title: Nitrogen cycle of a typical Suaeda salsa marsh ecosystem in the Yellow River estuary.
abstract: The nitrogen (N) biological cycle of the Suaeda salsa marsh ecosystem in the Yellow River estuary was studied during 2008 to 2009. Results showed that soil N had significant seasonal fluctuations and vertical distribution. The N/P ratio (15.73 +/- 1.77) of S. salsa was less than 16, indicating that plant growth was limited by both N and P. The N absorption coefficient of S. salsa was very low (0.007), while the N utilization and cycle coefficients were high (0.824 and 0.331, respectively). The N turnover among compartments of S. salsa marsh showed that N uptake from aboveground parts and roots were 2.539 and 0.622 g/m2, respectively. The N translocation from aboveground parts to roots and from roots to soil were 2.042 and 0.076 g/m2, respectively. The N translocation from aboveground living bodies to litter was 0.497 g/m2, the annual N return from litter to soil was far less than 0.368 g/m2, and the net N mineralization in topsoil during the growing season was 0.033 g/m2. N was an important limiting factor in S. salsa marsh, and the ecosystem was classified as unstable and vulnerable. S. salsa was seemingly well adapted to the low-nutrient status and vulnerable habitat, and the nutrient enrichment due to N import from the Yellow River estuary would be a potential threat to the S. salsa marsh. Excessive nutrient loading might favor invasive species and induce severe long-term degradation of the ecosystem if human intervention measures were not taken. The N quantitative relationships determined in our study might provide a scientific basis for the establishment of effective measures.
authors: Key laboratory of Coastal Environment Processes, CAS, Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China. xjmou@163.com
authors: Xiaojie
authors: X
authors: Mou
authors: Zhigao
authors: Z
authors: Sun
authors: Lingling
authors: L
authors: Wang
authors: Chuanyuan
authors: C
authors: Wang
mesh_terms: D018533:Biomass; D019663:Chenopodiaceae / Q000033:anatomy & histology / Q000737:chemistry* / Q000378:metabolism*; D002681:China; D017753:Ecosystem; D006801:Humans; D009584:Nitrogen / Q000378:metabolism; D058458:Nitrogen Cycle; D045483:Rivers / Q000737:chemistry*; D012621:Seasons; D012987:Soil / Q000737:chemistry*; D053833:Wetlands
chemical_list: D012987:Soil; D009584:Nitrogen