Table 7 — Herbage and shrub production before (1978) and after 

 (1980, 1985) treatment at Clay Springs 



Year 



Vegetation 1978 1980 1985 



Grasses 

 Perennial 

 Seeded 

 Native 

 Annual 

 Forbs 

 Sfirubs 



Total 



f^edian^ year 



estimate 

 f^edian year estimate 



adjusted to account 



for less productive 



soils^ 



' Pounds per acre 3cts.e. 



'Estimated herbage and shrub production under conditions of median 

 September to June precipitation (Sneva and Britlon 1983). 



The Clay Springs soils were estimated to be 60 percent as productive as 

 the remainder of the study area (Sloneman and others 1979). 



'0 ± 

 6 ± 2 



12 ± 3 

 9 ± 2 



27 ± 12 



55 ± 16 284 ± 69 



89 ± 39 



114 ± 17 



33 ± 2 



67 ± 26 



103 ± 53 



53 ± 23 



18 ± 5 



18 ± 8 



54 ± 15 358 ± 58 4 76 ± 76 



37 

 62 



222 

 370 



331 

 552 



Table 8 — Herbage and shrub production for treated and control areas during pretreatment (1980) 

 and posttreatment periods (1982, 1985) at Church Hills 



1980 1982 1985 



Vegetation 



Chained 



Control 



Chained 



Control 



Chained 



Control 



Grasses 















Perennial 















Seeded 



'0 ± 



+ 



51 ± 10 



± 



243 ± 25 



1 ± 



Native 



42 ± 2 



26 ± 2 



122 ± 10 



31 ± 4 



133 ± 14 



50 ± 5 



Annual 



21 ± 2 



16 ± 2 



173 ± 13 



92 ± 10 



9 ± 3 



18 ± 4 



Forbs 



52 ± 3 



40 ± 3 



85 ± 12 



14 ± 4 



90 ± 10 



31 ± 4 



Shrubs 



41 ± 4 



51 ± 8 



159 ± 19 



113 ± 15 



76 ± 13 



64 ± 11 



Total 



156 ± 8 



133 ± 12 



590 ± 28 



250 ± 18 



551 ± 27 



164 ± 18 



Median^ year 















estimate 



98 



83 



408 



174 



383 



114 



'Pounds per acre, jtts.e. 



'Estimated herbage and shrub production under conditions of median September to June precipitation (Sneva 

 and Britton 1983). 



The assumptions from a more local viewpoint, developed 

 in a Forest Service environmental statement on chaining 

 of National Forest System lands in Utah (USDA FS 1973), 

 project that an increase of 500 to 700 lb per acre due to 

 chaining and seeding could be expected "under favorable 

 conditions." If the average pretreatment production of 

 106 lb per acre is added to the assumed increase, the envi- 

 ronmental statement projection is close (within 66 to 76 lb 

 per acre) to the actual measured production (table 9). Pro- 

 duction in the swale bottom topographic position exceeded 

 the environmental statement assumption by 228 to 428 lb 

 per acre. 



The productivity assumptions made in the soil report 

 (Stoneman and others 1979) were the furthest from 

 reality. The estimates were about double the average 

 measured production and even exceeded the production of 

 the swale bottom topographic position of the older seed- 

 ings by a substantial margin (-487 lb per acre) (tables 5, 

 6, and 9). 



Another evaluation approach used was to approximate 

 the production to be expected under normal precipitation. 

 The production levels of the four study areas were ad- 

 justed to a median-precipitation-year basis by the 

 methodology of Sneva and Britton (1983) (tables 5 to 8). 



8 



