ALTERNATIVE A – NO ACTION

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Biological Environment

Vegetation and Fire Ecology

Potential for Impacts from Catastrophic Fire

Subalpine Forests.  Vegetation in this group shows no departure from the normal fire return interval (table 2.1).  This indicates that stand structure, composition, and fuel loads are within the natural range of variability and potential for catastrophic fire is low.  Since 1930, the largest fire in this vegetation zone was only 773 acres.  Fire behavior and fire effects would be expected to closely track historical norms with minimal potential for non-native plant establishment.  Thus, the No Action Alternative would not reduce the risk of catastrophic fires and the effect on subalpine forests would be adverse, short-term, and negligible. 

Upper Montane Forests.  Vegetation in this group would continue to show moderate to high departures from the median fire return intervals (table 2.1).  About 25% of the acreages of upper montane forests are within one return interval of normal.  Of the red fir forest and montane chaparral, about 75% would continue to have moderate departures (2-3 intervals).  About 70% of western white pine/Jeffery pine forest are and would continue to be four or more return intervals from normal.  The structure and composition of all upper montane forests would continue to c hange to include higher densities of small, shade-tolerant species, contributing to the potential for catastrophic fire.  Chaparral would be reduced in size and extent.  Large areas would be converted to vegetation types that would not have historically occurred in the area.  Fuel loads would remain higher than the natural range, also contributing to significantly increased chance of catastrophic fire in these areas.  While large, stand-replacing fire occasionally occurred in these areas naturally, the existing trend toward high fuel loading would cause a gradual increase in the size and extent of these types of fires.  This would be an adverse effect.  The relatively small annual average acreage of managed wildland fire in this alternative would increase the chances of stand-replacing fires and associated encroachment into these sites by non-native plant species.  The risk of catastrophic fire under Alternative A on upper montane forests would increase, thus effects would be adverse, long-term, and major. 

Lower Montane Forests.  About 50% of these forests are within two median fire return intervals of natural due to an active prescribed fire program.  At the same time, about 50% of these areas are three or more return intervals from normal and some have extremely high departures from the median fire return interval, consequently the chance of catastrophic fire has significantly increased under the existing program.  Under Alternative A, vegetation in this group would continue to show moderate to high departures from the median fire return intervals (table 2.1).  Of the ponderosa pine/bear clover forest, 36% has missed 17 median return intervals.  Fire exclusion has changed these relatively open forests to forests with dense thickets of shade-tolerant tree species at the higher elevations, and dense shrub at lower elevations.  Thus, both structure and composition of ponderosa pine/bear clover forest is significantly outside the natural range of variability.  Both ponderosa pine/mixed conifer and ponderosa pine/bear clover are undergoing a vegetative type change—becoming white fir/mixed-conifer forest.  Fuel loads are significantly higher than they were historically.  While large stand-replacing fires occasionally occurred in these forests; fires burning in existing conditions would have a much greater intensity than under the natural fire regime. 

Under this alternative, wildland fire in much of the lower montane forest type would be larger in size and extent than expected under the natural range of variability.  Such fires would alter gap distribution and the vegetative mosaic.  High-intensity, catastrophic fire would convert large areas to vegetation types that would not have historically occurred in the area and would increase the likelihood for invasion of non-native plant species.  The Mariposa Grove of Giant Sequoias occurs in lower montane forest and could be one of the areas converted by catastrophic fire.  These effects would be outside the range of natural variability, and adverse.  The relatively small annual average acreage treated with prescribed fire would increase the potential of stand-replacing fires, thus the effects of the No Action Alternative on lower montane forests would be adverse, long-term, and major.

Montane Meadow.  Vegetation in lower montane meadows shows high departures from the mean fire return interval (table 2.1).  Almost 80% of the meadows are four or more return intervals from normal.  Hydrologic regimes have been altered in many meadows in Yosemite Valley and intensive ecological restoration is ongoing.  However, fire exclusion has significantly increased the potential for catastrophic fires in the forests surrounding these meadows.  Under this alternative, severe encroachment by conifers would continue and meadows would continue to contain large amounts of Kentucky bluegrass and other non-native, cool season grasses.  Fuel loads would be higher because of the number of years between fires and because of conifer encroachment.  The relatively small annual average for acreage treated with prescribed fire in this alternative would increase the chances of having stand replacing fires in the forests surrounding meadows.  High-intensity fire would likely have more of an effect upon encroaching conifers than on the montane meadow native and non-native species.  The effects of the No Action Alternative on meadows would be adverse, short-term, and minor.

Foothill Woodlands.  Vegetation in the foothill woodlands would continue to show low to moderate departures from mean fire return interval (table 2.1).  Most of the areas in this vegetation type were burned in the large wildland fires that occurred in and around the park during the 1990s.  Cheatgrass and other non-native annual grasses have invaded the foothill woodlands.  High-severity fires are normal for this group, and the effects from them are within the natural range of variability, although in many areas native species have been replaced with non-native species favored by and/or facilitating unnatural fire frequencies.  The relatively small annual average number of acres that would be treated with prescribed fire under this alternative would increase the chances of catastrophic fires due to the potential of fire to spread from the lower montane forests, as happened during the 1990 A-Rock fire.  The effects of Alternative A on foothill woodlands would be adverse, long-term, and minor, due to the gradual shift in dominance from native to non-native species that have unnatural fire regimes.

Fire Management Treatments

The No Action Alternative would utilize managed wildland and prescribed fire and a limited array of site preparation, including fuel reduction, techniques.  Site preparation for prescribed burns include fire line construction, hand thinning, and some snagging.  Fuels may be piled for burning.  Fuel reduction is performed in advance of prescribed burning to reduce the potential for an escaped burn and to reduce impacts to air quality from smoldering material following the prescribed burn.  Some material is moved to wood yards and chips have been given away or used in the park or El Portal. 

Managed Wildland Fire

Subalpine Forests.  Of the subalpine forest, 99% would occur within the Fire Use and Conditional Units.  There is no departure from normal fire return interval for this group.  The structure, composition, and fuel loading are within the natural range of variability.  Fire behavior and fire effects would be expected to closely track historical norms.  However, the small annual average number of acres burned with managed wildland fire would limit the beneficial impacts to these areas.  Overall, the effect of managed wildland fire on subalpine forest would be beneficial, long-term, and minor. 

Upper Montane Forests.  Of upper montane forest, 95% would occur in the Fire Use and Conditional Units.  Fire behavior and fire effects would be expected to be normal to slightly outside the natural range of variability due to changes in the structure, composition, and fuel loads.  It is expected that managed wildland fire would have a beneficial, long-term, major effect in areas that burn.  However, under this alternative, the small annual amount of managed wildland fire, on average, would likely result in changes that would significantly increase the chance of catastrophic fire in upper montane forests.  This is because a large number of fires would be suppressed in the Conditional Unit, which would lead to increased fuel loads.  Many areas in red fir and western white/Jeffery pine forests would move outside the natural range of variability during the life of this plan.  The effects of Alternative A in upper montane forests would be adverse, long-term, and moderate to major. 

Lower Montane Forests.  About 40% of lower montane forests occur in the Fire Use and Conditional Units.  Half of that acreage is in the Conditional Unit—where wildland fires are likely to have been suppressed.  Because the structure and composition of these forests would continue to be significantly outside the natural range of variability, particularly in the Conditional Unit, fire behavior and fire effects also would be expected to be at or outside the natural range of variability.  It is expected that managed wildland fire would have a beneficial, long-term, and major effect in the areas that burn.  But, the small annual average of acres treated with managed wildland fire would result in overall increases in the potential for catastrophic fire in this type.  Additionally, a large number of fires would be suppressed in the Conditional Unit, leading to increased fuel loads.  Many areas of lower montane forest would move outside the natural range of variability during the life of this plan.  The effects of Alternative A on lower montane forests would be adverse, long-term, and major.

Meadows.  About 60% of dry montane meadows would occur in the Fire Use and Conditional Units.  Fuel loads are higher than normal due to the accumulation of grass and woody fuels (small conifers) in the years between fires, which would be greater than under historic conditions.  Fire behavior and fire effects would be expected to be slightly to moderately outside the natural range due to these changes.  The small number of acres to be burned annually by managed wildland fire would be expected to significantly increase the potential for catastrophic fire in the forests surrounding these meadows, but not in the meadows themselves.  The effects of managed wildland fire on meadows, under this alternative, would be beneficial, long-term, and minor to moderate, due to the limited size of burns and lack of appropriate timing and frequency.

Foothill Woodlands.  About one quarter of foothill woodlands would occur in the Fire Use and Conditional Units.  Most of that acreage would be in the Fire Use Unit where fires are less likely to be suppressed than in the Conditional Unit so most fires in this vegetation group would be managed for resource benefit.  High severity or catastrophic fires are now normal in the foothills woodland vegetation types, due in part to the establishment of non-native, annual grasses and forbs encouraged by these fire events.  The effects of Alternative A for managed wildland fire on foothill woodlands would be beneficial, long-term, and minor.

Re-ignition clause.  The re-ignition clause would not be used under this alternative.

