* 



I 



t scientists possess even land capabilities are not precise. 



! However, the best available knowledqe on the following factors 



i were used in developing criteria: (a) ecology of the wetlands, 



(b) relationship of wetlands to the surrounding uplands, (c) 

 wetland threat from destruction, (d) the species of waterfowl 

 using the area, (e) the capability of a unit (delineated area) 

 to produce waterfowl and (f) the cost of the area per acre. 

 All of these were considered in delineation and in assigning 

 the relative value of the delineated area. Following is an 

 analysis of how the rating system was derived: 



Since the first printing of Circular 39, Wetlands of the United 

 States, in 1953, biologists working in wetland ecology have used 

 the handbook in various ways. There have been others who have 

 tried to improve upon our understanding of wetlands and water- 

 fowl. The publication, "Classification of Natural Ponds and , 

 Lakes In the Glaciated Prairie Region" by Stewart and Kantrud' 

 (1971) put new light on understanding wetland ecology. The 

 old type classification which incorporated water depth and 

 vegetative species to determine a wetland type was modified 

 by Stewart and Kantrud. Martin, etal. (1953) seemed to place 

 too much emphasis on water depths and cover interspersion to i 

 give the real picture of prairie wetlands. "^ It was during 

 a seven year study of wetlands in North Dakota that Stewart and 

 Kantrud made their adaptation *T:o classifying wetlands. We de- 

 cided that ecological similarities of the habitat of North Dakota 

 and Montana made their data and classification applicable 

 in most parts of Montana. Stewart and Kantrud incorporated a 

 "class" of wetlands which was determined by the pTant species 

 most dominant in the wetland and also a "cover type" which was 

 the percent of the wetland basin covered by emergent vegetation. 

 A detailed explanation of the classes and cover types is found 

 on pp. 5-13 of this publication and a comparison of the two 

 wetland classification studies on pp. 13-14. 



In personal correspondence with personnel of the Northern Prairie 

 Wildlife Research Center, I obtained information from the work 

 of several people on waterfowl production and land requirements. 

 Director Harvey Nelson compiled the data in a letter to the 

 Assistant Director, Operations, U.S. Fish and Wildlife Service, 

 Washington, D.C., dated July 10, 1973. It was from this memo 

 and others from Northern Prairie that the production criteria 

 of the rating system were developed. Following is an excerpt 

 from that memo: "For example, in semi -permanent ponds and lakes 

 (Class IV) we recommend that acquisition priority be given to 



