Do changes in flood pulse duration disturb soil carbon dioxide emissions in semi-arid floodplains?
Do changes in flood pulse duration disturb soil carbon dioxide emissions in semi-arid floodplains?
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DOI：
10.1007/s10533-010-9472-z
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发表时间：
2010-06
期刊：
影响因子：
4
通讯作者：
R. Sánchez-Andrés;S. Sánchez-Carrillo;M. J. Ortíz-Llorente;M. Álvarez-Cobelas;S. Cirujano
中科院分区：
文献类型：
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作者：
R. Sánchez-Andrés;S. Sánchez-Carrillo;M. J. Ortíz-Llorente;M. Álvarez-Cobelas;S. Cirujano
在半干旱洪泛平原，洪水之间的平均时间被引用来驱动随后洪水脉冲期间的代谢和生物地球化学反应。然而，洪水脉冲持续时间和洪水间隔时间对碳收支的交互作用尚不清楚。通过野外试验，在西班牙中部半干旱洪泛平原模拟了洪水脉冲-干旱循环（SF样地-短洪/干循环：15洪涝天+ 7干旱天+ 15洪水天，LF样地-长洪/干循环：21洪水天+ 14干旱天+ 21洪水天），以研究其对土壤co2排放的影响。试验期SF、LF与对照区土壤含水量差异均有统计学意义（p< 0.01）。干旱期土壤co2排放率与前汛期持续时间和间隔期显著相关（R2= 0.52 ~ 0.64,p= 0.03）。在干燥的第一阶段，高土壤含水量似乎限制了有氧代谢。1 ~ 2周后土壤呼吸速率与对照样地相似。然后，土壤呼吸增加到最大速率，延迟5-8周，因为土壤含水量高限制了微生物的活性。而超过7天的淹没促进了反硝化作用，洪水提供的有机养分使土壤呼吸在干燥期间增加了1%。丰水区与低水区土壤co2排放量的差异仅在连续两次洪干循环后才出现；第二次淹水结束后70 d，各处理co2通量均达到相似值。在整个研究期间（117天），与洪水持续时间和洪水间隔时间无关，土壤co2日排放量具有可比性（SF和LF分别为75.76±1.59和77.94±0.45 mmol co2²−2day−1）。洪水干扰影响特定地点的微生物过程，但只在很短的时间内。为了确定水文变化对半干旱洪泛平原土壤碳平衡的长期影响，需要在未来的研究中重新评估土壤微生物群落应对或适应新条件的机制。
In semi-arid floodplains the average times between floods have been cited to drive metabolic and biogeochemical responses during the subsequent flooding pulse. However, the interaction effects of flood pulse duration and the length of time between floods on the carbon budget are not well understood. Using field experiments, flood pulses—dry cycles were simulated (SF plots—short flood/dry cycles: 15 flood days + 7 dry + 15 flood and LF plots—long flood/dry cycles: 21 flood + 14 dry + 21 flood) in a semi-arid floodplain in Central Spain, in order to study the effects on soil CO2emissions. Differences on soil water content among SF, LF and control plots were statistically significant throughout the experiment (p< 0.01). Soil CO2emission rates during drying time were significantly related with the duration of previous flooding and inter-flooding intervals (R2= 0.52–0.64,p= 0.03). During the first stage of desiccation, the high soil water content appears to limit aerobic metabolism. Soil respiration rates similar to those of control plots measurements occurred 1–2 weeks later. Then, soil respiration increased to a maximum rate which was delayed 5–8 weeks, as high soil water content limited microbial activity. While more than 7 days of inundation promoted denitrification, organic nutrients supplied by flood water increased 1% soil respiration during drying. Differences between SF and LF plots in soil CO2emissions only appeared after floodplain soil had been subjected to two consecutive flood-dry cycles; 70 days after the second inundation ended, CO2fluxes achieved similar values in all treatments. Daily soil CO2emission rates during the entire study period (117 days) were comparable, independently of the flood duration and the time between floods (75.76 ± 1.59 and 77.94 ± 0.45 mmol CO2m−2day−1, in SF and LF, respectively). Flood disturbance affects site-specific microbial processes, but only during very short time periods. The mechanism by which soil microbial communities cope or adapt to new conditions needs to be reassessed in future research in order to determine the long-term effects of hydrological changes in the soil carbon balance of semi-arid floodplains.