Context

Dispersal is a crucial process for species persistence under natural and disturbed landscapes. The effectiveness of stepping stones as a connectivity strategy for increasing dispersal success depends on landscape structure and animal behaviour, such as the perceptual range.

Objectives

We quantify the relative contribution of stepping stones (small fragments and scattered trees) to dispersal success considering interactions with perceptual range, habitat amount and configuration.

Methods

We develop an individual-based model (IBM) to simulate the dispersal movement of small mammals. The model is parametrized using empirical estimates of perceptual range and movement properties (turning angles and steps length). Simulations are implemented in landscapes with varying gradients of habitat amount and clumpiness, with and without the presence of stepping stones.

Results

Small patches and scattered trees combined, or only scattered trees, have a positive effect on dispersal. Meanwhile, the presence of only small patches has negative effects on dispersal. Habitat amount positively influences dispersal, which decreases abruptly when the habitat amount is less than 20%. This threshold disappears in the presence of stepping stones. In landscapes with intermediate levels of habitat amount, landscape fragmentation (low clumpiness) has a positive effect on dispersal success.

Conclusions

Stepping stones, especially scattered trees, are a fundamental connectivity strategy for the conservation of small non-flying vertebrates in human-modified landscapes, particularly landscapes with less than 20% of habitat amount. However, small patches stepping stones may act as ecological traps leading the individuals to dead-ends. Their effectiveness in improving dispersal depends on both landscape structure and perceptual range.

中文翻译：

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通过支离破碎的景观扩散运动：垫脚石和感知范围的作用

语境

散布是自然和受干扰景观下物种持久性的关键过程。垫脚石作为提高传播成功率的连通性策略的有效性取决于景观结构和动物行为，例如感知范围。

目标

考虑到与感知范围、栖息地数量和配置的相互作用，我们量化了垫脚石（小碎片和分散的树木）对传播成功的相对贡献。

方法

我们开发了一个基于个体的模型 (IBM) 来模拟小型哺乳动物的扩散运动。该模型使用感知范围和运动属性（转动角度和步长）的经验估计进行参数化。模拟在具有不同栖息地数量和块状梯度的景观中实施，无论是否存在踏脚石。

结果

小斑块和零星树木相结合，或仅零星树木，对传播有积极影响。同时，只有小斑块的存在会对传播产生负面影响。栖息地数量对扩散有积极影响，当栖息地数量小于20%时，扩散急剧减少。在存在垫脚石的情况下，此阈值会消失。在栖息地数量处于中等水平的景观中，景观碎片化（低块状）对扩散成功有积极影响。

结论

垫脚石，尤其是散落的树木，是保护人类改造景观中小型非飞行脊椎动物的基本连接策略，尤其是栖息地数量不到 20% 的景观。然而，小块垫脚石可能会作为生态陷阱，将个体引向死胡同。它们在改善扩散方面的有效性取决于景观结构和感知范围。