Dispersal and persistence traits inform long-term herbaceous plant community change in encroached savannas
Dispersal and persistence traits inform long-term herbaceous plant community change in encroached savannas
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DOI：
10.1007/s11258-023-01307-3
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发表时间：
2023-03
期刊：
影响因子：
1.7
通讯作者：
Sam J. Ahler;Laura M. Ladwig;Katherine T. Charton;Jonathan J. Henn;Ellen I. Damschen
中科院分区：
文献类型：
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作者：
Sam J. Ahler;Laura M. Ladwig;Katherine T. Charton;Jonathan J. Henn;Ellen I. Damschen
稀树草原植物群落具有高度多样性，具有开阔的冠层结构和丰富的草本植物多样性，并以频繁的低强度火烧和放牧维持着。由于栖息地的丧失和碎片化，稀树草原在全球范围内受到威胁，在美国中西部发现的以前的橡树稀树草原土地覆盖只剩下不到1%。在过去的一个世纪里，在残留的橡树稀树草原上，火和放牧的丧失导致了木本植物的侵蚀和树冠的关闭，对分类组成产生了连锁的后果。能否使用物种功能特征(影响物种适合度的形态-生理-物候特征)来广泛预测这些分类变化是一个关键问题。我们问，木本植物入侵对草本植物物种的影响是否可以从物种的持久(避免灭绝)和分散(殖民新地区)的能力来预测。具体地说，我们将持久性特征(例如克隆、地下储存)和扩散特征(例如种子质量、扩散模式、开花高度)与来自美国威斯康星州橡树稀树草原的罕见的60年数据集进行配对，以了解这些特征在草本植物群落中的表现随时间发生了怎样的变化。60多年来，物种组成的变化既可以用扩散能力来解释，也可以用持久性特征来解释；依赖非辅助扩散的小种子物种和中等克隆物种遭受的损失最大。这些功能成分的变化可能是由于木本植物入侵的增加，这可能会阻碍繁殖体的生产和运动。恢复工作需要优先考虑扩散受限的物种和产生优良燃料的物种，这有助于火灾维持的露天栖息地稀树草原的持续存在。
Savanna plant communities are highly diverse, characterized by an open-canopy structure with rich herbaceous diversity, and maintained by frequent low-intensity fire and grazing. Due to habitat loss and fragmentation, savannas are globally threatened, with less than 1% of former oak savanna land cover found in the Midwestern United States remaining. In remnant oak savannas, loss of fire and grazing has led to woody encroachment and canopy closure over the past century with cascading consequences for the taxonomic composition. Whether these taxonomic changes can be broadly predicted using species functional traits (morpho-physio-phenological characteristics that impact the fitness of a species) is a key question. We ask whether the impacts of woody encroachment on herbaceous species can be predicted from species’ abilities to persist (avoid extinction) and disperse (colonize new areas). Specifically, we pair persistence traits (e.g., clonality, belowground storage) and dispersal traits (e.g., seed mass, dispersal mode, flowering height) with a rare 60-year dataset from oak savannas in Wisconsin, USA to understand how the representation of these traits has changed in the herbaceous community over time. Over 60 years, change in species composition was explained both by dispersal abilities and persistence traits; small-seeded species reliant on unassisted dispersal and moderately clonal species experienced the greatest losses. These changes in functional composition are likely due to increased woody encroachment, which may impede propagule production and movement. Restoration efforts need to prioritize species that are dispersal limited and those that create fine fuels, which aid the persistence of fire-maintained open habitat savannas.