The Aspen‐FACE (Free‐Air Carbon Enrichment) experiment was an 11‐yr study of the effect of elevated CO₂ and ozone (alone and in combination) on the growth productivity of model aspen communities (pure aspen, aspen‐birch, and aspen‐maple) in the field in northern Wisconsin, USA. Uncertainty remains about how these short‐term plot‐level responses might play out at landscape scales where climate change, competition, succession, and disturbances interact with tree‐level responses. In this study, we used a recent physiology‐based approach (PnET‐Succession v3.1) within the forest landscape model LANDIS‐II to scale the site‐scale FACE results to landscape extents by mechanistically accounting for the globally changing drivers of CO₂, ozone, temperature, and precipitation. We conducted a factorial simulation experiment to test five hypotheses about the effects of three treatments (CO₂ concentration, cumulative ozone exposure, and disturbance). CO₂ was clearly the dominant driver of landscape response, with disturbance also having a large effect. Ozone was not a dominant driver of landscape dynamics or total landscape biomass, but its negative effect on mean landscape biomass was nevertheless significant. We found that CO₂ mitigation of water stress may not have a major effect on species composition or biomass accumulation. We found that species diversity was somewhat decreased by elevated CO₂ as expected, but somewhat increased by O₃, contrary to expectations. The spatial pattern of the landscape was minimally affected by the treatments. While rising CO₂ concentrations have some mitigating effect on the negative O₃ effect on the species studied, additional research is needed to confirm whether researchers and managers can be justified in disregarding O₃ as a primary driver of forest dynamics in other ecosystems. Our results also add more support to the growing consensus that projections of climate change effects must include robust, direct links between CO₂ and tree growth and competition; temperature effects (as demonstrated elsewhere) appear to be less by comparison.

中文翻译：

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森林景观如何应对升高的二氧化碳和臭氧？缩放Aspen‐FACE绘图比例实验结果

Aspen-FACE（自由空气碳富集）实验是一项为期11年的研究，研究了升高的CO ₂和臭氧（单独和组合使用）对模型白杨群落（纯白杨，白杨桦和在美国威斯康星州北部的田间。这些短期的地块级响应如何在景观尺度上发挥作用还不确定，在这些尺度上，气候变化，竞争，演替和干扰与树级响应相互作用。在这项研究中，我们在森林景观模型LANDIS-II中使用了一种最新的基于生理学的方法（PnET-Succession v3.1），通过机械地考虑全球变化的CO ₂驱动力，将场地规模的FACE结果扩展到景观范围，臭氧，温度和降水。我们进行了阶乘模拟实验，以测试关于三种处理（CO ₂浓度，累积臭氧暴露和干扰）影响的五个假设。显然，CO ₂是景观反应的主要驱动力，干扰也有很大影响。臭氧不是景观动力学或景观总生物量的主要驱动因素，但它对平均景观生物量的负面影响仍然很显着。我们发现，缓解水分胁迫的CO ₂可能不会对物种组成或生物量积累产生重大影响。我们发现，如预期的那样，物种多样性因CO ₂升高而有所降低，但因O ₃而有所提高，与预期相反。景观的空间格局受处理的影响最小。尽管升高的CO ₂浓度对研究物种的负O ₃效应有一定程度的缓解作用，但还需要进一步的研究来确认研究人员和管理人员是否有理由无视O ₃作为其他生态系统中森林动力的主要驱动因素。我们的研究结果也为越来越多的共识提供了更多支持，这些共识是对气候变化影响的预测必须包括CO ₂与树木生长和竞争之间的牢固，直接联系；相比之下，温度效应（如在其他地方所证明的）似乎要少。