Birmingham Institute of Forest Research (BIFoR), University of Birmingham, Birmingham, UK.
School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK.
Glob Chang Biol. 2020 Feb;26(2):1023-1037. doi: 10.1111/gcb.14786. Epub 2019 Sep 11.
In 2017, the Birmingham Institute of Forest Research (BIFoR) began to conduct Free Air Carbon Dioxide Enrichment (FACE) within a mature broadleaf deciduous forest situated in the United Kingdom. BIFoR FACE employs large-scale infrastructure, in the form of lattice towers, forming 'arrays' which encircle a forest plot of ~30 m diameter. BIFoR FACE consists of three treatment arrays to elevate local CO concentrations (e[CO ]) by +150 µmol/mol. In practice, acceptable operational enrichment (ambient [CO ] + e[CO ]) is ±20% of the set point 1-min average target. There are a further three arrays that replicate the infrastructure and deliver ambient air as paired controls for the treatment arrays. For the first growing season with e[CO ] (April to November 2017), [CO ] measurements in treatment and control arrays show that the target concentration was successfully delivered, that is: +147 ± 21 µmol/mol (mean ± SD) or 98 ± 14% of set point enrichment target. e[CO ] treatment was accomplished for 97.7% of the scheduled operation time, with the remaining time lost due to engineering faults (0.6% of the time), CO supply issues (0.6%) or adverse weather conditions (1.1%). CO demand in the facility was driven predominantly by wind speed and the formation of the deciduous canopy. Deviations greater than 10% from the ambient baseline CO occurred <1% of the time in control arrays. Incidences of cross-contamination >80 µmol/mol (i.e. >53% of the treatment increment) into control arrays accounted for <0.1% of the enrichment period. The median [CO ] values in reconstructed three-dimensional [CO ] fields show enrichment somewhat lower than the target but still well above ambient. The data presented here provide confidence in the facility setup and can be used to guide future next-generation forest FACE facilities built into tall and complex forest stands.
2017 年，伯明翰森林研究所（BIFoR）开始在英国一个成熟的阔叶落叶林进行自由空气二氧化碳富集（FACE）实验。BIFoR FACE 采用大规模基础设施，以网格塔的形式形成“阵列”，环绕直径约 30 米的森林地段。BIFoR FACE 由三个处理阵列组成，通过将局部 CO 浓度（e[CO ]）升高 150 µmol/mol。实际上，可接受的操作富化（环境 [CO ] + e[CO ]）是设定点 1 分钟平均目标的±20%。还有另外三个阵列复制基础设施，并提供环境空气作为处理阵列的配对对照。对于具有 e[CO ]的第一个生长季节（2017 年 4 月至 11 月），处理和对照阵列中的 [CO ]测量表明成功地输送了目标浓度，即：+147±21 µmol/mol（平均值±标准偏差）或设定点富化目标的 98±14%。e[CO ]处理完成了计划操作时间的 97.7%，其余时间因工程故障（0.6%的时间）、CO 供应问题（0.6%）或不利天气条件（1.1%）而损失。设施中的 CO 需求主要由风速和落叶林冠的形成驱动。对照阵列中偏离环境基线 CO 的偏差大于 10%的情况<1%。进入对照阵列的交叉污染超过 80 µmol/mol（即处理增量的>53%）的情况<0.1%的富化期。重建的三维 [CO ]场中的中位数 [CO ]值显示，富化程度略低于目标，但仍远高于环境水平。这里呈现的数据提供了对设施设置的信心，并可用于指导未来建入高大复杂林分的下一代森林 FACE 设施。
