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: 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=612111
• 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.

发现干扰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。对演替轨迹进行可靠的预测是制定生态理论和自然资源管理战略的基础。一般认为，在北方森林野火重置演替最终达到火灾前林分结构。在这种渐进式继承中，竞争排斥被认为是主要驱动力。但重要的例外情况发生在火灾后的寒带和温带针叶林中，那里有白垩系下层，在那里，低强度的火灾往往导致退化演替。在这里，基于竞争的装配规则被以厚残余有机质（ROM）为特征的生境条件所取代。我之前对这种以黑云杉（Picea mariaia）和黑云杉（Kalmia angustifolia）为主的系统的研究表明，厚厚的ROM对云杉形成了较差的苗床，但保护了黑云杉的地下芽，这些芽迅速出现，在火灾后群落中占主导地位，并抵抗树木的定植。对这种白垩健康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，而另一些人则认为交替的稳定状态，几乎没有关于群落动态和植物土壤反馈的数据。这一知识对于了解大西洋两岸许多营养贫乏的针叶林群落的退化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，特别是优势林下物种和林冠物种之间的相互作用。以黑云杉-卡尔米娅群落为研究系统，围绕几个当代广义生态概念和土地管理挑战构建我的研究问题，在接下来的五年里，我将重点关注四个短期目标，到1。检查火灾后残留有机物（ROM）的生物物理特性以及过滤物种如何再生特征；2 .检验群落水平性状分析如何描述演替方向和生态系统功能；3 .评估黑穗病的寿命和生长阶段；发现针叶树在白垩纪荒地恢复的创新方法。本研究将有助于我们进一步了解生境驱动的群落组合和次生演替的基础知识，验证优势植物种群动态、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，以及评估与恢复生态相关的生物抗性。本研究将聚焦于与健康形成的原因和后果有关的几个当代生态学概念，发现与火灾严重程度相关的苗床过滤器和优先效应对次生演替方向的意义。