Dissimilatory and Assimilatory Controls on Nitrogen Retention and Loss: Oxygen and Nitrate Dynamics in Tropical Forest Soils

热带森林土壤中氧气和硝酸盐的动态变化在潮湿的热带森林中，充足的降雨、高持水能力的土壤和高代谢活动相结合，可以导致土壤中的氧气被迅速和完全地消耗。这些条件也增加了氮痕量气体损失和淋溶的可能性。在全球范围内，热带森林目前的N2O排放量是最高的，与温带森林相比，热带森林可能会有大量的氮流失到地下水中。尽管有很高的氮素损失潜力，但热带森林植物的生产力通常不受氮素的限制。Silver博士和他的同事建议将田间和实验室实验结合起来，研究波多黎各森林中的氮保留(通过异化硝酸盐还原为铵，以及植物和微生物吸收)和氮损失(通过淋溶和反硝化)。这项研究将有助于我们理解湿润热带森林氮素动态的控制机制，并提高我们预测人为氮沉积和全球变化对氮素循环影响的能力。

Abstract00-89783SilverDissimilatory and assimilatory controls on nitrogen retention and loss: Oxygen and nitrate dynamics in tropical forest soilsIn humid tropical forests, the combination of abundant rainfall, soils with high water-holding capacity, and high metabolic activity can lead to conditions where oxygen is rapidly and completely consumed in the soil. These conditions also increase the potential for nitrogen trace gas loss and leaching. In a global context, tropical forests currently have the highest N2O emissions, and can exhibit large nitrogen losses to groundwater relative to temperate forests. Despite this high potential for nitrogen loss, tropical forest plant productivity is not generally nitrogen limited. Dr. Silver and colleagues propose to combine field and laboratory experiments to study nitrogen retention (via dissimilatory nitrate reduction to ammonium, and plant and microbial uptake) and nitrogen loss (via leaching and denitrification) in forests of Puerto Rico. This research will contribute to our understanding of the mechanisms controlling nitrogen dynamics in humid tropical forests, and improve our ability to predict the effects of anthropogenic nitrogen deposition and global change on nitrogen cycling