Wednesday, August 22, 2007

Turnbull Canyon fire

Approximately 80 acres of open space burned yesterday in the upper Turnbull Canyon watershed, ignited by a car that went over the side of the road near the midpoint of Turnbull Cyn. Rd. (the driver escaped with apparently minor injuries). The fire burned a bit of the downhill (northern) slope below the road, but quickly raced uphill to the south and east before being contained at the ridgeline. If you're familiar with hiking or riding in this area, the burn area is mainly south of Turnbull Cyn. Rd., roughly bounded by the Schabarum Trail on the east and by fireroads/trails on the west and south, and includes a portion of Workman Hill.

This fire occurred in the wide portion of the corridor, in an area that has seen frequent fire over the years. Thus, it should not appreciably affect the movement of animals through the hills. As with all small fires, most animals flee the area briefly during the burn, or retreat to burrows, emerging only hours after the flames subside (only the top few millimeters of soil are burned). Plants will start resprouting almost immediately.

Unfortunately, frequent fires, as have occurred here, have resulted in the degradation of the soil microflora over recent decades. Extensive fields of non-native black mustard and thistle - and dense stands of laurel sumac shrubs - attest to a history of disturbance, both from grazing and fire. Still, the upper Turnbull watershed is still very diverse in terms of habitat types, with oak woodland, sumac-elderberry scrub, coastal sage scrub and native grassland occurring in patches of various sizes. Several of these patches were coded as "high quality habitat" by the Resource Management Plan (Fig. 5), a designation that was based on the dominance of native plant species.

Two populations of the rare Catalina Mariposa-Lily and one population of the rare Plummer's Mariposa-Lily (per Fig. 10A) were detected during recent surveys within the area affected by the fire; fieldwork this spring is needed to assess their current status. Fortunately, the unique vernal pool area just to the south (upper Worsham Canyon watershed) was unaffected, and neither were the large prickly-pear/buckwheat patches on south-facing slopes north of Turnbull Cyn. Rd., which are important for many rare plant and animal species.

We will be monitoring the recovery of this area in upcoming years.

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