Institute of Ecology, University of Innsbruck, Sternwartestr. 15, 6020, Innsbruck, Austria.
Technische Universität München, Lehrstuhl für Grünlandlehre, Alte Akademie 12, D-85350, Freising-Weihenstephan, Germany.
New Phytol. 2013 Apr;198(1):116-126. doi: 10.1111/nph.12138. Epub 2013 Feb 6.
Carbon (C) allocation strongly influences plant and soil processes. Short-term C allocation dynamics in ecosystems and their responses to environmental changes are still poorly understood. Using in situ (13) CO(2) pulse labeling, we studied the effects of 1 wk of shading on the transfer of recent photoassimilates between sugars and starch of above- and belowground plant organs and to soil microbial communities of a mountain meadow. C allocation to roots and microbial communities was rapid. Shading strongly reduced sucrose and starch concentrations in shoots, but not roots, and affected tracer dynamics in sucrose and starch of shoots, but not roots: recent C was slowly incorporated into root starch irrespective of the shading treatment. Shading reduced leaf respiration more strongly than root respiration. It caused no reduction in the amount of (13) C incorporated into fungi and Gram-negative bacteria, but increased its residence time. These findings suggest that, under interrupted C supply, belowground C allocation (as reflected by the amount of tracer allocated to root starch, soil microbial communities and belowground respiration) was maintained at the expense of aboveground C status, and that C source strength may affect the turnover of recent plant-derived C in soil microbial communities.
碳（C）分配强烈影响植物和土壤过程。生态系统中短期 C 分配动态及其对环境变化的响应仍知之甚少。本研究采用原位（13）CO2脉冲标记法，研究了 1 周遮荫对高山草甸地上和地下植物器官中糖和淀粉之间近期光合作用产物转移以及向土壤微生物群落分配的影响。C 向根系和微生物群落的分配速度很快。遮荫强烈降低了地上部分的蔗糖和淀粉浓度，但对根系没有影响，并且影响了地上部分蔗糖和淀粉中示踪剂的动态，但对根系没有影响：最近的 C 缓慢地掺入根淀粉中，而与遮荫处理无关。遮荫使叶片呼吸作用的降低幅度大于根呼吸作用，且不会减少真菌和革兰氏阴性细菌中（13）C 的掺入量，但会增加其停留时间。这些发现表明，在 C 供应中断的情况下，地下 C 分配（反映在分配给根淀粉、土壤微生物群落和地下呼吸的示踪剂数量上）以牺牲地上 C 状态为代价得以维持，并且 C 源强度可能会影响土壤微生物群落中近期植物衍生 C 的周转。
