Impact of CO2 rise on root, leaf and wood production: The future of tree C allocation

在全球范围内，树木通过光合作用吸收二氧化碳，并将碳分配到树叶、木材和根中，在那里它可以在生物质和土壤中保留数十年。因此，陆地植被的碳吸收是全球碳汇的重要参与者，吸收了大约三分之一的人为二氧化碳排放。然而，问题仍然是，在二氧化碳浓度升高的情况下，森林是否会继续对全球碳汇做出贡献，以及在多大程度上会继续做出贡献。研究表明，在二氧化碳浓度升高的情况下，树木可以进行更高水平的光合作用，但由于养分供应等其他限制因素，树木的生长不可能无限增加。树木可以通过增加根的生长、分泌物和微生物活动，在一定程度上分配地下额外的碳，从而探索土壤，获得更多的养分和水分，从而在一定程度上解决这一问题。该项目旨在揭示二氧化碳熏蒸的影响，重点是成熟森林的地下过程。以前的研究发现了更大的碳捕获，特别是通过增加根的生长，往往集中在年轻的森林和种植园；所谓的“第一代”FACE(自由空气碳浓缩)设施，不一定能准确地反映二氧化碳增加对成熟森林的影响。该项目将在伯明翰林业研究所(BIFoR)进行，这是世界上唯一与森林研究和气象局合作的第二代人脸设施。根产量将通过使用微型加速器相机收集图像来测量，这是一种尖端的非破坏性根系调查技术，然后将被矢量化并转换为根产量。这种方法将与更传统的根提取和使用土芯进行检查的方法一起使用。然后，有关根系生产的数据将与BIFoR实验前几年收集的其他相关碳储存数据(如叶面积)一起考虑，以进一步了解在二氧化碳升高的情况下树木将在哪里分配额外的碳，并为了解全球碳汇的未来提供重要信息。

Globally, trees absorb CO2 in photosynthesis and allocate carbon into leaves, wood, and roots where it can then remain within biomass and soil for decades. Therefore, carbon uptake by terrestrial vegetation is a vital player in the global carbon sink, absorbing around 1/3 of anthropogenic CO2 emissions. The question remains however, whether, and to what extent, forests will continue to contribute to the global carbon sink under elevated CO2 concentrations. Research suggests that trees can carry out increased levels of photosynthesis under elevated CO2, but growth cannot increase indefinitely due to other limiting factors such as nutrient availability. Trees may be able to combat this to an extent by allocating this extra carbon belowground by increasing root growth, exudation, and microbial activity to explore the soil and obtain more nutrients and water. This project aims to unravel the effect of CO2 fumigation, focussing on belowground processes of mature forests. Previous studies which have found greater carbon capture, notably by increasing root growth, have often been focussed on younger forests and plantations; so-called 'first generation' FACE (Free Air Carbon Enrichment) facilities, and do not necessarily produce an accurate representation of the impact of elevated CO2 on mature forests. This project will be carried out at the Birmingham Institute of Forestry Research (BIFoR), only the second running 'second generation' FACE facility in the world in collaboration with Forest Research and the Met Office.Root production will be measured through the collection of images using a minirhizotron camera, a cutting edge, non-destructive root investigation technique, which will then be vectored and converted to rates of root production. This methodology will be used alongside more traditional methods of root extraction and examination using soil cores. Data on root production will then be considered alongside other relevant carbon storage data collected in the previous years of the BIFoR experiment, such as leaf area, to further understand where trees will allocate extra carbon under elevated CO2 and provide vital information to understand the future of the global carbon sink.