Data from: Citizen science program shows urban areas have lower occurrence of frog species, but not accelerated declines

Understanding the influence of landscape change on animal populations is critical to inform biodiversity conservation efforts. A particularly important goal is to understand how urban density affects the persistence of animal populations through time, and how these impacts can be mediated by habitat provision; but data on this question are limited for some taxa. Here, we use data from a citizen science monitoring program to investigate the effect of urbanization on patterns of frog species richness and occurrence over 13 years. Sites surrounded by a high proportion of bare ground (a proxy for urbanization) had consistently lower frog occurrence, but we found no evidence that declines were restricted to urban areas. Instead, several frog species showed declines in rural wetlands with low-quality habitat. Our analysis shows that urban wetlands had low but stable species richness; but also that population trajectories are strongly influenced by vegetation provision in both the riparian zone and the wider landscape. Future increases in the extent of urban environments in our study area are likely to negatively impact populations of several frog species. However, existing urban areas are unlikely to lose further frog species in the medium term. We recommend that landscape planning and management focus on the conservation and restoration of rural wetlands to arrest current declines, and the revegetation of urban wetlands to facilitate the re-expansion of urban-sensitive species.

探究景观变化对动物种群的影响，可为生物多样性保护实践提供关键决策支撑。明确城市密度如何随时间影响动物种群存续，以及栖息地供给能否调节此类影响，是一项尤为重要的研究目标；但针对部分类群的此类研究数据仍较为有限。本研究依托公民科学监测项目获取的数据集，针对13年间蛙类物种丰富度与出现格局受城市化的影响展开了调查。结果显示，周边裸露地面占比偏高（作为城市化水平的替代指标）的调查样点，其蛙类出现率始终较低；但本研究未发现种群衰退仅局限于城区的证据。相反，多个蛙类物种在栖息地质量欠佳的乡村湿地中同样出现了种群衰退。分析表明，城区湿地的物种丰富度较低但保持稳定；同时，种群动态轨迹显著受河岸带及更广范围景观内的植被配置影响。本研究区域未来城市用地规模的扩张，大概率会对多个蛙类物种的种群造成负面影响。但从中长期来看，现有城区的蛙类物种丰富度不太可能进一步下降。我们建议，景观规划与管理工作应聚焦于乡村湿地的保护与修复以遏制当前的种群衰退趋势，并通过城区湿地的植被恢复，助力对城市敏感的物种实现重新扩张。