FACE underground:can trees in mature forests gain greater access to soil nutrients under elevated atmospheric CO2?

面向地下：在大气二氧化碳浓度升高的情况下，成熟森林中的树木能否获得更多土壤养分？

• 批准号: NE/T000449/1
• 负责人: Sami Ullah
• 金额: $ 78.11万
• 依托单位: University of Birmingham
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FT000449%2F1
• 关键词: FACE; underground; trees; mature; forests

Land ecosystems including forests capture about 30% of the carbon dioxide (CO2) released by human activities. This uptake is mainly attributed to the beneficial effects of increasing atmospheric CO2 concentrations (eCO2) on rates of photosynthesis (the "CO2 fertilisation effect"). Based on current CO2 uptake rates and the predicted increases in atmospheric CO2 concentrations, an attempt has been made to predict future Carbon (C) uptake by forests using different large-scale models. However, the model estimates are highly uncertain because we lack a clear understanding of how the limited availability of soil nutrients, particularly nitrogen (N) and phosphorus (P), regulate the CO2 fertilisation effect. For example, incorporating nitrogen availability into models reduced predicted uptake rates of CO2 by ~50%, which shows that previous estimates may have been optimistic. Furthermore, previous experiments have focused on young forests and to date there are no large-scale CO2 enrichment experiments in mature temperate forests. This is important because: 1) mature forests in northern temperate regions are currently responsible for almost half (~40%) of the global net C uptake and 2) young forests may be able to increase access to nutrients by increasing root growth under eCO2 to explore more of the soil space, whereas mature forests already have well-developed root systems, so greater carbon allocation to roots and their associated fungal partners (mycorrhizas) may have less potential to increase access to nutrients. Therefore, a realistic assessment of the role of nutrient availability in controlling the responses of mature temperate forests to eCO2 is essential. Given the global significance of temperate forests, the Birmingham Institute of Forest Research (BIFoR), established a CO2 fertilization experiment (>£15 million investment) in a >160 year old deciduous forest stand in Staffordshire in 2017. This is the first such experiment in a mature temperate forests and thus provides a unique opportunity to test a key question: can mature trees gain greater access to limiting nutrients under eCO2 and, if so, which strategies do they employ to do so? Thus, we aim to test the broad hypothesis that under eCO2 a mature, deciduous temperate forest will transfer additional carbon belowground to increase nitrogen and phosphorus availability and subsequent uptake by trees. The research will be undertaken in three plots under eCO2 and three control plots. We will measure root and mycorrhizal hyphal production, and the release of substrates (exudates) from roots throughout the year. We will also carry out a series of experiments to determine the relative roles of roots versus mycorrhizal fungi in controlling rates of decomposition and nutrient cycling, and the extent to which these are affected by eCO2. These decomposition experiments will involve root and/or mycorrhizal fungi exclusion, as well as a novel approach for simulating root exudation. The results will enable us to determine whether, and through which mechanisms, trees can stimulate decomposition and nutrient mobilization under eCO2. Finally, we will determine if the types of nitrogen containing compounds that roots take up changes under eCO2 and how this relates to their availability in the soil. In summary, we will use the first FACE experiment in a mature temperate forest to determine whether mature temperate forest trees will be able to access more soil nutrients under eCO2, and therefore, whether there is likely to be a large and sustained carbon sink in these ecosystems, addressing a major uncertainty in carbon cycle modelling. If our results suggest that the forest uptake will become increasingly nutrient limited in the future then it would have major societal implications as greater cuts in greenhouse gas emissions would be needed to avoid the most dangerous consequences of climate change.

