ABSTRACT: Every year in the contiguous United States (U.S.), on average 2.3-2.7 million hectares of wildlands were burned; and fire burned area also showed a strong increasing trend since about 1990. Wildland fires have profound ecosystem and social consequences. For instance, fire burning releases greenhouse gases and aerosols into the atmosphere; and frequently returning fires can also modify landscape and ecosystem functions. In particular, many of the fire impacts on wildland ecosystem functions are made through fire-altered vegetation spatial structure and species composition, such as potentially increased ecosystem vulnerability to the invasion of non-native species. Forests are significant biological components of the land system, which play a critical role in carbon cycles and provide numerous ecosystem services and products. An improved understanding of fire disturbance impacts on forest community structures is therefore important for forest management under consistent disturbances from fires and other agents.Investigations on post-fire forest succession and community structure changes are often of local scales with limited spatial coverage. Understanding of fire impacts on forest community structure and species composition over a broad geographical scale is still scarce. Here, we incorporated large data sets, including the U.S. Forest Inventory and Analysis (FIA) data, MODIS derived the Global Fire Emission Database Version 4 (GFEDv4), and the Monitoring Trends in Burn Severity (MTBS) database, to investigate how fire disturbances, including their severity, may have impacted forest community structure and species composition in the contiguous U.S. over recent years. Preliminary results suggested that fire disturbances had highly variable impacts on post-fire forest community species composition, seedling regeneration, and understory layer coverage of different forest types and geographical regions, which also depended on fire severities. Our results highlight the importance of long-term monitoring data of fire occurrence and forest dynamics for meeting forest management and research needs.