Data from: Evaluating interspecific niche overlaps in environmental and geographic spaces to assess the value of umbrella species

The concept of umbrella species assumes that concentrating resources on the protection of a single species contributes to the conservation of a suite of species and ecological processes belonging to the same ecosystem. The environmental requirements and geographical distribution of the umbrella species should thus overlap those of the group of targeted species. In western France, the conservation of several large grassland floodplains relies on agri-environmental schemes targeting one single bird species, the corncrake Crex crex. It is considered as an umbrella species but no real assessment of its effectiveness has been carried out so far. We used a two-step methodology to assess the potential of the corncrake to act as an umbrella species by estimating niche overlap in the environmental and geographic space between the main ground-nesting species of the bird community in these grasslands, including the corncrake and four passerines. The five species showed substantial differences in their ecological niches so that their distributions did not perfectly overlap. Overlaps in predicted distributions between pairs of species depended on the threshold used to convert suitability to binary maps. Moreover, the number of species that could be protected by a candidate umbrella species was affected by the overlap criterion of success. Although the corncrake may be used as an umbrella species, it would be outperformed by several passerine species. Our study highlights the potential of using niche overlap to select umbrella species. It also reveals the importance of analysing the sensitivity of outputs when changing thresholds and overlap criteria.

伞护种（umbrella species）的核心概念为：将保护资源集中于单一物种，即可助力同一生态系统内多个物种类群与生态过程的保护。因此，伞护种的环境需求与地理分布，应当与目标物种类群的环境需求和地理分布相重叠。在法国西部，数处大型草原洪泛区的保护工作依托针对单一鸟类物种——长脚秧鸡（corncrake，*Crex crex*）的农业环境计划开展。尽管长脚秧鸡被视作伞护种，但截至目前尚未有针对其保护有效性的实证评估。本研究采用两步法开展研究，通过估算该类草原鸟类群落中主要地面筑巢物种（包含长脚秧鸡与4种雀形目鸟类）在环境与地理空间中的生态位（niche）重叠程度，评估长脚秧鸡作为伞护种的潜力。研究结果显示，5个物种的生态位存在显著差异，因此其分布并未完全重叠。物种间预测分布的重叠程度，取决于将适宜性转换为二元分布图所使用的阈值。此外，候选伞护种所能保护的物种类群数量，会受到成功重叠判定标准的影响。尽管长脚秧鸡可被用作伞护种，但其保护效果不如数种雀形目鸟类。本研究凸显了利用生态位重叠筛选伞护种的潜力，同时也揭示了在变更阈值与重叠判定标准时，分析输出结果敏感性的重要性。