No abstract

No abstract

Many species of plants and animals associated with grasslands are rare or declining due to habitat loss and degradation. Although grassland plants and insects evolved in the context of both grazing and fire, the appropriate use of grazing and fire has been debated among those concerned with protecting insect communities. We established an experiment to test insect responses to three grassland management treatments: (1) patch‐burn graze (burning of spatially distinct patches and free access by cattle), (2) graze‐and‐burn (burning of entire tract with free access by cattle), and (3) burn‐only. Because we expected that land‐use legacies could also affect insect abundance and diversity, we evaluated effects of time since fire, grazing history, remnant history (remnant or reconstructed grassland) and pre‐treatment vegetation characteristics, which were assumed to be a legacy of prior land‐use. Butterflies (Lepidoptera), ants (Hymenoptera: Formicidae), and leaf beetles (Coleoptera: Chrysomelidae) were surveyed for three years to compare their responses to each of these treatments as measured by abundance, richness and species diversity. Each of these taxa is relatively diverse and was expected to have the potential to have strong negative responses to grazing and burning, but we predicted more positive responses to patch‐burn grazing. Our results showed that land‐use legacies affected insect abundance, richness and diversity, but treatments did not. Ant abundance was lower in tracts with a history of heavy grazing. Ant species richness was positively associated with pre‐treatment time since fire and vegetation height and negatively associated with pre‐treatment proportion native plant cover. Butterfly abundance was positively associated with pre‐treatment litter cover. Leaf beetle diversity was positively associated with pre‐treatment native plant cover, and leaf beetle abundance was negatively associated with time since fire. Our results indicate that land‐use legacies can exert more influence on grassland insect community composition than current management, but the particular aspects of these land‐use legacies that are important vary across insect taxa. The implications of these finding are that (1) land‐use legacies should garner more attention in grassland management and (2) conservation of grassland insect communities will be improved by taxon‐specific analysis of land‐use legacy variables.

Tallgrass prairies of central North America have experienced disturbances including fire and grazing for millennia. Little is known about the effects of these disturbances on prairie ants, even though ants are thought to play major roles in ecosystem maintenance. We implemented three management treatments on remnant and restored grassland tracts in the central U.S., and compared the effects of treatment on abundance of ant functional groups. Management treatments were: (1) patch-burn graze-rotational burning of three spatially distinct patches within a fenced tract, and growing-season cattle grazing; (2) graze-and-burn-burning entire tract every 3 years, and growing-season cattle grazing, and (3) burn-only-burning entire tract every 3 years, but no cattle grazing. Ant species were classified into one of four functional groups. Opportunist ants and the dominant ant species, Formica montana, were more abundant in burn-only tracts than tracts managed with either of the grazing treatments. Generalists were more abundant in graze-and-burn tracts than in burn-only tracts. Abundance of F. montana was negatively associated with pre-treatment time since fire, whereas generalist ant abundance was positively associated. F. montanawere more abundant in restored tracts than remnants, whereas the opposite was true for subdominants and opportunists. In summary, abundance of the dominant F. montana increased in response to intense disturbances that were followed by quick recovery of plant biomass. Generalist ant abundance decreased in response to those disturbances, which we attribute to the effects of competitive dominance of F. montana upon the generalists. Abstract. Tallgrass prairies of central North America have experienced disturbances including fire and grazing for millennia. Little is known about the effects of these disturbances on prairie ants, even though ants are thought to play major roles in ecosystem maintenance. We implemented three management treatments on remnant and restored grassland tracts in the central U.S, and compared the effects of treatment on abundance of ant functional groups. Management treatments were: 1) patch-burn grazerotational burning of three spatially distinct patches within a fenced tract, and growing-season cattle grazing; 2) graze-and-burn -burning entire tract every 3 yrs, and growing-season cattle grazing, and 3) burn-only -burning entire tract every 3 yrs, but no cattle grazing. Ant species were classified into one of four functional groups. Opportunist ants and the dominant ant species, Formica montana, were moreThe final publication is available at Springer via http://dx.doi.org/10.1007/s10841-013-9554-z.2 abundant in burn-only tracts than tracts managed with either of the grazing treatments. Generalists were more abundant in graze-and-burn tracts than in burn-only tracts. Abundance of F. montana was negatively associated with pre-treatment time since fire, whereas generalist ant abundance was positively associated. Formica montana were more abundant in restored tracts than ...