Effect Of Crabs On Soil Properties,Greenhouse Gases Emission And Litter Decomposition In Minjiang River Estuarine Spartina Alternifora Wetland

Zoobenthos as the secondary producers of estuarine ecosystem, are important part of the wetland ecological system, profoundly affects the ecological function of wetland ecosystem. Compared with other aspects of wetland ecosystem research, there are few understanding of the nutrient dynamics and greenhouse gas emission response to zoobenthos in wetland. Therefore, this paper taking Minjiang River estuarine Spartina alterniflora wetland as the study area, the effect of crabs on soil properties, greenhouse gases emission and litter decomposition were determined by the combination of field measurement and laboratory analysis method from November 2014 to September 2015. The main results were as follows:?1? In the high tidal-flat and middle tidal-flat, the averaged values of soil DOC contents were 120.63 and 71.33 mg/kg in crab group, and soil DOC contents were 140.01 and 79.07 mg/kg in the control group. Soil DOC contents of crab group were slightly lower than the control group. In the high tidal-flat and middle tidal-flat, the averaged soil MBC contents were 11.10 and 11.16 mg/kg in the crab group, and soil MBC contents were 8.85 and 6.23 mg/kg in the control group. Soil MBC content of crab group was significantly higher than the control group in the middle tidal-flat ?P<0.05?.?2? In the high tidal-flat and middle tidal-flat, the averaged soil NH₄⁺-N contents were 22.98 and 21.91 mg/kg in the crab group, and soil NH₄⁺-N contents were 24.33 and 22.97 mg/kg in the control group, respectively. Soil NH₄⁺-N contents of crab group were significantly lower than the control group ?P<0.05?. In the high tidal-flat and middle tidal-flat, the averaged soil NO₃^--N contents were 1.54 and 0.61 mg/kg in the crab group, and soil NO₃^--N contents were 2.15 and 0.74 mg/kg in the control group. Soil NO₃^-N contents of crab group were significantly lower than the control group ?P<0.05?.?3? In the high tidal-flat and middle tidal-flat, the averaged soil CO₂ fluxes were 125.15 and 128.40 mg m^-2h^-1 in the crab group, and the averaged soil CO₂ fluxes were 67.11 and 58.84 mg m^-2 h^-1 in the control group, respectively. The soil CO₂ flux of crab group was significantly higher than the control group in spring ?P<0.05?, and there was not significant difference for other seasons ?P>0.05?. In the high tidal-flat and middle tidal-flat, the averaged soil CH₄ fluxes were 0.35 and 0.29 mg m^-2 h^-1 in the crab group, and the averaged soil CH₄ fluxes were 0.10 and -0.11 mg m^-2 h^-1 in the control group, respectively. There was not significant difference of soil CH₄ fluxes in the crab group and control group for the seasons ?P>0.05?. In the high tidal-flat and middle tidal-flat, the averaged soil N₂O fluxes were 165.49 and 27.51 ?g m^-2 h^-1 in the crab group, and the averaged soil N₂O fluxes were 36.68 and 12.15 ?g m^-2 h^-1 in the control group, respectively. There was not significant difference of soil N₂O fluxes in the crab group and control group for the seasons ?P>0.05?.?4? In the high tidal-flat and middle tidal-flat, the decomposition rates of litter were 0.0047d^-1 and 0.0043d^-1, and the time required of 95% litter decomposition were 1.09 a and 1.11 a in crab group. The decomposition rates of litter were 0.0031 d^-1 and 0.0033 d^-1, and the time required of 95% litter decomposition were 1.58 a and 1.43 a in control group. Litter decomposition rate of crab group was slightly higher than the control group ?P>0.05?.