|Weltzin, Jake - TEXAS AGRIC EXP STATION|
|Dowhower, Steve - SCHOOL OF RENEWABLE NAT R|
Submitted to: Southwestern Naturalist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 1, 1997
Publication Date: N/A
Interpretive Summary: Study was conducted to examine the effects of prairie dogs on herbage standing crops, plant species composition, and plant diversity. Results showed that the activities of prairie dogs caused a 4-fold decrease in herbage standing crop, a shift in plant species composition toward less productive shortgrasses, and a reduction in plant diversity. Results counter claims that prairie dog colonies enhance rangeland primary productivity and species diversity.
Technical Abstract: Black-tailed prairie dogs (Cynomys ludovicianus) influence ecosystem structure and function through their burrowing and grazing activities, and reportedly increase plant species diversity relative to uncolonized portions of the landscape. Consequently, systematic eradication of prairie dogs-a widespread practice over much of the Great Plains-may ultimately reduce plant species diversity. To determine the effects of prairie dogs and associated fauna on herbaceous vegetation in a southern mixed-grass prairie ecosystem, we quantified herbaceous standing crop, species composition, and plant species diversity on and off a prairie dog colony in north-central Texas in 1988 and 1989. Total live herbaceous standing crop was 3 times to 4 times greater off the prairie dog colony than on the prairie dog colony in 1988 and 1989, respectively. Mid-grass biomass was 6 and 15 times greater off-colony than on-colony in 1988 and 1989, respectively. Shortgrass biomass did not differ between on-colony and off-colony zones in either year. Principal components analysis (PCA) revealed plant species distribution patterns attributable to colonization by prairie dogs. Axis I sample scores were strongly correlated with mid- grass biomass but not shortgrass biomass. Statistical analyses of jack- knifed Shannon's and Simpson's diversity indices indicated that plant species diversity was greater off than on the prairie dog colony. Thus, blacktailed prairie dogs and associated fauna substantially altered the relative distribution, abundance, and composition of herbaceous vegetation at this southern mixed-grass prairie site.