Research Group of Plant and Vegetation Ecology, Department of Biology, University of Antwerp, Wilrijk, B-2610, Belgium; School of Earth and Environmental Sciences, Faculty of Science and Engineering, James Cook University, Smithfield, 4878, QLD, Australia.
Glob Chang Biol. 2012 Sep;18(9):2681-93. doi: 10.1111/j.1365-2486.2012.02745.x. Epub 2012 Jun 27.
In recent years, increased awareness of the potential interactions between rising atmospheric CO2 concentrations ([ CO2 ]) and temperature has illustrated the importance of multifactorial ecosystem manipulation experiments for validating Earth System models. To address the urgent need for increased understanding of responses in multifactorial experiments, this article synthesizes how ecosystem productivity and soil processes respond to combined warming and [ CO2 ] manipulation, and compares it with those obtained in single factor [ CO2 ] and temperature manipulation experiments. Across all combined elevated [ CO2 ] and warming experiments, biomass production and soil respiration were typically enhanced. Responses to the combined treatment were more similar to those in the [ CO2 ]-only treatment than to those in the warming-only treatment. In contrast to warming-only experiments, both the combined and the [ CO2 ]-only treatments elicited larger stimulation of fine root biomass than of aboveground biomass, consistently stimulated soil respiration, and decreased foliar nitrogen (N) concentration. Nonetheless, mineral N availability declined less in the combined treatment than in the [ CO2 ]-only treatment, possibly due to the warming-induced acceleration of decomposition, implying that progressive nitrogen limitation (PNL) may not occur as commonly as anticipated from single factor [ CO2 ] treatment studies. Responses of total plant biomass, especially of aboveground biomass, revealed antagonistic interactions between elevated [ CO2 ] and warming, i.e. the response to the combined treatment was usually less-than-additive. This implies that productivity projections might be overestimated when models are parameterized based on single factor responses. Our results highlight the need for more (and especially more long-term) multifactor manipulation experiments. Because single factor CO2 responses often dominated over warming responses in the combined treatments, our results also suggest that projected responses to future global warming in Earth System models should not be parameterized using single factor warming experiments.
近年来，人们越来越意识到大气中二氧化碳浓度（[CO2]）升高和温度升高之间潜在的相互作用，这说明了进行多因素生态系统操作实验来验证地球系统模型的重要性。为了满足对多因素实验中响应的深入理解的迫切需求，本文综合了生态系统生产力和土壤过程对联合升温和[CO2]操纵的响应，并将其与单一因子[CO2]和温度操纵实验的响应进行了比较。在所有联合升高[CO2]和升温的实验中，生物量生产和土壤呼吸通常会增强。对联合处理的响应与仅[CO2]处理的响应更相似，而与仅升温处理的响应不同。与仅升温实验相反，联合处理和仅[CO2]处理均会更大程度地刺激细根生物量的增加，而不是地上生物量的增加，持续刺激土壤呼吸，并降低叶片氮（N）浓度。尽管如此，由于升温引起的分解加速，在联合处理中，可利用的矿物 N 减少程度小于仅[CO2]处理，这可能意味着渐进式氮限制（PNL）不会像从单一因子[CO2]处理研究中预期的那样普遍发生。总植物生物量的响应，尤其是地上生物量的响应，揭示了升高的[CO2]和升温之间的拮抗相互作用，即联合处理的响应通常小于加性响应。这意味着，当模型根据单一因子响应进行参数化时，生产力预测可能会被高估。我们的结果强调了进行更多（尤其是更多长期）多因素操纵实验的必要性。由于在联合处理中，单一因子 CO2 的响应通常会超过升温的响应，因此我们的结果还表明，地球系统模型中对未来全球变暖的预计响应不应使用单一因子升温实验来参数化。
