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1.
David J. Augustine Marc R. Matchett Theodore P. Toombs Jack F. CullyJr. Tammi L. Johnson John G. Sidle 《Landscape Ecology》2008,23(3):255-267
Black-tailed prairie dogs (Cynomys ludovicianus) are a key component of the disturbance regime in semi-arid grasslands of central North America. Many studies have compared
community and ecosystem characteristics on prairie dog colonies to grasslands without prairie dogs, but little is known about
landscape-scale patterns of disturbance that prairie dog colony complexes may impose on grasslands over long time periods.
We examined spatiotemporal dynamics in two prairie dog colony complexes in southeastern Colorado (Comanche) and northcentral
Montana (Phillips County) that have been strongly influenced by plague, and compared them to a complex unaffected by plague
in northwestern Nebraska (Oglala). Both plague-affected complexes exhibited substantial spatiotemporal variability in the
area occupied during a decade, in contrast to the stability of colonies in the Oglala complex. However, the plague-affected
complexes differed in spatial patterns of colony movement. Colonies in the Comanche complex in shortgrass steppe shifted locations
over a decade. Only 10% of the area occupied in 1995 was still occupied by prairie dogs in 2006. In 2005 and 2006 respectively,
74 and 83% of the total area of the Comanche complex occurred in locations that were not occupied in 1995, and only 1% of
the complex was occupied continuously over a decade. In contrast, prairie dogs in the Phillips County complex in mixed-grass
prairie and sagebrush steppe primarily recolonized previously occupied areas after plague-induced colony declines. In Phillips
County, 62% of the area occupied in 1993 was also occupied by prairie dogs in 2004, and 12% of the complex was occupied continuously
over a decade. Our results indicate that plague accelerates spatiotemporal movement of prairie dog colonies, and have significant
implications for landscape-scale effects of prairie dog disturbance on grassland composition and productivity. These findings
highlight the need to combine landscape-scale measures of habitat suitability with long-term measures of colony locations
to understand the role of plague-affected prairie dogs as a grassland disturbance process.
The U.S. Government’s right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged. 相似文献
2.
Anthropogenic habitat loss and fragmentation are the principle factors causing declines of grassland birds. Declines in burrowing
owl (Athene cunicularia) populations have been extensive and have been linked to habitat loss, primarily the decline of black-tailed prairie dog
(Cynomys ludovicianus) colonies. Development of habitat use models is a research priority and will aid conservation of owls inhabiting human-altered
landscapes. From 2001 to 2004 we located 160 burrowing owl nests on prairie dog colonies on the Little Missouri National Grassland
in North Dakota. We used multiple linear regression and Akaike’s Information Criterion to estimate the relationship between
cover type characteristics surrounding prairie dog colonies and (1) number of owl pairs per colony and (2) reproductive success.
Models were developed for two spatial scales, within 600 m and 2,000 m radii of nests for cropland, crested wheatgrass (Agropyron cristatum), grassland, and prairie dog colonies. We also included number of patches as a metric of landscape fragmentation. Annually,
fewer than 30% of prairie dog colonies were occupied by owls. None of the models at the 600 m scale explained variation in
number of owl pairs or reproductive success. However, models at the 2,000 m scale did explain number of owl pairs and reproductive
success. Models included cropland, crested wheatgrass, and prairie dog colonies. Grasslands were not included in any of the
models and had low importance values, although percentage grassland surrounding colonies was high. Management that protects
prairie dog colonies bordering cropland and crested wheatgrass should be implemented to maintain nesting habitat of burrowing
owls. 相似文献