Global warming is accompanied by increasing water stress across much of our planet. We studied soil biological processes and changes in soil organic carbon (SOC) storage in 30 Hungarian oak forest sites in the Carpathian Basin along a climatic gradient (mean annual temperature (MAT) 9.6–12.1 °C, mean annual precipitation (MAP) 545–725 mm) but on similar gently sloped hillsides where the parent materials are loess and weathered dust inputs dating from the end of the ice age. The purpose of this research was to understand how a drying climate, predicted for this region, might regulate long-term SOC sequestration. To examine the effects of decreasing water availability, we compared soil parameters and processes in three categories of forest that represented the moisture extremes along our gradient and that were defined using a broken-stick regression model. Soil biological activity was significantly lower in the driest (“dry”) forests, which had more than double the SOC concentration in the upper 30 cm layer (3.28 g C/100 g soil ± 0.11 SE) compared to soils of the wettest (“humid”) forests (1.32 g C/100 g soil ± 0.09 SE), despite the fact that annual surface litter production in humid forests was ~ 37% higher than in dry forests. A two-pool SOM model constrained to fit radiocarbon data indicates that turnover times for fast and slow pools are about half as long in the humid soil compared to the dry soil, and humid soils transfer C twice as efficiently from fast to slow pools. Enzyme activity and fungal biomass data also imply shorter turnover times associated with faster degradation processes in the soils of humid forests. Thermogravimetry studies suggest that more chemically recalcitrant compounds are accumulating in the soils of dry forests. Taken together, our results suggest that the predicted climate drying in this region might increase SOC storage in Central European mesic deciduous forests even as litter production decreases.

中文翻译：

---

更干燥的气候将如何改变中欧落叶林土壤中的碳固存？

全球变暖伴随着地球上大部分地区的水资源压力增加。我们研究了喀尔巴阡盆地 30 个匈牙利橡树林地的土壤生物过程和土壤有机碳 (SOC) 储存的变化，沿气候梯度（年平均气温 (MAT) 9.6–12.1 °C，年平均降水量 (MAP) 545– 725 毫米），但在类似的缓坡山坡上，其母质是黄土和可追溯到冰河时代末期的风化灰尘输入。这项研究的目的是了解为该地区预测的干燥气候如何调节长期的 SOC 封存。为了检查可用水量减少的影响，我们比较了三类森林中的土壤参数和过程，这些森林代表了我们梯度上的水分极端值，并使用断棒回归模型定义。最干燥（“干燥”）森林的土壤生物活性显着较低，与最湿润的土壤相比，上层 30 cm 层（3.28 g C/100 g 土壤 ± 0.11 SE）的 SOC 浓度高出两倍多（“潮湿”）森林（1.32 g C/100 g 土壤 ± 0.09 SE），尽管潮湿森林的年地表凋落物产量比干燥森林高约 37%。受约束以拟合放射性碳数据的双池 SOM 模型表明，与干燥土壤相比，潮湿土壤中快池和慢池的周转时间大约是干燥土壤的一半，并且潮湿土壤从快池到慢池的 C 转移效率是其两倍。酶活性和真菌生物量数据也意味着更短的周转时间与潮湿森林土壤中更快的降解过程相关。热重分析表明，更多的化学顽固化合物正在干旱森林的土壤中积累。综上所述，我们的结果表明，即使凋落物产量下降，该地区预测的气候干燥也可能会增加中欧中叶落叶林的 SOC 储存量。