Location of Wetland Change 



Wetland Conversion for Agriculture 



Loss of wetlands between the mid-1950's and 

 mid-1970's was concentrated in the Southeast and 

 Lower Mississippi (fig. 2). Louisiana and Missis- 

 sippi lost more than 1.7 million acres of wetland 

 each, Arkansas lost more than 1.5 million acres, 

 and Florida lost more than 1.4 million acres of 

 wetlands. 



Wetland losses in the North Carolina pocosin area 

 and in Minnesota's prairie pothole region were also 

 substantial, with more than 500,000 acres lost in 

 each. Wetland loss in these six States was primarily 

 due to agricultural conversion. 



Figura 1 



Changes in U.S. wetlands, 1850-1982 



Million acres 

 250 



200 



150 



100 



50 



HWl 



Low 



Low 



NWSIK 



Onulw 

 39 



NWSTA 



hit 



SK Nn 



and 



Fcdaral 



Nn 



1850 1919 Mid-1950's Mid-1970's 1982 



SoutOV {Xf. M. 19. 38. 43. S3. S4) 



Figura 2 



Wetland loss mid-1950's to mid-1970's 



Loss of wetlands in 

 1.000 acres 



^^^^:' 



^ 



0-100 

 100-500 

 500-1.000 

 More than 1.000 

 Increased 



Given the exploitive attitude toward natural 

 resources that prevailed in the late 19th and early 

 20th centuries, it is not surprising that most interest 

 in wetlands centered on their potential for conver- 

 sion to "useful" purposes, mainly agriculture. Six 

 surveys were conducted between 1906 and 1982 to 

 assess, among other things, the agricultural poten- 

 tial of remaining wetlands across the Nation (see 

 app. 1). There was little attempt to use consistent 

 wetland defintions or comprehensiveness of 

 coverage in these inventories. Consequently, they 

 provide little information for assessing long-term 

 trends in wetland loss. They do, however, reflect 

 changes in the perception of wetlands as a resource 

 for potential conversion to farming. 



Historical data on drainage have been developed 

 for analysis of investments in natural resource 

 capital (30). While drainage is often installed on 

 land that is merely wet, not wetland, these data in- 

 clude information on wetlands that have been 

 converted. 



Figure 3 shows the results of the six conversion 

 potential assessments and Pavelis' data on installed 

 drainage. These data allow comparison of conver- 

 sion potentials perceived by Government officials 

 and by farmers actually investing in drainage. 

 Drainage potential is based on the six inventories 

 and interpolated linearly for 5-year intervals be- 

 tween inventories, so it is comparable with the data 

 on drainage installation. 



Drained land increased dramatically during the first 

 20 years of the 20th century, leveled off during the 



Figura 3 



Installed and potential drainage, 

 United States, 1905-80 



1900 



1920 



1940 



1960 



1980 



Sourcw (a) 



V Intsfpolated Irom 1907, 1919. 1946. 1958. 1967. 1977. and 1982 data. 

 Souroa: (2. U. 30. S), 52, S3. £7). 



