Dynamic connectivity of temporary wetlands in the southern Great Plains
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We quantified fluctuations in the status of individual patches (wetlands) in supporting connectivity within a network of playas, temporary wetlands of the southern Great Plains of North America that are loci for regional biodiversity. We used remote sensing imagery to delineate the location of surface waters in >8,000 playa basins in a ~31,900 km2 portion of Texas and quantified connectivity in this region from 2007 to 2011. We ranked playas as stepping-stones, cutpoints, and hubs at different levels of environmental conditions (regionally wet, dry, and average periods of precipitation) for dispersal distances ranging from 0.5 to 34 km, representing a range of species’ vagilities, to provide baseline dynamics within an area likely to experience disrupted connectivity due to anthropogenic activities. An individual playa’s status as a stepping-stone, cutpoint, or hub was highly variable over time (only a single playa was a top 20 stepping-stone, cutpoint, or hub in >50 % of all of the dates examined). Coalescence of the inundated playa network usually occurred at ≥10 km dispersal distance and depended on wetland density, indicating that critical thresholds in connectivity arose from synergistic effects of dispersal ability (spatial scale) and wet playa occurrence (a function of precipitation). Organisms with dispersal capabilities limited to <10 km routinely experienced effective isolation during our study. Connectivity is thus a dynamic emergent landscape property, so management to maintain connectivity for wildlife within ephemeral habitats like inundated playas will need to move beyond a patch-based focus to a network focus by including connectivity as a dynamic landscape property.
KeywordsBetweenness centrality Cutpoint Graph theory Habitat network Hub Playa Stepping-stone
This research was made possible in part by NSF-Proactive Recruitment in Introductory Science and Mathematics Grant 1035096 (“RMR-TTU: Recruitment, Mentoring, and Research in Mathematics and Science at Texas Tech University”), NSF-Macrosystems Biology Grants 1065773 and 1065845 (“Collaborative Study: Climatic Forcing of Wetland Landscape Connectivity in the Great Plains”), and the Texas Tech University Center for Undergraduate Research. S.D. Starr was partially supported by The CH Foundation. N.E. McIntyre was partially supported by the Virginia and J. Edward Holtry Visiting Scientist Program at the Geographic Information Science Center of Excellence at South Dakota State University. We gratefully acknowledge the West Texas Mesonet for precipitation data. Comments from the coordinating editor and three anonymous reviewers improved the manuscript.
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