Insam H, Bååth E, Berreck M, Frostegård A, Gerzabek M H, Kraft A, Schinner F, Schweiger P, Tschuggnall G
Institut für Mikrobiologie, Universität Innsbruck, Austria.
J Microbiol Methods. 1999 May;36(1-2):45-54. doi: 10.1016/s0167-7012(99)00010-x.
Plants in artificial tropical ecosystems were grown under ambient (340 microl l(-1)) and elevated (610 microl l(-1)) atmospheric CO2 for 530 d under low-nutrient conditions on a substrate free of organic C. At the end of the experiment a number of soil chemical and microbiological variables were determined. Although we found no changes in total soil organic matter under elevated CO2, we did find that after physical fractionation the amount of organic C in the supernatant (< 0.2 microm) and the amount of water extractable organic C (WEOC) was lower under elevated CO2. The extractable optical density (OD) indicated a higher degree of humification for the elevated than for the ambient CO2 samples (P = 0.032). Microbial biomass C was not significantly altered under high CO2, but total bacterial counts were significantly higher. The microbial biomass C-to-N ratio was also higher at elevated (15.0) than at ambient CO2 (10.0). The number of mycorrhizal spores was lower at high CO2, but ergosterol contents and fungal hyphal lengths were not significantly affected. Changes were found neither in community level physiological profiles (CLPPs) nor in the structural attributes (phospholipid fatty acids, PLFAs) of the microbial community. Overall, the effects on the soil microbiota were small, perhaps as a result of the low nutrient supply and low organic matter content of the soil used in our study. The few significant results showing changes in specific, though relatively minor, organic matter pools may point to possible long-term changes of the more major pools. Furthermore, the data suggest increased competition between plants and microbes for N at high CO2.
在无有机碳的基质上，人工热带生态系统中的植物在低养分条件下于环境大气二氧化碳浓度（340微升/升）和高浓度大气二氧化碳（610微升/升）条件下培养530天。实验结束时，测定了一些土壤化学和微生物变量。尽管我们发现高浓度二氧化碳条件下土壤总有机质没有变化，但我们确实发现经过物理分级后，高浓度二氧化碳条件下上清液中有机碳含量（<0.2微米）和水溶性有机碳（WEOC）含量较低。可提取光密度（OD）表明，高浓度二氧化碳条件下的样品比环境二氧化碳条件下的样品腐殖化程度更高（P = 0.032）。高浓度二氧化碳条件下微生物生物量碳没有显著变化，但细菌总数显著更高。高浓度二氧化碳条件下微生物生物量碳与氮的比值（15.0）也高于环境二氧化碳条件下（10.0）。高浓度二氧化碳条件下菌根孢子数量较低，但麦角固醇含量和真菌菌丝长度没有受到显著影响。微生物群落的群落水平生理图谱（CLPPs）和结构属性（磷脂脂肪酸，PLFAs）均未发现变化。总体而言，对土壤微生物群的影响较小，这可能是由于我们研究中使用的土壤养分供应低和有机质含量低所致。少数显示特定但相对较小的有机物质库发生变化的显著结果可能表明更主要库的可能长期变化。此外，数据表明在高浓度二氧化碳条件下植物与微生物之间对氮的竞争加剧。
