Examining the protection of organic carbon in mineral soils of managed landscapes

检查管理景观矿质土壤中有机碳的保护

• 批准号: RGPIN-2020-04941
• 负责人: Kellman, Lisa
• 金额: $ 3.13万
• 依托单位: St. Francis Xavier University
• 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=751149
• 关键词: Examining; protection; organic; carbon; mineral

Recent changes in atmospheric carbon dioxide concentrations are linked to human activities that accelerate the movement of carbon from long-term global reservoirs into the atmosphere as carbon dioxide, contributing to planetary warming. Soils represent one of the largest actively cycling terrestrial carbon reservoirs, and hold three times as much carbon as the atmosphere or living vegetation. Changes in land use such as conversion of forests to agricultural land and repeated harvesting of forests can cause carbon stored in soils as organic matter to be released to the atmosphere. This can have additional consequences for overall soil health and fertility. The bulk of carbon stored in soils is held within the mineral soil, up to half of it below 20cm depth. It was long assumed that carbon held within the mineral soil had a complex chemical structure that made it difficult for microbial communities to decompose. Recent studies, however, show that much of the older carbon held in soils is actually readily decomposable, but is protected from decomposition by interactions with soil minerals. These interactions may result in the loose adsorption of organic matter to mineral surfaces, or the combining of organic matter with minerals in new stable compounds of varying complexity. In soils where conditions are unaltered over time, this form of carbon can be quite stable, and remain in soils for hundreds to thousands of years. However, when soil conditions are altered by factors such as land surface disturbance and changes in climate, the mechanisms that protect soil organic matter can be reversed, making it available to be decomposed and returned it to the atmosphere. Little is known about how carbon associated with minerals is released when subjected to an altered physical and chemical environment arising from changes in land use and/or climate. Likewise, there is little information about the potential of soils to recover these carbon stores when these disturbances cease. This proposal outlines a research plan to investigate how carbon is partitioned within a range of mineral-associated carbon pools of varying strength and complexity in soils typical of Eastern Canada. Forests of varying ages will be examined, and compared to local agricultural soils to determine the size and variability of these soil carbon pools. Soils will be collected from existing stored archives and sampled in the field. Experiments will subject a subset of these soils to long term increases in soil temperature, and measure how the carbon held in these pools and its chemical composition changes. The goals are to understand how susceptible this protected carbon is to changes in soil conditions, and to be able to make predictions about how this carbon will respond to altered soil conditions. It also seeks to identify important measurements that can be used as standard indices for monitoring changes in soil organic matter within mineral soils.

大气二氧化碳浓度的最新变化与人类活动有关，这些活动将碳从长期的全球储层转移到大气中，作为二氧化碳的运动，这导致了行星变暖。土壤代表着最大的积极循环陆地碳储层之一，并拥有三倍的碳或生存植被的三倍。土地利用的变化，例如将森林转化为农业土地和重复收获森林，可能会导致碳存储在土壤中，因为有机物可以释放到大气中。这可能会对整体土壤健康和生育能力产生其他影响。存储在土壤中的大部分碳被保持在矿物土壤中，最多一半以下20厘米。长期以来，人们认为持有矿物质内的碳具有复杂的化学结构，使微生物群落很难分解。然而，最近的研究表明，在土壤中持有的许多较旧碳实际上很容易分解，但可以通过与土壤矿物质相互作用来保护分解。这些相互作用可能会导致有机物对矿物表面的吸附松散，或者将有机物与矿物质与矿物质结合在一起，使新的复杂性不同。在随着时间的流逝不变的土壤中，这种形式的碳可能非常稳定，并且在土壤中持续数百万年。但是，当土壤条件因土地表面干扰和气候变化等因素而改变时，可以逆转保护土壤有机物的机制，使其可以分解并将其归还到大气中。 对于由于土地使用和/或气候变化而产生的改变物理和化学环境时，与矿物质相关的碳释放方式知之甚少。同样，在这些干扰停止时，几乎没有关于土壤恢复这些碳储存的潜力的信息。该提案概述了一项研究计划，以研究如何在加拿大东部典型的土壤中与矿物质相关的碳库中分配碳。将检查各种年龄段的森林，并与局部农业土壤进行比较，以确定这些土壤碳池的大小和可变性。将从现有的存储档案中收集土壤，并在现场取样。实验将使这些土壤的一部分长期增加土壤温度，并测量碳在这些池中的碳及其化学成分的变化。目标是了解这种受保护的碳对土壤条件变化的敏感性，并能够预测该碳如何应对土壤条件的改变。它还试图确定重要的测量值，这些测量值可用作监测矿物土壤中土壤有机物变化的标准指数。