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University of Nevada, Reno Extent and Distribution of Montane University of Nevada, Reno Extent And Distribution Of Montane Riparian Zone Vegetation And Representation In Protected Areas In The Sky Island Region Of The Southwestern United States A thesis sbumitted in partial fulfillment of the requirements for the degree of Master of Science in Geography By Nicole H. Shaw Dr. Thomas P. Albright/Thesis Advisor Dr. Brett G. Dickson/Thesis Co-advisor August, 2016 © by Nicole H. Shaw 2016 All Rights Reserved THE GRADUATE SCHOOL We recommend that the thesis prepared under our supervision by NICOLE H. SHAW Entitled Extent And Distribution Of Montane Riparian Zone Vegetation And Representation In Protected Areas In The Sky Island Region Of The Southwestern United States be accepted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Thomas P. Albright, Advisor Brett G. Dickson, Committee Member Marjorie D. Matocq, Graduate School Representative David W. Zeh, Ph.D., Dean, Graduate School August, 2016 i Abstract The Sky Island region of the southwestern United States hosts some of the richest biodiversity anywhere in the world. In the mountain ranges of the Sky Islands, most vertebrate biodiversity is dependent on riparian areas for all or some of their life cycles. Riparian vegetation is threatened by human impacts and climate change. Though riparian vegetation along rivers and major perennial streams is already mapped in this region, vegetation in ephemeral and intermittent riparian areas, arguably equally important for biodiversity in the mountain ranges, has not been quantified. I developed a Random Forest classification model of riparian vegetation for all three types of riparian areas, mapped this vegetation for each of the 25 mountain ranges, described the spatial distribution and connectivity of the vegetation among and between mountain ranges, and demonstrated enhancement of regional riparian land cover classes with the new model of riparian zone vegetation. The resulting map indicates a much broader distribution of riparian zone vegetation than previous land cover mapping efforts indicate, likely due to inclusion of ephemeral and intermittent riparian types. The spatial distribution and connectivity of riparian zone vegetation varied widely within and between mountain ranges, possibly as a result of variability in environmental factors affecting aridity, temperature, water availability, landscape position, and disturbances. The model can be used with other information to augment understanding of the integrity, connectivity, and vulnerability of riparian zone vegetation in this unique and important region. To analyze the conservation status of riparian zone vegetation, I quantified its representation in protected areas. I then compared the representation relative to the overall amount of riparian zone vegetation in each mountain range. The relationships between ii representation of riparian zone vegetation in protected areas, degree of mountain range protection, and amount of riparian zone vegetation are complex and variable among mountain ranges. I used patterns of representation to place protected status of riparian zone vegetation in a regional context, highlighting mountain ranges where riparian zone vegetation is well-represented in protected areas as well as locations where further investigation may be warranted to understand conservation status and potentially vulnerable riparian areas. These outcomes benefit agencies and organizations that require spatially-explicit information about the amount, connectivity, and distribution of riparian zone vegetation and its representation in protected areas across the region for conservation, management, and planning. iii Table of Contents Abstract ............................................................................................................................... i List of Tables .................................................................................................................... iv List of Figures .....................................................................................................................v Introduction (thesis)...........................................................................................................1 Chapter 1 Extent and distribution of montane riparian zone vegetation in the Sky Islands region of the southwestern United States ...........................................................4 Introduction ......................................................................................................................5 Methods ..........................................................................................................................11 Results ............................................................................................................................23 Discussion ......................................................................................................................27 Conclusion ......................................................................................................................36 Chapter 2 Representation of riparian zone vegetation in protected areas among mountain ranges in the Sky Islands region of the southwestern United States ........37 Introduction ....................................................................................................................37 Methods ..........................................................................................................................41 Results ............................................................................................................................45 Discussion ......................................................................................................................47 Conclusion ......................................................................................................................53 Conclusion (thesis) ..........................................................................................................55 Literature Cited ...............................................................................................................57 Tables ................................................................................................................................67 Figures ...............................................................................................................................76 Thesis chapters are formatted to meet the manuscript requirements for the Journal of Arid Environments iv List of Tables Table 1 Predictor variables in the Random Forest supervised classification model Table 2 Classification scheme for training data collection Table 3 Landscape metrics, scales, method of calculation Table 4 Results of 10-fold cross validation of training data Table 5 Out-of-bag (OOB) error Table 6 Landscape metric results for each mountain range Table 7 Summary statistics of landscape metrics Table 8 The percent of riparian zone vegetation (RZV) by dominant land cover class Table 9 Gap status category descriptions and examples Table 10 Amounts of RZV and protected areas for each mountain range Table 11 Summary statistics for all mountain ranges of amount of RZV, protected status land, and unprotected status land v List of Figures Figure 1 The study area Figure 2 Pearson’s correlation matrix of predictor variables Figure 3 Pearson’s correlation matrix of selected landscape metrics Figure 4 The same location on national and regional land cover maps with riparian zone vegetation (RZV) map superimposed Figure 5 The supervised classification model across the study extent Figure 6 Importance of predictor variables in Random Forest classification model Figure 7 The percent of canyon bottoms that are riparian zone vegetation (RZV) summarized for each mountain range of the study area Figure 8 Riparian zone vegetation (RZV) patch area (ha) summarized as the mean for each mountain range of the study area Figure 9 Riparian zone vegetation (RZV) patch density in canyon bottoms summarized as the mean for each mountain range of the study area Figure 10 The distance between nearest neighbor patches of riparian zone vegetation (RZV) summarized as a mean for each mountain range of the study area Figure 11 Connectivity in canyon bottoms summarized as the mean for each mountain range of the study area Figure 12 Gap statuses of mountain ranges Figure 13 Percent of RZV in protected areas for each mountain range Figure 14 Comparison index for each mountain range 1 INTRODUCTION The Sky Islands region of the southwestern U.S. hosts some of the richest biodiversity anywhere on the planet (Mittermeier et al., 2004). This unique area of small mountain ranges separated by broad desert and grasslands is at the confluence of the Nearctic and Neotropical faunal realms and centered between the Sonora and Chihuahua deserts. The mountain ranges act as stepping stones linking the Rocky Mountains to the Sierra Madre, harboring many species at the edges of their distribution, and providing opportunity for uncommon overlap and exceptional diversity (Warshall, 1995). Within the Sky Islands, over 60% of species are dependent on riparian systems to sustain their populations and use riparian vegetation for habitat, water, shelter, movement corridors and other resources (DeBano and Baker, 1999; Zaimes et al., 2007). Across the western United States, riparian areas are threatened by anthropogenic influences and climate change (Theobald and Norman, 2010). In the Southwest, riparian systems are
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