Population Variation in Dune-dwelling Lizards in Response to Patch Size, Patch Quality, and Oil and Gas Development
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چکیده
We studied relationships between quality and quantity of habitat and conversion of land to caliche roads and well pads associated with oil and gas development. We asked how these factors affected abundance of dune-dwelling lizards, with emphasis on a habitat specialist, the dunes sagebrush lizard Sceloporus arenicolus. Open depressions in dune complexes are a critical landscape feature for S. arenicolus, and extensively used by all species; thus, size and total area of open depressions in a study site were our measures of habitat quality and quantity. There were significant differences in habitat quality among sites, and habitat quality and quantity were correlated significantly. Abundances of all lizards, including S. arenicolus, varied significantly among sites and this variation could be explained by amount of habitat at a given site. Relationships between oil and gas development, quantity and quality of habitat, and abundances of lizards likely occur on different spatial scales constraining our ability to detect direct effects of oil and gas development alone. Our research is the first to investigate effects of oil and gas development on an assemblage of dune-dwelling lizards. RESUMEN—Se estudiaron las relaciones entre la calidad y la cantidad de hábitat y la conversión de hábitat a caminos y plateas de caliche para pozos petroleros asociados al desarrollo petrolero. Preguntamos cómo dichos factores afectan la abundancia de lagartijas que habitan dunas, con énfasis en una especie especialista Sceloporus arenicolus. Las depresiones abiertas en los complejos de dunas de arena son una caracterı́stica importante del paisaje para S. arenicolus y son usadas mucho por todas las especies, entonces el tamaño y área total de estas depresiones en un sitio fueron nuestras medidas de calidad y cantidad de hábitat. Se encontraron diferencias significativas en la calidad de hábitat entre los sitios, y la calidad y cantidad de hábitat estuvieron significativamente correlacionadas entre sı́. Las abundancias de lagartijas de todas las especies, inclusive S. arenicolus, variaron significativamente entre sitios, y tal variación podrı́a estar explicada por la cantidad de hábitat en un sitio determinado. Las relaciones entre el desarrollo petrolero, la calidad y cantidad de hábitat, y las abundancias de lagartijas probablemente ocurren a distintas escalas espaciales, limitando nuestra capacidad de detectar los efectos directos de desarrollo petrolero exclusivamente. Este trabajo es el primero en investigar algunos efectos del desarrollo petrolero en un ensamblaje de lagartijas de dunas. The association between availability of habitat and persistence of species is clear, and recent work elucidates how cumulative loss of habitat at large spatial scales erodes capacity of the landscape to sustain biodiversity (Pope et al., 2000; Gaston et al., 2003). Farming croplands, extraction of timber, urban development, and construction of roads all contribute to loss of habitat and result in variable configuration of remaining patches of habitat and associated effects on biodiversity (Andren, 1994; Hokit et al., 1999; Fahrig, 2003). For example, with agricultural or urban development, large tracts of land may be converted leading to a few patches of habitat that are relatively isolated. Habitat also is lost to road construction or timber extraction, but the resulting fragmentation may lead to an increase in number of patches and variation in size and isolation of patches. Thus, it is important to understand how land-management practices influence availability and quality of habitats across landscapes. Oil and gas exploration and development began in the 1800s and occurs on large spatial scales spanning hundreds of thousands of hectares (Bureau of Land Management, http://www. blm.gov/nm/st/en/prog/energy/oil_and_gas/ lease_sale_notices.html). Yet there are few studTHE SOUTHWESTERN NATURALIST 56(3):315–324 SEPTEMBER 2011
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تاریخ انتشار 2011