Abstract

Land-use practices can alter shallow groundwater and salinity, further impacting greenhouse gas (GHG) emissions, particularly in the hydrologically dynamic riparian zones of wetlands. Emissions of CO₂, CH₄, and N₂O were estimated in soil cores collected from two prairie pothole region (PPR) sites with three adjacent land-use practices (i.e., annual crop = AC, pasture = PA, and short rotation willow = SRW) and treated with declining water table depths (2 to 26 cm), and salinity (S0 = control, S1 = 6 mS cm⁻¹, and S2 = 12 mS cm⁻¹) in a microcosm experiment. Land-use practices significantly (p < 0.001) affected GHG emissions in soils from both sites in the order of PA > AC = SRW. Compared to the control, emissions of CO₂ and CH₄ were significantly lower under higher salinity treatments (i.e., S1 and S2), while N₂O was significantly higher (p < 0.05). Emissions under declining groundwater table depths were significantly (p < 0.001) variable and specific to each gas, indicating the impacts of shifted soil moisture regime. Overall, the CO₂ and CH₄ emissions increased up to week four and then decreased with declining water table depths, whereas N₂O emission increased up to a maximum at week six. The soils from SRW had considerably lower global warming potential compared to AC and PA. Groundwater salinity in soils from contrasting land-use in the PPR has significant impacts on GHG emissions with potential for crucial climate feedback; however, the magnitude and direction of the impacts depend on hydrology.

Graphic Abstract

中文翻译：

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高盐度和地下水位下降显着影响了草原坑洼地区土地利用方式不同的土壤中的温室气体排放

摘要

土地利用做法可以改变浅层地下水和盐度，进一步影响温室气体 (GHG) 排放，特别是在湿地的水文动态河岸带。CO ₂、CH ₄和 N ₂ O 的排放量在从两个草原坑洼区 (PPR) 地点收集的土壤核心中进行了估计，这些地点具有三个相邻的土地利用实践（即一年生作物 = AC、牧场 = PA 和短轮作柳） = SRW）并在微观实验中用下降的地下水位深度（2 至 26 厘米）和盐度（S0 = 对照，S1 = 6 mS cm ^-1和 S2 = 12 mS cm ^-1）进行处理。土地利用实践显着 ( p < 0.001) 以 PA > AC = SRW 的顺序影响两个地点土壤中的 GHG 排放。与对照相比，高盐度处理（即S1 和S2）下CO ₂和CH _{4 的}排放量显着降低，而N ₂ O 的排放量显着增加（p  < 0.05）。地下水位下降深度下的排放量显着 ( p  < 0.001) 可变且特定于每种气体，表明土壤水分状况变化的影响。总体而言，CO ₂和 CH ₄排放量增加到第 4 周，然后随着地下水位深度的下降而减少，而 N ₂O 排放量在第六周增加到最大值。与 AC 和 PA 相比，来自 SRW 的土壤具有相当低的全球变暖潜力。来自 PPR 中对比土地利用的土壤中地下水盐度对温室气体排放有重大影响，并可能产生关键的气候反馈；然而，影响的大小和方向取决于水文。

图形摘要