只有一个网站的拓扑率差异不同。水，P和pH解释了24％的变化。在叶子垃圾中，FLNF率差异差异，没有网站或地形差异。水，C，N和P解释了观察到的46％。我们在我们的网站上发现了Mo的监管角色。结论在圭亚那盾牌上的贫困土壤中，FLNF的速率低。水是最重要的速率调节因子，并且使用P增加了FLNF，但随着N的增加而降低。我们的结果支持热带低地森林中N固定的一般假设受到P可用性的限制。

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