The negative effects of habitat loss on biodiversity are undisputed, while the effect of habitat configuration, i.e., the spatial arrangement of habitat area, has been debated for decades. To develop a more comprehensive understanding, it is important to know when and how configuration matters. In this study, we tested whether forest configuration influences the richness of species in groups characterized by varying shade tolerance in different ways and how such effects are related to habitat amount (i.e., the percentage of forest cover) at the landscape scale. Based on 104 survey plots (each measuring 1 ​km2) of vascular plants on the Swiss Plateau, and using two statistical approaches (i.e., multiple regression and path analysis), we modeled the effects of habitat amount and configuration (measured as number of forest patches, total edge length, and proximity index) across all the plots and separately for three habitat amount classes: <10%, 10%–30%, and >30% forest cover. When we modeled all plots together, we found that, after controlling for habitat amount, the forest configuration significantly affected species richness. When we considered the different habitat amount classes separately, most of the significant effects of habitat configuration on species richness occurred only for habitat amounts of <10% forest cover. Additionally, the response to forest configuration differed among species with different shade tolerances. When forest area was <10%, the effects of the number of patches and the total edge length on the species richness of light-demanding forest species were greater than the effect of habitat amount, whereas neither configuration metric affected the richness of shade-tolerant species. In conclusion, our findings highlight the importance of configuration in landscapes with a small amount of habitat. At the same time, they demonstrate that considering the confounding factors (e.g. species traits) is important for understanding the effects of forest configuration on biodiversity and that generalizations remain a challenge for landscape ecology.

中文翻译：

---

生境配置对瑞士高原森林覆盖梯度生物多样性的影响


栖息地丧失对生物多样性的负面影响是无可争议的，而栖息地配置的影响，即栖息地区域的空间布局，已经争论了几十年。为了更全面地了解配置，了解配置何时以及如何重要非常重要非常重要。在这项研究中，我们测试了森林配置是否影响以不同耐荫方式表征的群体中物种的丰富度，以及这种影响与景观尺度上的栖息地数量（即森林覆盖率的百分比）的关系。基于瑞士高原维管植物的 104 个调查图（每个测量 1 km2），并使用两种统计方法（即多元回归和路径分析），我们模拟了栖息地数量和配置（以森林斑块数量、总边缘长度和邻近指数衡量）的影响在所有地块中，并分别针对三个栖息地数量类别： <10%、10%–30% 和 >30% 森林覆盖。当我们将所有样地建模在一起时，我们发现，在控制栖息地数量后，森林配置显着影响了物种丰富度。当我们分别考虑不同的栖息地数量类别时，栖息地配置对物种丰富度的大多数显着影响仅发生在 <10% 森林覆盖率的栖息地数量上。此外，不同耐荫性的物种对森林形态的响应不同。当森林面积为 <10% 时，斑块数量和总边长对需光森林物种丰富度的影响大于生境数量的影响，而两个配置指标都不会影响耐阴物种的丰富度。 总之，我们的研究结果强调了配置在栖息地较少的景观中的重要性。同时，他们表明，考虑混杂因素（例如物种特征）对于理解森林配置对生物多样性的影响很重要，并且概括仍然是景观生态学的一个挑战。