To cite package 'FIESTA' in publications use:

  Frescino, Tracey S.; Moisen, Gretchen G.; Patterson, Paul L.; Toney,
  Chris; White, Grayson W. (2023). FIESTA: A forest inventory
  estimation and analysis R package. Ecography 2023: e06428 (ver. 1.0).

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {FIESTA: A forest inventory estimation and analysis R package},
    author = {Tracey S. Frescino and Gretchen G. Moisen and Paul L. Patterson and Chris Toney and Grayson W. White},
    year = {2023},
    organization = {USDA Forest Service, Rocky Mountain Research Station},
    address = {4919 S 1500 W, Ste. 200, Riverdale, UT, USA},
    note = {tracey.frescino@usda.gov},
  }