Holding Action and Monitoring Effects (water and retardant drops, helispots, and spike camps).  The effects of holding actions and monitoring would be similar for all vegetation types so all vegetation will be grouped for this analysis. 

Water and retardant drops release liquids onto burning or unburned areas.  Vegetation can be physically damaged from the impact of the liquid, but the areas tend to be small and the effects relatively local.  Most fire retardant contains fertilizer type compounds, including ammonia, nitrogen, and phosphorous that can change pristine vegetation, especially in areas low in nitrate/ammonia type nutrients.  Added nutrients can lead to a decrease in growth of native vegetation and a proportionate increase in the establishment of non-native species that favor higher nutrient levels.  However, the chemical components of retardant only remain for a few months at most, and long-term, chemical alteration of the soil would not occur.  Impacts in high elevation, low nitrogen areas would be mitigated if needed by avoiding use of retardant or by using “clear” retardant that minimizes active nutrients within the mix.  Physical damage to vegetation can be avoided by requesting that pilots fly aircraft quickly enough to dissipate water and retardant over larger, more linear areas.  Overall, the effect of water and retardant drops on vegetation is adverse, short-term, and minor.

Fire monitoring activities would potentially require the development, use, and management of helispots and spike camps, which could disturb vegetation and soils.  In forested areas, trees and/or snags would be removed under some situations, to open areas for safe operation of aircraft or to make camps safe for fire personnel.  The effects generally are local.  Common practice is to use, when available, previously used sites and open areas that require little disturbance.  Aircraft skids or wheels, boots, equipment, and camp and base supplies could be contaminated with non-native seed, providing vectors for non-native species that would not otherwise disperse to these sites.  Mitigation measures would include: (1) avoiding known populations of special-status species; (2) cleaning vehicles and equipment prior to actions to make them weed-seed free; (3) rehabilitating sites (return to natural grade) as quickly as possible to restore natural drainage and prevent unnatural runoff patterns; and (4) replacing litter and duff, to make these sites less susceptible to invasion by non-native species.  Overall, the effects of helispots and spike camps on vegetation would be adverse, short-term, and negligible. 

Prescribed Fire

Prescribed burns are carried out for two primary reasons—to restore or maintain vegetation within target conditions and to reduce fuels to protect buildings or achieve other administrative objectives (e.g. maintenance of cultural landscapes or view sheds).  At times, the two reasons contradict each other because their effects differ on various components in a burn unit (Kauffman, 1990).  For example, unnaturally frequent burns or burns done outside of the natural fire season would favor some species and target others, shifting vegetation away from natural conditions.  On the other hand, fires conducted solely to restore fire to the ecosystem or to maintain fire’s role may lead to unacceptable fuel loading or species composition.  For example, the natural fire regime in ponderosa pine/bear clover favors a continuous cover of bear clover.  This highly flammable and fire-adapted species poses threats to buildings.  Therefore, unnaturally frequent burns would be conducted to reduce or eliminate bear clover near developed areas.

Subalpine Forests.  Less than 1% of subalpine forests occur within prescribed fire units under the No Action Alternative.  These forests are within the normal fire return interval and structure, composition, and fuel loading are within the natural range of variability.  Fire behavior and fire effects would be expected to closely track the historical norms, if prescribed burns were conducted during the normal fire season.  Although effects of burning during the shoulder season (outside of the normal fire season) are yet to be studied, the potential of adverse effects exists.  The very small acreage involved makes this potential effect local.  Overall, the effect of prescribed fire on subalpine forest would be beneficial, short-term, and minor. 

Upper Montane Forests.  Less than 10% of upper montane forests occur within prescribed fire units under the No Action Alternative.  Vegetation in this group shows moderate to high departures from the median fire return intervals (table 2.1).  Fire behavior and fire effects would be expected to be normal to slightly outside the natural range of variability due to changes in structure, composition, and fuel loads.  First entry burns have been conducted during the shoulder season and while the overall effect of these burns has been beneficial, potential for adverse effects on some plant species exists.  For example, spring burning has shown high mortality in mature sugar pines.  The small annual average number of acres treated with prescribed fire would allow the potential for catastrophic fire to increase in these areas.  The effects of Alternative A on prescribed fire in upper montane forests would be beneficial, long-term, and minor.

Lower Montane Forests.  Most of the prescribed burn units in the park occur in lower montane forests, and about 40% of lower montane forests are in prescribed burn units.  Under Alternative A, vegetation in this group would continue to show moderate to high departure from median fire return intervals (table 2.1).  Prescribed fire could effectively reverse the undesirable increase in dense thickets of shade-tolerant tree species at the higher elevations and shrubs at lower elevations, and could return these forests to relatively open stands.  However, the amount of prescribed fire treatment proposed annually is limited.  At the current rate of burning, departure from normal return interval is increasing and larger areas are at risk for high-intensity fire.  Because the structure and composition of these forests is significantly outside their natural range of variability, fire behavior and fire effects would be expected to be from normal to outside the natural range of variability.  First entry burns would often be conducted during the shoulder seasons to aid in control.  While the overall effect of these burns would be beneficial, there would be the potential for adverse effects on some plant species.  For example, the mortality rate for large sugar pines is often higher during spring burns than in fall burns.  The small annual average number of acres burned would not significantly decrease the potential for catastrophic fire in these areas.  It would not be possible to realize restoration targets, except in small areas.  The effects of continuing the current level of prescribed fire under Alternative A on lower montane forests would be adverse, long-term, and moderate.

Meadows.  Less than one third of dry montane meadows occur in prescribed fire units.  Vegetation in the dry montane meadows would continue to show high departures from the mean fire return interval (table 2.1).  Fuel loads would be higher than normal because of conifer encroachment and the long interval between fires.  Fire behavior and effects would be expected to be outside the normal range of variability due to these changes.  The small annual average for acres treated with prescribed fire is resulting in a loss of dry montane meadow habitats at a rate greater than what would normally occur.  At the current rate of prescribed fire, restoration and maintenance targets would not be met, except on a local basis.  Overall, the effects of the No Action Alternative from prescribed fire on meadows would be adverse, long-term, and moderate.

Foothill Woodlands.  Less than 20% of foothill woodlands occur in prescribed fire units under the existing program.  Vegetation in foothill woodlands would continue to show low to moderate departures from the mean fire return interval (table 2.1).  High-severity fires are now normal in these types of vegetation, due to the presence of a mix of native and non-native species.  Through the removal of numerous non-native plant species, restoration of the native suite of grasses and forbs within the foothill woodlands would continue.  Prescribed fires to reduce non-native species would be conducted outside of the normal fire season for this type, which would potentially have adverse fire effects on some native vegetation.  However, if highly invasive non-native species are not removed, the structure, composition, and fuel loads in foothill woodlands would be significantly altered and remain outside the normal range of variability.  Overall, the effects of the current level of prescribed fire on foothill woodlands would be adverse, long-term, and minor to moderate.

Site Preparation Associated with Managed Wildland Fire and Prescribed Fire (hand line, snagging, mop-up)

The effects of holding actions and monitoring would be expected to be the same for all vegetation types, so they will be grouped for this analysis.  Hand line would disturb surface vegetation and soils, potentially opening micro-sites for invasion by non-native species.  Snagging could lead to unnaturally high concentrations of fuels.  Mop-up activities would create soil disturbance and open sites that non-native species could invade.  The effects of these activities would be generally local, and would rarely have landscape scale implications, unless unmitigated.  All of these activities would be mitigated through avoidance and/or rehabilitation measures.  Overall, the effect of site preparation on vegetation would be adverse, short-term, and minor.

Fuel Reduction by Hand or Machine

Aggressive Reduction Techniques.  These treatments would not be used in Alternative A.

Passive Reduction and Lower Profile Techniques. 

Low-Impact Skidding.  Would not be used in this alternative.

Hand Cutting.  These activities would continue to be used in the Conditional and Suppression Unit, in Special Management Areas, and in the wildland/urban interface.  Impacts that would not change by vegetation type include the potential for trampling and burial of sensitive plants and communities (e.g. wetlands); the appearance of cut stumps; and the loss of fuel ladders.  Most of these impacts would be mitigated through project planning and coordination with the Resource Management Division.  Hand cutting would not occur in subalpine forests, upper montane forests, and meadows in this alternative.

Current prescriptions for hand thinning have been developed for lower montane forests where most of the thinning activity would be done.  Cutting small diameter trees in the past has actually increased the smallest time-lag fuels, which are the most flammable (Yosemite Fire Management File Data).  Removing small diameter trees amounts to removing some of the ladder fuels which are needed for fire to kill some of the larger trees that have come into the area since fire exclusion.  Additionally, because of the small number of acres treated annually with hand thinning, the potential for large, high-severity fires would remain high.  Thus, unless prescribed fire is used on hand-thinned fuels, the effects of hand thinning on lower montane forests would be adverse, short-term, and minor.  If these fuels are also treated with prescribed fire, under controlled conditions, the effects of hand thinning would be beneficial, long-term, and minor to moderate. 

