Effects of exotic Spartina alterniflora on saltmarsh nitrogen removal in the Yangtze River Estuary, China
Effects of exotic Spartina alterniflora on saltmarsh nitrogen removal in the Yangtze River Estuary, China
复制标题
外来互花米草对长江口盐沼脱氮的影响
DOI：
10.1016/j.jclepro.2020.122557
复制
发表时间：
2020-10-20
影响因子：
11.1
通讯作者：
Wu, Jihua
中科院分区：
文献类型：
--
作者：
Li, Niu;Li, Bo;Wu, Jihua
盐沼通过反硝化和厌氧氨氧化（anammox）等微生物过程在去除过量氮中发挥着重要作用，而外来物种的入侵是影响盐沼氮净化能力的主要因素之一。以往关于入侵植物对氮素去除影响的研究主要集中在上层土壤，而只有少数研究外来物种对深层土壤氮素去除的影响。因此，在试图对外来物种提供的生态系统服务进行综合评估时，这种差异可能导致评价不具代表性。利用N-15示踪技术，研究了长江口崇明岛4种生境类型（原生植物海三棱藨草（Scirpus mariqueter）、芦苇（Phragmites australis）和入侵植物互花米草（Spartina alterniflora）为主的裸滩涂和沼泽地）沉积物中反硝化和厌氧氨氧化过程. 2018年5月和10月，在土壤剖面内的六个不同深度范围（0-5、5-10、10-20、20-30、30-50和50-100厘米）进行了测量。就整个土壤剖面而言，我们发现S。互花米草与本地植物S. mariqueter和P. australis。然而，S.互花米草显著提高了土壤上层50 cm的氮素去除率，而在深层50-100 cm的土壤中，氮素去除率略有下降。这些结果表明，氮的去除显着增加，只有在上层土壤后S。互花米草入侵，这有助于我们现有的知识，入侵物种对盐沼氮循环的影响。此外，我们确定，在0至50厘米之间的上层土壤中，反硝化作用主要受NO3-和C/N比的调节，而厌氧氨氧化作用主要受堆积密度的调节。相反，在50和100 cm之间的深层土壤中，这两个过程在很大程度上受氧化还原电位和pH值的调节。在盐沼中的互花米草，有必要估计在上层和深层土壤中的氮去除。(C)2020爱思唯尔有限公司版权所有。
Salt marshes play an important role in removing excess nitrogen through microbial processes such as denitrification and anaerobic ammonia oxidation (anammox), and one of the major factors known to influence the nitrogen purification capacity of salt marshes worldwide is the invasion of alien species. Previous studies on the effects of invasive plants on nitrogen removal have tended to focus on the upper soils, whereas only a few have sought to examine the effects of exotic species on nitrogen removal in deep soils. This disparity may thus have led to unrepresentative evaluations when attempting to make integrated assessments of the ecosystem services provided by exotic species. Here, using the N-15 tracer technique, we investigated the processes of denitrification and anammox in sediments of four habitat types (bare mudflat and marshlands dominated by the native plant species Scirpus mariqueter and Phragmites australis and the invasive plant Spartina alterniflora) on Chongming Island, located in the Yangtze River Estuary, China. Measurements were taken in May and October 2018 from six different depth ranges (0-5, 5-10, 10-20, 20-30, 30-50, and 50-100 cm) within the soil profile. With respect to the entire soil profile, we found that S. alterniflora did not facilitate effective nitrogen removal compared with the native plants S. mariqueter and P. australis. However, S. alterniflora did significantly increase nitrogen removal in the upper 50 cm of soil, whereas a slight reduction in nitrogen removal was observed in the deeper 50-100 cm soil layer. These results indicate that nitrogen removal was significantly increased only in the upper soils subsequent to S. alterniflora invasion, which contributes to our existing knowledge regarding the effects of invasive species on the nitrogen cycle in salt marshes. Furthermore, we established that in the upper soil layers between 0 and 50 cm, denitrification is primarily regulated by NO3- and the C/N ratio, whereas anammox is predominantly regulated by bulk density. Contrastingly, in the deeper soil layers between 50 and 100 cm, both these processes are largely regulated by redox potential and pH. These results serve to highlight that when evaluating the ecosystem services provided by S. alterniflora in salt marshes, it is necessary to estimate nitrogen removal in both the upper and deeper soil layers. (C) 2020 Elsevier Ltd. All rights reserved.