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首页> 外文期刊>Plant and Soil >Interactive effects of soil nitrogen and atmospheric carbon dioxide on root/rhizosphere carbon dioxide efflux from loblolly and ponderosa pine seedlings.
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Interactive effects of soil nitrogen and atmospheric carbon dioxide on root/rhizosphere carbon dioxide efflux from loblolly and ponderosa pine seedlings.

机译：土壤氮和大气二氧化碳对火炬松和黄松树苗根/根际二氧化碳外流的相互作用。

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摘要

CO2 efflux from intact root/rhizosphere systems of 155-day-old loblolly (Pinus taeda) and ponderosa pine (P. ponderosa) seedlings was measured in order to study the effects of increased atmospheric CO2 on the below-ground carbon. Seedlings were grown in sterilized sand culture, given 1, 3.5 or 7 mM NH4+ daily, and maintained in an atmosphere of either 35 or 70 Pa CO2. Carbon dioxide efflux (鎚ol CO2 plant-1 s-1) from the root/rhizosphere system of both species significantly increased when seedlingswere grown in high CO2, primarily due to large increases in root mass. Specific CO2 efflux (鎚ol CO2 g root-1 s-1) responded to CO2 only under conditions of adequate soil nitrogen availability (3.5 mM). Under these conditions, CO2 efflux rates from loblolly pine increased by 70% from 0.0089 to 0.0151 鎚ol g-1 s-1 with high CO2 while ponderosa pine responded with a 59% decrease, from 0.0187 to 0.0077 鎚ol g-1 s-1. Although below-ground CO2 efflux from seedlings grown with either sub-optimal (1 mM) or supra-optimal (7 mM) N did not respond to CO2, there was a significant nitrogen treatment effect. Seedlings grown with supra-optimal soil nitrogen had significantly increased specific CO2 efflux rates, and significantly lower total biomass compared with either of the other two nitrogen treatments. These results indicate that carbon losses from the root/rhizosphere systems are responsive to environmental resource availability, that the magnitude and direction of these responses are species dependent, thatthey may lead to significantly different effects on the whole plant carbon balance of these two forest tree species.
机译：测量了155天大的火炬树（Pinus taeda）和黄松（P. pokerosa）幼苗的完整根/根际系统的CO2流出量，以研究大气CO2浓度升高对地下碳的影响。幼苗在无菌沙培养中生长，每天施用1、3.5或7 mM NH4 +，并保持在35 Pa或70 Pa CO2的气氛中。当幼苗在高CO2条件下生长时，两个物种的根/根际系统的二氧化碳外流（锤酚CO2植物-1 s-1）都显着增加，这主要是由于根的大量增加。特定的CO2流出（锤醇CO2 g root-1 s-1）仅在土壤氮素充足（3.5 mM）的条件下才对CO2产生响应。在这些条件下，火炬松的CO2外排率从0.0089上升了70％，达到0.0151锤酚g-1 s-1，而高黄松的响应则从59.87下降到0.0077锤酚g-1 s- 59％。 1。尽管从亚最佳（1 mM）或超最佳（7 mM）N生长的幼苗的地下CO2外流对CO2没有反应，但氮处理效果显着。与其他两种氮处理中的任何一种相比，用超优土壤氮培养的幼苗均具有显着提高的特定CO2外排率，并显着降低了总生物量。这些结果表明，根/根际系统的碳损失对环境资源的利用有反应，这些反应的程度和方向取决于物种，这可能导致这两种林木对整个植物碳平衡的影响显着不同。 。

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