Abstract:Yearly Landsat imagery from 1986 to 2011 of a typical plantation region in Fogang County, Guangdong Province, southern China, was used as a case study. The pre-processing Landsat Ecosystem Disturbance and Adaptive Processing System (LEDPAS) algorithm was implemented to generate standard surface reflectance images to construct a Landsat time series stack (LTSS). The LTSS was fed to the Landsat-based detection of trends in disturbance and recovery (LandTrendr) algorithm to monitor long-term changes in plantation disturbance and recovery, followed by an intensive validation and a continuous 24 years change analyses on annual change, and disturbance amount and duration. Validations derived from two chosen sample plots of 4 km2 indicated that the LandTrendr-based mapped disturbance results strongly agreed with those derived from the visual interpretation of the pre-and post-disturbance multispectral images and visualization of the local disturbance documents, with an error of 0.1 km2. Results indicated that the forest disturbances that occurred in Fogang County were relatively drastic. An annual disturbance of 1000 hm2 was witnessed for most years of the study, and an annual disturbance of over 2000 hm2 occurred in 1987, 2002, 2004, 2005, 2006, 2007, and 2009. Particularly, the disturbance of 1987 and 2007 exceeded 6000 hm2. In comparison to forest disturbance, forest recovery areas were relatively stable. Through a trend analysis of forest disturbance and recovery in Fogang County, forest disturbance and recovery areas mapped in the late 1980s through 1990s were less than those mapped after 2000, and the trend was lower than that after 2000. Since 2000, the forest disturbance areas have gradually increased, with a slight increase in forest recovery, but the overall magnitudes of forest disturbance exceeded those of forest recovery. The area of forest disturbance with a duration of 1 year accounted for 38%, 28% for a duration of 2 years, 25% for a duration of 3 years, and 7% for a duration of 4 years; these disturbances were classified as abrupt and short-term disturbance events. Gradual forest disturbance and recovery events for a duration over 4 years existed, but the overall areas were less than 100 hm2/a, and were highly different from the areas of abrupt disturbance events. Prior to 2000, abrupt and gradual disturbance areas were almost equal, with a gentle change. After 2000, abrupt disturbance areas were greater than those of gradual disturbances, with a maximum of 2800 hm2, and both abrupt and gradual disturbances showed an undulatory increasing trend. Based on the history and status of forest disturbances in Fogang County, the factors contributing to the environmental disturbance of forest plantations were analyzed to develop effective forest management strategies and countermeasures. The current study demonstrated the need to use dense time series images to map forest disturbance and recovery events in plantation forests. This approach could provide qualitative, locational, and quantitative forest change results for the land use decision-makers and conservation communities, enabling the strategic development of sustainable forest management and provide effective data support to evaluate forest productivity and carbon storage.