Unveiling the Secrets of Peatlands for Climate Change Mtigation

苏格兰泥炭地（即沼泽、沼泽和沼泽）覆盖了全国约20%的面积，在土壤中储存了约16亿吨碳，因此，在全新世时间尺度上，它们是温室气体收支的重要组成部分（Frolking等人，2006）。泥炭地在水质和供水方面也发挥着重要作用，是一系列独特物种的栖息地，提供休闲空间，并保存了过去环境和人类活动的记录（Bain et al., 2011）。然而，据估计，超过80%的苏格兰泥炭地已经退化（苏格兰土壤，2022）。未退化的泥炭地积累土壤有机质，由于在淹水土壤条件下没有有氧分解和相关的二氧化碳排放，因此充当大气二氧化碳的汇生态系统（Dise, 2009）。尽管如此，受管理的泥炭地（如排水、栽培或造林）在空间和时间水平上显示出高度的温室气体排放变异性，这是由于土壤水分动态、氧化还原电位、基质材料的可用性以及人为对水文和植被的改变（Schrier-Uijl等人，2010；Abdalla等人，2014；Abdalla等人，2016）。有一种担忧是，退化的泥炭地可能通过从土壤中释放二氧化碳而显著加剧人为气候变化（Hooijer et al, 2010）。这种担忧目前正在推动苏格兰和世界各地广泛尝试保护和恢复泥炭地。一方面，恢复退化的泥炭地可以将其与集水区重新连接起来，从而减少二氧化碳排放并增加碳储量（Horsburgh et al., 2022）。另一方面，与原始管理前的CH4排放相比，再湿润恢复使CH4排放（其辐射强迫高于CO2）增加了46% （Abdalla et al., 2016）。然而，目前尚不清楚恢复如何影响温室气体净排放（即温室气体排放与碳储量之间的平衡）。该项目将利用实验数据、过程建模和元分析，通过调查温室气体排放和碳储存来评估温室气体净排放量，以填补这一知识空白。此外，将温室气体排放归因于人为和自然驱动因素是一个巨大的挑战，也是成功评估减少泥炭地排放潜力的先决条件。据我们所知，到目前为止，退化或恢复的苏格兰泥炭地对基线和气候变化下的净温室气体排放的影响尚未完全量化/绘制，也没有对潜在的恢复技术进行建模。本研究将实现以下目标：1)绘制苏格兰泥炭地年度温室气体净排放量基线图；2)绘制气候变化下泥炭地年温室气体净排放量图；3)绘制和调查排水/恢复对温室气体净排放的影响；4)研究苏格兰泥炭地温室气体排放对人为和自然驱动因素的敏感性。

The Scottish peatlands (i.e. mires, fen and bog) cover about 20% of the country, storing approximately 1600 million tonnes of carbon in the soils, and therefore, represent an essential component of GHG budget at the Holocene time scale (Frolking et al., 2006). Peatlands also play important roles in water quality and supply, host a range of unique species, provide spaces for recreation and preserve a record of past environments and human activity (Bain et al., 2011). However, it is estimated that over 80% of the Scottish peatlands are degraded (Scotland soils, 2022). Un-degraded peatlands accumulate soil organic matter and act as a sink ecosystem for atmospheric CO2 due to the absence of aerobic decomposition and associated CO2 emissions under waterlogged soil conditions (Dise, 2009). Nevertheless, managed peatlands (e.g. drained and cultivated or afforested) show a high variability in GHG emissions at both spatial and temporal levels due to active systems in soil moisture dynamics, redox potential, availability of substrate materials and man-made alterations to hydrology and vegetation (Schrier-Uijl et al., 2010; Abdalla et al., 2014; Abdalla et al., 2016). There is a concern that degraded peatlands may significantly exacerbate anthropogenic climate change through release of CO2 from soils (Hooijer et al, 2010). This concern is currently motivating extensive attempts to conserve and restore peatlands in Scotland and around the world. On one hand, restoring degraded peatlands can reconnect them to their catchments and thereby, decreases CO2 emissions and increases carbon storage (Horsburgh et al., 2022). On the other hand, restoration by rewetting increases CH4 emissions (which has a higher radiative forcing than CO2) by 46% compared to the original pre-management CH4 emissions (Abdalla et al., 2016). However, it is still not clear how restoration affects net GHG emissions (i.e. balance between GHG emissions and carbon storage). This project will use experimental data, process modelling and meta-analyses to assess net GHG emissions by investigating both GHG emissions and carbon storage to fill this gap in knowledge. Further, the attribution of GHG emissions to anthropogenic and natural drivers is a great challenge, and is a prerequisite to successfully assess the potential to reduce the emissions from peatlands.To the best of our knowledge, until this date, the impact of degraded or restored Scottish peatlands on net GHG emissions under baseline and climate change are not fully quantified/ mapped, nor potential restoration techniques modelled. This study will achieve the following objectives:1) Create maps of baseline annual net GHG emissions from the Scottish peatlands; 2) Create maps of annual net GHG emissions from peatlands under climate change; 3) Map and investigate the impacts of drainage/ restoration on net GHG emissions; and 4) Investigate sensitivity of GHG emissions from the Scottish's peatlands to anthropogenic and natural drivers.