Upland forest cover in the Amazon basin has been reduced by land use changes, e.g., the establishment of hydropower plants. Such plants cause permanent flooding and may produce periodic flooding in adjacent upland forests. We determined the short- and long-term effects of artificial flooding on the soil chemistry of upland forests adjacent to the Balbina Hydroelectric Reservoir, Amazonas State, Brazil. We randomized 20 sampling units in upland forests located on the banks of streams adjacent to the hydropower plant. Each sampling unit consisted of two paired forests: one artificial “flooded forest” near the stream and an unflooded “control forest.” We performed soil chemical analyses to determine the pH and total organic C, N, Al3+, and nutrient levels (P, Ca, Mg, and K). In the short term, flooding caused soil acidification, C loss, and increased soil nutrient availability, but this effect did not occur in the long term. In the long term, soil acidity decreased, C loss occurred, and available N cumulatively decreased because of annual flooding after the impoundment of the reservoir. These cumulative N losses, associated with high C emissions, may alter the regional climate and contribute to global climate change.

中文翻译：

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人工洪水改变亚马逊流域水电站附近高地森林的土壤化学和碳动态

亚马逊流域的高地森林覆盖率因土地用途的变化而减少，例如，建立水力发电厂。这些植物会造成永久性洪水，并可能在邻近的高地森林中造成周期性洪水。我们确定了人工洪水对巴西亚马孙州巴尔比纳水库附近高地森林土壤化学的短期和长期影响。我们在位于水电站附近溪流岸边的高地森林中随机抽取了 20 个采样单元。每个采样单元由两对森林组成：靠近溪流的人工“水淹林”和未水淹的“对照林”。我们进行了土壤化学分析，以确定 pH 值和总有机 C、N、Al3+ 和营养水平（P、Ca、Mg 和 K）。短期内，洪水造成土壤酸化，碳流失，和增加土壤养分的有效性，但这种影响不会长期发生。长期来看，水库蓄水后，由于常年泛滥，土壤酸度下降，发生碳流失，有效氮累积减少。这些与高碳排放相关的累积氮损失可能会改变区域气候并导致全球气候变化。