Biomass and nitrogen accumulation and allocation in Suaeda salsa in response to exogenous nitrogen enrichment in the newly created marshes of the Yellow River Estuary, China

We examined the influence of different nitrogen( N) import treatments on organ biomasses and patterns of N accumulation and allocation in Suaeda salsa growing in the high tidal flat marshes of the northern Yellow River Estuary.Although patterns in the seasonal variation of aboveground biomass were unaffected by the different N import treatments,aboveground biomass of S. salsa was generally enhanced( by 19. 71% -62. 29%),in the order N3 N2 N1 N0; moreover,N import treatments prolonged the period of peak growth of S. salsa,and,in the N1,N2,and N3 treatments,attainment of the maximum aboveground biomass was delayed by approximately 20 days compared to that in the N0 treatment. In contrast with aboveground biomass,different N import treatments altered the seasonal variation patterns of belowground biomass,especially plants subjected to the N2 and N3 treatments. Compared to the N1 and N0 treatments,in the N2 and N3 treatments,the greater abundance of belowground biomass in the early growth period was shifted forward by20-50 days. Litter amounts increased slightly during the initial stages,but rapidly in the final stage,in the order of N3 N2 N1 N0. Total nitrogen( TN) concentrations in different organs of S. salsa under different N import treatments generally followed a leaf stem root pattern,indicating that leaves were the key tissues of N accumulation. Although different N import treatments did not alter the patterns of N accumulation and allocation in different organs of S. salsa or the nutrient supply relationships between aboveground and belowground tissues,adaptation to different nutrient conditions was particularly evident in plants in the N2 treatment. This study found that the growth time of S. salsa seeds under N2 treatment conditions was advanced by approximately one month compared to the N0,N1,and N3 treatments,for two probable reasons: first,carbon allocation in S. salsa was significantly affected by N2 import level,and second,S. salsa may have unique adaptation strategies for coping with fluctuating nutrient inputs. In summary,the increasing supply of N in the newly created marshes of the Yellow River Estuary may significantly alter the biomass,growth rate( especially in regard to seed growth time),and N accumulation and allocation in different organs of S. salsa plants growing in this system