Thesis

Targeted Grazing as an Effective Control for Non-Native (Lolium Multiflorum) Among the Rare Species (Cordylanthus Palmatus) in Alkali Meadow Habitats.

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.

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