Spatial patterns in soil biogeochemical process rates along a Louisiana wetland salinity gradient in the Barataria Bay estuarine system, June 2014

We sampled 3 plots (0.25m x 0.25m) at each of four sites along a salinity gradient downstream of the Davis Pond Diversion in the Barataria estuarine system in June 2014. Net soil greenhouse gas (CO2, CH4, N2O) fluxes were quantified for each plot. Live and dead above-ground and below-ground biomass was quantified from each plot except at BT4 where areal extent and average height of Avicennia germinans stand was assessed and stem and pneumatophore density determined. Biogeochemical process rates (greenhouse gas production, nitrification potential, denitrification enzyme activity (DEA), iron reduction, phosphorus sorption) and microbial community abundances were determined and soil properties were characterized for surface (0-5cm) and subsurface (10-15cm) soils at each plot. Additionally, porewater salinity and dissolved inorganic nutrient concentrations were measured.

2014年6月，我们在巴拉塔里亚河口系统（Barataria estuarine system）内戴维斯池塘分流坝（Davis Pond Diversion）下游的盐度梯度沿线的4个采样点中，每个点位布设了3块0.25m×0.25m的样地。对每块样地的土壤温室气体（二氧化碳（CO₂）、甲烷（CH₄）、氧化亚氮（N₂O））净通量进行了定量测定。除BT4样地外，我们对所有样地的地上活体、地上枯落物以及地下生物量开展了定量测定；BT4样地则针对美洲白骨壤（Avicennia germinans）林，调查了其分布面积与平均株高，并测定了茎秆密度与呼吸根密度。我们还测定了各样地表层（0~5cm）与亚表层（10~15cm）土壤的生物地球化学过程速率（涵盖温室气体产生潜力、潜在硝化速率、反硝化酶活性（DEA）、铁还原速率、磷吸附速率）、微生物群落丰度，并完成了土壤属性表征。此外，本研究还测定了孔隙水盐度与溶解态无机养分浓度。