New frontiers in forest carbon processes: soil chars, methane emission hotspots, and high-resolution inventory

森林碳过程的新领域：土壤炭、甲烷排放热点和高分辨率清单

• 批准号: RGPIN-2015-06209
• 负责人: Thomas, Sean
• 金额: $ 3.57万
• 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: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=614491
• 关键词: New; frontiers; forest; carbon; processes

Forests play a central role in global greenhouse gas dynamics, constituting a critical but environmentally sensitive sink for both carbon dioxide and methane. The present proposal addresses emerging research problems that link tree biology to forest carbon processes, with a focus on two important and inter-related components of the forest carbon cycle that are poorly resolved: soil charcoals (both natural chars and designed “biochars”) and effects of trees on soil fluxes of CO2 and methane, with particular attention to “methane emission hotspots”. Natural chars occur in most forest soils, and are increasingly recognized as playing a critical role in soil nutrient and carbon dynamics that has been drastically modified by fire suppression. The physico-chemical properties and dynamics of chars remain poorly characterized, but likely vary greatly with source tree species, fire intensity, and char weathering; the comparability of natural chars to designed “biochars” has received almost no attention. The proposed studies will: (1) quantify spatial variability in natural chars in temperate, boreal, and tropical forest ecosystems, testing the hypothesis that char quantities are predictable from site topography and hydrology and influence both productivity and community composition; (2) quantify and experimentally elucidate mechanisms for species-specific tree responses to char; (3) examine long-term effects of char additions to forest productivity, ecosystem processes, and biodiversity. Methane flux is similarly critical in understanding forest-climate feedbacks, but the drivers of methane dynamics in forest ecosystems remain poorly understood. Instrumentation has only recently become available to enable rapid, accurate field measurements of methane flux. The proposed studies will: (1) quantify spatial variability in soil methane and CO2 efflux in relation to soil variables and local tree community composition; (2) test for effects of tree size and species on soil methane and CO2 efflux; (3) assess methane emissions from coarse woody debris and live tree heartrot; (4) examine soil methane and CO2 efflux rates in relation to soil chars, testing the hypothesis that chars will increase soil oxygenation (and thus increase net methane uptake) due to increased porosity. Together the proposed studies will provide fundamental science needed to better manage forests for climate mitigation, specifically focusing on novel approaches involving designed biochars and enhancements for forest methane sinks.

森林在全球温室气体动力学中起着核心作用，构成了二氧化碳和甲烷的关键但对环境敏感的水槽。本提案解决了将树生物学与森林碳过程联系起来的新兴研究问题，重点是解决森林碳循环的两个重要且相关的组件，这些碳循环的解决方案很差：土壤木炭（自然炭和设计的“生物炭”）以及树木对二氧化碳和甲烷的土壤磁通的影响，尤其是注意二氧化碳和甲烷的注意力，并注意“甲烷发射的摄入量”。 天然炭发生在大多数森林土壤中，并且越来越被认为是在土壤养分和碳动力学中起着至关重要的作用，而碳动态已被火灾抑制大大改变。炭的物理化学特性和动力学的特征仍然很差，但可能随源树种，火力强度和炭化风化而差异很大。自然炭与设计“生物char”的可比性几乎没有引起关注。拟议的研究将：（1）在温度，北方和热带森林生态系统中自然炭的空间变异性数量，检验了以下假设：char数量可以从现场地形和氢中预测，并影响生产力和社区组成； （2）量化并实验阐明了针对炭的特异性树反应的机制； （3）检查对森林生产力，生态系统过程和生物多样性的炭的长期影响。 甲烷通量在理解森林气候反馈方面同样至关重要，但是森林生态系统中甲烷动力学的驱动因素仍然知之甚少。仪器直到最近才可以实现甲烷通量的快速，准确的现场测量。拟议的研究将：（1）与土壤变量和当地树群落组成有关的土壤甲烷和二氧化碳外排的空间变异性； （2）测试树木大小和物种对土壤甲烷和二氧化碳外排的影响； （3）评估粗木质碎屑和活树赫特特的甲烷排放； （4）检查土壤甲烷和二氧化碳排出率与土壤炭相关，检验了以下假设：炭将增加土壤氧合（从而增加甲烷摄取），这是由于孔隙率提高而导致的。拟议的研究将共同​​提供基本的科学，以更好地管理森林以缓解气候，专门针对涉及森林甲烷水槽设计的新方法和增强。