Hand thinning has been used in very small areas in foothill woodlands, all within the El Portal Administrative Site.  Thinning would continue to be used for removing small diameter trees and brush, to reduce the fire hazard to structures.  Due to the intensive nature of this work, some ground disturbance would take place and there would be a potential for additional non-native species establishment.  Mitigation would include minimizing soil disturbance and performing post-treatment surveys for non-native plants and implementation of control measures as needed.  Overall, the effects of hand thinning on foothill woodlands would be beneficial, short-term, and negligible.

Pile burning.  The effects of pile burning would be essentially the same for all vegetation types, so they will be grouped for this analysis.  Piles generally are burned following hand thinning, and would precede the use of prescribed fire.  Impacts associated with pile burning would potentially include surface and soil disturbance associated with dragging materials to each pile; the very localized, intense burn effects upon surface fuels, litter and duff, and soil layers; and the long lasting effects upon soil chemistry and structure due to extreme heating over long time periods.  Because of these effects, piles would be kept small, to the size of a small car.  This would minimize the extent of soil damage.  The small size would also allow for the recolonization of sterilized patches by mycorrhizal fungi and other soil organisms.  These locations are potential micro-sites for colonization by invasive non-native species.  Mitigation would include minimizing soil disturbance and performing post-treatment surveys for non-native plants and implementation of control measures as needed.  Overall, the impacts of pile burning on vegetation would be adverse, short-term, and negligible.

Chipping.  Chipping would only be used occasionally in this alternative.  Chipping cut material and then distributing it over a site could occur where air quality, visitor use, or other management concerns prohibit burning.  Such impact, however, would be adverse, short-term, and negligible. 

Cumulative Impacts

Vegetation within Yosemite National Park and the El Portal Administrative Site has been affected by a variety of actions, including past fire suppression activities, logging, development, construction of O’Shaughnessy Dam (and the creation of the Hetch Hetchy Reservoir), and agricultural and other activities below the park.  The effect of 100 years of fire exclusion cannot be overstated.  With the exception of subalpine forests, all other vegetation groups have moderate to high departures from normal fire return intervals.  The large areas of moderate and high departure vegetation indicate the high potential for catastrophic wildland fires and the potential for type conversion from one vegetation type to another.  The overall effect of these activities on forest structure, composition, and fuel loading has been adverse, long-term, and major.

Other actions expected to occur within Yosemite that would affect vegetation would be implementation of the Merced Wild and Scenic River Comprehensive Management Plan/EIS (NPS 2000) and the Yosemite Valley Plan/SEIS (2000c).  The first identifies a protection zone along the Merced River that will allow for enhanced protection of native plant communities that occur in drainages and areas adjacent to the river.  Implementation of the Yosemite Valley Plan would substantially increase the human population in the El Portal Administrative Site, which would increase the potential for human caused fires and the potential for catastrophic fire, as well as the introduction, establishment, and spread of non-native plant species.  Smaller increases in human population would also occur in Wawona, Hazel Green, and Foresta with similar effect.  Mitigation measures identified in the Yosemite Valley Plan would reduce the potential level of impact to adverse, long-term, and minor.

Actions taken in Yosemite Valley associated with the Yosemite Valley Plan would reduce fragmentation.  Meadows and California black oak woodland would be increased.  However, due to the small areas treated, the overall effect is negligible to minor when looking at park vegetation as a whole.  Overall, the effect would be beneficial, long-term and negligible to minor. 

Past, present, and reasonably foreseeable actions include fire management and fuel treatment activities outside the park, many of which would be on national forest lands.  These would include A-Rock Reforestation, Aspen Fuels Reduction, Orange Crush Fuels Program, Rogge-Ackerson Fire Reforestation, and the Fire Management Plan for Wilderness in Stanislaus National Forest.  These projects would include reductions in the spread of noxious weeds, management of fuels and fire in a manner more in line with current federal wildland fire management policies, and protection of riparian resources.  These efforts, if successful, would improve habitat conditions for vegetation by controlling weeds and managing fire as part of the ecosystem.  These actions would have net beneficial impacts on vegetation by either reducing the potential for high severity fire or restoring vegetation to more ecologically stable targets. 

Overall, the effects of these projects on vegetation would be beneficial, long-term, and minor to moderate.  These present and reasonably foreseeable future actions would contribute to reversing the adverse impacts of past actions in the region.  These effects, in combination with the impacts of Alternative A, would result in beneficial, long-term, and minor cumulative impacts.

Conclusion

Fire management activities would effect vegetation in generally beneficial ways, through actions that would maintain plant communities within their natural range of variability.  Continuing an active managed wildland fire program will keep the subalpine forests in the Fire Use Unit within the normal range of variability.  Effects in the Conditional and Suppression Units would be limited by the amount of forests treated annually.  Because of the likelihood of increasing the risk of large, high intensity fires that would cause type conversion in foothill woodlands and lower and upper montane forests in the Conditional Unit, this alternative would continue to have a high potential for adverse, long-term, and major effects of the type that resulted from the A-Rock Fire.  Because over 62% of the park has departed little from the natural range of variability, overall, these effects would be adverse, long-term, and minor to moderate.

The Mariposa Grove of Giant Sequoias is one of the resources specifically identified in the enabling legislation for Yosemite National Park.  If catastrophic fire were to eliminate or severely damage this grove, the impact would be impairment. 

Wetlands

Potential for Impacts from Catastrophic Fire

Fires of high intensity or large size could have moderate, adverse impacts on wetlands.  However, depending on the specific activities associated with individual fires and considering effects at multiple scales, impact levels could vary from negligible to major.  Because of the limited scope of work under Alternative A, there would be little reduction in the potential for catastrophic fire.  Large, high-intensity fires could cause ecosystem fragmentation, which could impose unnatural barriers on plant and wildlife movements and affect seed sources, nutrients, and plant distribution patterns in wetland communities.  These effects would be magnified for spatially limited or isolated wetlands.  Fires that consumed all or the majority of available habitat within an area could have major effects on organisms dependent on that habitat type as well.  High-intensity fire could initiate a process of type conversion to a less desirable plant assemblage in a wetland, which could result in short-term alterations in occupation by certain species.  These effects could occur at multiple spatial scales and result in long-term impacts to wetland ecosystems.

Some additional adverse ecological impacts would be expected following extreme fire events in wetland communities.  Most fires spread through the combustion of organic matter that is in contact with the soil, making fire and soil interactions significant (Agee 1993).  Fire creates physical, chemical, and biological changes that may be either beneficial or detrimental to long-term soil productivity.  Fire events typically involve a transfer of nitrogen from the litter to both air and soil, a transformation of nitrogen from organic to inorganic forms, and a conversion from nitrogen-consuming to nitrogen-fixing plants (Woodmansee and Wallach 1981).  These chemical changes associated with fire may impact water quality and quantity as well.

General observations suggest that fire accelerates erosion rates in areas normally subject to erosion but creates little erosion in areas of normally stable soils (Pyne et al. 1996).  Wetlands described here are likely to represent communities with low potential for erosion, however, they may also represent areas of deposition for material eroding from upland sites.  In regard to catastrophic fire, the effects of Alternative A on wetlands would continue to be adverse, long-term, and minor, due to potential habitat fragmentation and deposition with drying effects on wetland sites caused by catastrophic fire.

Fire Management Treatments

Managed Wildland Fire

In most burning conditions, low- and moderate-intensity fires would burn near or around wetlands—in dry years fires could burn into wetlands.  In the short-term, the loss of isolated or spatially limited wetlands habitat would have adverse effects, but over the long-term, these effects would be beneficial as fire is part of the dynamic disturbance cycle of these landscapes.  Effects would thus be beneficial, long-term, and moderate.

Re-ignition clause.  Re-ignition of wildland fires is not permitted under this alternative.

Holding Action and Monitoring Effects (water and retardant drops, helispots, and spike camps).  Wetland habitats would be avoided to the greatest extent possible during holding actions or fire monitoring.  While meadows might be used as temporary helispots, this would only be done at dryer sites.  Impacts associated with holding actions on wetlands would be adverse, short-term, and negligible.

Prescribed Fire

Fire management activities would likely result in significant ecological benefits for wetlands throughout the park.  Although some of these communities have a history of repeated burning and exhibit strong response mechanisms, it is likely that these events occurred at a lower periodicity and severity than has been documented in the contemporary Sierra Nevada (Skinner 2001). 

Fires near wetlands would be ignited when wetlands are moist enough not to sustain fire spread, therefore prescribed fire impacts to wetlands would be minimized.  Mechanical pre-treatments would be designed to avoid impacts to designated wetlands.  The landscape impacts of these combined treatments would benefit wetlands by reducing the likelihood of catastrophic fires of greater intensity to which wetlands are adapted.  Appropriately timed and structured prescribed fire events would help significantly with the control of woody tree invasion, as well as the loss of species diversity and structural complexity (Miller et al. 1998). 

Risks associated with prescribed fires would include vegetation type conversion (wetland sites to undesirable vegetation types) and adverse impacts to some wetlands species.  Prescribed fire activities would only be implemented in designated wetlands when ecologically defensible objectives were presented for habitat, vegetation response, or soil management.  Unit arrangement, firing strategies, and prescription parameters would all be designed to minimize the direct effects of prescribed fire.  Under this alternative, benefits of prescribed fire would include burning and possibly cutting small trees to achieve more natural structural conditions for specific habitats and well-timed burning to enhance wetland species.  These impacts would be beneficial, typically short-term, and minor to moderate.

