Responses of Carbon Dynamics to Nitrogen Deposition in Typical Freshwater Wetland of Sanjiang Plain

Yang Wang,Jingxin Dou,Longxue He,Hongmei Zhao,Jingshuang Liu

doi:10.1155/2014/603948

Abstract

The effects of nitrogen deposition (N-deposition) on the carbon dynamics in typicalCalamagrostis angustifoliawetland of Sanjiang Plain were studied by a pot-culture experiment during two continuous plant growing seasons. Elevated atmospheric N-deposition caused significant increases in the aboveground net primary production and root biomass; moreover, a preferential partition of carbon to root was also observed. Different soil carbon fractions gained due to elevated N-deposition and their response intensities followed the sequence of labile carbon > dissolved organic carbon > microbial biomass carbon, and the interaction between N-deposition and flooded condition facilitated the release of different carbon fractions. Positive correlations were found between CO2and CH4fluxes and liable carbon contents with N-deposition, and flooded condition also tended to facilitate CH4fluxes and to inhibit the CO2fluxes with N-deposition. The increases in soil carbon fractions occurring in the nitrogen treatments were significantly correlated with increases in root, aboveground parts, total biomass, and their carbon uptake. Our results suggested that N-deposition could enhance the contents of active carbon fractions in soil system and carbon accumulation in plant of the freshwater wetlands.

Highlights

Interest in the impacts of nitrogen deposition (N-deposition) on ecosystem processes has increased in recent years because of the concerns that global change may alter their frequency and intensity [1]
The results showed that the contents of microbial biomass carbon (MBC) and labile carbon (LBC) attained their peaks at the plant heading stage, which were in accordance with the changes of N-deposition effects on CO2 and CH4 fluxes
The increase in aboveground net primary productivity (ANPP) was likely to be driven by higher rates of photosynthesis from the increase of leaf area, while the stimulation of soil active carbon release under N-deposition treatments appeared to be driven by the increase of root biomass allocation, which would constrain the decomposition of inherent organic carbon and enhanced the storage of soil organic carbon

Summary

Introduction

Interest in the impacts of nitrogen deposition (N-deposition) on ecosystem processes has increased in recent years because of the concerns that global change may alter their frequency and intensity [1]. Human activities, such as fossil fuel burning and land conversion, have elevated the atmospheric Ndeposition, which has been shown to impact ecosystem production, diversity, and carbon cycling in consistent ways [2, 3]. Most studies found that N-deposition could stimulate the release of soil active carbon fractions and increase the storage of carbon [6, 7]. The study of active and labile carbon fractions can serve as a clue for soil organic carbon dynamics on a long-term exposure to elevated level of N-deposition

Methods

Results

Discussion

Conclusion