income gains from conversion are dwarfed by 

 potential loss of benefits on nonwetland cropland. 

 Finally, opportunities to shelter nonfarm income 

 through tax breaks for conversion costs are small in 

 the prairie pothole area, compared with potential 

 tax breaks from the high clearing and drainage 

 costs in the pocosins. 



Indirect Motivations for Conversion 



Conversion of wetlands for farming can be ex- 

 pected if operators think conversion will be profit- 

 able. However, conversion to crop production can 

 occur indirectly, even though it may not be 

 profitable. 



Forestry and agriculture are often linked in wetland 

 conversion. Timber harvest of wooded swamps may 

 be the primary reason for some wetland destruc- 

 tion, with agriculture a residual user of the newly 

 cleared land. More than half of palustrine wetlands 

 converted to agriculture between the 1950*8 and 

 1970's were forested, but there is no information on 

 how much of these wet forests were directly 

 cleared for agriculture and how much went into 

 agriculture after these wetlands had been cleared 

 for timber. About 60 percent {42.6 million acres) of 

 palustrine wetlands were forested in 1982. 



Other wetlands are converted to remove obstacles 

 to large-scale agriculture. The prairie pothole 

 wetlands of the Dakotas and Minnesota are the 

 primary example of this kind of conversion. Here, 

 the value of the converted wetland for crop produc- 

 tion is less important than removing an obstacle to 

 straight-row farming or center-pivot irrigation 



systems. Isolated wetlands within fields require 

 more turns for machinery and form point rows and 

 dead rows that cannot be planted or harvested; 

 wetlands within fields also can restrict machinery 

 choices to smaller, less economical sizes. 



Many activities lower water tables, destroying 

 wetlands and making agricultural conversion more 

 attractive. Stream channelization for flood control, 

 as occurred in the Central and Southern Florida 

 Flood Control Project [42) and in the Lower 

 Mississippi Alluvium (44), can increase flow rates 

 and lead to lower water levels in nearby wetlands. 

 Irrigation can lower water levels through pumping 

 and through construction of dugouts as catchments 

 for irrigation water. 



These indirect modes of conversion will not be af- 

 fected by swampbuster sanctions, since they may 

 destroy wetlands well before the land is farmed. 



Wetland Values Foregone From 

 Conversion 



A variety of private and public benefits are lost 

 when wetlands are drained. These highly produc- 

 tive ecosystems are essential habitat for a variety of 

 fish and wildlife species. They provide many 

 ecological services and recreational opportunities, 

 as well as producing renewable resources. For the 

 most part, these benefits have not been measured in 

 monetary terms because they are hard to estimate. 

 Nevertheless, the values of wetlands are real and 

 need to be recognized when conversion is possible. 

 This section reviews values of wetlands and gives 

 examples of monetary estimates. 



Table 12— Discounted present value of wetland conversion with and without deficiency payments, North Dakota 

 prairie potholes' 



N/A = Not applicable. 



'Conversion of 10 wetland acres on a t,170-acre wheat operation with deficiency payments, sold after 10 years and discounted at 

 5-percent real interest. See text and appendix 2. 

 »Farm cash income plus nonfarm income plus capital gains less taxes owed and remaining debt on the conversion. 



18 



