Ignoring spatial heterogeneity in social conditions overestimates extinction risk of aquatic macrophytes.

Abstract: Aim: Abandoned lands are expanding globally due to depopulation in rural areas; biodiversity is declining due to the cessation of traditional management practices. However, the awareness of abandonment as a serious threat is still limited. Knowledge of the influence of the responsible factors on the assessment of regional extinction risk of species due to abandonment is sparse although it is indispensable for conservation decision‐making. This study aimed to clarify the influence of the heterogeneity in abandonment risk and interspecies differences in sensitivity to abandonment on regional species extinction risk and to identify the attributes of the species whose extinction risk is prone to be assessed inaccurately by ignoring the abandonment risk. Location: Awaji Island, Hyogo, Western Japan. Methods: We assessed the extinction risk of 64 species of macrophytes under four scenarios: 2 × 2 combinations whether to incorporate interspecies differences in sensitivity to abandonment and the abandonment risk, respectively. Results: Ignoring the abandonment risk overestimated the extinction risk of most species by 10%, whereas ignoring interspecies differences in sensitivity did not significantly affect the extinction risk. Ignoring the abandonment risk overestimated the extinction risk of emergent plants by 12%, whereas it underestimated that of free‐floating plants or threatened plants by 5%. Spatial bias in abandonment risk markedly reduced the correlation between the extinction risk and the frequency of species occurrence. Main conclusions: The abandonment risk was more effective in accurately assessing the extinction risk due to abandonment than interspecies differences in sensitivity. Extinction risk of emergent, free‐floating or threatened species were assessed inaccurately by ignoring the abandonment risk. Focusing only on the area of occurrence or the extent of occurrence of a species as a surrogate for its extinction risk is likely to produce inaccurate assessments, and thus should be avoided. [ABSTRACT FROM AUTHOR]