The role of tree species diversity in mitigating negative impacts of reduced water availability in boreal forests: Patterns and mechanisms

树种多样性在减轻北方森林可用水量减少的负面影响方面的作用：模式和机制

• 批准号: RGPIN-2019-05109
• 负责人: Chen, Han
• 金额: $ 4.01万
• 依托单位: Lakehead University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=690639
• 关键词: role; tree; species; diversity; mitigating; role; tree; species; diversity; mitigating

Biodiversity loss and climate change are two significant stressors on ecosystem productivity, element cycling, and other ecological processes. Observational studies have shown that tree mortality of Canadian boreal forests and elsewhere has increased in the past decades, accompanied by smaller or no increase or even decrease in growth, suggesting that reduced water available to trees induced by warming have negatively affected forest functions, particularly carbon sequestration. However, the direct evidence and mechanistic understanding of the impact of altered water availability on ecosystem function in natural forests is surprisingly limited. Moreover, we lack an understanding of whether, how and why species-rich forests help mitigate the negative impacts of altered water availability on forest functions. My past research program is centered on using observational approaches to understanding the consequences of biodiversity loss and climate change on productivity and element cycling at the ecosystem level including above- and belowground. This proposed research will examine the role of tree species diversity in mitigating negative impacts of reduced water availability in boreal forests. This work builds upon our recent discoveries from observational studies and relies upon a water alteration experiment in natural boreal forests. The experiment consists of three water treatments (ambient, 25% decrease and 25% increase of growing season precipitation (May to October) since 2016) in 10-year-old fire-origin pure jack pine, pure trembling aspen, and their even mixture, each replicated three times, with a total of 27 experimental units. Specifically, I will address: (1) the aboveground responses of growth, mortality, net biomass change, community structure, composition and diversity of all vegetation layers, (2) the responses of litterfall, coarse and fine roots, soil carbon, nutrients, microbial community, and respiration, (3) whether species mixture (diversity) help to mitigate adverse impacts of reduced water and enhance the positive impacts of increased water on processes assessed in objectives 1-2; (4) physiological mechanisms associated with the responses observed in objectives 1 to 3. The success of my research program is highly dependent upon the effective training HQP. As evidenced by the publication record and current positions of my previous lab members, I have been successful in my training efforts. I plan to carry forward with the HQP training momentum I have generated over the last 15 years. This proposed research aims at not only the patterns of but also mechanisms for the responses of natural forests to pulse and press water alteration. Our findings will help to develop strategies to cope with climate change in Canada's boreal forests, and shed mechanistic insights into the diversity effects on global change mitigation for natural systems.

生物多样性丧失和气候变化是生态系统生产力，元素循环和其他生态过程的两个重要压力源。观察性研究表明，在过去的几十年中，加拿大北方森林和其他地方的树木死亡率增加，伴随着生长的较小或没有增加甚至没有减少，这表明由变暖引起的树木可获得的水减少了受影响的森林功能，尤其是碳固执。但是，令人惊讶的是，直接证据和机械理解水对水的影响对天然林生态系统功能的影响非常有限。此外，我们对物种富裕的森林是否有助于减轻水可用性对森林功能的负面影响是否有助于减轻负面影响。我过去的研究计划以使用观察方法来理解生物多样性丧失和气候变化对生产力和元素循环的后果在生态系统层面上的后果。这项拟议的研究将研究树种多样性在减轻北方森林降低水的负面影响中的作用。这项工作是基于我们最近发现的观察性研究发现，并依靠自然北方森林中的水改变实验。该实验包括三种水处理（环境，降低25％，生长季节降水增加25％（自2016年以来5月至10月）中增加了25％的灭火，纯净的千斤顶松树，纯净的颤抖的aspen及其偶数混合物，每种复制三次，共有27个实验单位。具体而言，我将解决：（1）所有植被层的增长，死亡率，净生物量变化，社区结构，组成和多样性的地上反应，（2）滴定层，粗糙和细小的根，土壤碳，养分，养分，微生物群落和呼吸的反应，（3）物种混合物（多样性）是否会增强水的影响（3）水上的水分（3），以及在不良水上的影响效果，对不良的水分产生了不良影响的影响，从而降低了降水的影响，从而降低了不良水的影响，而降低了降低的水分，而无效的水则影响了降低的水分。目标1-2; （4）与目标1到3中观察到的反应相关的生理机制。我的研究计划的成功高度取决于有效的培训HQP。我以前的实验室成员的出版记录和当前职位证明了这一点，我在培训工作中取得了成功。我计划以过去15年的HQP训练势头延续。这项拟议的研究不仅旨在旨在探讨天然林对脉冲和压水的反应的机制。我们的发现将有助于制定应对加拿大北方森林中气候变化的策略，并为自然系统的全球变化缓解措施的多样性影响提供机械见解。