San Jose State University SJSU ScholarWorks Master's Theses Master's Theses and Graduate Research Fall 2015 Complex effects of Nitrogen Pollution and Grazing on Nectar resources of the Adult Bay Checkerspot Butterfly (Euphydryas editha bayensis) Nidhi Jain San Jose State University Follow this and additional works at: https://scholarworks.sjsu.edu/etd_theses Recommended Citation Jain, Nidhi, "Complex effects of Nitrogen Pollution and Grazing on Nectar resources of the Adult Bay Checkerspot Butterfly (Euphydryas editha bayensis)" (2015). Master's Theses. 4640. DOI: https://doi.org/10.31979/etd.wydq-986f https://scholarworks.sjsu.edu/etd_theses/4640 This Thesis is brought to you for free and open access by the Master's Theses and Graduate Research at SJSU ScholarWorks. It has been accepted for inclusion in Master's Theses by an authorized administrator of SJSU ScholarWorks. For more information, please contact [email protected]. COMPLEX EFFECTS OF NITROGEN POLLUTION AND GRAZING ON NECTAR RESOURCES OF THE ADULT BAY CHECKERSPOT BUTTERFLY (EUPHYDRYAS EDITHA BAYENSIS ) A Thesis Presented to The Faculty of the Department of Environmental Studies San José State University In Partial Fulfillment of the Requirements for the Degree Master of Science by Nidhi Jain December 2015 ©2015 Nidhi Jain ALL RIGHTS RESERVED The Designated Thesis Committee Approves the Thesis Titled COMPLEX EFFECTS OF NITROGEN POLLUTION AND GRAZING ON NECTAR RESOURCES OF THE ADULT BAY CHECKERSPOT BUTTERFLY (EUPHYDRYAS EDITHA BAYENSIS ) by Nidhi Jain APPROVED FOR THE DEPARTMENT OF ENVIRONMENTAL STUDIES SAN JOSÉ STATE UNIVERSITY December 2015 Dr. Rachel O’Malley Department of Environmental Studies Dr. Lynne Trulio Department of Environmental Studies Dr. Jae Pasari Berkeley City College ABSTRACT COMPLEX EFFECTS OF NITROGEN POLLUTION AND GRAZING ON NECTAR RESOURCES OF THE ADULT BAY CHECKERSPOT BUTTERFLY (EUPHYDRYAS EDITHA BAYENSIS ) by Nidhi Jain Recent anthropogenic increases in atmospheric nitrogen due to urbanization and combustion have had many adverse effects on natural systems, including loss of biodiversity, especially in sensitive habitats. One such region is the serpentine ecosystem of Coyote Ridge in San Jose, CA, the last refuge for recurring populations of the federally threatened Bay Checkerspot Butterfly (BCB) ( Euphydryas editha bayensis ). Increases in non-native grass cover and decreases in native forb cover (including cover of the BCB’s native larval host plants) have been attributed to the fertilizing effects of increased atmospheric nitrogen deposition. To counteract this effect, grazing has been implemented as a grassland management strategy. However, the effects of nitrogen enhancement and grazing, and the combined effects on shoulder-season nectar resources, have not been previously studied. This research aimed to fill this gap by utilizing a split block experimental setting at Coyote Ridge with four treatments, comprising of fertilized, unfertilized, grazed and ungrazed plots. According to the study results, nitrogen enhancement tended to reduce the abundance of nectar resources in both grazed and ungrazed plots. It also tended to reduce native vegetation in the grazed plots, while potentially increasing its prevalence in the ungrazed plots. These findings suggest that the effects of grazing and nitrogen on serpentine ecosystems are complex, highlighting the need to reduce nitrogen deposition. ACKNOWLEDGMENTS I would like to firstly thank Dr. Rachel O’Malley, for assisting me through every step of this process. My thesis committee Dr. Lynne Trulio for her valuable comments and input. Dr. Jae Pasari for his time and suggestions, and for allowing me to utilize his experimental set-up at Coyote Ridge. Thank you to Open Space Authority for allowing me access to the study site. I would like to thank all my professors at SJSU for guiding me. Thanks to the College of Social Science for the financial support. Thanks for the support to the O’Malley lab group and my 2012 ENVS cohort. Data collection would not have been possible without my research assistant, Eric Acedo, thank you. Thanks to my wonderful parents Manju and Arun Jain for all the support. Thanks to my sister Pragi Jain for your time, resources, support and guidance. My sister Nupur Jain and my brothers in law. Lastly, I would like to thank all my friends for their encouragement. v TABLE OF CONTENTS LIST OF TABLES................................................................................................................. vii LIST OF FIGURES............................................................................................................... viii Introduction............................................................................................................................ 1 Background....................................................................................................................... 2 Literature Review.................................................................................................................. 2 Native-exotic species competition in Serpentine ecosystems......................................... 3 The effects of nitrogen increase....................................................................................... 4 Managing disturbed ecosystems: Grazing....................................................................... 6 Animals as umbrella species............................................................................................ 8 Bay checkerspot butterfly.......................................................................................... 9 Feeding strategies: specialists vs. generalists............................................ 10 Larval diet.................................................................................................. 10 Adult diet................................................................................................... 11 Seasonality................................................................................................. 13 Research objectives............................................................................................................... 14 Research questions........................................................................................................... 14 Methods................................................................................................................................. 15 Study site......................................................................................................................... 15 Study design............................................................................................................... 18 Data collection........................................................................................................... 20 Analytical methods................................................................................................... 22 Results.................................................................................................................................... 23 Discussion.............................................................................................................................. 31 Conclusion and Management implication............................................................................ 34 References.............................................................................................................................. 35 vi LIST OF TABLES Table 1 Diet Breadth of Checkerspot Adults........................................................................ 12 Table 2 All Vegetation Identified in Surveys between February and May 2014.................. 24 Table 3 Adult Butterfly Observation of Nectar Utilization Between March 27th , 2014 and May 1st , 2014.................................................................................................... 25 Table 4 Flowering Vegetation Present on the First Three Survey Dates ................................ `7 26 vii LIST OF FIGURES Figure 1 Bay checkerspot butterfly feeding on Amsinckia intermedia (N.Jain, personal photograph, April 2014)............................................................................................ 10 Figure 2 Study region. Experimental set up location in Coyote Ridge, California (Map by Nidhi Jain).................................................................................................. 17 Figure 3 Split-block experimental setup.................................................................................. 20 Figure 4 Distribution of plots on study site: Coyote Ridge, San Jose (Image source: Google Earth™ 2015)............................................................................................... 23 Figure 5 Presence/Absence of the perennical herb Muilla maritima in Enhanced N/ Ambient N plots on February 21st , 2014.................................................................. 27 Figure 6 Presence/Absence of Allium serra in Enhanced N/Ambient N plots on March 21st , 2013....................................................................................................... 28 Figure 7 Presence/Absence of Chlorogalum pomeridianum in grazed/ungrazed plots on March 18th , 2013................................................................................................. 29 Figure 8 Effects of enhanced N and grazing on flower resource on March 23rd , 2014........... 30 Figure 9 Effects of enhanced N and grazing on native plant growth on March