meeting projected regional timber and range grazing 

 demands, and their impact on other resource uses, 

 environmental effects, intensity of land use, and costs. 

 The demands for timber and range grazing serve as 

 the basic output requirements which the model must 

 achieve. The model incorporates a technique for 

 estimating the change in wild ruminant grazing, 

 water yield, dispersed recreation use, and sediment 

 yield. Wild ruminant grazing and dispersed recreation 

 are produced to the level where the cost of one more 

 unit of that output would have been greater than 

 its benefit value. ^'' The results of the model for 

 the Southeast region will be shown in some detail. 

 Only highlights of applying the model to the other 

 regime will be given here. 



Southeast. — Sample results from the model of 

 supplying targeted timber and range grazing amounts 

 in 1985 and 1995 in the Southeast are shown in 

 table 8.1. Some of the impacts illustrated by this 

 table are: 



• In addition to meeting timber and range 

 targets in 1985, dispersed recreation can be 

 increased by 10 percent more than 1977 

 with the marginal benefits equalling mar- 

 ginal costs. However, in order to meet the 

 1995 targets for timber and range, dis- 

 persed recreation use will have to drop 

 below the 1977 use by 4 percent. 



• The impact of meeting the required tar- 

 gets are either beneficial or negligible on 

 herbage and browse production, wild 

 ruminant grazing, water yield, and storm 

 runoff. 



• Increased timber harvesting and grazing 

 by 1985 and 1995 will require moving to 

 lands which are more susceptible to ero- 

 sion and therefore result in substantially 

 increased sediment yields. 



• Meeting the timber and range targets plus 

 increasing dispersed recreation to the 

 point where marginal costs equal marginal 

 benefits requires intensification of man- 

 agement. While only 11 percent of the 

 National Forests were managed inten- 

 sively in 1977 (according to the definition 

 of "intensive" used for model specifi- 

 cation), 23 and 28 percent will have to be 

 managed intensively by 1985 and 1995, 

 respectively. Similarly, on State-owned 

 or privately owned lands, 35 percent will 



^ The model restruction technique is discussed in Ashton, et. al., 

 op. cii. 



■•For a discussion on benefit values see; Dyrland, Richard E., 

 Working paper 1980 RPA value. Unpublished report on file at 

 Washington Office. Forest Service, U.S. Department of Agricul- 

 ture, Washington, D.C.. May 8, 1979. 



require intensive management by 1995 

 compared to 22 percent in 1977. 

 • As management intensity increases and re- 

 sources are supplied from less productive 

 lands, the marginal costs of producing 

 timber and range grazing will increase by 

 substantial amounts. 



South Central. — In the South Central region dis- 

 persed recreation initially displays a complementary 

 relationship to the increasing demands for timber and 

 range grazing, as recreation rises 49 percent by 1985. 

 However, as timber and range demands increase 

 beyond the 1985 level, dispersed recreation drops. 



Herbage and browse steadily increase in response 

 to the rising range grazing demand. Wild ruminant 

 grazing rises continually throughout the projection 

 period, suggesting that this resource use is comple- 

 mentary with increasing demands for timber and 

 and range grazing. This relationship is the result 

 of increased timber harvest which, in this region, 

 apparently improves the opportunities for wildlife 

 habitat. 



Water yield and storm runoff are again very insen- 

 sitive to the increases in timber and range grazing, 

 a result of the geology, topography, and soil types of 

 the region. However, sediment yield does rise sub- 

 stantially, as the acreage of intensive use increases 

 to meet higher demands. 



As in all other regions, the marginal costs of meeting 

 timber and range grazing demands increase substan- 

 tially. 



North Central. — The model results indicate some 

 important changes occur in the levels of resource 

 use and environmental effects as a result of meeting 

 the projected demands for timber and range grazing. 

 Herbage and browse and sediment yield increase to 

 a 1995 peak of 108 percent and 124 percent above 

 the 1977 value, respectively. Sediment yield is pri- 

 marily dependent on the total number of acres under 

 treatment and associated intensive land use. 



Water yield is apparently insensitive to changes in 

 other outputs as it remains unchanged with time. 

 Storm runoff rises slightly to a peak of 5 percent 

 above the base year in 1995, due very Hkely to the 

 increase in intensive land use necessary to meet 

 range grazing demands. 



The intensity of land use values remains virtually 

 unchanged on National Forest System and other 

 Federal lands. However, on State and private lands, 

 which comprise about 80 percent of the region, the 

 intensity of land use increases with demands. 



The marginal cost of softwood timber remains 

 unchanged over time, suggesting that the increasing 

 demands are well within the productive capability 



323 