Site Preparation Associated with Managed Wildland Fire and Prescribed Fire (hand line, snagging, mop-up)

Site preparation for managed wildland fires and prescribed burns would include the use of wetlands as natural barriers and water sources where water is available.  When a wetland area is being used for a boundary, line construction and some snagging would occur in the adjacent uplands.  Burns would be allowed to back into and burn around wetlands and meadows or through them if the vegetation were dry enough to carry fire.  Wetland habitats would be avoided to the greatest extent possible during implementation of confinement and containment strategies.  If the objectives of a prescribed burn were to reduce conifer invasion of meadow, some cutting of already established trees might be performed.  Since no actual disturbance to the wetland characteristics would be realized, the impacts would be beneficial, short-term, and minor to moderate.

Fuel Reduction by Hand or Machine

Passive Reduction and Lower Profile Techniques. 

Hand Cutting.  Hand cutting would not typically occur in wetlands.  In some meadows small invading conifers would be cut, in which case the effects would be beneficial, short-term, and minor to moderate.

Pile burning.  Piles are sited to avoid wetland areas wherever possible.  When fuel reduction work is done on the edge of a meadow wetland, piles might be put on the upland areas adjacent to the wetland, where they would be burned.  Some movement of ash particles may subsequently wash into the wetland area resulting in an increase of nutrient levels.  The impact of pile burning on wetlands would be beneficial, short-term, and minor to moderate.

Chipping.  No wetlands plant material would be chipped under this alternative and chip application would avoid riparian and meadow areas.

Cumulative Impacts

Cumulative effects to wetland and aquatic resources discussed herein are based on analysis of other wetlands activities in the Yosemite region and the potential effects of this alternative.  The projects identified below include those projects that have the potential to affect local wetland patterns and processes as well as large-scale or regional wetland patterns and processes.

Aquatic and riparian systems are the most altered and impaired habitats of the Sierra Nevada and, as a small proportion of the landscape, are relatively rare.  Wetlands in the Sierra Nevada have been drained since the earliest settlers attempted to improve forage and permit agriculture (Hughes 1934, as in NPS 1997b, University of California, Davis 1996e).  Development and activity in Yosemite has reduced meadow acreage by 60-65%.  Dams, roads, and diversions throughout most of the Sierra have profoundly altered stream-flow patterns and water temperatures.  Within the mountains, broad valleys with wide riparian areas were often reservoir sites, and much of the former riparian habitat in the Sierra Nevada is now under water.  The extent of the inundation across the range becomes apparent when one realizes that virtually all flatwater on the western slope of the Sierra Nevada below 5,000 feet is artificial (University of California, Davis 1996e).  These past actions have had long-term, adverse effects on regional wetland and aquatic habitats. 

Regional and park wide planning efforts such as the Sierra Nevada Framework for Conservation and Collaboration (USFS); U.S. Forest Service management plans for adjacent wilderness; and the Wilderness Management Plan Update (NPS) would provide benefits to the size, integrity, and connectivity of wetlands.  Cooperation among land management agencies would increase the opportunity to share common objectives and improve resource protection.  These plans also could increase knowledge of resources and recreational use.  These plans have the potential to have long-term, moderate, beneficial impacts on wetlands, though the proposed management direction has not been finalized.

Other projects approved or planned for construction that could have beneficial effects on wetlands include campground rehabilitation projects in Tamarack, Yosemite Creek, Bridalveil and Hodgdon Meadows Campgrounds, and the Merced River Eagle Creek Ecological Restoration Project (Yosemite Valley).  Erosion control and mitigation from these projects would enhance and strengthen palustrine forest and palustrine scrub/shrub wetlands.  The Eagle Creek project would revegetate currently denuded riverbanks that were formerly palustrine forest and palustrine scrub/ shrub wetlands.  The erosion control and restoration projects would have long-term, localized, beneficial impacts on wetlands.

Regional and park plans that would have positive cumulative impacts on wetlands are tempered by adverse impacts that include an extensive infrastructure that diverts water away from wetlands in Yosemite Valley, continued unnatural widening of the Merced River in the east Valley, the potential direct loss of wetland habitat at the Yosemite View Parcel Land Exchange, and other projects outside of the park.

Considered in combination with these beneficial, long-term, and moderate effects, the cumulative impacts of the Alternative A would be adverse on wetlands because of the potential for large, high-intensity fires, with subsequent short-term changes in nutrients, water quality, and vegetation connectivity.  Some of these impacts could be long-term, but most would be short-term and negligible.  The potential for beneficial or adverse impacts to wetlands would be greater from projects occurring within the cumulative impact assessment area of the Sierra Nevada bioregion than from this alternative. 

Conclusion

The effects of the No Action Alternative would be adverse, short-term, and minor to moderate, and would include the continued alteration of forest types surrounding wetlands and the increased likelihood of fire intensities outside the range of tolerance for wetland species.  Although most fire management activities would have little or no impact on wetland resources, this alternative would do little to minimize the adverse effects of large, high-intensity fires, and would result in an increase in fire threat through time.  These effects would not represent impairment.

Wildlife

Potential for Impacts from Catastrophic Fire

Under Alternative A, park personnel would follow existing fire management practices.  The primary threat to wildlife and their habitat would be intense, stand-replacing fires over large areas of the park, especially at lower elevations.  Such fires would greatly change the diversity and abundance of wildlife species in the park, through wide-scale and radical changes in habitat (e.g., Finch et al. 1997).  Under this alternative, achieving target conditions, and thus more natural vegetation assemblages, for many habitat types would be unlikely.  Therefore, the threat of large, catastrophic fires in much of the park would continue or increase indefinitely.  Because of the higher risk of catastrophic fire, impacts from fire suppression actions (e.g., fire line construction, helispots, spike camps) are most likely to occur under Alternative A as well. 

The mixed-intensity fires that are typical under the natural fire regime for most forested habitats in the park create habitat heterogeneity (assorted patches of vegetation types inter-mixed across the landscape).  For example, patches of stand-replacing fire within a larger fire create small gaps and openings in the forest canopy while leaving other areas hardly scorched.  These processes sustain a wide diversity of wildlife species and promote ecosystem resilience.  Sierra Nevada wildlife species have existed for thousands of years under the natural fire regime.  They have developed behavioral and life-history adaptations that allow them to take advantage of the spatial and temporal changes in habitats through fire.  Under current conditions of abnormally high fuel loading in many forest vegetation types, however, the large, high-intensity fires that are likely would lead to habitat homogeneity.  As a consequence, the forest supports an unnatural assemblage and succession of wildlife species adapted to the altered, nearly uniform, habitat. 

The A-Rock and Steamboat fires of 1990 provide examples of the adverse effects of stand-replacement fires.  These fires burned in unnatural forest conditions and increased the homogeneity of the landscape.  In the Foresta area, the fire burned a ponderosa pine/mixed-conifer forest in which years of fire exclusion had caused high fuel loads.  The lightning-fire killed virtually all of the trees and understory vegetation during a dramatic crown run of approximately 3,000 acres.  Now, over a decade later, the area is dominated by a shrub community interspersed with numerous large snags.  While a shift in species composition and succession is natural after a stand-replacing fire, a 3,000 acre type conversion with no interspersed patches of the former habitat type is not characteristic of the fire regime for this type of forest. 

This unnaturally large, homogenous habitat area presents several problems for park wildlife that will extend many years into the future.  While the area is favorable to bird species such as lazuli bunting, fox sparrow, and numerous woodpecker species, virtually none of the forest-dependent species, such as black-headed grosbeak, white-breasted nuthatch, and western tanager have returned (NPS 2001c).  Two California spotted owl territories were lost as well (Gould and Norton 1993).  High-intensity fires create large numbers of snags that are normally of high value to many wildlife species (Lyon et al. 2000).  Their value, however, is reduced for some species if the area of snags is too large and surrounding vegetation does not afford other necessities, for example, food and cover.  Also, high-intensity fires result in fewer snags several years later as the fire created snags fall and growth of the single-age class forest to a snag-producing age takes many decades (Huff and Smith 2000). 

Given the potential impact of unnaturally large, intense fires that are likely under current fuel conditions and the relatively long duration of this risk under Alternative A, the effect from the potential impact to wildlife in regard to catastrophic fire is adverse, long-term, and major. 

Fire Management Treatments

Managed Wildland Fire

In Yosemite and in surrounding forests, many mid- to low-elevation forests are overgrown with dense shrubs and young trees because of a history of fire exclusion.  At the same time, as explained above, some areas are at high risk of unnatural high-intensity fire events.  These conditions affect the abundance and diversity of wildlife species directly by creating unfavorable habitat conditions for some species.  For example, dense understory growth may adversely affect habitat quality for California spotted owls and northern goshawks by limiting their access to prey (Weatherspoon et al. 1992, Maurer 2000, respectively).  Fires started by lightning strikes and managed in the Fire Use Unit and, under appropriate conditions, in the Conditional Fire Use Unit, are an important tool in working toward target vegetation conditions and, therefore, a return to more natural habitat diversity and structure.  This allows a return to a more natural distribution, abundance, and diversity of wildlife species in areas that are currently severely altered by a long history of fire exclusion and at risk of catastrophic fire. 

