Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, 37831-6301, TN, USA.
ARC Centre of Excellence for Climate Extremes, University of New South Wales, Sydney, 2052, NSW, Australia.
Nat Commun. 2019 Feb 14;10(1):454. doi: 10.1038/s41467-019-08348-1.
Increasing atmospheric CO stimulates photosynthesis which can increase net primary production (NPP), but at longer timescales may not necessarily increase plant biomass. Here we analyse the four decade-long CO-enrichment experiments in woody ecosystems that measured total NPP and biomass. CO enrichment increased biomass increment by 1.05 ± 0.26 kg C m over a full decade, a 29.1 ± 11.7% stimulation of biomass gain in these early-secondary-succession temperate ecosystems. This response is predictable by combining the CO response of NPP (0.16 ± 0.03 kg C m y) and the CO-independent, linear slope between biomass increment and cumulative NPP (0.55 ± 0.17). An ensemble of terrestrial ecosystem models fail to predict both terms correctly. Allocation to wood was a driver of across-site, and across-model, response variability and together with CO-independence of biomass retention highlights the value of understanding drivers of wood allocation under ambient conditions to correctly interpret and predict CO responses.
大气中 CO2 浓度的增加会刺激光合作用，从而增加净初级生产力（NPP），但从更长的时间尺度来看，它不一定会增加植物生物量。在这里，我们分析了四个长达四十年的木本生态系统 CO2 富集实验，这些实验测量了总 NPP 和生物量。CO2 富集使生物量增量增加了 1.05 ± 0.26 kg C m-2，在这些早期次生演替的温带生态系统中，生物量的增加刺激了 29.1 ± 11.7%。通过将 NPP 的 CO 响应（0.16 ± 0.03 kg C m-2 y-1）与 CO 不依赖的、生物量增量与累积 NPP 之间的线性斜率（0.55 ± 0.17）相结合，就可以预测这种响应。一组陆地生态系统模型都无法正确预测这两个术语。木材的分配是跨站点和跨模型响应变异性的驱动因素，加上生物量保留的 CO 不依赖性，突出了在环境条件下理解木材分配驱动因素的重要性，以便正确解释和预测 CO 响应。
