Abstract:
ABSTRACT
TARGETED GRAZING AS AN EFFECTIVE CONTROL FOR
NON-NATIVE LOLIUM MULTIFLORUM AMONG THE
RARE SPECIES CORDYLANTHUS PALMATUS IN
ALKALI MEADOW HABITATS
by
Sheli M. Wingo
Master of Science in Biological Sciences
California State University, Chico
Spring 2009
Alkali meadow habitats can be defined by their soil alkalinity and high
salinity, creating an extreme environment for most plant species. An exception is
Cordylanthus palmatus, a native rare endemic to this habitat and currently only found in
five locations in the Central and Livermore Valleys in California. Currently the two
largest populations of Cordylanthus palmatus are on the Colusa and Delevan National
Wildlife Refuges (NWR) and are potentially being threatened by an increasing
population density of Lolium multiflorum, a non-native annual grass. I investigated
targeted grazing as a management tool to reduce L. multiflorum while having no impact,
or improving, the fitness of C. palmatus populations. I evaluated two grazing treatments
within the reproductive growing season of L. multiflorum, over two years. The study
was conducted at Colusa NWR within the C. palmatus population at the site with
response variables being C. palmatus relative fitness, soil pH and salinity, percent cover
of native host focal species, and changes in species richness within the alkali meadow
grazing plots. Climatic variation between the two study years at the site was extreme
(150% and 50% normal precipitation) and may have influenced the lack of clear pattern
resulting from the treatments. Results were mixed regarding an increase in C. palmatus
fitness; however no decrease in fitness resulted from the targeted grazing. This study
determined that with well-defined management prescriptions, and closely monitored
removal from the site, cattle could be grazed within alkali meadow habitats to reduce
non-native grass cover without negatively impacting C. palmatus fitness and may even
increase fitness in certain conditions. However, a longer term study is recommended to
determine affect trends of grazing through time.
