Publication characteristics, topic trends and knowledge domains of karst ecological restoration: a bibliometric and knowledge mapping analysis from 1991 to 2021

Aims Karst ecological restoration (KER) publication characteristics, topic trends, and knowledge domains were analysed to provide a global perspective. Methods Bibliometric and knowledge map analyses were used to analyse KER documents (319) in the WoSCC. The whole period was divided into the germination (GP), slow growth (SGP) and rapid growth (RGP) periods based on the number of annual publications (NAP). Results (1) The NAP increased over time, with China contributing the most. (2) The study topics varied and flourished over time. Plant was the most studied class and Animal the least studied in the Biology category. In the Environment category, Water was the most studied medium in the GP, while Soil was the most studied in the SGP and RGP. Remote sensing and Model were the leading methods in the SGP and RGP; Field investigation and/or experimental methods, including Leaf traits, Vegetation investigation, and Chlorophyll fluorescence, were the main methods in the GP. Ecological engineering was the leading restoration method overall. Planting pattern was a new restoration method in the SGP, while Biochar, Seed bank, and Soil translocation were new methods in the RGP. (3) Eleven knowledge domains and 10 vital documents well support studies on KER. Future research directions are proposed. Conclusions The results provide a new, global, objective perspective for understanding KER research over the past 3 decades.