Disruptions in species interactions derived from forest fragmentation are a major driver of biodiversity declines. Atmospheric bromeliads, a group of extreme epiphytes in the Tillandsia genus, often thrive in anthropogenic landscapes, spreading beyond their usual distribution. Here, we investigate how distinct tree densities affect the interactions between tree traits and patterns of atmospheric bromeliad host selection, abundance, functional composition, and canopy distribution. We measured a total of 3130 atmospheric bromeliads hosted on 140 of the 384 trees sampled and found a greater contribution of tree traits on their host selection and abundance at low tree density. We observed that distinct tree traits were significantly correlated to atmospheric bromeliad traits under low and high tree densities, with most correlations positive under low tree density and negative under high tree density. Additionally, the canopy distribution of individuals under high tree density was less scattered and slightly restricted to outer canopy layers. Shading levels seem to be a strong environmental filter on atmospheric bromeliad fitness, limiting their spread in forests with high tree densities; however, major reductions in tree density may allow atmospheric bromeliads to spread to other canopy layers and increase their abundance, mainly boosted by traits related to tree size. Our results suggest that reductions in tree densities of forests may alter ecological interactions among plants, which could lead to the spread of opportunistic species.

中文翻译：

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降低树木密度会影响树木与大气铁兰种（凤梨科）之间的相互作用

由森林破碎造成的物种相互作用的破坏是生物多样性下降的主要驱动力。大气凤梨科，铁兰中的一组极端附生植物属，通常在人为景观中壮成长，并超出其通常的分布范围。在这里，我们调查不同的树木密度如何影响树木特征与大气凤梨寄主选择，丰度，功能组成和冠层分布之间的相互作用。我们对384棵树木中的140棵中的3,130个大气凤梨科寄主进行了测量，发现在低树密度下，树木性状对其寄主选择和丰度的贡献更大。我们观察到，在低和高树密度下，明显的树木性状与大气菠萝科植物的性状显着相关，在低树密度下，大多数相关性为正，在高树密度下为负相关。此外，高树密度下个体的冠层分布较少散布，仅局限于外层冠层。遮荫水平似乎是大气凤梨科植物适应性的强大环境过滤器，限制了它们在高树木密度的森林中的传播；然而，树木密度的大幅度降低可能会使大气凤梨科植物传播到其他冠层，并增加其丰度，这主要是由于与树木大小有关的性状所致。我们的结果表明，森林树木密度的降低可能会改变植物之间的生态相互作用，这可能导致机会性物种的扩散。树木密度的大幅降低可能会使大气凤梨科植物传播到其他冠层，并增加其丰度，这主要是由于与树木大小有关的性状所致。我们的结果表明，森林树木密度的降低可能会改变植物之间的生态相互作用，这可能导致机会性物种的扩散。树木密度的大幅降低可能会使大气凤梨科植物传播到其他冠层，并增加其丰度，这主要是由于与树木大小有关的性状所致。我们的结果表明，森林树木密度的降低可能会改变植物之间的生态相互作用，这可能导致机会性物种的扩散。