New frontiers in forest carbon processes: novel methane dynamics, pyrogenic carbon, and restoration of highly impacted sites

森林碳过程的新领域：新型甲烷动力学、热解碳和受严重影响的地点的恢复

• 批准号: RGPIN-2022-04627
• 负责人: Thomas, Sean
• 金额: $ 4.01万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=753645
• 关键词: New; frontiers; forest; carbon; processes

Forests play a central role in the global carbon cycle. Methane (CH4) accounts for >25% of anthropogenic climate forcing, with forests acting as both important CH4 sources and sinks. Recent studies suggest important fluxes through tree stems and foliar tissues, and our lab has discovered "hotspots" of CH4 efflux in highly impacted soils in managed forests. Recent studies also indicate pervasive but patchy fire-legacy pyrogenic carbon (PyC) in forest soils that can greatly increase tree growth and possibly enhance soil CH4 oxidation. There is currently insufficient knowledge on either patterns or mechanisms involved to integrate these processes into global models or to inform forest management. We propose three inter-related projects to address these research gaps. (1) RELATIONS BETWEEN PYC, FOREST COMPOSITION, AND SOIL GHG FLUX. PyC from fire residues or added to soils as biochar can potentially strongly enhance tree growth by increasing soil nutrient and water retention, and reduce CH4 emissions due to enhanced soil aeration. Soil CH4 oxidation may also be reduced beneath conifers due to inhibitory effects of monoterpenes leached from litter; effects of local tree diversity on soil GHG fluxes have been proposed but not examined in forests. This project will use measurements in a large, mapped forest stand, in conjunction with long-term biochar addition and stand conversion experiments, to address these potential effects, testing the hypotheses of that increased PyC, angiosperm abundance, and local tree diversity will increase local soil CH4 oxidation. (2) MITIGATION OF CH4 EMISSION HOTSPOTS IN MANAGED FOREST AND URBAN GREEN INFRASTRUCTURE. Our recent studies show that highly degraded soils at log landings in temperate forests are "hotspots" of high soil CH4 efflux. This project will use observational studies and experiments to assess whether this pattern also is found in managed boreal forests and urban green infrastructure, to better understand the mechanisms involved, and to test mitigation approaches involving biochar additions, soil inoculations, and other soil treatments. (3) NOVEL METHANE DYNAMICS: CH4 OXIDATION BY CANOPY FOLIAGE. Our preliminary measurements indicate that tree foliage on upland (well-drained) sites is an important CH4 sink; however, little is known concerning either mechanisms or patterns of variation among species or among forest types. Survey studies will test the hypothesis that foliar CH4 uptake capacity is correlated with "leaf economics" traits, that seasonal leaf colonization by methanotrophs results in predictable seasonal patterns and canopy stratification of CH4 uptake, and that foliar CH4 uptake is reduced in urban settings due to a lack of methanotroph colonization. The proposed research programme will contribute to fundamental understanding of CH4 dynamics and C processes in forests, and will also directly develop novel approaches to climate mitigation applicable in forestry and urban green infrastructure.

森林在全球碳循环中发挥着核心作用。甲烷（CH 4）占人类活动气候强迫的25%以上，森林既是重要的CH 4源，也是重要的CH 4汇。最近的研究表明，重要的流量通过树干和叶片组织，我们的实验室已经发现了“热点”的CH 4流出高度影响土壤中管理的森林。最近的研究还表明，森林土壤中普遍存在但不完整的火灾遗留热解碳（PyC），可以大大增加树木的生长，并可能增强土壤CH 4氧化。目前对将这些进程纳入全球模式或为森林管理提供信息所涉及的模式或机制缺乏足够的了解。我们提出了三个相互关联的项目，以解决这些研究差距。(1)PYC、森林组成和土壤温室气体通量之间的关系。从火灾残留物或添加到土壤中的生物炭热解碳可以通过增加土壤养分和保水能力，潜在地强烈促进树木生长，并由于增强土壤通气性而减少CH 4排放。土壤甲烷氧化也可能减少针叶树下由于单萜类的抑制作用，从凋落物沥滤;土壤温室气体通量的影响，当地的树木多样性已被提出，但在森林中没有检查。该项目将在一个大型的，绘制森林的立场，结合长期的生物炭添加和立场转换实验的测量，以解决这些潜在的影响，测试的假设，增加热解碳，被子植物丰度，和当地树木多样性将增加当地土壤甲烷氧化。(2)森林和城市绿色基础设施中甲烷排放热点的减缓我们最近的研究表明，高度退化的土壤在温带森林的日志登陆高土壤CH 4流出的“热点”。该项目将使用观测研究和实验来评估这种模式是否也存在于北方森林和城市绿色基础设施中，以更好地了解所涉及的机制，并测试包括生物炭添加，土壤接种和其他土壤处理的缓解方法。(3)新型甲烷催化剂：冠层叶片对甲烷的氧化作用我们的初步测量表明，树木的叶子在高地（排水良好）网站是一个重要的CH 4汇，然而，知之甚少的机制或物种之间或森林类型之间的变化模式。调查研究将测试的假设，叶面CH 4吸收能力与“叶经济学”的特点，季节性叶片定植甲烷营养菌的结果在可预测的季节性模式和冠层分层的CH 4吸收，叶面CH 4吸收减少在城市环境中，由于缺乏甲烷营养菌定植。拟议的研究方案将有助于从根本上了解森林中的CH 4动态和C过程，并将直接开发适用于林业和城市绿色基础设施的气候减缓新方法。