Long‐Term Population Declines of Habitat‐Shifting Species in the City: A Living Planet Index Approach for Berlin, Germany

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ABSTRACT Urbanisation is a major driver of global biodiversity change, affecting both terrestrial and aquatic ecosystems. To assess biodiversity change at the city scale, indicators are needed that can represent long‐term population trends from heterogeneous monitoring data. The Living Planet Index (LPI) addresses policy‐relevant questions such as “how much has biodiversity declined where?”, while the Diversity‐weighted LPI (DW‐LPI) can reduce bias caused by uneven taxonomic representation. Here, we evaluate the application of both indices for long‐term urban biodiversity assessment in Berlin, Germany. We analysed population trends of habitat‐shifting species in Berlin waterbodies, focusing on odonates (dragonflies, damselflies) and amphibians (frogs, toads, newts). These taxa depend on both aquatic and terrestrial habitats and are therefore sensitive to urban environmental change. We compiled data from 16 waterbodies representing different habitat types across the city, spanning 60 years for odonates and 40 years for amphibians. Both taxa showed significant long‐term declines, amounting to > 50% in odonates and 76% in amphibians. Amphibians declined more strongly, likely reflecting their lower mobility and higher sensitivity to habitat fragmentation and disrupted connectivity. The DW‐LPI showed smaller declines than the unweighted LPI, indicating that diversity‐weighting reduced the influence of uneven taxonomic representation. Our findings show that LPI and DW‐LPI approaches can be applied at the urban scale and provide useful indicators of population change. However, results must be interpreted cautiously when datasets have limited temporal continuity, spatial coverage or taxonomic balance. The observed declines likely represent conservative estimates and highlight the need for structured, continuous and standardised biodiversity monitoring in Berlin.