Can nutrients put the breaks on forest carbon capture?

由于森林是碳的净汇，增加森林覆盖被广泛推广为一种有助于减缓气候变化的全球解决方案。在加拿大，联邦政府的目标是在未来10年内种植20亿棵树，以帮助实现减少温室气体排放的目标。然而，森林生长和森林土壤固碳高度依赖于其他营养物质的生物地球化学循环，如氮和钙，而这些营养物质已被几个世纪的人为活动所干扰。此外，气候变化可能影响森林的健康和组成，进一步影响净碳储量。该研究项目将把氮和钙的生物地球化学变化与森林生长和健康联系起来，重点放在安大略省南部，该地区由于酸性沉积而经历了广泛的土壤退化，该地区也是加拿大氮沉积水平最高的地区。作为安大略省南部的关键物种，糖枫的健康和生长将成为研究的目标，但研究将包括安大略省其他常见的硬木树种。这项研究将包括四个互补项目，这些项目将加强我们对氮和钙在森林生长中的作用以及气候变化可能对森林健康产生的影响的理解。该研究项目将提出以下问题：大气氮沉降和土壤碱态对树木生长和森林健康的影响2. 树木健康如何受到气候变化的影响？3. 生长在贫瘠土壤上的森林对钙和/或氮添加的短期生物地球化学反应是什么？4。在收获和不收获的情况下，土壤钙水平会如何变化？这项研究将利用现有的数据库，其中包括每年在100多个长期森林监测地块上监测的1万多棵树木，并利用稳定同位素等创新技术来解开潜在的生物地球化学机制。它将把广泛的实地抽样和试验性实地研究与最先进的生物地球化学模型结合起来，以评估目前的森林状况，并预测不同气候和管理情景下森林生长和健康的未来变化。这项工作将由一个多元化和包容性的HQP团队进行，该团队由3名博士生、2名硕士生、4名本科优秀生和一名研究技术人员组成，所有人都将与利益相关者合作，确保这些研究结果将被直接沟通并用于为政策决策提供信息。这项工作将使我们能够更准确地估计阔叶林未来的健康状况和生长情况，这是政府应对气候变化政策的重要组成部分。它还将确定有助于森林管理决策的潜在缓解措施，这些决策可能包括修订、调整采伐做法和（或）改变树种组成的必要性。

Increasing forest cover is widely promoted as a global solution to help mitigate climate change as forests are net sinks of carbon. In Canada, the Federal Government's objective is to plant two billion trees within the next 10 years to help meet greenhouse gas emission reduction targets. Forest growth and forest soil carbon sequestration, however, are highly dependent on the biogeochemical cycling of other nutrients, like nitrogen and calcium, which have been perturbed by centuries of anthropogenic activities. Furthermore, climate change will likely impact the health and composition of forests with further implications for net carbon storage. This research program will connect changes in nitrogen and calcium biogeochemistry with forest growth and health, focusing on southern Ontario, which has experienced widespread soil degradation because of acidic deposition and this region also receives the highest levels of nitrogen deposition in Canada. As the keystone species in southern Ontario, sugar maple health and growth will be targeted, but studies will include a range of other common hardwood tree species in Ontario. This research will encompass four complimentary projects that will enhance our understanding of the role of nitrogen and calcium in forest growth and what impact climate change may have on forest health. The research program will ask: 1. How are tree growth and forest health affected by atmospheric nitrogen deposition and soil base cation status?; 2. How is tree health affected by climate change?; 3. What are the short-term biogeochemical responses of forests growing on base-poor soil to calcium and/or nitrogen additions?, and 4. How will soil calcium levels change under harvest vs. no harvest scenarios? This research will utilize an existing database of more than 10,000 trees that are annually monitored at more than 100 long term forest monitoring plots and utilize innovative techniques like stable isotopes to disentangle potential biogeochemical mechanisms at play. It will combine extensive field sampling and experimental field studies with state-of-the-art biogeochemical models to assess the current forest condition and forecast future changes in forest growth and health under different climatic and management scenarios. The work will be conducted by a diverse and inclusive HQP team consisting of 3 PhD students, 2 MSc students, 4 undergraduate honors students and a research technician, all of whom will work with stakeholders to ensure that findings from these studies will be directly communicated and used to inform policy decisions. This work will enable a more accurate estimation of the future health and growth of hardwood forests, which is a vital component of government policy to combat climate change. It will also identify potential mitigation measures that will aid forest management decisions that may include the need for amendments, adjusted harvesting practices and/or changes in tree species composition.