Effects of drying-rewetting frequency on soil carbon and nitrogen transformations
Effects of drying-rewetting frequency on soil carbon and nitrogen transformations
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DOI：
10.1016/s0038-0717(02)00007-x
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发表时间：
2002-06-01
影响因子：
9.7
通讯作者：
Schimel, JP
中科院分区：
文献类型：
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作者：
Fierer, N;Schimel, JP
土壤干燥和复湿对土壤微生物群落造成了显著的压力。尽管湿润事件在大多数环境中都很常见，但土壤再湿化对微生物过程的短期和长期影响还没有得到很好的研究。此外，尚不清楚在对生态系统动态的微生物控制进行建模时，应激史是否重要。在这项实验中，我们操纵了2个月内土壤复湿事件的频率，以确定胁迫历史如何影响土壤微生物群落对复湿事件的响应。从加利福尼亚州圣伊内斯的塞奇威克牧场自然保护区采集了两种土壤，一种来自一年生草地，另一种来自橡树树冠下。土壤在实验室中培养，在2个月的时间里经历了0、1、2、4、6、9或15个干燥-再湿循环。调整土壤水分含量，使所有样品在培养过程中的平均水分含量相同，以补偿干燥-再湿循环的次数。对土壤的呼吸速率、基质利用效率、硝化潜力、微生物生物量以及NH4+和NO3-浓度进行了分析。在培养过程中，橡树土的总CO2损失量随着再湿事件次数的增加而显著增加，而对于草地土壤则不显著，因为大量的再湿事件会减少总的二氧化碳损失量。暴露在频繁的干燥-复湿事件中，减少了复湿时释放的二氧化碳，并显着增加了自养硝化细菌的活性。在最后一次干湿循环后长达6周的时间里，暴露于干湿事件历史中的土壤的呼吸速率显著低于非胁迫对照。在所有情况下，再湿应力在橡树土中的影响比在草地土壤中的影响更大。结果表明，干湿事件可以引起微生物C、N动态的显著变化，这些影响可以在最后一次胁迫后持续一个月以上。干湿胁迫事件的频率具有重要的生态系统水平的影响，应纳入土壤微生物动力学模型。(C)2002爱思唯尔科学有限公司。保留所有权利。
Soil drying and rewetting impose a significant stress on the soil microbial community. While wetting events are common in most environments, the short and long-term effects of soil rewetting on microbial processes have not been well studied. Furthermore, it is not clear if stress history is important to consider when modeling microbial controls on ecosystem dynamics. In this experiment, we manipulated the frequency of soil rewetting events during 2 months to determine how stress history influences the response of soil microbial communities to rewetting events. Two soils were collected from the Sedgwick Ranch Natural Reserve in Santa Ynez, CA, one from an annual grassland, the other from underneath an oak canopy. Soils were incubated in the lab and went through either 0, 1, 2, 4, 6, 9, or 15 drying-rewetting cycles over 2 months. Soil moisture content was adjusted so that the average moisture content over the course of the incubation was the same for all samples, compensating for the number of drying-rewetting cycles. Soils were analyzed for respiration rate, substrate utilization efficiency, nitrification potential, microbial biomass, and NH4+ and NO3- concentrations. Total CO2 loss during incubation significantly increased with number of rewetting events for oak soils but not for grass soils, where a large number of rewetting events decreased total CO2 loss. Exposure to frequent drying-rewetting events decreased the amount Of CO2 released upon rewetting and dramatically increased the activity of autotrophic nitrifier populations. For up to 6 weeks after the last drying-rewetting cycle, respiration rates in soils exposed to a history of drying-rewetting events were substantially lower than their non-stressed controls. In all cases, the effects of the rewetting stress were greater in oak than in grass soils. The results indicate that drying-rewetting events can induce significant changes in microbial C and N dynamics and these effects can last for more than a month after the last stress. The frequency of drying-rewetting stress events has important ecosystem-level ramifications and should be incorporated into models of soil microbial dynamics. (C) 2002 Elsevier Science Ltd. All rights reserved.