However, the rate of habitat restoration would be limited under this alternative.  Over the last 30 years, an average of about 4,000 acres has burned annually; well short of the average 16,000 acres that is believed to have burned naturally each year.  Therefore, the conditions of suppression-altered habitat and its effects on wildlife species abundance and diversity and the threat of catastrophic fire to wildlife and habitat are likely to continue indefinitely. 

Because this alternative relies heavily on natural ignitions and they are somewhat random events, areas burned may not be those of highest management priority (i.e., high fuel loads from fire exclusion).  Also, some areas are likely to burn at higher than natural intensities due to high levels of fuel accumulation, even when fire prescriptions are adhered to.  As a result, forest gaps may be larger and consumption of large woody debris that provides habitat may be greater than in natural burning conditions.  This may adversely affect species that favor dense, complex forests, such as hermit thrush, northern flying squirrel, and marten.  Such impacts, however, must be weighed against the benefit of reduced risk of catastrophic fire that would cause greater detrimental change in wildlife habitat.  Effects from Alternative A would be beneficial, long-term, and minor due to reductions in the threat of catastrophic fire, but such benefits would be limited by the relatively small number of acres that would be treated annually.

Re-ignition clause.  Would not occur under Alternative A.

Prescribed Fire

The use of prescribed fire provides the greatest potential for focused work to restore wildlife habitat and reduce the threat of catastrophic fire.  Areas furthest from the natural fire regime with identified threats to wildlife and habitat, can be targeted for treatment.  Fire can be planned to occur under conditions that maximize benefit to resources, including wildlife and habitat, and minimize fire-related impacts to sensitive wildlife resources (e.g., spotted owl nesting sites).

Under this alternative, high levels of fuel loading in some areas may cause prescribed fires to burn at higher than natural intensities, even when fire prescriptions are designed to minimize this event.  Creation of forest gaps and consumption of large woody debris may be greater than what would be expected under natural fire conditions in some areas of a burn.  Thus, intense burning may adversely affect species that favor dense forest, such as hermit thrush, northern flying squirrel, and marten.  Such impacts, however, must be weighed against the benefit of the reduced risk of catastrophic fire.  Under Alternative A, such benefits would be minimized by the relatively small number of acres that would be treated with prescribed fire. 

In habitats near developed areas, where protection of human-built structures and facilities is a concern, prescribed fire would be used to reduce fuel loads to the lower end of the natural variability.  If forests became more open (less understory vegetation) and contained less down wood, the effect on animal species that depend on these features, such as salamanders, small mammals, and ground-nesting birds, would be adverse.  However, overall a larger number of species would benefit from restoration of forests to a more natural condition. 

Prescribed fires would be started when conditions are favorable for their control.  This is often in the spring or fall, which is outside of the dry season when most natural fires occur.  This would have an adverse effect on species of wildlife that are adapted to the natural timing of fires.  For example, small mammals that hibernate in leaf litter could suffer higher mortality during prescribed fires. 

Under Alternative A, impact of prescribed fire on wildlife would be beneficial, long-term, and minor, because this action provides habitat improvement in areas most severely altered by fire suppression and some reduction in the risk of catastrophic fire, but such benefits are limited by the relatively small number of acres that would be treated annually.

Holding Action and Monitoring Effects (water and retardant drops, helispots, and spike camps) and Site Preparation Associated with Managed Wildland Fire and Prescribed Fire (hand line, snagging, mop-up)

Maintaining control of managed wildland fires and prescribed fires would occasionally involve hand line construction, snagging, water drops, and other actions.  Such efforts are necessary and likely to be less intense than they would be during fire suppression activity. 

Water Drops.  Dropping water on fires from helicopter buckets would carry inherent risks to wildlife.  Water that is removed from small bodies of water may adversely affect aquatic organisms by depleting their habitat, or causing it to dry up prematurely in the same year.  Some aquatic species, such as mountain yellow-legged frogs, have small, isolated populations that could be devastated by removal of water and/or frogs.  In addition, Chitrid fungus has recently been identified as a factor in the disappearance of mountain yellow-legged frog populations.  Helicopter buckets, mostly through dipping in separate water bodies, would potentially spread this fungus to non-infected populations of frogs.  Non-native fish inhabit many park lakes and streams, and bullfrogs are present in several others.  Water dipped from such areas could lead to the spread of non-native species to pristine waters.  The physical impact of a water drop could adversely affect individual animals.  On the positive side, water drops can, in some circumstances, be used instead of hand lines ("wet-lining") to control fire movement.  This tactic would result in less impact to soil, forest litter, and vegetation than hand line construction and, therefore, would have less impact on wildlife, both in intensity and duration.  Under Alternative A, the impact of water drops on wildlife would be adverse, long-term, and minor based upon possible impacts to aquatic ecosystems, especially in relation to amphibians.  Mitigation: Avoid dipping from waters known to contain mountain yellow-legged frogs; avoid dipping from small bodies of water, spread water when dropping.

Retardant Use.  Some terrestrial wildlife could be affected by retardant drops if they were struck by the chemicals, resulting in injury or contamination.  Wildlife could also be disturbed by the low-flying aircraft.  Under Alternative A, impact to wildlife from retardant drops is expected to be negligible, adverse, and short-term because of its limited application in the park, and protocols for its use designed to protect aquatic resources.  Mitigation: Adhere to established protocols for retardant use; limit use in park.

Helispot Construction.  Construction of helispots often results in the felling of trees and snags, which are potential wildlife habitat.  Snags are especially important wildlife habitat.  In addition, helicopter traffic would likely disturb wildlife, such as nesting raptors.  Under Alternative A, impact of helispots on wildlife is expected to be adverse, long-term, and minor, based upon their likely limited use, although their use under this alternative is likely to be higher than under other alternatives, due to the greater chance of suppression activities.  Mitigation: Limit helispot construction; site helispots away from sensitive resources; use natural clearings for helispots.

Spike Camps.  Fire crews staying in spike camps can have an adverse effect on wildlife by allowing them access to human food.  This would lead to individuals becoming conditioned to human foods and cause human-wildlife conflicts.  In such cases, animals are often eventually killed to protect human safety.  Presence of hand crews in remote areas would introduce an element of disturbance, which could affect sensitive species, such as nesting raptors.  Under Alternative A, impact to wildlife from spike camps is expected to be adverse, short-term, and minor.  Mitigation: Site spike camps away from sensitive resources.  Provide strict control of availability of food to wildlife at camps.

Hand Line.  Hand line construction would remove and disturb soil and forest litter, possibly affecting animals such as small mammals, amphibians, invertebrates, and ground-nesting birds.  The presence of hand line crews in remote locations could cause direct disturbance of some wildlife species and introduce unnatural food sources (see spike camps above).  Impacts could be minimized by on-site avoidance of valuable or sensitive wildlife resources (e.g., raptor nests).  This would include sensitive habitats, such as meadows and riparian areas.  Removal of forest litter and vegetation can also lead to soil erosion and increased siltation in adjacent lakes and streams.  This could have an adverse effect on aquatic species, such as amphibians and invertebrates.  Impact of hand line construction in association with managed wildland fire and prescribed fire under Alternative A would be adverse, short-term, and negligible given the present limited use of fire, the use of minimum impact management techniques (MIMT), and fire line rehabilitation.  Mitigations: Continued use of MIMT; careful planning of fire line construction to avoid sensitive wildlife resources and habitats, avoidance of unnecessary line construction, and proper storage of food.

Snagging.  Snags are probably the most valuable tree-form to wildlife (Brown and Bright 1997).  They provide cavities and loose bark for nesting and roosting and food in the form of wood-boring insects.  Any holding action that requires the felling of snags to protect human safety and the integrity of the fire line would potentially affect wildlife by reducing the availability of snags to species such as pileated woodpeckers, northern flying squirrel, and several bat species.  Felling would likely kill some animals.  The number of snags lost would vary, depending upon factors such as the type and age of tree stand, its history of fire and/or disease or insect infestation, and the intensity of the fire.  Under Alternative A, snagging associated with holding actions would potentially have moderate, long-term, and adverse impacts because of the relatively small areas that would be affected.  Mitigation: Use MIMT and limit snag removal to those snags identified as a clear threat to human safety and fire line integrity.

Mop-up.  The churning of soil and forest litter to extinguish residual hot spots along the periphery of a fire would cause some mortality of buried organisms by exposing them to heat and flames.  Such impact, however, would be along short sections of the lined perimeter and affect few species.  Impact of mop-up would therefore be adverse, short-term, and negligible.

Holding Action Summary:  Under Alternative A, actions associated with managing wildland fire would have adverse effects on wildlife, but such effects would be slight and localized.  Holding actions would facilitate the use of wildland fire to move forests toward natural conditions, which would provide beneficial, long-term, and minor effects on wildlife.  Under Alternative A, these effects would be limited by the relatively small number of acres that would be treated each year. 