包括森林在内的土地生态系统捕获了人类活动发布的约30％的二氧化碳（CO2）。这种吸收主要归因于增加大气二氧化碳浓度（ECO2）对光合作用速率的有益影响（“ CO2受精效应”）。基于当前的二氧化碳摄取速率和预测的大气二氧化碳浓度的升高，已经尝试使用不同的大型模型来预测森林的未来碳（C）吸收。但是，该模型估计值高度不确定，因为我们对土壤养分（尤其是氮（N）和磷（P）的有限可用性缺乏清晰的了解，可以调节CO2受精效应。例如，将氮的可用性纳入模型中，将二氧化碳的摄取率降低了约50％，这表明先前的估计值可能很乐观。此外，以前的实验集中在年轻的森林上，迄今为止，在成熟的温度森林中还没有大规模的二氧化碳富集实验。 This is important because: 1) mature forests in northern temperature regions are currently responsible for almost half (~40%) of the global net C uptake and 2) young forests may be able to increase access to nutrients by increasing root growth under eCO2 to explore more of the soil space, whereas mature forests already have well-developed root systems, so greater carbon allocation to roots and their associated fungal partners (mycorrhizas) may have less potential to increase获得营养。因此，对养分可用性在控制成熟温度森林对ECO2的反应中的作用的现实评估至关重要。鉴于温度森林的全球意义，伯明翰森林研究所（BIFOR）在2017年在斯塔福德郡建立了二氧化碳施肥实验（> 1500万英镑的投资）。这是这是在成熟的森林中获得更大的问题，并在限制限制的情况下，这是一个成熟的温度范围，因此这是一个成熟的森林中的第一个此类实验。 所以？这是我们旨在检验一个广泛的假设，即在Eco2下，决定性温度森林将在地下转移额外的碳，以增加氮和磷的可用性，并随后被树木吸收。这项研究将在ECO2和三个对照图下进行三个地块进行。我们将测量根和菌根菌丝的产生，并全年从根中释放底物（渗出液）。我们还将进行一系列实验，以确定根与菌根真菌在控制分解和养分循环速率以及对这些影响的程度中的相对作用。由Eco2。这些分解实验将涉及根和/或菌根真菌排除，以及一种模拟根部渗出的新方法。结果将使我们能够确定树木在ECO2下是否可以刺激分解和营养动员。最后，我们将确定氮的类型是否含有根部在ECO2下进行变化的化合物，以及与土壤中的可用性有关。总而言之，我们将在成熟的温度森林中使用第一个面孔实验来确定成熟的温度森林树木是否能够在ECO2下获取更多的土壤养分，因此，是否可能在这些生态系统中有大型且持续的碳汇，以解决碳循环建模的主要不确定性。如果我们的结果表明，将来森林的吸收将变得越来越有限，那么它将产生重大的社会影响，因为需要更大的温室气体排放量减少，以避免气候变化的最危险后果。

项目成果

Nitrogen cycling in forest soils under elevated CO2: response of a key soil nutrient to climate change

二氧化碳浓度升高下森林土壤的氮循环：关键土壤养分对气候变化的响应

• DOI: 10.5194/egusphere-egu22-178
• 发表时间: 2022
• 作者: Rumeau M

Soil – atmosphere exchange of greenhouse gases under future climates

土壤

• DOI: 10.5194/egusphere-egu22-10237
• 发表时间: 2022
• 作者: Douwes Dekker N

Stimulation of soil gross nitrogen transformations and nitrous oxide emission under Free air CO2 enrichment in a mature temperate oak forest at BIFoR-FACE

BIFoR-FACE 成熟温带橡树林在自由空气 CO2 富集下对土壤总氮转化和一氧化二氮排放的刺激

• DOI: 10.1016/j.soilbio.2023.109072
• 发表时间: 2023
• 期刊: Soil Biology and Biochemistry
• 影响因子: 9.7
• 作者: Sgouridis, Fotis;Reay, Michaela;Cotchim, Suparat;Ma, Jiaojiao;Radu, Aleksandar;Ullah, Sami
• 通讯作者: Ullah, Sami

Root exudation rate increases, and composition changes in a mature temperate forest under elevated carbon dioxide

二氧化碳升高下成熟温带森林的根系分泌率增加和成分变化

• DOI: 10.5194/egusphere-egu22-5026
• 发表时间: 2022
• 作者: Reay M

BIFoR FACE : Water-soil-vegetation-atmosphere data from a temperate deciduous forest catchment, including under elevated CO 2

BIFor FACE：来自温带落叶林流域的水-土壤-植被-大气数据，包括在 CO 2 升高的情况下

• DOI: 10.1002/hyp.14096
• 发表时间: 2021
• 期刊: Hydrological Processes
• 影响因子: 3.2
• 作者: MacKenzie A