Decomposition of 14C-labeled roots in a pasture soil exposed to 10 years of elevated CO2
Decomposition of 14C-labeled roots in a pasture soil exposed to 10 years of elevated CO2
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DOI：
10.1016/j.soilbio.2004.08.013
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发表时间：
2005-03
影响因子：
9.7
通讯作者：
K. V. van Groenigen;A. Gorissen;J. Six;D. Harris;P. Kuikman;J. V. van Groenigen;C. van Kessel
中科院分区：
文献类型：
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作者：
K. V. van Groenigen;A. Gorissen;J. Six;D. Harris;P. Kuikman;J. V. van Groenigen;C. van Kessel
土壤碳净通量取决于土壤碳输入和微生物分解之间的平衡，这两者都可能在长期大气CO2浓度升高的情况下发生变化。研究了CO2浓度升高对多年生黑麦草（Lolium perenne L.）14C标记的根材料，在环境（35 Pa pCO2）或升高的CO2（70 Pa pCO2）下产生的土壤中培养64天。土壤取自牧场生态系统，该生态系统在FACE条件下暴露于环境（35 Pa pCO2）或升高的CO2（60 Pa pCO2）10年，两种肥料氮水平：140和560 kg N ha−1year−1。在暴露于CO2浓度升高的土壤中，生长在环境或CO2浓度升高的根材料的分解率始终低于暴露于环境CO2的对照土壤，表明微生物活性的变化。在土壤中，收到高速率的N肥，根材料生长在高CO2的分解降低了约17%，培养64天后，根材料生长在环境CO2。当根在高CO2下生长时，与在低CO2下生长的根相比，在微生物量（q14CO2）中掺入的每14 C量所呼吸的14CO2的量显著降低。我们假设这种减少是微生物群落转变的结果，导致代谢效率增加。暴露于CO2浓度升高的土壤往往会呼吸更多的本地SOC，无论有和没有添加的根材料，可能是由于较高的C供应到土壤中，在10年的治疗与CO2浓度升高。结果表明，在研究二氧化碳浓度升高下生长的根系分解时，使用适应二氧化碳浓度升高的土壤非常重要。我们的研究结果进一步表明，负启动效应可能会掩盖CO2数据在孵育实验与未标记的基板。从所获得的结果，我们得出结论，一个缓慢的营业额的根材料生长在一个“高CO2的世界”可能会导致有限的净增加C存储在黑麦草草地。
The net flux of soil C is determined by the balance between soil C input and microbial decomposition, both of which might be altered under prolonged elevated atmospheric CO2. In this study, we determined the effect of elevated CO2on decomposition of grass root material (Lolium perenne L.).14C-labeled root material, produced under ambient (35Pa pCO2) or elevated CO2(70Pa pCO2) was incubated in soil for 64 days. The soils were taken from a pasture ecosystem which had been exposed to ambient (35Pa pCO2) or elevated CO2(60Pa pCO2) under FACE-conditions for 10 years and two fertilizer N rates: 140 and 560kg N ha−1year−1. In soil exposed to elevated CO2, decomposition rates of root material grown at either ambient or elevated CO2were always lower than in the control soil exposed to ambient CO2, demonstrating a change in microbial activity. In the soil that received the high rate of N fertilizer, decomposition of root material grown at elevated CO2decreased by approximately 17% after incubation for 64 days compared to root material grown at ambient CO2. The amount of14CO2respired per amount of14C incorporated in the microbial biomass (q14CO2) was significantly lower when roots were grown under high CO2compared to roots grown under low CO2. We hypothesize that this decrease is the result of a shift in the microbial community, causing an increase in metabolic efficiency. Soils exposed to elevated CO2tended to respire more native SOC, both with and without the addition of the root material, probably resulting from a higher C supply to the soil during the 10 years of treatment with elevated CO2. The results show the importance of using soils adapted to elevated CO2in studies of decomposition of roots grown under elevated CO2. Our results further suggest that negative priming effects may obscure CO2data in incubation experiments with unlabeled substrates. From the results obtained, we conclude that a slower turnover of root material grown in an ‘elevated-CO2world’ may result in a limited net increase in C storage in ryegrass swards.