Poomacha Fire

Vegitation and Wildlife

 

The Poomacha Fire, aided by the strong winds, was quick moving with an extremely rapid rate of spread. Approximately 15,100 acres of the fire overlapped with the 2003 Paradise Fire burn area. Seven habitat communities were affected, including Coastal sage scrub, chaparral, oak woodlands, mixed conifer forest, grassland, riparian, and other wetland vegetation communities (see vegitation map of burn area). Specific habitat impacts are summarized in Table 4 below.

Table 4:

Summary of Habitat Acres Burned

Habitat

Acres Burned

Coastal Sage Scrub

6,197

Grassland

3,138

Riparian

823

Other Wetlands

196

Chaparral

15,958

Oak Woodlands

9,148

Mixed conifer forest

11.503

The burn area included plant and animal communities found in both upland and lowland habitats. Upland habitats are at higher and dryer elevations, more fire prone, and support plant and animal types that are adapted to cycles of drought. These include Coastal sage scrub, grasslands, chaparral, and oak woodlands, and mixed conifer forest habitats, as well as integrated (i.e. overlapping) habitats. Fire impacts to upland habitats are expected to be direct and recovery will depend on tolerance to fire, including for plants resprouting and regeneration (e.g., seed banks, tubers, corms, rehizomes) and, for animals, burrowing or mobility strategies. Indirect fire effects to animals species in these upland habitats are expected to be mostly a function of loss of habitat.

Lowland habitats are found at lower elevations and are that wetter, and include or more watershed drainages, such as, riparian woods and scrub habitats, freshwater marshes, and vernal pools. Lowland habitats are expected to experience indirect fire effects due to less outright fire-burned acreage. Additional indirect affects will occur, subsequently, due to runoff and erosion, with these concentrated in the downslope drainage basins.

Upland Habitats

Coastal sage scrub and grassland generally burned at a low to moderate severity. Chaparral, oak woodlands, and mixed conifer forests burned at a low to high severity. 

Coastal sage scrub and chaparral species. Although coastal sage scrub is adapted to periodic fires, disturbance from fire facilitates infestation by non-native, invasive weeds. Increased fire frequency may convert coastal sage scrub habitat to grassland thereby reducing California gnatcatcher populations. Typically, California gnatcatcher populations recover from fire within several years, consistent with the time it takes coastal sage scrub to regenerate. However, the 2007 San Diego County census found extremely few California gnatcatcher territories had actually re-established after the 2003 Cedar Fire. The overlap of the Cedar and Poomacha Fires in the Guejito area in California gnatcatcher occupied coastal sage scrub may have even longer-lasting effects on this species.

Buildup of high fuel loads in chaparral communities results in unnaturally hot fires that may kill plants and destroy the seed banks of some species. Nevin’s barberry has been documented northeast of Palomar Mountain County Park. This species is a stump-sprouter after wildfires, but the effects of an altered fire regime on this species are currently unknown. Seed production is sporadic and fertility has been observed to be low.

Chaparral/Mixed conifer forest species. Dunn’s mariposa lily, known to occur in the burned area on Palomar Mountain, sprouts from a bulb and occurs in dry stony ridges and fire breaks in chaparral and yellow pine forests. In the first post-fire growing season, the plant sprouts from the corm. Ground disturbance activities should in areas where the species is known to occur.

The Laguna Mountains skipper butterfly occupies an extremely narrow range within San Diego County and is found only on Mt. Palomar and in the Laguna Mountains. The skipper inhabits wet montane meadows at higher elevations, approximately 4,000 to 6,000 feet, within yellow pine forests. The larvae of the skipper feed solely on Cleveland's horkelia, a perennial plant in the rose family. Threats to the skipper include decreasing abundance of this host plant due fire, along with cattle grazing, recreational activities, and development.

The large-blotched salamander occupies evergreen and deciduous forests, oak woodlands, chaparral, and coastal sage scrub from the San Jacinto Mountains in southern California to northern Baja California. The salamander is frequently found under rocks and rotting logs or bark. The salamander remains underground during the dry season and emerges when it rains in winter or spring. The species is fully terrestrial and does not require water to breed. Typical threats to the salamander include habitat degradation and fragmentation due to development, substrate disturbance, and clear cutting of habitat. The Poomacha fire may have resulted in direct mortality to some of the large blotched salamander population, but many individuals may have avoided the fire while underground. Large-scale removal of canopy by the fire will result in reduced shading of the salamander habitat for a number of years.

Grassland species. While grassland habitat typically recovers fairly rapidly after fires, weeds may invade where bulldozer lines disturbed the soil, causing an overall reduction in habitat value. The golden eagle is found in grassland habitat (also in Coastal sage scrub and chaparral habitats). This species has been documented near the southern boundary of the La Jolla Indian Reservation. The severity and the extent of the burn in this area likely impacted rodent and rabbit populations upon which golden eagles prey. Golden eagles are expected to rebound as small and medium-sized mammal populations recover.

(Note: The Wildlife Research Institute has been documenting the San Diego County population of golden eagles since 1987. Their research has determined that most San Diego eagle pairs have a home range territory of 20-30 square miles with a smaller, core nesting and foraging area. The San Diego population appears to have declined by approximately 53 percent; and may be the most threatened population of golden eagles in North America. Research by the Wildlife Research Institute has shown that golden eagles are extremely sensitive to nest site disturbance by humans and will fly off the nest when humans approach within 1,500 feet of the nest.)

 

Lowland Habitats

The burn was of moderate to high intensity within riparian and other wetland habitats. The riparian habitat along the San Luis Rey River burned at moderate intensity with patches of high severity. In the San Luis Rey/Paradise Creek area, the primary concern was the moderate burn on north facing slopes that flow into the San Luis Rey River. Anticipated impacts included burn debris and sediment flowing to the San Luis Rey River. It was also likely that aquatic species would be affected by poor water quality resulting from debris and sediment.

Due to extremely high burn severity within the upper watershed of Plaisted and Cedar Creeks, it was likely that there would be significant levels of ash and sediment. Possible effects to water quality could extend to other downstream riparian areas. In general, it was likely these high intensity burn areas would negatively impact downstream aquatic biota, as well increase large woody debris throughout and beyond the specific burn areas.

Riparian Species. Southwestern willow flycatchers inhabit dense riparian tree and shrub communities in proximity to rivers, swamps, lakes, and reservoirs. This species breeds in southwestern North America and winters in Mexico, Central America, and northern South America. The largest population of the flycatcher inCalifornia (45 to 50 pairs) is found along an approximately four-mile stretch of the San Luis Rey River directly west of Lake Henshaw, one mile upstream from the burn area. The Poomacha Fire did not reach the stretch of the river occupied by the flycatcher colonies. Even post-fire impacts from siltation may be limited, with runoff from the fire being deposited downstream of the colonies. The fire may result in an initial reduction in insect forage for this species.

Poomacha Fire impacts on the arroyo toad will be dependent on the severity of the burn in the riparian drainages. Arroyo toads in Bee Canyon likely survived the fire but could be impacted by extensive sedimentation after the fire.

 

Source:

Interagency State Burned Area Response (BAER) Report. (2007, November 17). The Poomacha Fire

USDA Forest Service Burned-Area Report. (2007, November 21). Poomacha Witch Fires (FSH 2509.13).