Fuel Reduction by Hand or Machine

Aggressive Reduction Techniques.  These treatments would not be used in Alternative A.

Passive Reduction and Lower Profile Techniques. 

Hand Cutting.  Hand thinning of understory vegetation, down fuels, and small-diameter trees in the wildland/urban interface would have mixed effects on wildlife and habitat.  Hand cutting trees and brush to attain target conditions provides a more natural habitat and helps reduce the threat of catastrophic fire; especially from human-caused ignitions that occur in developed areas.  The resulting forest structure, however, tends to be less complex and more homogeneous, because protection of property and safety through fuel reduction is a major consideration in these areas.  A few species, such as marten, hermit thrush, and some small rodents may be adversely affected by this reduced complexity, but many more species, such as Cooper's hawk, Hammond's flycatcher, and several bat species, would benefit from a more open forest.  At the current rate of treatment (< 25 acres/year), restoration of habitat and mitigation of the risk of catastrophic fire to both wildlife and humans is inhibited. 

During hand-thinning operations, wildlife in the area might be affected in two ways.  Removal of trees and other vegetation would adversely affect wildlife, such as insects and nesting birds, currently using these habitat features.  Secondly, human presence and use of chainsaws and other tools during thinning operations may disturb wildlife, although such disturbance would be short-lived.  Impact to wildlife from hand-thinning would be beneficial, long-term, and minor, because habitat affected by fire suppression would be returned to a more natural condition, and threat of catastrophic fire would be reduced in these areas.  Mitigation: Identify and avoid sensitive wildlife resources.

Pile Burning.  Piling and burning of downed trees and shrubs may have an adverse effect on some wildlife.  Some species, such as small rodents and reptiles, may take up residence in burn piles between the time they are stacked and the time they are burned; which can be at least several months.  Many of these animals are likely to flee the flames once the piles are ignited, but some may perish.

Under Alternative A, effects on wildlife from hand thinning and piling and burning would be beneficial, long-term, and negligible because improvement of habitat adjacent to developed areas toward target conditions would proceed slowly.  The area of habitat affected would be relatively small.  Some wildlife species may be adversely affected by emphasis on fuel reduction, but more species are likely to benefit from achievement of target conditions, and reduction in the threat of catastrophic fire, small as it is under this alternative. 

Chipping.  When removed biomass cannot be burned on site or removed for logistical, administrative, or ecological reasons, it may be chipped and distributed over the site.  When chips are spread deeply enough to affect the growth of native plants, wildlife would be affected.  Such impacts, however, would be limited to areas adjacent to roads and developed areas, and standard mitigation for chipping calls for chips to be spread as thinly as possible on the site—usually to a depth of not more than 1 inch.  The machinery used for chipping and shredding would be loud, which would disturb wildlife, such as nesting birds, in the short-term.  Impact to wildlife from chipping would therefore be negligible, adverse, and short-term.

Peregrine Falcon

The peregrine falcon, until recently, was an endangered species that the National Park Service considered a special-status species.  It has, however, been removed from the endangered species list after a successful recovery program.  The park continues to monitor peregrine falcons in Yosemite as part of its larger wildlife management program.  Peregrine falcons occupy a broad range of habitats, but need suitable nesting cliffs, which would not be affected by fire management activities due to the vertical aspect of nesting habitat and its lack of vegetation.  Some of the major species that peregrine falcon eat (e.g cliff dwelling birds, such as white throated swift and violet green swallow), are not likely affected by fire management practices because they forage along cliff faces and in the airspace above the Valley floor.  Peregrines tend to adjust to changes in the array of bird species available within a forest type, and thus would find suitable prey in a wide variety of forest conditions.  Effects on the peregrine falcon would be adverse, short-term, and negligible.  However, the park would continue to monitor the status of the peregrine, and if deleterious effects were detected, related to fire management operations, these operations would be adjusted or refined.

Cumulative Impacts

The past activities within the region that have had the greatest adverse impacts upon wildlife have included development, timber harvest, and fire suppression activities.  The present and reasonably foreseeable future projects that would have an effect upon wildlife and habitat would include:

Yosemite Wilderness Management Plan Update: This plan could affect how fires are managed in Wilderness by modifying current minimum tool policies.  It is likely, however, that the plan will recognize the value of fire in maintaining wilderness values, and be compatible with fire management goals.  On one hand, impacts from fire line construction, snagging, etc., could be reduced, but, on the other hand, policies that inhibit full and quick implementation of the fire program would potentially delay achievement of target conditions which would be beneficial to wildlife over wide areas of the park.  Impact on wildlife is expected to be beneficial, long-term, and moderate.

Yosemite Valley Plan/SEIS (2000): Implementation of the preferred alternative would restore highly-valued habitats in Yosemite Valley and decrease the fragmentation of these habitats.  This would help restore wildlife abundance and diversity in Yosemite Valley.  The construction of facilities outside of Yosemite Valley would cause localized destruction of forest habitat, but the overall impact is expected to be major, beneficial, and long-term.

Merced Wild and Scenic River Comprehensive Management Plan/EIS (2000): Implementation of the preferred alternative would help protect river-related wildlife habitat and species.  This is especially true in Yosemite Valley, where past development has encroached on river habitats.  The Merced River Plan would provide the framework for reducing present development and limiting future development in these areas, with moderate, beneficial, long-term impacts on wildlife.

Yosemite West Re-zoning: This project would likely lead to an increase in the Yosemite West wildland/urban interface area, requiring intensive management of vegetation and fuels over a wider area.  This would have an adverse effect on wildlife because an additional 55 acres would be developed in mixed-conifer habitat near the park boundary.  Impact on wildlife is expected to be moderate, adverse, and long-term.

Yosemite West, 31 Acre Bed and Breakfast: Like the above project, this project would have an adverse effect on park wildlife by reducing mixed-conifer habitat near the park boundary.  No effect on wildland/urban interface treatment in the park is expected, since the affected property abuts national forest land.  Impact on wildlife is expected to be moderate, adverse, and long-term.

Hazel Green Ranch: Development of this facility adjacent to the park would affect an area of mixed-conifer and meadow habitat.  Impact on wildlife is expected to be adverse, long-term, and minor to moderate, due to likely consideration by the developer for preservation of sensitive habitats.

Evergreen Lodge Expansion: This development would affect an area of mixed-conifer habitat near the park.  Effect on wildlife is expected to be adverse, long-term, and minor because of the long-term human occupation of this area.

Rush Creek Guest Lodging and Conference Facilities: This project would affect an area of mixed conifer habitat.  Effect on wildlife is expected to be adverse, long-term, and minor.

A-Rock Reforestation (USFS): This project would hasten the return of the area burned in the 1990 fire to a forested habitat of 5,000 acres.  This would eventually benefit forest-dependent species such as spotted owls, but techniques used to achieve this condition (burning, mechanical thinning, herbicides), would have an adverse effect on wildlife, such as lazuli bunting, fox sparrow, and mule deer, that have occupied the post-fire, shrub-dominated community.  Overall impact is expected to be adverse, long-term, and minor because of the artificial influence on the natural succession of habitats and associated wildlife.

Aspen Fuels Reduction (USFS): This project would enhance habitat quality for spotted owls over a 500 acre area near the park.  This would have a beneficial, long-term, and minor impact.

Fire Management Plan for Wilderness (USFS): This plan would provide beneficial, long-term, and moderate impact on wildlife by allowing naturally-ignited fires that stay in prescription to cross boundaries between National Park Service and U.S. Forest Service lands.  This could result in wider areas of wildlife habitat benefiting from habitat improvement from fire.

Orange Crush Fuels Program (USFS): This project would manage fuels through prescribed burning.  This would have a beneficial, long-term, and minor effect on wildlife by working toward the return of a natural fire cycle for the area, and reduce the chance of catastrophic fire, which could carry into the park.

Rogge-Ackerson Fire Restoration (USFS): This would eventually benefit forest-dependent species such as spotted owls, but techniques used to achieve this condition (burning, tilling, shredding, herbicides), would have an adverse effect on wildlife that have occupied the post-fire, shrub-dominated community, such as lazuli bunting, fox sparrow, and mule deer.  Overall impact is expected to be adverse, long-term, and minor because of the artificial influence on the natural succession of habitats and associated wildlife.

Sierra Nevada Forest Plan Amendment (USFS): Implementation of this plan would have a major, beneficial, long-term effect on wildlife by leading to more ecosystem-based management of national forests in the Sierra Nevada.

The impacts of these actions, considered in combination with the impacts of Alternative A, would result in beneficial, long-term, and minor cumulative effects on park wildlife and habitat.  This is because past, present, and reasonably foreseeable projects inside and outside the park would beneficially affect large areas of wildlife habitat in the central Sierra Nevada.  The Sierra Nevada Forest Plan Amendment would affect virtually all U.S. Forest Service land around the park by more ecosystem-based management.  In comparison, projects with adverse impacts involve small areas and/or have minor impacts over larger areas.

