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Effects of enclosed large ungulates on small mammals at Land Between The Lakes, Kentucky

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Effects of enclosed large ungulates on small mammals at Land Between The Lakes, Kentucky

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Abstract

Ungulates can affect primary production, plant and animal species composition, nutrient cycling, and soil properties. We conducted a study at the Tennessee Valley Authority's Land Between The Lakes to investigate the effects of introduced Elk (Cervus elaphus) and Bison (Bison bison) on small mammal fauna in a 324-ha enclosure. From June 1998 through May 1999, live traps were set for small mammals in open-canopy hardwood, closed-canopy hardwood, and pine sites both inside and outside the enclosure, for 7020 trap nights. Small mammals were captured significantly more often inside than outside the enclosure; habitat type was not a significant factor, Habitat management practices inside the ungulate enclosure, including burning, mowing, and fertilizing, may have contributed to the higher abundance of small mammals.

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... Husdyrbeiting har i tidligere studier i alt fra saltørkner til arktiske økosystemer både økt (Jones & Longland 1999;Keesing & Crawford 2001) og senket aktivitet eller tettheter av smågnagere (Jones & Longland 1999;Weickert et al. 2001). Enkelte ganger har man vist ulik effekt avhengig av habitat for en gitt art (Hanley & Page 1980;Hewson 1982) og mellom ulike arter (Hanley & Page 1980;Jones & Longland 1999). ...
... Vi brukte så den beste modellen til å estimere effekter. Analyser ble kjørt i S-Plus vs. 6.2 (Crawley 2003 (Hanley & Page 1980;Hewson 1982;Keesing 1998;Jones & Longland 1999;Keesing 2000;Keesing & Crawford 2001;Weickert et al. 2001), mens vi vet fra konkurranseteori (Tokeshi 1999) at det er tettheten av beitedyr som er avgjørende for om det blir konkurranse eller ikke, ikke bare tilstedevaerelsen av en annen art. Vi fant da også stor forskjell på effekten av høy og lav tetthet av sau på vekstratene i markmusbestandene. ...
... Husdyrbeiting har i tidligere studier i alt fra saltørkner til arktiske økosystemer både økt (Jones & Longland 1999;Keesing & Crawford 2001) og senket aktivitet eller tettheter av smågnagere (Jones & Longland 1999;Weickert et al. 2001). Enkelte ganger har man vist ulik effekt avhengig av habitat for en gitt art (Hanley & Page 1980;Hewson 1982) og mellom ulike arter (Hanley & Page 1980;Jones & Longland 1999). ...
... Vi brukte så den beste modellen til å estimere effekter. Analyser ble kjørt i S-Plus vs. 6.2 (Crawley 2003 (Hanley & Page 1980;Hewson 1982;Keesing 1998;Jones & Longland 1999;Keesing 2000;Keesing & Crawford 2001;Weickert et al. 2001), mens vi vet fra konkurranseteori (Tokeshi 1999) at det er tettheten av beitedyr som er avgjørende for om det blir konkurranse eller ikke, ikke bare tilstedevaerelsen av en annen art. Vi fant da også stor forskjell på effekten av høy og lav tetthet av sau på vekstratene i markmusbestandene. ...
... A raising number of exclosure experiments have demonstrated strong effects of grazing on the abundance and species richness of small mammals (Eccard et al., 2000;Flowerdew & Ellwood, 2001;Jones, Bock, & Bock, 2003;Keesing, 1998;Matlack, Kaufman, & Kaufman, 2001;Moser & Witmer, 2000;Smit et al., 2001;Schmidt & Olsen, 2003;Schmidt, Olsen, Bildsøe, Sluydts, & Leirs, 2005;Weickert, Whittaker, & Feldhamer, 2001). Most studies have found larger abundance and species richness inside exclosures than in grazed controls. ...
... Trap locations were marked with tape tied to tall herbs. We established 11 trapping plots within the exclosures, seven in three of the four exclosures in areas with natural kestrel densities, which were more than 5 km away from occupied nest boxes and hence outside the home ranges of kestrels breeding in them (Village, 1997), and four in the three exclosures available in the area with experimentally increased kestrel populations (Fig. 1). Trapping plots were located more than 50 m away from fences. ...
