Context

Habitat fragmentation and land use intensification are major threats to biodiversity worldwide, affecting both species (SD) and genetic (GD) diversity. It remains unclear whether SD and GD respond to the same components of landscape changes and to what extent they correlate in fragmented systems.

Objectives

We explore the role of current and historical patch and landscape features on SD and GD, in and between forest fragments, along a gradient of landscape matrix permeability. We seek the circumstances under which SD and GD correlate.

Methods

Within three contrasted agricultural landscapes of northern France, we assessed vascular plant SD and the GD of two plant species with contrasted life history traits in all forest fragments. Species richness and expected heterozygosity were taken as proxies for SD and GD respectively. Using regression and correlation analyses, we explored relationships between SD/GD and local, landscape and historical factors; and between SD and GD.

Results

When landscape permeability is above a certain threshold, SD and GD appear to be patterned by the same processes, which results in a positive SD-GD correlation. This permeability threshold is species-specific, depending upon species’ dispersal traits and niche width. The SD-GD correlation depends upon current and past landscape permeability, so that the lack of correlation emerges as the rule in weakly permeable landscape matrices, especially when fragments are small.

Conclusions

Landscape matrix permeability and patch features drive SD and GD of vascular plants within and between forest fragments. A generalist, fast-colonizing species better reflects diversity patterns in fragmented forests.

中文翻译：

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不同渗透性农业景观中森林元群落内物种和遗传多样性的驱动因素

语境

栖息地破碎化和土地利用集约化是全球生物多样性的主要威胁，影响物种 (SD) 和遗传 (GD) 多样性。目前尚不清楚 SD 和 GD 是否对景观变化的相同组成部分做出反应，以及它们在碎片化系统中的相关程度如何。

目标

我们沿着景观矩阵渗透率的梯度探索了当前和历史斑块和景观特征对 SD 和 GD、森林碎片内部和之间的作用。我们寻找 SD 和 GD 相关的情况。

方法

在法国北部三个对比鲜明的农业景观中，我们评估了所有森林片段中具有对比生活史特征的两种植物物种的维管植物 SD 和 GD。物种丰富度和预期杂合度分别作为 SD 和 GD 的代理。使用回归和相关分析，我们探索了 SD/GD 与当地、景观和历史因素之间的关系；在 SD 和 GD 之间。

结果

当景观渗透率高于某个阈值时，SD 和 GD 似乎由相同的过程形成模式，这导致 SD-GD 正相关。这个渗透性阈值是物种特异性的，取决于物种的扩散特征和生态位宽度。SD-GD 相关性取决于当前和过去的景观渗透率，因此在弱渗透性景观矩阵中，缺乏相关性是普遍存在的，尤其是当碎片很小时。

结论

景观基质渗透性和斑块特征驱动森林碎片内和森林碎片之间维管植物的 SD 和 GD。一个多面手、快速定殖的物种更能反映支离破碎的森林中的多样性模式。