|Motteram, Ernest -|
Submitted to: Western North American Naturalist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 18, 2011
Publication Date: November 1, 2011
Repository URL: http://dx.doi.org/10.3398/064.071.0307
Citation: Ralphs, M.H., Motteram, E.S., Panter, K.E. 2011. Velvet lupine (Lupinus leucophyllis) population cycles with climate. Western North American Naturalist. 71(3): 396-403. Interpretive Summary: Velvet lupine contains the teratogenic alkaloid anagyrine that causes a crooked calf syndrome when a cow ingests lupine between the 40-100 day of gestation. An outbreak of crooked calves occurred in the Scabland region of eastern Washington in 1997 following two years of above average precipitation. Following this catastrophic loss, we began studies to track velvet lupine density and relate its population cycle to precipitation. A series of years with high precipitation led to outbreaks of velvet lupine populations, and these populations died back in subsequent years of below average precipitation. Summer precipitation appears critical for survival of new seedlings. Previous spring precipitation may be necessary for development of perenniating buds, and current water year fall precipitation may be necessary for the continued development of the buds.
Technical Abstract: Velvet lupine (Lupinus leucophyllis Dougl. ex Lindl) contains the teratogenic alkaloid anagyrine that causes a crooked calf syndrome when a cow ingests lupine between the 40-100 day of gestation. An outbreak of crooked calves occurred in the Scabland region of eastern Washington in 1997 following two years of above average precipitation. Following this catastrophic loss, we began studies to track velvet lupine density and relate its population cycle to precipitation. In the first study, five 1m2 quadrats were systematically placed in dense lupine patches at each of 5 locations throughout the scabland region. The quadrats were permanently marked and the number of seedlings and established mature plants were counted bi-weekly or monthly through the growing seasons of 2001-2005. In the second study, four 30 m belt transects were established at each of 3 locations in the scabland region. The number of seedlings and mature lupine plants were counted within these transects in June or July each year from 2002 - 2009. A third study was conducted to determine the slope or aspect where lupine was most abundant to determine its preferred habitat. Ten sites were located along the Cow Creek drainage which runs through the region. At each site, 10 m belt transects were established in alluvial bottoms, slopes, and shallow rocky ridges. In study 1, density of mature lupine plants generally declined between 2001 and 2005 and was correlated with spring precipitation (r = 0.77). In study 2, density of mature lupine plants declined from 2002 through 2005, but increased in 2007, in response to heavy precipitation the previous fall and spring (correlation coefficients between mature lupine plants and the respective season precipitation, r = 0.75 and r = 0.62). Density of lupine was greatest on slopes (2.6 plants/m2) compared to the alluvial bottoms (1.5 plants/m2), or the shallow rocky ridges (0.26 plants/m2). Velvet lupine populations appear to cycle with climatic patterns, increasing following wet years and dying back in drought.