Amphibian Populations Utilizing Historic Military Maneuver Damage
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Amphibian Use of Man-Made Pools Created by Military Activity on Kisatchie National Forest, Louisiana A thesis presented to the faculty of the College of Arts and Sciences of Ohio University In partial fulfillment of the requirements for the degree Master of Science Stephen M. Ecrement August 2014 © 2014. Stephen M. Ecrement. All Rights Reserved. 2 This thesis titled Amphibian Use of Man-Made Pools Created by Military Activity on Kisatchie National Forest, Louisiana by STEPHEN M. ECREMENT has been approved for the Program of Environmental Studies and the College of Arts and Sciences by Kelly Johnson Associate Professor of Biological Sciences Robert Frank Dean, College of Arts and Sciences 3 ABSTRACT ECREMENT, STEPHEN M., M.S., August 2014, Environmental Studies Amphibian Use of Man-Made Pools Created by Military Activity on Kisatchie National Forest, Louisiana (46 pp.) Director of Thesis: Kelly Johnson Pools created from military training provide breeding habitat for many amphibian species. Six hundred and twenty four surveys were conducted for larval amphibians on 48 small man-made pools, created from military maneuver training (tank defilades), on the Fort Polk Intensive Use Area (IUA) of Kisatchie National Forest, Louisiana. Surveys were conducted monthly from April to early October 2012 and March to September 2013. Anuran species composition varied across tank defilades, with environmental variables explaining the presence and abundance of some species. Bronze frogs (Lithobates clamitans), Northern Cricket frogs (Acris crepitans), Fowler’s toads (Anaxyrus fowleri), Eastern Narrow-Mouthed toads (Gastrophryne carolinensis), Gray tree frog complex (Hyla versicolor/chrysoscelis), and Squirrel tree frogs (Hyla squirellii) were not abundant enough for analysis. Cajun Chorus frogs (Pseudacris fouquettei) and Southern Leopard frogs (Lithobates sphenocephalus) occurred in 79% of the pools. Salamanders were not encountered at the study site either year. Of seven variables evaluated using regression models, open canopy, low percent slope, and fish absence were positively related to the abundance of Cajun Chorus frogs (Pseudacris fouquettei). Percent dissolved oxygen and low canopy closure were positively associated with Southern Leopard frogs (Lithobates sphenocephalus) abundance. My results show that 4 the two species use these man-made pools differently, highlighting the importance of having pools in varying conditions. In light of documented declines of anuran populations, it has become increasingly important to protect their breeding habitat. It is equally important to gain an understanding of habitat characteristics that attract or deter breeding amphibians from natural or man-made aquatic systems. Although these pools were created unintentionally they now serve as amphibian breeding habitat. 5 ACKNOWLEDGEMENTS I would like to thank my wife, Mariamar Gutierrez Ramirez, for her love and unconditional support during the duration of my master’s thesis. I am eternally grateful because without her I would not have achieved this goal. I also want my family to know how much I appreciate their continuously optimistic attitudes toward my ambition to complete a Master’s degree even when I gave them reason to believe otherwise. I give special recognition and appreciation to Dr. Stephen Richter (Eastern Kentucky University) for walking me through the research design and statistical analysis via emails and phone conferences. Dr. Richter went above and beyond expectations. A special thanks to my advisor Dr. Kelly Johnson, first for accepting me as a graduate student and second for guiding me through the data analysis and writing process. I thank my committee members – Dr. Natalie Kruse and Dr. Matthew White – for their support and guidance. Special appreciation for the Fort Polk, Conservation Branch and the Center for the Environmental Management of Military Lands (CEMML) supervisors for providing me with the opportunity to finish my graduate course work. My gratitude to the Kisatchie National Forest for allowing me to conduct my research on their property. I also want to express my sincere gratitude to everyone that assisted me from the day we “discovered” the tank defilades through one year of trial and error and two years of field data collection: Brian Early, Jeff Wilson, Bridgett Goldsmith, Brett Cooper, Jim Johnson, Christopher Melder, Dean Maas, Willis Sylvest, Ray Geroso, Shane Carnahan, Brittany Chaumont, Mariamar Gutierrez, Ken Moore, Sheila Guzman, Rocky Numbers, Sarah Pearce, Jeanne Daigle, Madison Daigle, and Stacy Huskins. 6 TABLE OF CONTENTS Page Abstract……………………………………………………………………………………3 Acknowledgements……………………………………………………………….