Reply on RC3

Abstract

The land of the conterminous United States (CONUS) has been transformed dramatically by humans over the last four centuries through land clearing, agricultural land expansion and intensification, and urban sprawl. Spatial-temporal data on long-term historical changes in land use and land cover (LULC) across the CONUS is essential for understanding and predicting the dynamics of coupled natural-human systems. A few efforts have focused on reconstructing historical databases to characterize changes in cropland and urban extent in the CONUS. However, the high-resolution and long-term trajectories of multiple land use types remain unclear. By integrating multi-source data, such as high-resolution remote sensing image-based LULC data, model-based LULC products, and historical census data, we reconstructed LULC history at an annual time scale and 1 km x 1 km spatial resolution for the CONUS in the past 390 years (1630–2020). The results show widespread expansion of cropland and urban land associated with rapid loss of natural vegetation. Newly reclaimed croplands are mainly converted from forest, shrubland, and grassland, especially in the Great Plains and North Central. Forest planting and regeneration accelerated the forest recovery in the Northeast and Southeast since the 1920s. The geospatial and long-term historical land use data from this study can be applied to assess the LULC impacts on regional climate, hydrology, carbon cycle, and greenhouse gas emissions. The datasets are available at https://doi.org/10.5281/zenodo.6469247 (Li et al., 2022).