Shofner, Jerrell, “Forced Labor in the Florida Forests,” Journal of Forest History 25, No. 1 (Jan 1981): 14-25 that can be found here:
For almost three quarters of a century after the end of Reconstruction, the convict lease and debt-peonage systems provided cheap labor for some forest industry firms in Florida. In the photo above, taken ca. 1938, a convict plants seedlings on a state-owned property as part of a reforestation project.
Additional articles you may be interested in can be found below:
"There are 27 phosphate mines in Florida, covering more than 450,000 acres. Nine phosphate mines are currently active. Nine mines are 100 percent reclaimed and released from reclamation obligations. The remaining mines are either not started or are shut down. Phosphate mines typically range in size from approximately 5,000 to 100,000 acres. Phosphate mining disturbs between 3,000 to 6,000 acres annually in Florida. Approximately 25 to 30 percent of these lands are wetlands or other surface waters."
From Florida EPA - Click here or on image above to read full article.