Carbon Sequestration and Nutrient Accumulation (N and P) in Two Typical Wetlands in Sanjiang Plain, Northeast China

Estimating carbon sequestration and nutrient accumulation rates are important to understanding wetland's roles on regional or global carbon cycles. The objectives of this study were to estimate accretion rates of carbon and nutrients (nitrogen and phosphorus) by Cs-137 dating technology in typical meadows (Deyeuxia angustifolia wetland) and marshes (Carex lasiocarpa wetland) in Sanjiang Plain, and to reveal the potential factors influencing carbon sequestrations in wetland. Results indicated that soil accretion rates were 4.26 mm yr(-1) in C. lasiocarpa wetland and 2.55 mm yr(-1) in D. angustifolia wetland, respectively. Consequently, carbon sequestration, N and P accumulation rates were 95.95 +/- 22.76 g C yr(-1) 8.23 +/- 2.30 g N yr(-1) m(-2), and 2.04 +/- 0.90 g P yr(-1) m(-2) inD. angustifolia wetland while these rates were 149.47 +/- 39.54 g C yr(-1) m(-2), 13.17 +/- 3.45 g N yr(-1) m(-2) and 1.96 +/- 0.20 g P yr(-1) m(-2) inC. lasiocarpa wetland, respectively. Carbon sequestration and N accumulation rates were higher in marsh than in meadow while P appeared in contradiction. High carbon and nutrient accumulation rates might due to large plant biomass variations and persistent surface water in marsh.. Correlation analysis showed a high significant positive correlation between carbon sequestration rates and ratios of N to P in soil, implying that its comparative low P contents in marsh soils might contribute to high carbon sequestration rates. It is estimated that carbon sequestration potential abilities had decreased by 2.46x10(6)similar to 3.84x10(6) t C per year in 2005 because of the large wetland areas loss