Fire effects on diversity patterns of the understory communities of Araucaria-Nothofagus forests
Fire effects on diversity patterns of the understory communities of Araucaria-Nothofagus forests
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DOI：
10.1007/s11258-022-01247-4
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发表时间：
2022-06
期刊：
影响因子：
1.7
通讯作者：
Paola Arroyo-Vargas;A. Holz;T. Veblen
中科院分区：
文献类型：
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作者：
Paola Arroyo-Vargas;A. Holz;T. Veblen
短间隔和高强度的火灾组合正在成为林下植物群落重大重组的催化剂。在智利中南部的温带森林中，人们担心受到威胁的araucaria - nothofagusus森林的恢复能力，包括其林下群落在广泛而严重的火灾后的恢复能力。在这项研究中，我们使用了一系列的多样性指数和功能特征作为社区恢复力的代理。我们询问物种和群落是否受到野火的影响，以及这些反应如何受到烧伤严重程度和频率以及其他生物物理变量的调节。首先，我们探索了火灾是群落变化的主要驱动因素的假设，并且烧伤严重程度是改变群落组成属性的主要因素。其次，我们假设再燃烧会导致林下成分属性的变化比单次燃烧更大，其中重新繁殖的物种取代了专门的种子，减少了当地的多样性。我们在两个研究地点建立了120个烧伤严重程度梯度的田间样地：一个受单一火灾影响（2015年烧毁），另一个受两次火灾影响（2002年和2015年烧毁），其中维管植物物种丰度，以及其他生物、非生物和地形变量进行了估计。研究发现，燃烧（高）严重程度是火灾后林下植被组合的主要驱动因素，导致群落的竞争力和异质性降低，外来物种数量增加。此外，火灾后的反应导致群落中易燃类群和火灾后呼吸物种在早期阶段的高丰度，可能导致再燃烧地区从mesic森林生态系统大规模过渡到干燥，开放的森林和易火的灌丛。我们的研究结果强调了短间隔和严重的野火在针叶林林下群落向火灾后专性呼吸系统主导的系统过渡中的生态重要性，其中树木物种较少，损害了这些生态系统的恢复。这些发现提高了对当前影响可燃性反馈的火灾后过程的理解，并有助于在火灾制度改变的世界中建立当前模式的基线。
Short-interval and high-severity fires combined are emerging as a catalyst of major reorganization of understory plant communities. In temperate forests of south-central Chile, concern exists about the resilience of threatenedAraucaria-Nothofagusforests, including its understory community following extensive and severe fires. In this study we use an array of diversity indices and functional traits as proxies of community resilience. We ask if the species and communities are affected by wildfires, and how these responses are mediated by burn severity and frequency, and other biophysical variables. First, we explore the hypothesis that fire is the major driver of community changes, and that burn severity is the main factor that shifts compositional attributes of communities. Secondly, we hypothesize that a reburn will lead to a greater shift than a single burn in understory compositional attributes, where resprouting species replace obligate seeders, reducing local diversity. We established 120 field plots across a burn severity gradient in two study sites: one affected by a single (burned 2015), and the second by two fires (burned 2002 and 2015), where vascular plant species abundance, among other biotic, abiotic, and topographic variables were estimated. We found that burn (high) severity is the main driver of post-fire understory assemblages, resulting in communities less competitive and heterogeneous, with an increasing number of exotic species. Also, post-fire responses are resulting in communities in which the high abundance of flammable taxa and post-fire resprouter species at the early-seral stage may lead to large-scale transitions from mesic forest ecosystems to dry, open forest and fire-prone shrublands in reburned areas. Our results highlight the ecological importance of short-interval and severe wildfires as leading factors in the transition of post-fire understory communities ofAraucaria-Nothofagusforests to a system dominated by post-fire obligate resprouters, where tree species are less represented compromising the recovery of these ecosystems. These findings improve the understanding of the current post-fire processes that affect flammability feedbacks and contribute to a baseline of the current patterns in a world of altered fire regimes.