……….5 List of Tables……………………………………………………………………………...7 List of Figures……………………………………………………………………………..8 Introduction………………………………………………………………………………..9 Methods…………………………………………………………………………………..13 Study Site………………………………………………………………………...13 Data Collection…………………………………………………………………..14 Data Analysis…………………………………………………………………….16 Results……………………………………………………………………………………19 Discussion………………………………………………………………………………..34 Literature Cited…………………………………………………………………………..40 7 LIST OF TABLES Page Table 1: Minimum, maximum and mean of the seven variables used in a Global model for predicting amphibian Catch Per Unit Effort in tank defilade pools in 2012 (A) and 2013 (B), Kisatchie National Forest, Louisiana…………………………………………18 Table 2: Species of anurans confirmed using the tank defilades pools for reproduction..19 Table 3: Seven anuran species confirmed using the tank defilade pools for reproduction in 2012…………………………………………………………………………………...20 Table 4: 2012 species abundant enough for analysis of abundance and the output from the Tweedie regression model for statistically significant independent variables……..…….21 Table 5: Five anuran species confirmed using the tank defilade pools for reproduction in 2013….……..…………………………………………………………………………….23 Table 6: 2013 species abundant enough for analysis and the output from the Tweedie regression model for statistically significant independent variables…………………….24 8 LIST OF FIGURES Page Figure 1: Aerial photo of the 48 tank defilades on the Kisatchie National Forest Intensive Use Area....……………………………..……………………………….…….…….........14 Figure 2: Total tadpole count for other species encountered at the tank defilade study site in 2012………………....………………………………………………………...………21 Figure 3: Relationship of fish presence (A) (P = 0.010) and canopy closure (B) (P = 0.041) on Pseudacris fouquettei maximum catch per unit effort in 2012. Only two pools with relatively open canopy and no P. fouquettei had established fish populations.…….22 Figure 4: Relationships of percent canopy closure (A) (P = 0.037) and dissolved oxygen (B) (P = 0.081) on Lithobates sphenocephalus maximum Catch Per Unit Effort in 2013………………………………………………………………………………………25 Figure 5: Relationship of fish presence (P = 0.067) to Pseudacris fouquetteii maximum CPUE in 2013…………………………………………………….……………………...26 Figure 6: Relationship of mean % slope (A) (P = 0.015), and % canopy closure (B) (P = 0.026) to Pseudacris fouquetteii maximum CPUE in 2013. Red diamonds indicate pools with relatively open canopy, established fish populations, and no P. fouquetteii larvae..27 Figure 7: Monthly rain data for Fort Polk, Louisiana in 2012 and 2013……….…..........28 Figure 8: Mean and standard error values for center depth for all 48 tank defilades during each month that the pools were sampled in 2012 (A) and 2013 (B) …………………….29 Figure 9: Mean values and standard error values for wetted surface area for all 48 tank defilades during each month pools were sampled in 2012 (A) and 2013 (B)...………….30 Figure 10: Mean and standard error values for bottom temperature on all 48 tank defilades each month pools were sampled in 2012 (A) and 2013 (B) ……...…………...31 Figure 11: 2012 3D NMDS ordination based on similarity of presence/absence of anuran species and vectors showing the influence of environmental variables (Stress = 0.09, Axis 1R² = 0.62, Axis 2R² = 0.32)…………………………………………………………….33 Figure 12: 2013 3D NMDS ordination based on similarity of presence/absence of anuran species and vectors showing the influence of environmental variables (Stress = 0.07, Axis 1R² = 0.64, Axis 2R² = 0.27)……………………………………………………….....…33 9 INTRODUCTION Evidence indicates that amphibian populations are suffering from declines, range restrictions, and species extinctions on a local and potentially global scale (Blaustein et. al. 1994, Alford and Richards 1999, Gardner 2001, Babbitt et. al. 2009), which are often directly or indirectly the result of human activity (Dorcas and Gibbons 2008). Amphibians require both terrestrial and aquatic habitats, and thus are negatively impacted by clear cuts and habitat fragmentation, poor water quality, development, invasive species, and wetland destruction (Alford and Richards 1999). The conservation of amphibians requiring a habitat mosaic of small, isolated breeding pools in addition to large areas of upland habitat is of global interest (Colburn 2004). Dispersing juveniles and migrating adults of most pool-breeding amphibians are also dependent on terrestrial habitat for foraging and overwintering (Semlitsch 1998; Semlitsch and Bodie 2003). Conservation planning for pool-breeding amphibians thus must be informed from habitat investigations at multiple scales – pool, local, and landscape scales (Baldwin et al. 2006; Marsh and Trenham 2001; Semlitsch 2002; Porej et al. 2004) At the pool-scale, unique environmental features may influence breeding of particular