Excessive extraction of groundwater leads to (irreversible) changes in the physical soil properties, causing land subsidence associated with soil compaction to occur. Using a combined image processing and field approach, we examined: (1) how variation in the land subsidence rate induces different soil compaction degrees; and (2) the response patterns of microbial communities to such variations. By using Sentinel Synthetic Aperture Radar image processing, we selected three locations that exhibited different land subsidence rates, including high (HSR), moderate (MSR), and low (LSR). Then, soil sampling was undertaken within these representative locations. Indicators of soil compaction, including total porosity, air-filled porosity, water-filled porosity, and bulk density, were measured. The soil microbial community was determined using qPCR and sequencing. The highest and lowest values for bulk density were observed in the HSR–MSR and LSR zones, respectively. The greatest values of total porosity and macropore volume were displayed in the LSR zone compared to other zones. Bacterial abundance in the LSR zone was significantly greater than that in the HSR and MSR zones. The relative abundances of bacterial taxa indirectly demonstrated that the anaerobic phyla were significantly increased (by 10–13%), and the aerobic phyla decreased (by 30–40%) in the HSR zone compared to the LSR zone. This result demonstrates that the aerobes declined as larger volumes of the soil became more anaerobic. Indeed, the increased abundance of anaerobes was not able to compensate for the larger decrease in the abundance of aerobes. Our work showed that at the increased rates of land subsidence, the abundance distribution of the microbial community critically declined. These findings highlight the critical impacts of increasing the land subsidence rate on the emergence of high soil compaction degrees, which can significantly affect the resilience thresholds of the microbial communities in dryland soils.

中文翻译：

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地下水开采引起的地面沉降速率的变化及其对土壤微生物群落响应模式的影响

过度开采地下水会导致（不可逆转的）土壤物理性质的变化，从而导致与土壤板结相关的土地沉降。使用组合图像处理和现场方法，我们检查了：（1）地面沉降率的变化如何引起不同的土壤压实度；(2) 微生物群落对这种变化的反应模式。通过使用哨兵合成孔径雷达图像处理，我们选择了三个表现出不同地面沉降率的位置，包括高 (HSR)、中 (MSR) 和低 (LSR)。然后，在这些有代表性的地点进行土壤取样。测量了土壤压实的指标，包括总孔隙率、充气孔隙率、充水孔隙率和堆积密度。使用 qPCR 和测序确定土壤微生物群落。体积密度的最高值和最低值分别在 HSR-MSR 和 LSR 区域中观察到。与其他区域相比，LSR 区域显示了总孔隙度和大孔体积的最大值。LSR 区的细菌丰度显着高于 HSR 和 MSR 区。细菌类群的相对丰度间接表明，与 LSR 区相比，HSR 区的厌氧门显着增加（10-13%），而好氧门减少（30-40%）。该结果表明，随着更大体积的土壤变得更加厌氧，需氧菌会下降。事实上，厌氧菌丰度的增加并不能弥补需氧菌丰度的大幅下降。我们的工作表明，随着地面沉降速率的增加，微生物群落的丰度分布急剧下降。这些发现强调了增加土地沉降率对高土壤压实度出现的关键影响，这会显着影响旱地土壤微生物群落的恢复力阈值。