To detect the trend of vegetation change in Changbai mountain, analyze the dynamic changes in vegetation and its stability, and reveal the impact of the natural forest resource protection project on vegetation restoration in Changbai mountain. This study aims to provide scientific reference and key data support for vegetation restoration and ecological environment protection in the area.

The Quanyang Forestry Bureau on the northwest slope of Changbai mountain was taken as the research area. Surface reflectance data provided by Landsat series satellites from 1993 to 2023 were selected using the Google Earth Engine (GEE) platform. After preprocessing and correction, the spatial-temporal dynamic changes of forest vegetation coverage (FVC) in the operational area of Changbai mountain were calculated and analyzed. Using the high-precision land cover classification dataset (GLC_FCS30), land cover data for 1995, 2000, 2010, and 2020 were obtained. Based on the actual conditions, land cover types were divided into evergreen coniferous forest, deciduous coniferous forest, deciduous broadleaf forest, mixed forest, cultivated land, grassland, built-up land, wetland, and water bodies. Combined with Theil-Sen trend analysis and the Mann-Kendall test, the LandTrendr method was used to construct time series data based on the normalized burning rate to detect disturbances in forest vegetation over the past 30 years, and the trend of FVC changes was analyzed in detail.

1) The dominant land use type is deciduous broadleaf forest, and the total area of forest land, wetland, and water increased year by year, while the area of cultivated land significantly decreased. 2) From 1993 to 2023, FVC in the study area recovered to a high vegetation cover level after being seriously damaged, but the forest ecosystem remained unstable. The overall spatial distribution trend is “high in the west and low in the east, high in the north and low in the south”. 3) The annual disturbance area in the study area decreased year by year, mainly in the central region. The disturbance peak in 2014 was caused by the construction of the Heda expressway.

Under the influence of the natural forest resource protection project, forest coverage has been effectively restored and the degree of disturbance has been significantly reduced.

Monitoring vegetation change trends on the north slope of Changbai Mountain, analyzing the relationship between vegetation distribution and different factors and changes in forest disturbance, with a view to revealing more comprehensively the vegetation changes in the study area before and after the Natural Forest Resource Protection Project, it provides a scientific basis for evaluating the effect of the Natural Forest Resource Protection Project and formulating vegetation resource restoration measures and ecological environment protection policies.

Based on the Google Earth Engine (GEE) platform, this study used Landsat remote sensing data from 1987 to 2020, using normalized difference vegetation index (NDVI) and normalized combustion rate (NBR), based on Sen-Theil trend analysis, Mann-kendall test, geographic detector and LandTrendr change detection algorithm, the temporal and spatial distribution characteristics and change trend of vegetation cover in Baihe Forestry Bureau were analyzed. Based on the data of annual mean temperature, average annual precipitation, altitude, slope, forest category and forest type, the effects of different factors on the spatial distribution of vegetation cover were studied.

From 1987 to 2020, the overall NDVI in the study area showed an increasing trend, while in 2000, it showed a non-significant decreasing trend in most areas, in particular, the first stage of the Natural Forest Resource Protection Project was the most significant trend of improvement; The spatial distribution of NDVI was strongly explained by temperature and precipitation, followed by forest type and altitude; From 1987 to 2020, the annual disturbance area of the study area showed a fluctuating and decreasing trend. Before 2000, forest disturbance was relatively frequent. After the implementation of the Natural Forest Protection Project in 2000, the area of forest disturbance decreased significantly, and forest disturbance mainly occurred in the central and northern parts of the study area, no significant disturbance was observed in the southern deciduous coniferous forest area during the study period.

Over the past 30 years, the vegetation on the northern slope of Changbai Mountain has shown an improvement trend, and the Natural Forest Protection Project has played an important role in both vegetation improvement and disturbance reduction.