Conclusion

Effect of Alternative A on wildlife would be adverse, long-term, and major because of the indefinite continuation of the direct effects of high-fuel loading on habitat structure and quality in some areas and the continued threat of catastrophic fire.  High-intensity fire has the potential to cause wide-scale, long-term, changes in park habitats as well as large-scale changes in wildlife abundance and diversity in those areas affected.  Impacts from actions to suppress fires would be most intense under this alternative, because of the prolonged period over which undesirable wildland fires are likely to occur.  Large, high-intensity fires would potentially affect large areas of wildlife habitat, which would be considered key to the natural integrity of the park.  The effect would potentially be that of impairment. 

Special-Status Species – Plants

The four California rare plant species grow within the lower montane forest and foothill woodland vegetation zones, where fires frequently occur.  These plants occur mainly within the El Portal Administrative Site, although isolated populations of the Yosemite onion are also found within the park.  Threats to these species are from suppression-related impacts and establishment of non-native plant species in areas that have been severely burned (Hessl and Spackman 1995).  As fire lines are tied into creek bottoms and moist areas, populations occurring in those sites may be affected.  These impacts can be mitigated by avoidance of known populations and habitats of these species.  Soil and substrate disturbance from line construction and trampling is especially harmful to perennial species—in this case, Yosemite onion, Tompkin’s sedge, and Congdon’s lewisia.

Non-native plants have become established throughout the lower elevations of Yosemite and are concentrated in areas that receive constant disturbance and/or a constant influx of seed and plant material—e.g. along transportation corridors and drainages (Gerlach et al. 2001).  As fires burn they open up habitat that may be taken over by non-native plant species.  These plants are more aggressive colonizers, have a phenology different than natives, and may be favored by fire-caused changes in the soil.  Fires started in the shoulder seasons for hazard fuel reduction or other management reasons may actually exacerbate this problem, favoring non-native plants over the native suite of species.  In addition, these fires may negatively affect the rare plants themselves, which are adapted to fires occurring during the normal fire season—May through October at these elevations.  For example, Congdon’s woolly-sunflower blooms into May and sometimes into June.  Prescribed fires held earlier in the year will destroy mature plants and their potential to produce seed for the following season—thereby harming population size and viability.

Potential for Impacts from Catastrophic Fire

Due to fire exclusion and high fire return interval departures in most areas within the vegetation groups inhabited by these special-status plant species, fires tend to have unnaturally high intensity, with impacts to overstory as well as ground cover vegetation.  In drainages (which act as chimneys by concentrating high-intensity fire) these fires cook vegetation and create hydrophobic soils.  Yosemite onion, Tompkin’s sedge, and Congdon’s lewisia all occur on moist slopes or in drainages, and are at most risk of direct impacts from unnaturally high intensity fires.  Congdon’s woolly-sunflower is an annual species that is in seed during the fire season.  It grows on sparsely vegetated slopes with light fuels so fire intensity is generally within normal limits, and this plant thrives under post-burn conditions when competing plants have been burned off and woolly-sunflower seedlings can become established on very exposed slopes.  Level of effect to any of these species would depend on the extent of the event (whether it affected the entire species or an isolated population) and the proximity of the disturbed area to non-native seed sources (whether other species became established within the habitat).  Impacts from Alternative A to special-status species in regard to catastrophic fire would be adverse, long-term, and minor to moderate, due to the likelihood of extreme exposure of these sites to the sun and heating (due to loss of overstory cover and shade) following the fire.

Fire Management Treatments

Managed Wildland Fire

Under the No Action Alternative, all of the plant special-status species described in this document occur within either the Conditional or Suppression Units.  During fire events, input from a Resource Advisor would continue to be used to minimize or eliminate impacts to these species (see Chapter 2, Mitigation under Actions Common to All Alternatives and Appendix 3).  Human-caused fires would be suppressed regardless of the potential for ecological benefits, and attempts would be made to protect known populations through direct suppression actions.  Lightning fires in areas inhabited by these species would most often be suppressed; the only exception would be within the Conditional Unit where there could be isolated populations of the Yosemite onion.  In this unit, lightning fires would be allowed to burn if conditions (including ecological, political, and administrative) permitted.  These fires would occur within the natural fire season, when plants would be dormant and resistant to direct fire effects.  The departure from natural fire return intervals in these areas would continue to increase over time, with increased potential for catastrophic fire as explained above.  Therefore, impacts associated with managed wildland fire to special-status species under this alternative would be adverse, long-term, and moderate, because fire in some areas that would benefit from burning would continue to be suppressed.

Re-ignition clause.  Not used under this alternative.

Holding Action and Monitoring Effects (water and retardant drops, helispots and spike camps).  Water and retardant drops release liquids onto burning or unburned areas.  The physical impact of hundreds of gallons of fluid can cause erosion of soils both from the direct impact and from runoff from the site (due to the nature of decomposed granite soils and sparsely vegetated metamorphic substrates).  The woolly-sunflower could be washed from the slope, if soils containing seed for this species are dislodged and carried to lower, possibly less suitable slopes and gullies.  Perennial species of onion, sedge, and lewisia, due to their below-ground bulb and root structures, could lose the above-ground portions of individual plants with minimal impact to the perennial portions.  However, loss of above-ground biomass could eventually lead to reduced vigor in the season following a fire.

Retardant is high in phosphorous and nitrogen, both of which are generally found in very low concentrations within the habitats for these species.  Increased levels of nutrients could increase the potential for the establishment of non-native species.  However, the chemical components of retardant only remain for a few months at most, and long-term, chemical alteration of the soil does not occur.  Impacts are mitigated through avoiding the use of retardants, or by using “clear” retardants that minimize active nutrients within the mix.  Direct impacts would be avoided by asking pilots to keep their aircraft moving so that water and retardant is dissipated over a larger, more linear area.  In this way, less soil is disturbed, decreasing the amount of downslope erosion and topsoil lost.

Fire monitoring activities, including the development and management of helispots, spike camps, and fire camps can all lead to ground disturbance.  There is an increased potential of spills and soil contamination from aircraft as well as chainsaws and fuel cans in these areas.  Aircraft runners, boots, other equipment, and camp and base supplies contaminated with non-native seed, provide vectors for non-native species that otherwise would not have dispersed into these sites.  Mitigation measures include avoiding known populations of special-status species, cleaning weed seeds from vehicles and equipment, and rehabilitating sites as quickly as possible (which restores natural drainages, prevents further unnatural runoff; and restores locally gathered litter and duff to the site).  Mitigation measures as described in Chapter 2 would be adhered to.  All of the special-status species occur in relatively steep, inaccessible areas that would not serve for staging areas or helispots.  Therefore, impacts of these actions taken in conjunction with mitigation measures would be adverse, short-term, and negligible.

Prescribed Fire

Prescribed burns are carried out for two primary reasons—to restore or maintain vegetation within target conditions and to reduce fuels to protect buildings or achieve other administrative objectives (e.g. maintenance of cultural landscapes or view sheds).  At times, the two reasons contradict each other because their effects differ on various components in a burn unit (Kauffman, 1990). 

In the areas where the park’s listed plant species occur, prescribed burns are done for both reasons.  Efforts would continue to restore the native suite of grasses and forbs within the foothill pine/live oak/chaparral vegetation type, through the removal of numerous non-native plant species.  Other areas adjacent to developments (particularly in the El Portal Administrative Site) would be burned during the shoulder season and at higher frequencies to create a defensible barrier around houses, businesses, and administrative facilities.  Depending on the site and the species affected, impacts would vary.  Overall, due to the highly limited and isolated habitat of special-status plant species and their overall resilience to fire, these actions would have a minor, adverse, and long-term effect.

Site Preparation Associated with Managed Wildland Fire and Prescribed Fire (hand line, snagging, mop-up)

Preparations for managed wildland fire can significantly disturb vegetated areas.  Felling and moving snags can create large accumulations of fuel in sparsely covered areas not normally at risk of fire.  Hand line construction could cause ground disturbance across slopes and drainages that might divert run-off and cause a loss of topsoil, thus drying out drainages and impinging on individual plants within a special-status population.  Mop-up activities would churn up ash and soil, creating extensive disturbance within the upper soil layers, potentially establishing non-native species due to an increase in interstitial spaces in the soil.  Mop-up can also lead directly to the loss of seed and below-ground plant structures by exposing them to heat and flames.  All of these actions can negatively affect the park’s special-status plant species.  As much as possible, efforts would be made to identify known populations of these species during fire planning so that disturbance would not occur.  In the event that a population were disturbed, fire rehabilitation (which includes restoring natural topography by replacing soil layers scraped aside and rocks that were moved while building hand lines) would mitigate the impacts.  Mop-up would not be allowed within a certain distance of a special-status species plant population so that soils and below-ground plant structures would be left intact and undisturbed.  Snags would be felled away from sensitive sites to prevent damage from high-intensity burns.  Under this alternative, with these mitigations, impacts would be negligible to adverse, short-term, and minor.

Fuel Reduction by Hand or Machine

Aggressive Reduction Techniques.  These treatments would not be used in Alternative A.

Passive Reduction and Lower Profile Techniques.

