SOILS 



DIRECT AND INDIRECT 

 EFFECTS ON SOIL 

 EROSION 



NO-ACTION ALTERNATIVE 



No timber harvesting or road construction, 

 obliteration, or reconstruction activities would 

 be implemented in the Beaver Lake analysis 

 area. As a result, existing sediment sources 

 that are contributing to lake sedimentation 

 would continue to impair lake water quality 

 and reduce overall site productivity. 



ACTION ALTERNATIVES A AND B 



Ground-based equipment used for timber 



harvesting and hazard reduction would cause 



localized compaction to soils on skid trails 



within harvest units. Severe compaction 



would lower site productivity on landings, 



main skid trails, and temporary roads. Soils in 



these areas would most likely experience a 



reduction in root penetration and water 



infiltration. 



I 



BMPs would be implemented through enact- 

 ment of timber sale contract clauses. These 

 practices would be used to reduce the occur- 

 rence and severity of soil compaction in all 

 altemahves. Specific acres of various compac- 

 tion intensities are quantified in Table IV-6 by 

 displaying direct effects on soil productivity. 



Erosion would most likely occur in areas 

 where water has the tendency to flow and 

 detach soil particles, such as skid trails, 

 landings, firelines, and roads. Removal of duff 

 layers through equipment operation would 

 accelerate erosion processes. The 

 implementation of appropriate, site-specific 

 BMPs would ensure adherence to soil-erosion 

 mitigation techniques aimed at reducing on- 

 site erosion. Specific measures include 

 scarification and revegetation of disturbed 



areas. 



'iuniii 



Both action alternatives, through implementa- 

 tion of site-specific BMPs, are not expected to 

 produce or transport high levels of sediment 

 downslope. Riparian buffers around lakes and 

 sensitive wetland areas would be delineated to 

 provide for sediment filtration. 

 Nonchannelized flow from imits would be 

 controlled through the application of specific 

 BMPs aimed at reducing excessive runoff. 



DIRECT AND INDIRECT 

 EFFECTS TO SOIL 

 COMPACTION AND 

 DISPLACEMENT 



A comparison of potential direct effects (com- 

 paction and displacement) from proposed 

 management activities by alternative is dis- 

 played in Table IV-6. 



NO-ACTION ALTERNATIVE 



No measurable direct or indirect effects on soil 

 displacement and compaction would occur 

 within the analysis area. ... , , „ 



ACTION ALTERNATIVES A AND B 



Soil surface layers would be displaced during 

 excavator piling and skidding on landings, 

 firelines, new temporary roads, and skid trails. 

 The total area affected by surface disturbance 

 is quantified in Table IV-6. 



Monitoring on the adjacent Flathead and 

 Idaho Panhandle National Forests indicates 

 the following assumptions can be reasonably 

 made when predicting the extent of s 



detrimental effects from timber harvesting on 

 soil productivity in the analysis area: 



• In road construction, an average of 3.5 

 acres per mile would be disturbed and 

 have greatly reduced site productivity. 

 The specific acreage varies based on slope 

 steepness. Due to new road construction. 

 Alternatives A and B would permanently 



i reduce site quality on approximately 24 

 acres. 



Chapter IV: Environmental Consequences 



iN-2D 



