Forestry Improvements to Restore the Environment Act of 2021 or the FIRE Act of 2021 This bill provides for salvage activities after a wildfire is contained on certain National Forest System lands. No later than 60 days after a wildfire is contained on such lands (1) the Forest Service, to the maximum extent practicable, shall complete a survey of the lands that were impacted by such wildfire; and (2) the Department of Agriculture (USDA) shall convert the timber sales applicable to such lands that were impacted by such wildfire to salvage sales. The bill designates a categorical exclusion for forest management activities where the primary purpose of the activity is for roadside salvage activities that allow for the removal of hazard trees that are within 200 feet of a roadway center line. Activities carried out pursuant to this bill shall be subject to judicial review in the same manner as authorized hazardous fuels reduction projects. A court may not order a preliminary injunction enjoining the USDA from proceeding with timber sales authorized under this bill.