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首页> 外文期刊>Ecosystems >Deep Autotrophic Soil Respiration in Shrubland and Woodland Ecosystems in Central New Mexico
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Deep Autotrophic Soil Respiration in Shrubland and Woodland Ecosystems in Central New Mexico

机译：新墨西哥州中部灌木丛和林地生态系统的深层自养土壤呼吸

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摘要

Quantifying the controls on soil respiration is important for understanding ecosystem physiology and for predicting the response of soil carbon reservoirs to climate change. The majority of soil respiration is typically considered to occur in the top 20–30 cm of soils. In desert soils, where organic matter concentrations tend to be low and plants are deeply rooted, deeper respiration might be expected. However, little is known about the depth distribution of respiration in dryland soils. Here we show that the average depth of soil respiration between pulse precipitation events is almost always greater than 20 cm and is frequently greater than 50 cm in two central New Mexico desert shrublands. The average depth of soil respiration in a piñon-juniper woodland was shallower, between 5 and 40 cm. In the shrublands, 8‰ seasonal variations in the carbon isotope composition of soil-respired CO2 (δ13Cr-soil) that correlate with vapor pressure deficit support root/rhizosphere respiration as the dominant source of soil CO2. Such deep autotrophic respiration indicates that shrubs preferentially allocate photosynthate to deep roots when conditions near the surface are unfavorable. Therefore, respiration rates in these soils are not necessarily correlated with root biomass. The δ13Cr-soil values provide no evidence for CO2 evolved from soil inorganic carbon. Our results also suggest that organic carbon cycling is rapid and efficient in these soils and that the δ13C value of CO2 respired from soils in much of the southwestern US, and perhaps in other semiarid regions, varies seasonally by at least 4‰.
机译：量化土壤呼吸的控制对于理解生态系统生理和预测土壤碳库对气候变化的响应非常重要。通常认为大部分土壤呼吸发生在土壤的最上方20–30 cm。在沙漠土壤中，有机物浓度往往较低，而植物则根深蒂固，人们可能希望呼吸更深。但是，对于旱地土壤中呼吸深度的分布知之甚少。在这里，我们表明，在两个新墨西哥州中部沙漠灌木丛中，脉冲降水事件之间土壤呼吸的平均深度几乎总是大于20 cm，经常大于50 cm。松柏林的平均土壤呼吸深度较浅，介于5至40厘米之间。在灌丛中，土壤呼吸的二氧化碳（δ13 Cr-土壤）的碳同位素组成中有8‰的季节变化与蒸气压亏缺相关，支持根/根际呼吸土壤二氧化碳的来源。这种深层的自养呼吸表明，当靠近地面的条件不利时，灌木会优先将光合产物分配给深根。因此，这些土壤中的呼吸速率不一定与根生物量相关。 δ13​​ Cr-土壤的值不能提供从土壤无机碳释放出CO2 的证据。我们的结果还表明，在这些土壤中有机碳循环快速有效，并且美国西南部许多地区（也许在其他半干旱地区）从土壤中呼吸出的δ13 C C C值随季节变化至少增加4‰。

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  • 来源
    《Ecosystems》 |2012年第1期|p.83-96|共14页
  • 作者

    D. O. Breecker; L. D. McFadden; Z. D. Sharp; M. Martinez; M. E. Litvak;

  • 作者单位

    Department of Geological Sciences, The University of Texas at Austin, Austin, Texas, 78712, USA;

    Department of Earth and Planetary Sciences, The University of New Mexico, Albuquerque, New Mexico, 87131, USA;

    Department of Earth and Planetary Sciences, The University of New Mexico, Albuquerque, New Mexico, 87131, USA;

    Department of Geological Sciences, The University of Texas at Austin, Austin, Texas, 78712, USA;

    Department of Biology, The University of New Mexico, Albuquerque, New Mexico, 87131, USA;

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  • 正文语种 eng
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  • 关键词

    soil respiration; soil depth; desert; carbon isotopes; vapor pressure deficit; New Mexico; autotrophic;

    机译：土壤呼吸;土壤深度;沙漠;碳同位素;蒸气压亏缺;新墨西哥州;自养;

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