Outline of Quino Recovery Plan - The Xerces Society

Consumption of nonnative plants by domestic animals has been used as a tool to
prevent further deterioration of already degraded bay checkerspot habitat
(restricted to serpentine soils). In the short term, cattle may reduce non-native
grass invasion rates in already degraded habitat through preferential grazing and
enhanced nitrogen exportation (Weiss 1999). However, in Quino checkerspot
habitat cattle have also been observed to cause disturbance to soil crusts that
contributes to initial invasion rates (M. Dodero, pers. comm.). Livestock have
been found to contribute to non-native plant invasion in the arid western U.S. by:
1) transporting seeds into uninfested sites, 2) preferentially grazing native plant
species (although this has not been observed in Euphydryas editha habitat), 3)
creating bare, disturbed patches of soil and destroying crusts, 4) increasing soil
nitrogen concentration (if they are not managed to enhance exportation), 5)
reducing soil mycorrhizae, and 6) accelerating soil erosion (Belsky and Gelbard
2000). Observations of coastal sage scrub in the Western Riverside County
Multiple Species Reserve found that native forbs were readily consumed if
grazing was done at the time of year when they were abundant and flowering
(E. Allen, pers. comm.). It is doubtful that even carefully controlled grazing can
effectively reduce nonnative plant invasion in the variety of habitats that harbor
the Quino checkerspot, and it should be phased out and replaced by other less
destructive nonnative plant control methods. Intact cryptogamic crusts appear to
exclude nonnative plant invasion better than cattle grazing (M. Dodero, pers.
comm.)
5. Fire
Increased fire frequency is a cause of native California plant community decline,
and therefore a threat to Quino checkerspot survival. Frequent fire is caused by
increased human populations (increased ignition sources), and by increased
habitat fragmentation and transportation corridors that allow highly flammable
nonnative plants to penetrate undeveloped lands. Studies have shown that short
fire intervals of 5 years or less cause conversion of shrubland to grassland,
enhancing nonnative grass invasion (Zedler et al. 1983, Malanson 1985,
Calloway and Davis 1993). The typical fire return interval in coastal sage scrub
is approximately 30 years (Keeley and Keeley 1984, Westman and O'Leary
1986). Under shorter fire intervals, shrubs, unlike annuals, cannot grow to
maturity and reproduce. Urban parks in western Riverside County (such as Box
Springs Mountain and Mount Rubidoux, which were dominated by coastal sage
34