2017 ESA Annual Meeting (August 6 -- 11)

PS 40-120 - Primary productivity of floodplain meadow was determined by elevation rather than soil fertility in seven river estuaries of Poyang Lake

Wednesday, August 9, 2017
Exhibit Hall, Oregon Convention Center
Zhichun Lan1,2, Wei Shi1, Chen Jiakuan2, Yasong Chen3 and Mingyang Wang3, (1)Center for Watershed Ecology, Institute of Life Science and School of Life Science, Nanchang University, Nanchang, China, (2)Coastal Ecosystems Research Station of the Yangtze River Estuary, Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, School of Life Sciences, Fudan University, Shanghai, China, (3)Center for Watershed Ecology, Institute of Life Science and Ministry of Education Key Laboratory of Lake Poyang Environment and Resource Utilization, Nanchang University, Nanchang, China
Background/Question/Methods and Results/Conclusions

Plant growth in riverine wetland is determined by both elevation (or flooding regime) and soil fertility. In recent years, flooding regimes of rivers have been dramatically changed as global changes and dam constructions in upstream. Meanwhile, most river systems now suffer eutrophication as the increasing nutrient inputs from watershed. However, it remains unclear how these changes would affect primary production, especially the relative importance of each factor.

Question

how these changes would affect primary production, especially the relative importance of each factor

Methods and Results

Here, environmental factors and community biomass were determined for the floodplain Carex meadow (the most widespread vegetation in Poyang Lake) in seven estuaries of five main tributary of Poyang Lake. (1) soil nutrient or community biomass significantly differed among different tributaries. (2) community biomass did not correlate with soil nutrient (N, P) content, but negatively correlated with soil pH and positively correlated with elevation, (3) leaf N or P content did not correlated with soil nutrient and community biomass. (4) soil nutrient content did not correlated with nutrient concentration of river water, suggesting that spatial variations of soil fertility was determined by hydrological factors, rather than amount of N and P inputs

Conclusions

Our results demonstrate that flooding regime or the elevation is the predominant factor in determining primary production, while soil fertility is much inferior. Our study suggest that lowering water level in the recent years will increase primary production of floodplain meadow as the elongated growing season, and thus affect the ecosystem functions.