Effects of prescribed fire on small mammals and beetle assemblages in conservation reserve program (CRP) grasslands
Davis, Stephen Seth
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The Conservation Reserve Program (CRP) was established as a portion of the 1985 Food Security Act. The CRP removed highly erodible farmland from production by seeding perennial grasses. Acreage enrolled in CRP could not be grazed or harvested for 10 years. Since 1985, 400,000 ha in the Southern High Plains have been enrolled in CRP providing the unique opportunity for scientists to study a variety of animals in relatively homogenous man-made habitats. The stands of CRP in the Southern High Plains are dominated by weeping lovegrass (Eragrostis curvula). Information on community structure and microhabitat use of small mammals in homogenous CRP grasslands is severely lacking. Therefore, the hypothesis that rodents within CRP grasslands differed in microhabitat use was examined. Small mammals were live-trapped on 12 study plots from 11 to 15 March 1996 in Lynn County, Texas. First captures of small mammals were separated into four vegetation categories based on canopy cover at the trap site. Eight species of small mammals were captured during 6000 trapnights. The deer mouse (Peromyscus maniculatus) and the hispid pocket mouse rChaetodipus hispidus) differed from the expected distribution of captures (chi square, 3 df, P < 0.001 and P = 0.001) with more captures in open trap sites. In contrast, the cotton rat (Sigmodon hispidus) and the western harvest mouse (Reithrodontomys megalotis^ differed from the expected distribution of captures (chi square, 3 df, P < 0.001 and P = 0.058) with more captures in densely vegetated trap sites. Results suggest rodents living in weeping lovegrass monocultures select different microhabitat cover. The effects of prescribed fire on small mammals and beetle assemblages in CRP grasslands have yet to be documented. Small mammals and beetles were sampled on six burned and six non-burned areas over the summers of 1996 and 1997. Small mammal trapping revealed 2532 captures of 1380 individuals of 10 species. R. megalotis and S. hispidus decreased dramatically following fire (P = 0.001 and P = 0.003). The northern grasshopper mouse (Onychomys leucogaster) increased following fire ( P = 0.044). Three other species, the spotted ground squirrel (Spermophilus spilosoma). P. maniculatus. and C. hispidus. all exhibited burn by time interactions and increased in at least one time period on burned areas. Rodent postfire succession in CRP grassland is a dynamic process. Habitats are continually being optimized by changing groups of rodents even when grasses return to preburn densities. Beetle trapping revealed 13 different beetle families, with six families captured in sufficient numbers for statistical analysis. Scarabaeidae, Tenebrionidae, and Meloidae beetles were not affected by fire. Carabidae and Cicindelidae, although not significant at the P < 0.05 level, had trends which suggested possible fire effects. Elateridae beetles decreased 16 months postburn but did not differ in previous samples. Beetles seem to be resilient to fire and families that are affected most are those depended on litter and detritus for habitat.