Widespread winners and narrow-ranged losers: Land use homogenizes biodiversity in local assemblages worldwide

Human use of the land (for agriculture and settlements) has a substantial negative effect on biodiversity globally. However, not all species are adversely affected by land use, and indeed, some benefit from the creation of novel habitat. Geographically rare species may be more negatively affected by land use than widespread species, but data limitations have so far prevented global multi-clade assessments of land-use effects on narrow-ranged and widespread species. We analyse a large, global database to show consistent differences in assemblage composition. Compared with natural habitat, assemblages in disturbed habitats have more widespread species on average, especially in urban areas and the tropics. All else being equal, this result means that human land use is homogenizing assemblage composition across space. Disturbed habitats show both reduced abundances of narrow-ranged species and increased abundances of widespread species. Our results are very important for biodiversity conservation because narrow-ranged species are typically at higher risk of extinction than widespread species. Furthermore, the shift to more widespread species may also affect ecosystem functioning by reducing both the contribution of rare species and the diversity of species’ responses to environmental changes among local assemblages.人类土地利用（服务于农业与定居活动）对全球生物多样性（biodiversity）造成了显著负面影响。然而，并非所有物种都会受到土地利用的不利影响，事实上部分物种可从新生境的形成中获益。地理稀有种（geographically rare species）相较于广布物种，可能会受到土地利用更强的负面影响，但受数据限制，此前始终无法开展覆盖全球多个演化支的、针对土地利用对窄分布物种（narrow-ranged species）与广布物种（widespread species）影响的评估。 本研究依托大型全球数据库展开分析，揭示了物种群落组成的一致性差异。与自然栖息地相比，受干扰生境中的群落平均包含更多广布物种，这一现象在城市区域与热带地区尤为显著。在其他条件均保持一致的前提下，该结果表明人类土地利用正在使全球各地的群落组成趋于同质化。受干扰生境中，窄分布物种的丰度有所降低，而广布物种的丰度则有所提升。 本研究结果对生物多样性保护具有重要意义：相较于广布物种，窄分布物种通常面临更高的灭绝风险。此外，群落向广布物种的转变还可能影响生态系统功能——一方面会削弱稀有种的生态贡献，另一方面会降低本地群落中物种对环境变化的响应多样性。