Post-fire habitat conditions as drivers of progressive and retrogressive succession: seedbed filter, species traits and feedback of dominant plants

火后栖息地条件作为进步和倒退演替的驱动因素：苗床过滤、物种特征和优势植物的反馈

• 批准号: RGPIN-2014-06239
• 负责人: Mallik, Azim
• 金额: $ 1.75万
• 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=679936
• 关键词: Post; fire; habitat; conditions; drivers

Discovering the drivers of post-disturbance community assembly and succession has been a long-term preoccupation amongst ecologists. A reliable prediction of successional trajectory is essential for developing ecological theory and strategy for natural resource management. It is generally believed that wildfires in the boreal forest reset succession culminating to pre-fire stand structure. In this progressive succession competitive exclusion is thought to be the main driver. But important exceptions occur in post-fire boreal and temperate conifer forests with ericaceous understory where low-severity fires often lead to retrogressive succession. Here the competition based assembly rule is pre-empted by habitat conditions characterized by thick residual organic matter (ROM). My previous work on such a system dominated by black spruce (Picea mariaia) and Kalmia (Kalmia angustifolia) showed that thick ROM forms poor seedbeds for spruce but protects the belowground buds of Kalmia that emerge quickly and dominate the post-fire community and resist tree colonization. Not enough is known about the duration and dynamics of this ericaceous heath: some suggest it lasts for several years to several decades while others suggest alternate stable states with little data on community dynamics and plant soil-feedbacks. This knowledge is essential to understand the mechanism of retrogressive succession and for sustainable forest management in many nutrient-poor conifer-ericaceous communities on both sides of the Atlantic. The long-term goal of my research program is to understand disturbance mediated community dynamics particularly the interactions between the dominant understory and canopy species. Using black spruce-Kalmia community as a study system and framing my research questions around several contemporary broad ecological concepts and land management challenges, in the next five years I shall focus on four short-term objectives, to 1. examine the biophysical properties of post-fire residual organic matter (ROM) and how that filter species regeneration traits, 2. test how successional direction and ecosystem function can be described by community level trait analysis, 3. assess the longevity and growth phases of Kalmia heaths, and 4. discover innovative methods of conifer restoration in ericaceous heaths. This research will i) advance our fundamental knowledge on habitat driven community assembly and secondary succession, ii) test the stability of arrested succession or alternate stable states mediated by population dynamics of dominant plants, community trait filtering and plant soil feedbacks, and iii) evaluate biotic resistance in relation to restoration ecology. Focusing on several contemporary ecological concepts pertaining to causes and consequences of heath formation this research will discover the significance of fire severity related seedbed filter and priority effect on the direction of secondary succession. **The novelty of the proposed approach of this study is to determine functional trait diversity along successional trajectories as opposed to the traditional calculation of taxonomic species diversity and composition change along time since disturbance. I shall also use intra-species trait variability of dominant plants by onsite measurement of hard traits. By combining community level functional traits with dominant plants' response and effect traits this approach will enable me to offer functional interpretation of Kalmia heath and forest dynamics. This new knowledge on dynamics and longevity of Kalmia heath can be used in devising innovative methods of forest restoration in Kalmia heath, which has significant land management implications for eastern Canada.**This research will train 1 PhD, 3 MSc and 5 HBSc students.

发现扰动后群落聚集和演替的驱动因素一直是生态学家长期关注的问题。演替轨迹的可靠预测对于发展自然资源管理的生态理论和策略至关重要。人们普遍认为，北方森林的野火重置演替，最终形成火灾前的林分结构。在这种逐步演替中，竞争排斥被认为是主要驱动力。但重要的例外发生在火灾后的北方和温带针叶林，其林下有杜鹃花，低强度的火灾往往会导致倒退演替。在这里，基于竞争的装配规则被以厚厚的残留有机物（ROM）为特征的栖息地条件所取代。我之前对以黑云杉 (Picea mariaia) 和 Kalmia (Kalmia angustifolia) 为主的系统的研究表明，厚的 ROM 为云杉形成了不良的苗床，但保护了 Kalmia 的地下芽，这些芽迅速出现，在火灾后群落中占主导地位，并抵抗树木定殖。人们对这种杜鹃花丛的持续时间和动态知之甚少：一些人认为它会持续几年到几十年，而另一些人则认为存在交替的稳定状态，但关于群落动态和植物土壤反馈的数据很少。这些知识对于理解大西洋两岸许多营养贫乏的针叶树群落的倒退演替机制和可持续森林管理至关重要。我的研究计划的长期目标是了解干扰介导的群落动态，特别是主要林下物种和冠层物种之间的相互作用。 使用黑云杉-Kalmia群落作为研究系统，并围绕几个当代广泛的生态概念和土地管理挑战构建我的研究问题，在接下来的五年中，我将重点关注四个短期目标，即1.检查火灾后残留有机物（ROM）的生物物理特性以及如何过滤物种再生特征，2.测试如何通过群落水平特征分析来描述演替方向和生态系统功能，3.评估 4. 发现杜鹃花石南针叶树恢复的创新方法。这项研究将i）增进我们对栖息地驱动的群落组装和二次演替的基础知识，ii）测试由优势植物的种群动态、群落性状过滤和植物土壤反馈介导的停滞演替或交替稳定状态的稳定性，以及iii）评估与恢复生态学相关的生物抗性。这项研究重点关注与健康形成的原因和后果有关的几个当代生态概念，将发现与火灾严重程度相关的苗床过滤的重要性以及对次生演替方向的优先效应。 **本研究提出的方法的新颖之处在于确定沿演替轨迹的功能性状多样性，而不是传统计算自干扰以来分类物种多样性和组成变化的方法。我还将通过硬性状的现场测量来利用优势植物的种内性状变异性。通过将群落水平的功能性状与优势植物的反应和效果性状相结合，这种方法将使我能够对 Kalmia 荒地和森林动态提供功能解释。 有关 Kalmia 荒地动态和寿命的新知识可用于设计 Kalmia 荒地森林恢复的创新方法，这对加拿大东部具有重大的土地管理影响。**这项研究将培训 1 名博士生、3 名硕士生和 5 名 HBSc 学生。