Changes in climate and land management over the last half‐century have favoured woody plants native to grasslands and led to the rapid expansion of woody species. Despite this being a global phenomenon, it is unclear why some woody species have rapidly expanded while others have not. We assessed whether the most abundant woody encroaching species in tallgrass prairie have common growth forms and physiology or unique traits that differentiate their resource‐use strategies. We characterized the abundance, above‐ground carbon allocation, and leaf‐level physiological and structural traits of seven woody encroaching species in tallgrass prairie that span an order of magnitude in abundance. To identify species‐specific increases in abundance, we used a 34‐year species composition dataset at Konza Prairie Biological Station (Central Great Plains, USA). We then compared biomass allocation and leaf‐level traits to determine differences in carbon and water use strategies among species. While all focal species increased in abundance over time, encroachment in this system is primarily driven by three species: Cornus drummondii, Prunus americana and Rhus glabra. The most dominant species, Cornus drummondii, had the most extreme values for several traits, including the lowest leaf:stem mass ratios, lowest photosynthetic capacity and highest turgor loss point. Two of the most abundant species, Cornus drummondii and Rhus glabra, had opposing growth forms and resource‐use strategies. These species had significantly different above‐ground carbon allocation, leaf‐level drought tolerance and photosynthetic capacity. There were surprisingly few interspecific differences in specific leaf area and leaf dry matter content, suggesting these traits were poor predictors of species‐level encroachment. Synthesis. Woody encroaching species in tallgrass prairie encompass a spectrum of growth forms and leaf physiology. Two of the most abundant woody species fell at opposite ends of this spectrum. Our results suggest niche differences among a community of woody species facilitate the rapid encroachment by a few species. This study shows that woody encroaching species do not conform to a ‘one‐size‐fits‐all’ strategy, and a diversity of growth forms and physiological strategies may make it more challenging to reach management goals that aim to conserve or restore grassland communities.

中文翻译：

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侵占灌木的不同资源利用策略：性状可以预测高草草原的侵占成功吗？


过去半个世纪气候和土地管理的变化有利于草原原生的木本植物，并导致木本物种的迅速扩张。尽管这是一个全球现象，但目前尚不清楚为什么一些木本物种迅速扩张，而另一些则没有。我们评估了高草草原中数量最多的木本侵占物种是否具有共同的生长形式和生理机能或独特特征，从而区分其资源利用策略。我们表征了高草草原中 7 种木本入侵物种的丰度、地上碳分配以及叶级生理和结构特征，这些物种的丰度跨越了一个数量级。为了确定物种特异性丰度的增加，我们使用了 Konza Prairie 生物站（美国中部大平原）的 34 年物种组成数据集。然后，我们比较了生物量分配和叶水平性状，以确定物种之间碳和水利用策略的差异。虽然所有重点物种的丰度都随着时间的推移而增加，但该系统的侵占主要由三个物种驱动：Cornus drummondii、Prunus americana 和 Rhus glabra。最优势的物种 Cornus drummondii 在几个性状上具有最极端的值，包括最低的叶茎质量比、最低的光合能力和最高的膨胀损失点。两个最丰富的物种，Cornus drummondii 和 Rhus glabra，具有相反的生长形式和资源利用策略。这些物种的地上碳分配、叶片水平的耐旱性和光合作用能力存在显著差异。令人惊讶的是，比叶面积和叶干物质含量的种间差异很小，这表明这些性状是物种水平侵占的不良预测因子。合成。高草草原中的木本侵占物种包括一系列生长形式和叶子生理学。两个最丰富的木本物种落在这个光谱的两端。我们的结果表明，木本物种群落之间的生态位差异促进了少数物种的快速侵占。这项研究表明，木本入侵物种并不符合“一刀切”的策略，生长形式和生理策略的多样性可能使实现旨在保护或恢复草原群落的管理目标更具挑战性。