Ecological factors suitable for the endangered Lasthenia conjugens (Asteraceae)

For future introduction efforts, various ecological factors supporting the growth of the federally endangered Lasthenia conjugens E. Greene (Contra Costa goldfields; Asteraceae) were examined in seven vernal pool complexes at Fort Ord near Monterey, California. Over a two-year period, L. conjugens abundance was measured in addition to several descriptors of the abiotic and biotic environment, including seasonal inundation, aquatic and edaphic parameters, plant diversity, and pig disturbance. Linear regression was used to analyze percent cover of L. conjugens in relation to the abiotic and biotic factors examined. Those factors that related to L. conjugens abundance were then tested for differences across complexes with and without L. conjugens. Inundation, water temperature, water pH, water holding capacity, and native species richness were positively related to L. conjugens abundance. Of these factors, water temperature, water pH, and native species richness differed significantly among complexes with and without L. conjugens. The data suggest that L. conjugens thrives in pools with longer inundation regimes, warmer waters, neutral water pH, and greater native species richness. The four complexes that lack this rare endemic appear to fall out of the mean ecological range for several of the factors related to L. conjugens cover and, therefore, would be unsuitable for introduction efforts of L. conjugens.