Quantification and uncertainty of root growth stimulation by elevated CO 2 in mature temperate deciduous forest
Quantification and uncertainty of root growth stimulation by elevated CO 2 in mature temperate deciduous forest
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成熟温带落叶林中CO 2 升高对根系生长刺激的量化和不确定性
DOI：
10.1101/2021.04.15.440027
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Ziegler C
中科院分区：
文献类型：
--
作者：
Ziegler C
不断增加的CO2水平是一个重大的全球性挑战，对自然碳汇减少人为CO2排放的潜力仍然知之甚少。陆地生物圈对升高的CO2（eCO2）的吸收以及随后作为生态系统中的生物量的固存，在自然生态系统中仍然难以量化。在这里，我们结合联合收割机实地观察细根股票和流量，来自地下成像和土芯，图像分析，随机建模和统计推断，阐明地下根动态在一个成熟的温带落叶林下自由空气eCO2至150 ppm以上的环境水平。eCO2导致相对更快的根产生（峰值体积倍数变化为4.52 ± 0.44 eCO2，对照为2.58 ± 0.21），相对于腐烂，根伸长增加是这种加速的可能原因机制。552根系统从土壤芯的物理分析支持这一观点，细根的长度和宽度显着增加eCO2。估计细根对eCO2下地下净初级生产力增加的贡献（平均年204 ± 93 g dw m−2yr− 1eCO2，对照为140 ± 60 g dw m−2yr− 1）。因此，这种多方面的方法为成熟温带森林中根系生物量的eCO 2响应的具有挑战性的特征提供了定量的线索。
Increasing CO2levels are a major global challenge, and the potential mitigation of anthropogenic CO2emissions by natural carbon sinks remains poorly understood. The uptake of elevated CO2(eCO2) by the terrestrial biosphere, and subsequent sequestration as biomass in ecosystems, remain hard to quantify in natural ecosystems. Here, we combine field observations of fine root stocks and flows, derived from belowground imaging and soil cores, with image analysis, stochastic modelling, and statistical inference, to elucidate belowground root dynamics in a mature temperate deciduous forest under free-air eCO2to 150 ppm above ambient levels. eCO2led to relatively faster root production (a peak volume fold change of 4.52 ± 0.44 eCO2versus 2.58 ± 0.21 control), with increased root elongation relative to decay the likely causal mechanism for this acceleration. Physical analysis of 552 root systems from soil cores support this picture, with lengths and widths of fine roots significantly increasing under eCO2. Estimated fine root contributions to belowground net primary productivity increase under eCO2(mean annual 204 ± 93 g dw m−2yr−1eCO2versus 140 ± 60 g dw m−2yr−1control). This multi-faceted approach thus sheds quantitative light on the challenging characterisation of the eCO2response of root biomass in mature temperate forests.