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Abundance and diversity of small mammals are usually affected strongly by grazing either due to decreased food availability or quality, decreased suitability of soil for building burrow systems due to trampling and/or due to increased predation risk in the structurally simpler grazed areas. We estimated the effects of grazing-induced changes in vegetation and soil and of increased predation on small mammals in a Mediterranean grassland landscape. We measured vegetation structure, soil compaction and small mammal abundance and species composition in 22 plots of 8 Sherman live traps each, arranged according to an unbalanced two-way ANOVA design with two grazing levels (grazed areas and cattle exclosures) and two predator abundance levels (increased densities of Eurasian kestrels Falco tinnunculus by means of nest boxes and control). Plots were sampled during 2 consecutive years in early summer and early fall. Exclosure from cattle increased significantly vegetation height and volume and decreased soil compaction. Grazing-induced changes in vegetation height and volume and in soil compaction produced strong effects on small mammal abundance and species richness. Increased kestrel densities did not have significant additive or interactive effects, with the effects of grazing-induced vegetation and soil gradients on abundance or richness of small mammals. Our results suggest that the effects of grazing on small mammal communities in Mediterranean montane grasslands were mainly due to reduced food availability and by negative effects of trampling on the suitability of soils for building burrow systems. Decreased food quality and increased predation in grazed areas seemed to play a minor role, if any. Reductions in stock densities would then favor generalist predator populations in Mediterranean grasslands through the expected positive effects of such reductions on the availability of food and burrows for small mammals.
... A raising number of exclosure experiments have demonstrated strong effects of grazing by large mammals on the abundance and species richness of small mammals , Moser and Witmer 2000, Matlack et al. 2001, Weickert et al. 2001, Schmidt and Olsen 2003. Most studies have found larger abundance and species richness in exclosures than in grazed controls. ...
... For example, ungulates on LBL (the bison, elk, and deer) may influence small mammal populations indirectly through affects on primary plant production and species composition, nutrient cycling, and soil characteristics. Weickert et al. (2001) examined the impact of high densities of ungulates in LBL's 324-ha elk and bison enclosure on the population density and diversity of rodents. They live trapped small mammals each month for a year on six sites both inside and outside the enclosure. ...
... Trap locations were marked with tape tied to tall herbs. We established 11 trapping plots within the exclosures, seven in three of the four exclosures in areas with natural kestrel densities, which were more than 5 km away from occupied nest boxes and hence outside the home ranges of kestrels breeding in them (Village, 1997), and four in the three exclosures available in the area with experimentally increased kestrel populations (Fig. 1). Trapping plots were located more than 50 m away from fences. ...
... Trap locations were marked with tape tied to tall herbs. We established 11 trapping plots within the exclosures, seven in three of the four exclosures in areas with natural kestrel densities, which were more than 5 km away from occupied nest boxes and hence outside the home ranges of kestrels breeding in them (Village, 1997), and four in the three exclosures available in the area with experimentally increased kestrel populations (Fig. 1). Trapping plots were located more than 50 m away from fences. ...
... While the interpretation of exclosure studies may be complicated by factors such as the pre-treatment condition of the vegetation, the duration for which exclosures are in place, and the environmental variability experienced over that period, they remain an important source of information concerning the impact of grazing and browsing stock. Several studies have explored the interactions between livestock and small herbivorous rodents using such exclosures (Steen et al., 2005, Grant et al., 1982, Bock et al., 1984, Heske and Campbell, 1991, Kelt and Valone, 1995, Kerley and Whitford, 2000, Valone et al., 2002, Valone and Sauter, 2005, Flowerdew and Ellwood, 2001, Weickert et al., 2001, Jones and Longland, 1999, Hayward et al., 1997, Reynolds and Trost, 1980. These studies have provided evidence for both decreases and increases in the abundance of rodents following the removal of ungulate grazing in multiple combinations of ungulate and rodent species: red deer (Cervus elaphus) and wood mice (Apodemus sylvestris) in Dutch deciduous forest (Smit et al., 2001), sheep and field voles (Microtus agrestis) in a Norwegian alpine meadow (Steen et al., 2005), sheep, cattle and field voles at two Danish wet meadows (Schmidt et al., 2005), sheep, cattle and field voles in Scottish upland meadows (Evans et al., 2006), cattle and multiple rodent species in the American short grass steppe (Milchunas et al., 1998), and multiple ungulates versus multiple rodent species in African savannas (Keesing, 1998, Hagenah et al., 2009. ...
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