Hand Cutting.  Hand cutting to reduce overall stand density, break up continuous areas of shrubs and trees, and/or remove ladder fuels under this alternative would be focused on removing smaller size classes of tree seedlings and saplings.  Thinning prescriptions have been developed for most wildland/urban interface areas of the park, as well as undeveloped portions of Yosemite Valley and Wawona.  Prescriptions include species to target, desired density of smaller age classes (so that some seedlings and saplings would remain on the site), and (if applicable) species to be avoided.

In the case of special-status plant species, hand thinning would only affect known populations in the El Portal Administrative Site.  All thinning projects would go through review, with Resource Advisors providing input regarding the presence and necessary measures to protect and/or avoid these species.  Yosemite onion and Congdon’s lewisia generally are unaffected by thinning due to the locations of their populations.  Both Tompkin’s sedge and Congdon’s woolly-sunflower potentially would be affected by thinning activities if ground disturbance such as foot traffic or dragging cut materials were to occur.  Therefore, the impact of hand thinning in the No Action Alternative (with mitigations) would be adverse, short-term, and negligible to minor.

Pile burning.  Pile burning would generally follow hand thinning and would precede broadcast burning (as site preparation).  Impacts associated with pile burning would include surface and soil disturbance associated with dragging materials to each pile; very localized, intense burn effects on surface fuels, litter, and duff; and damage to soil layers (and thus subsurface plant structures such as seeds, roots, bulbs, rhizomes, and mycorrhizal mycelium).  Longer-term impacts might include changes in soil chemistry and structure, from extreme, long duration heating.  Piles would be kept rather small – about the size of small car – so they would be manageable when burned and so the effects would be localized and unlikely to impact larger, individual plants.  The small size would allow re-colonization of sterilized patches by mycorrhizal fungi and other soil organisms.

These activities would have the potential to impact both Tompkin’s sedge and Congdon’s woolly-sunflower because of the location of some populations and individuals of these species.  Yosemite onion and Congdon’s lewisia generally would not be impacted by these activities, because of the location of their populations.  Efforts would be made to avoid individual plants and populations, by identifying them during planning for the activity.  Vegetation is often so thick that resource specialists would be unable to gain access to a burn site to accurately identify isolated individual plants.  However, larger populations would be avoided, and piles would be placed in sites that are unlikely to support these species.  Therefore, impacts of pile burning on plant special-status species would be negligible to adverse, short-term, and minor.

Chipping.  Chipping activities would occur when biomass could not be burned on site or when it would need to remain on site for logistical, administrative, or ecological reasons.  Chips can cause localized denudation by burying soils and seed banks and robbing soils of available nutrients during the decomposition process.  Chips – due to their high cellulose content and the lack of moisture and nutrients in local soils to facilitate rapid breakdown – should only be applied up to 1 inch deep.  However, chips would be spread more thickly in some areas (such as road shoulders in the El Portal Administrative Site) to deter non-native plant species such as yellow star-thistle.  Impacts would occur to special-status species if chips were placed on top of populations and/or individuals, or on potential habitat for these species.  Careful project planning and notification to resource specialists prior to the start of a project would help avoid covering special-status plants.  Due to these mitigations, the impact of chipping on special-status species would be short-term, negligible to minor, and adverse. 

Cumulative Impacts

Other actions expected to occur within Yosemite that would affect these special-status species would be implementation of the Merced Wild and Scenic River Comprehensive Management Plan/EIS (NPS 2000) and the Yosemite Valley Plan/SEIS (2000c).  The first identifies a protection zone along the Merced River that will allow for enhanced habitat protection of Tompkin’s sedge, some populations of Yosemite onion, and Congdon’s lewisia, which occur in drainages and areas adjacent to the river.  Implementation of the Yosemite Valley Plan would substantially increase the human population in the El Portal Administrative Site, which would increase the potential for impacts (from radiating use and the increased potential for the introduction, establishment, and spread of non-native plant species) to individuals and populations of all of these plant species.  Mitigation measures identified in the Yosemite Valley Plan reduce the potential level of impact to adverse, long-term, and minor. 

Beyond the park and administrative site boundaries, the only projects that would affect these plants, because of their habitat requirements, would be those that occur within the Merced River drainage immediately west of the park.  The Sierra Nevada Forest Plan Amendment, which affects both Stanislaus and Sierra National Forests, would have potential effects in areas adjacent to the park.  Under this plan, efforts would be made to reduce the spread of noxious weeds, protect riparian resources, and manage fuels and fire similarly to the National Park Service. 

Thus, present and reasonably foreseeable projects in the region would potentially improve habitat conditions for these species (by controlling weeds and restoring fire as part of the ecosystem), with resultant long-term, minor, and beneficial impacts.  These effects, in combination with the effects of Alternative A, would result in minor, adverse and long-term cumulative impacts.

Conclusion

Overall, the effect of Alternative A would be adverse, long-term, and minor for special-status plant species, primarily because of the potential for habitat modification from high-intensity fire, and because of the effects of some on-site treatments on populations.  There would be no impairment from the effects of this alternative. 

Special-Status Species – Animals

Sierra Nevada Bighorn Sheep (Ovis canadensis sierrae) - Federal Endangered

This species has an extremely limited distribution in Yosemite; a few individuals occasionally venture into the park near Mount Dana and Gaylor Basin.  They come from a reintroduced population that is found primarily on Tioga and Warren Crests, east of the park.  Bighorn sheep summer on high, open terrain above treeline, and winter on high, windswept ridges or descend to lower elevations on the east side of the Sierra.  Critical habitat requirements include open terrain that has a low chance of concealing predators and steep, rocky escape terrain.  Green vegetation around water seeps is important in foraging areas (Moore 1993).  Because of the limited distribution in Yosemite, no wildlife habitat relationships (Mayer and Laudenslayer 1988) evaluation was done for this species. 

Potential for Impacts from Catastrophic Fire

Bighorns select high elevation, habitats that have sparse tree and shrub cover where fires rarely spread even though lightning strikes are frequent.  The natural fire return interval is 200 to 400 years.  Catastrophic fire would, therefore, be highly unlikely.  The fires that do occur would help open up the landscape, making it more suitable for bighorns.  For bighorn sheep, impact of Alternative A in regards to catastrophic fire, would be adverse, long-term, and negligible.

Fire Management Treatments

Managed Wildland Fire

All bighorn habitat in Yosemite is in the Fire Use Unit, where lightning-fires are the primary method of habitat management.  Fires would be evaluated and allowed to burn when they would accomplish resource management objectives.  The rarity, low intensity, and slow rate of spread of fires make their suppression, and possible re-ignition, unlikely.  As such, managed wildland fire would have a negligible, beneficial, long-term effect on bighorn sheep under Alternative A.

Prescribed Fire

Prescribed burns in bighorn sheep habitat would be unlikely since these areas are well within the natural fire return interval of 200 to 400 years.  The U.S. Forest Service has recently burned bighorn wintering areas outside the park in order to enhance habitat quality, reduce predator cover, and stimulate forage growth.  Yosemite has no wintering habitat.  Prescribed fire under Alternative A would therefore, have a negligible, beneficial, long-term effect on bighorn sheep.

Site Preparation Associated with Managed Wildland Fire and Prescribed Fire (hand line, snagging, mop-up)

Because management of wildland and prescribed fires would be unlikely in bighorn habitat, actions to manage such fires would also be unlikely.  Any human presence would potentially disturb bighorns and affect their survival and reproduction (Papouchis et al. 2001).  Therefore, fire crews in bighorn habitat would have an adverse effect.  Helicopters dropping water and retardant would also distress bighorns.  The improbability of these actions happening in bighorn habitat, however, limit their expected impact to adverse, short-term, and negligible.

Fuel Reduction by Hand or Machine

Passive Reduction Techniques.  Would not occur in bighorn sheep habitat.

Cumulative Impacts

Two regional plans for adjacent U.S. Forest Service land would affect Sierra Nevada bighorn sheep.  Implementation of the Sierra Nevada Forest Plan Amendment/FEIS (USFS) would potentially benefit bighorns by protecting resources of value to bighorns.  The Management Direction for the Ansel Adams, John Muir, and Dinkey Lakes Wilderness Revised Draft/EIS would have a beneficial effect on bighorns by allowing habitat enhancement of wintering areas through prescribed burning.

The Inyo National Forest has implemented restrictions on dogs within all occupied bighorn habitat.  Removal of three mountain lions over the last year from bighorn habitat outside the park has helped reduce predation.  The cancellation of two domestic sheep grazing allotments (Bloody Canyon and Alger Lakes) on the Inyo National Forest, and the modification of two others, have helped reduce the threat of disease transmission from domestic sheep to bighorn sheep.  These actions are all designed as part of the interagency recovery efforts for this endangered species.

The resulting cumulative impacts from these actions on Sierra Nevada bighorn sheep are major, beneficial, and long-term because they will help the species recover to larger, more stable self-sustaining populations.  In combination with the negligible impacts from Alternative A, cumulative impacts would remain major, beneficial, and long-term.

Conclusion

The impact of Alternative A on Sierra Nevada bighorn sheep would be beneficial, long-term, and negligible because of the continued, though rare, influence of fire on their habitat.

Valley Elderberry Longhorn Beetle (Desmocerus californicus dimorphus) – Federal Threatened