Vantage to Pomona FEIS Index 34 - Laserfiche WebLink

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Vantage to Pomona Heights Chapter 3 230 kV Transmission Line Project FEIS Affected Environment PAGE 3-262 cover of fire sensitive shrubs. In drier Wyoming big sagebrush (A. tridentata ssp. wyomingensis) communities, mean fire return intervals have been estimated to span 50 to 240 years (Whisenant 1990; Baker 2006). Cheatgrass is common in the Project study area, producing a fuel type that was not previously present and creating conditions that cause many areas to now burn at intervals of five years or less (Brooks 2008). After fires occur, cheatgrass recovers rapidly, typically before native species in the area. Cheatgrass is adapted to a wide range of germination temperatures and this adaptation allows it to germinate during the winter when temperatures are too cold for the germination of most native plants (Pyke and Novak 1994). Thus, the quick recovery and fuel source formed by cheatgrass perpetuates an invasive plant/fire cycle (Brooks 2008). This increase in fire frequency quickly removes non-sprouting shrubs such as big sagebrush. Sagebrush is extremely susceptible to the effects of fire. Shrubs will die if they are partially burned or come in contact with the heat generated by wildfires for as little as 30 seconds (Britton and Clark 1985). Although rabbitbrush (Ericameria spp. and Chrysothamnus spp.) may initially increase with fire, it is killed when the fire-return interval decreases to five years or less (Whisenant 1990; Mosley et al. 1999). Continued increases in fire frequency eventually remove and exclude all perennial shrubs, grasses and forbs from the landscape and competition from cheatgrass prevents their reestablishment. Fire History in the Project study area is shown in Appendix A - Vegetation and Fire History. Wildfires have occurred within and near the Project study area, the majority of which were concentrated within the JBLM YTC boundary. The Project wildland fire analysis used fire data from 1987-2016. Fires have been largely ignited by lightning or military training, but there are several instances of other human- caused fires (e.g., fireworks). Due to the type and intensity of training that occurs at the JBLM YTC, the incidence and risk of fire is higher compared with adjacent lands and naturally occurring fire cycles. Training activities such as live fire exercises, use of tracer rounds, explosive ordnance, and some aspects of maneuver training can cause fire. However, the incidence of fire ignition and spread at the JBLM YTC has been declining since 1996 due to improvements to their fire management policy and increased initial attack and suppression support. Improvements include annual Prescribed Burn Plans, implementation of the Fire Risk Assessment, pyrotechnic restrictions during periods of high fire danger, wildland fire fighting training, and remote sensing and fire history monitoring (Nissen and Melcher 2004). In addition, JBLM YTC annually maintains over 240 miles of firebreaks to serve as a barrier to limit the potential spread of wildland fires and provide access for fire suppression crews. The JBLM YTC has also enhanced their existing road network, with approximately 300 miles of roads acting as fire breaks and has installed approximately 25 dip ponds in strategic locations to provide a water supply for fire suppression activities (JBLM YTC 2002). 3.12.2.2 Fuel Factors Fire risk associated with vegetation depends on the amount of fuel present and fuel continuity. Fuel continuity determines where a fire can go and how fast it travels. In shrublands with bunchgrasses and widely spaced shrubs, fire spread is limited by the patchiness of the fuel source (Brown 2000; Paysen et al. 2000). In these communities, fires tend to burn small areas and need conditions that are hotter and drier (Whisenant 1990). Increased fire frequencies are associated with the introduction of cheatgrass. Cheatgrass has a very fine structure, tends to accumulate litter, and dries completely in early summer, thus becoming a highly flammable fuel. Cheatgrass changes the fire regime of the sagebrush-steppe by filling in the spaces between shrubs, thereby creating a more continuous fuel source that carries wildfires to the widely spaced shrubs. As cheatgrass spreads in sagebrush communities, community structure shifts from a complex, shrub-dominated canopy with low fuel loads in the shrub interspaces to one with continuous fine fuels in the shrub interspaces thus increasing the probability of fire ignition and spread (Rice et al. 2008).