A multi-satellite comparison of forest growth between karst and adjacent non-karst nature reserves

Karst forests have long been considered inferior to non-karst forests under natural conditions because of the high leakage and thin soils of the karst critical zone. However, intensive human interventions in these regions have largely obscured the role of geological background in forest growth, making the underlying hypothesis difficult to validate. This study aims to test the hypothesis that forest growth in karst landscapes is inferior to that in non-karst landscapes under natural conditions without human intervention. Nature reserves are free from human interventions and provide a representative and typical test bed to validate this hypothesis. By integrating multisource satellite datasets (greenness, EVI; coverage, LAI; and productivity, NIRv), we comprehensively compared forest dynamics and their environmental drivers (temperature, CO 2 , radiation, precipitation, relative humidity, and soil moisture) between 19 karst nature reserves (KNRs) and 20 adjacent non-karst nature reserves (NKNRs) from 2001 to 2022. Our results revealed no significant difference in forest growth between KNRs and NKNRs, which differs from the traditional hypothesis. Specifically, during 2001–2022, forest dynamics showed a comparable mean status (VIs avg ), an increasing rate (+ ΔVIs), and an increasing proportion of forests (+ ΔVIs area ) between KNRs and NKNRs. Furthermore, environmental factors explained 80–85% of the forest variability in KNRs, which was significantly greater than that in NKNRs (71–82%). This pattern is driven primarily by the significantly higher sensitivity to temperature and CO 2 (P < 0.05) in KNRs (74–83%), indicating the dominant role of climatic factors in forest growth. This study highlights that the role of karst bedrock in constraining forest growth is more limited than previously assumed. Given sufficient recovery time without human intervention, forests in karst landscapes can achieve a status comparable to those in non-karst landscapes. However, compared with non-karst landscapes, forests in karst landscapes are more sensitive to climatic variations. These findings provide critical theoretical foundations for future ecological restoration and climate adaptation strategies in ecologically fragile karst landscapes under global warming.