Williams, Kimberlyn .
Habitat correlates of two mariposa lilies, Calochortus plummerae and Calochortus splendens, on the campus of California State University, San Bernardino.
CALOCHORTUS plummerae E. Greene, which is endemic to southern California, and Calochortus splendens Benth., which occurs primarily in California, co-occur on the campus of California State University, San Bernardino. This study was conducted to determine the microhabitat distribution of these species on Badger Hill, an isolated, convoluted ridge rising from alluvial coastal sage scrub on campus. We studied Calochortus distribution using belt transects in four landscape blocks, each containing a ridge, a south-facing slope, a north-facing slope, and a gully. In each 10-m segment of each transect, we counted mariposa lilies, measured steepness of slope, and estimated densities of non-native annuals. Densities of were estimated for (1) all annual grasses, (2) Centaurea melitensis L. (tocalote or maltese star-thistle), and (3) Brassica nigra (L.) Koch (black mustard). Each was recorded as absent (scored as 0), 1-10 plants m-2 (scored as 1), 10-20 plants m-2 (scored as 2), or >20 plants m-2 (scored as 3). Summing scores for all the three classes of annuals yielded a "total weed score". The densest populations of mariposa lilies occurred along ridgelines. South-facing slopes had the lowest densities. Steepness of slope had little discernable effect on lily density when topographic position was factored out. Within each topographic position, lilies appeared to be negatively associated with the density of non-native annual plants. These data suggest that, although these mariposa lilies may be found in swards of non-native annuals, these annuals may negatively affect them.
This study was carried out as part of a pilot offering of a class in which students learned elements of field research studying problems suggested by personnel from nearby national forests. This course is part of a program funded by the U.S. Department of Agriculture to stimulate education in natural resources and conservation in Hispanic-serving institutions.
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1 - California State University San Bernadino, Biology Department, 5500 University Parkway, San Bernardino, California, 92407, USA
Bromus madritensis ssp. rubens
Presentation Type: Poster:Posters for Sections
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM