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Plant-associated microbes, specifically fungal endophytes, augment the ability of many grasses to adapt to extreme environmental conditions. Tripsacum dactyloides (Eastern gamagrass) is a perennial, drought-tolerant grass native to the tallgrass prairies of the central USA. The extent to which the microbiome of T. dactyloides contributes to its drought tolerance is unknown. Ninety-seven genotypes of T. dactyloides were collected from native populations across an east–west precipitation gradient in Kansas, Oklahoma and Texas, and then grown together in a common garden for over 20 years. Root and leaf samples were visually examined for fungal density. Because fungal endophytes confer drought-tolerant capabilities to their host plants, we expected to find higher densities of fungal endophytes in plants from western, drier regions, compared to plants from eastern, wetter regions. Results confirmed a negative correlation between endophyte densities in roots and precipitation at the genotype's original location (r  = −0.21 P  = 0.04). Our analyses reveal that the host genotype's origin along the precipitation gradient predicts the absolute abundance of symbionts in the root, but not the relative abundances of particular organisms or the overall community composition. Overall, these results demonstrate that genetic variation for plant–microbe interactions can reflect historical environment, and reinforce the importance of considering plant genotype in conservation and restoration work in tallgrass prairie ecosystems. [ABSTRACT FROM AUTHOR]

While the relationship between genetic diversity and plant productivity has been established for many species, it is unclear whether environmental conditions and biotic associations alter the nature of the relationship. To address this, we investigated the interactive effects of genotypic diversity, drought and mycorrhizal association on plant productivity and plant traits. Our mesocosm study was set up at the Konza Prairie Biological Research Station, located in the south of Manhattan, Kansas. Andropogon gerardii , the focal species for our study, was planted in two levels of genotypic richness treatment: monoculture or three-genotype polyculture. A rainout shelter was constructed over half of the experimental area to impose a drought and Thiophanate-methyl fungicide was used to suppress arbuscular mycorrhizal fungi in selected pots within each genotypic richness and drought treatment. Genotypic richness and mycorrhizal association did not affect above-ground biomass of A. gerardii. Drought differentially affected the above-ground biomass, the number of flowers and bolts of A. gerardii genotypes, and the biomass and the functional traits also differed for monoculture versus polyculture. Our results suggest that drought and genotypic richness can have variable outcomes for different genotypes of a plant species. [ABSTRACT FROM AUTHOR]

Mature ewes were used in a 4-yr study to evaluate effects of intensive late-season sheep grazing on vigor of sericea lespedeza in native tallgrass prairie. Pastures (N = 8; 31 ± 3.6 ha) infested with sericea lespedeza (initial basal frequency = 1.4%) were assigned randomly to one of two treatments: early-season beef steer grazing (1.1 ha/steer; initial BW = 258 ± 34 kg) from April 15 to July 15 followed by no grazing for the rest of the year (control; STR) or steer grazing from April 15 to July 15 followed by intensive grazing by mature ewes (0.2 ha/ewe; SHP) from August 1 to October 1. Ewes (initial BW = 65 ± 3.1 kg) were assigned randomly to graze four of eight pastures; remaining pastures were not grazed from August 1 to October 1. Vegetation responses to treatment were measured along four permanent 100-m transects in each pasture. Herbivory on sericea lespedeza was monitored weekly in each pasture from July 21 to October 7. Herbivory on sericea lespedeza in SHP and STR after steer grazing and before sheep grazing was not different (P = 0.51). In contrast, sericea lespedeza herbivory following sheep grazing was greater (P < 0.01) in SHP than in STR. Herbivory of individual sericea plants was greater (P < 0.01) in SHP than in STR by the end of week 1 of the sheep-grazing period (10.6% vs. 0.5%); moreover, herbivory on sericea lespedeza steadily increased (P ≤ 0.01) such that 92.1% of sericea lespedeza plants were grazed in SHP compared to 1.4% in STR by week 8 of the sheep-grazing period. Whole-plant DM weight of sericea lespedeza at dormancy was less (P < 0.01) in SHP than in STR. Additionally, annual seed production by sericea lespedeza was less (P < 0.01) in SHP than in STR (114 vs. 864 seeds/plant). Pasture forage biomass was not different (P = 0.76) between SHP and STR after the steer-grazing period. Conversely, STR had more (P < 0.01) residual forage biomass than SHP at the end of the sheep-grazing period. Growth performance of beef steers grazing from April 15 to July 15 annually was not different (P ≥ 0.59) between treatments. Our results were interpreted to suggest that intensive late-season grazing by sheep decreased vigor of sericea lespedeza. Late-season sheep grazing decreased forage biomass by 904 kg DM/ha compared with late-season rest; however, residual biomass was adequate to prevent soil-moisture loss and erosion during the dormant season. [ABSTRACT FROM AUTHOR]

Leaf trait variation enables plants to utilize large gradients of light availability that exist across canopies of high leaf area index (LAI), allowing for greater net carbon gain while reducing light availability for understory competitors. While these canopy dynamics are well understood in forest ecosystems, studies of canopy structure of woody shrubs in grasslands are lacking. To evaluate the investment strategy used by these shrubs, we investigated the vertical distribution of leaf traits and physiology across canopies of Cornus drummondii, the predominant woody encroaching shrub in the Kansas tallgrass prairie. We also examined the impact of disturbance by browsing and grazing on these factors. Our results reveal that leaf mass per area (LMA) and leaf nitrogen per area (Na) varied approximately threefold across canopies of C. drummondii, resulting in major differences in the physiological functioning of leaves. High LMA leaves had high photosynthetic capacity, while low LMA leaves had a novel strategy for maintaining light compensation points below ambient light levels. The vertical allocation of leaf traits in C. drummondii canopies was also modified in response to browsing, which increased light availability at deeper canopy depths. As a result, LMA and Na increased at lower canopy depths, leading to a greater photosynthetic capacity deeper in browsed canopies compared to control canopies. This response, along with increased light availability, facilitated greater photosynthesis and resource-use efficiency deeper in browsed canopies compared to control canopies. Our results illustrate how C. drummondii facilitates high LAI canopies and a compensatory growth response to browsing—both of which are key factors contributing to the success of C. drummondii and other species responsible for grassland woody encroachment. [ABSTRACT FROM AUTHOR]

Intensification of livestock production has reduced heterogeneity in vegetative structure in managed grasslands, which has been linked to widespread declines in grassland songbird populations throughout North America. Patch-burn grazing management aims to restore some of that heterogeneity in vegetative structure by burning discrete pasture sections, so that cattle preferentially graze in recently burned areas. Although patch-burn grazing can increase reproductive success of grassland songbirds, we know little about possible interactions with regional variation in predator communities or brood parasite abundance, or annual variation in weather conditions. Using six years of data from two tallgrass prairie sites in eastern Kansas, USA, we tested effects of patch-burn grazing on the rates of brood parasitism, clutch size, nest survival, and fledging success of three common grassland songbirds, Dickcissels (Spiza americana), Eastern Meadowlarks (Sturnella magna), and Grasshopper Sparrows (Ammodramus savannarum), among pastures managed with patch-burn grazing versus pastures that were annually burned and either grazed or ungrazed. Dickcissel nests experienced lower parasitism (72.8 ± 4.6% SE vs. 89.1 ± 2.2%) and Eastern Meadowlarks had higher nest survival (63.2 ± 20.5% vs. 16.5 ± 3.5%) in annually burned and ungrazed pastures than pastures managed with patch-burn grazing. However, average number of host fledglings per nesting attempt did not differ among management treatments for any species. Annual variation in weather conditions had a large effect on vegetation structure, but not on reproductive success. Probability of brood parasitism was consistently high (25.5?84.7%) and nest survival was consistently low (9.9-16.9%) for all species pooled across treatments, sites, and years, indicating that combined effects of predation, parasitism and drought can offset potential benefits of patchburn grazing management previously found in tallgrass prairies. Although differences in reproductive success among management treatments were minimal, patch-burn grazing management could still benefit population dynamics of grassland songbirds in areas where nest predators and brood parasites are locally abundant by providing suitable nesting habitat for bird species that require greater amounts of vegetation cover and litter, generally not present in burned pastures. [ABSTRACT FROM AUTHOR]

Ecosystem restoration is a critical component of land management, countering the loss of native biodiversity. Restoration efforts are enhanced by reintroducing naturally occurring ecosystem processes, including disturbances that may impact species characteristics such as niche position or niche size. In grasslands, grazing and fire affect plant diversity and habitat complexity, which potentially influence insect dietary behaviors and thus their contributions to functions like seed and arthropod predation. Using carbon and nitrogen stable isotopes, we characterized variation in the dietary niche of six ground beetle species (Coleoptera: Carabidae) in response to grazing by reintroduced bison and prescribed fire disturbances in twenty tallgrass prairies. Management disturbances did not affect activity density for most beetle species and mean trophic position was mostly unaffected. However, five of six species exhibited increased trophic niche area and breadth with disturbances, indicating a switch to a more generalist diet that incorporated a wider range of food items. The combination of bison and fire impacts may increase vegetation patchiness and heterogeneity, driving these diet changes. Morphological traits and microhabitat preferences might mediate response to disturbances and the resulting heterogeneity. Combining prescribed fire and grazing, which increases plant diversity and vegetation structural diversity, may help beetle communities establish over time and support the ecological functions to which these insects contribute. [ABSTRACT FROM AUTHOR]

In highly disturbed environments, clonality facilitates plant survival via resprouting after disturbance, resource sharing among interconnected stems and vegetative reproduction. These traits likely contribute to the encroachment of deep-rooted clonal shrubs in tallgrass prairie. Clonal shrubs have access to deep soil water and are typically thought of as relatively insensitive to environmental variability. However, how leaf physiological traits differ among stems within individual clonal shrubs (hereafter 'intra-clonal') in response to extreme environmental variation (i.e. drought or fire) is unclear. Accounting for intra-clonal differences among stems in response to disturbance is needed to more accurately parameterize models that predict the effects of shrub encroachment on ecosystem processes. We assessed intra-clonal leaf-level physiology of the most dominant encroaching shrub in Kansas tallgrass prairie, Cornus drummondii , in response to precipitation and fire. We compared leaf gas exchange rates from the periphery to centre within shrub clones during a wet (2015) and extremely dry (2018) year. We also compared leaf physiology between recently burned shrubs (resprouts) with unburned shrubs in 2018. Resprouts had higher gas exchange rates and leaf nitrogen content than unburned shrubs, suggesting increased rates of carbon gain can contribute to recovery after fire. In areas recently burned, resprouts had higher gas exchange rates in the centre of the shrub than the periphery. In unburned areas, leaf physiology remained constant across the growing season within clonal shrubs (2015 and 2018). Results suggest single measurements within a shrub are likely sufficient to parameterize models to understand the effects of shrub encroachment on ecosystem carbon and water cycles, but model parameterization may require additional complexity in the context of fire. [ABSTRACT FROM AUTHOR]

Extensive habitat loss and degradation have transformed the grasslands of North America into one of the continent's most vulnerable ecosystems and have greatly imperiled the plants and animals that depend on them. Small mammal communities play a pivotal role in maintaining the health and function of grasslands, and managing small mammal populations is an important, though overlooked, part of grassland restoration and management. We identified habitat variables in restored tallgrass prairie patches that were most strongly associated with variation in small mammal abundance and community composition, with the goal of aiding management efforts to manipulate small mammal populations. We found that small mammal abundance at the local vegetation scale was negatively related both to litter depth and plant diversity. At the landscape scale, small mammal abundance was positively associated with the amount of water surrounding a patch, and negatively associated with the amount of grassland surrounding a patch. Variation in small mammal community composition largely was governed by differences in habitat structure at the landscape scale, rather than differences in vegetation structure at the local scale. We suggested that managers interested in influencing small mammal abundance in grasslands employ tools such as prescribed fire to decrease litter depth if increased small mammal abundance is desired, or increase plant diversity by sowing a high diversity of seeds to depress small mammal abundance. [ABSTRACT FROM AUTHOR]

Populations of wild and managed pollinators are declining in North America, and causes include increases in disease pressure and decreases in flowering resources. Tallgrass prairies can provide floral resources for managed honey bees (Hymenoptera: Apidae, Apis mellifera Linnaeus) and wild bees. Honey bees kept near prairies may compete with wild bees for floral resources, and potentially transfer viral pathogens to wild bees. Measurements of these potential interactions are lacking, especially in the context of native habitat conservation. To address this, we assessed abundance and richness of wild bees in prairies with and without honey bee hives present, and the potential spillover of several honey bee viruses to bumble bees (Hymenoptera: Apidae, Bombus Latrielle). We found no indication that the presence of honey bee hives over 2 yr had a negative effect on population size of wild bee taxa, though a potential longer-term effect remains unknown. All levels of viruses quantified in bumble bees were lower than those observed in honey bees. Higher levels of deformed wing virus and Israeli acute paralysis virus were found in Bombus griseocollis DeGeer (Hymenoptera: Apidae) collected at sites with hives than those without hives. These data suggest that the presence of honey bees in tallgrass prairie could increase wild bee exposure to viruses. Additional studies on cross-species transmission of viruses are needed to inform decisions regarding the cohabitation of managed bees within habitat utilized by wild bees. [ABSTRACT FROM AUTHOR]

Nectar larcenists target flowers with a long nectar spur. The western prairie fringed orchid, Platanthera praeclara Sheviak and Bowles (Orchidaceae), has a 50-mm-long spur and is pollinated by hawk moth (Lepidoptera: Sphingidae) species with tongues that are shorter than the spur. We placed net traps above inflorescences at P. praeclara sites in southeastern North Dakota to survey potential nectar larcenists, including hawk moth thieves (2004-2014) and bumble bee robbers (2007-2014). We captured two hawk moths, Manduca quinquemaculata (Llaworth) and Agrius cingulata (E), that have tongues over twice the length of P. praeclara's spur. Also captured were eight bumble bee species (genus Bombus), which may produce the holes discovered in P. praecala's spur. Holes triggered loss of the spur and its nectar. In 2007, 2013, and 2014, robbery was observed in 10, 60, and 37% flowers per plant, respectively. At the flower level, robbery had a positive effect on removal of pollinaria and no effect on pollen deposition or seed capsule production. Based on results of an experiment, we propose that P. praeclara deploys variable nectar rewards across the inflorescence to promote a balance of selfing and outcrossing pollination. We expect less harm to this strategy from a robber bee satisfied by feeding on a single flower and more harm from a hawk moth thief that removes nectar from every flower of the inflorescence. Experiments are needed to determine whether nectar larceny is creating problems for conservation and recovery of P. praeclara, a threatened species in the United States and Canada. [ABSTRACT FROM AUTHOR]

Woody plant encroachment has become a global threat to grasslands and has caused declines in aboveground richness and changes in ecosystem function; yet we have a limited understanding on the effects of these phenomena on belowground microbial communities. We completed riparian woody plant removals at Konza Prairie Biological Station, Kansas and collected soils spanning land-water interfaces in removal and woody vegetation impacted areas. We measured stream sediments and soils for edaphic variables (C and N pools, soil water content, pH) and bacterial (16S rRNA genes) and fungal (ITS2 rRNA gene repeat) communities using Illumina MiSeq metabarcoding. Bacterial richness and diversity decreased with distance from streams. Fungal richness decreased with distance from the stream in wooded areas, but was similar across landscape position while Planctomycetes and Basidiomycota relative abundance was lower in removal areas. Cyanobacteria, Ascomycota, Chytridiomycota and Glomeromycota relative abundance was greater in removal areas. Ordination analyses indicated that bacterial community composition shifted more across land-water interfaces than fungi yet both were marginally influenced by treatment. This study highlights the impacts of woody encroachment restoration on grassland bacterial and fungal communities which likely subsequently affects belowground processes and plant health in this ecosystem. [ABSTRACT FROM AUTHOR]

How grazing-induced ecosystem changes by ungulates indirectly affect other consumers is a question of great interest. I investigated the effect of grazing by American Bison ( Bos bison L.) on an arthropod community in tallgrass prairie. Grazing increased the abundance of arthropods, an increase that was present in both herbivorous and carnivorous assemblages, but not in detritivores. The increase in herbivores and reduction in plant biomass from grazing resulted in an arthropod herbivore load almost three times higher in grazed plots compared with controls. Among herbivores, the sap-feeding insect guild was dramatically more abundant, while chewing herbivores were not affected. Herbivorous and carnivorous arthropod richness was higher in grazed plots, although the response was strongest among herbivores. Arthropod abundance on individual grasses and forbs was significantly higher in grazed areas, while plant type had no effect on abundance, indicating that the change was ecosystem-wide and not simply in response to a reduction in grass biomass from grazing. The response of arthropods to grazing was strongest in the early part of the growing season. Published research shows that ungulate grazing, although decreasing available biomass to other consumers, enhances plant quality by increasing nitrogen level in plants.Thearthropod results of this study suggest higher plant quality outweighs the potential negative competitive effects of plant biomass removal, although other activities of bison could not be ruled out as the causative mechanism. Because arthropods are extremely abundant organisms in grasslands and a food source for other consumers, bison may represent valuable management tools for maintaining biodiversity. [ABSTRACT FROM AUTHOR]

Aims and Methods Diversity-disturbance research has focused on community diversity, but disturbance frequency could impact diversity within species as well, with important consequences for community diversity and ecosystem function. We examined patterns of genetic diversity of a dominant grass species, Andropogon gerardii, in native North American tallgrass prairie sites located in eastern Kansas that have been subjected to a gradient of fire frequency treatments (burned every 1, 2, 4 or 20 years) since the 1970s. In addition, we were able to assess the relationships between genetic diversity of A. gerardii, species diversity and productivity across this range of fire frequencies. Important Findings We found no significant relationships between genetic diversity of A. gerardii at the local scale (1 m2 plot level) and disturbance frequency (burned 2 to 32 times over a 38-year period). However, at the site level (i.e. across all plots sampled within a site, ~100 m2) there were differences in genotype richness and composition, as well as genomic dissimilarity among individuals of A. gerardii. Genotype richness was greatest for the site burned at an intermediate (4-year) frequency and lowest for the infrequently (20-year) burned site. In addition, genotypes found in the frequently burned sites were more similar from each other than expected by random chance than those found in the infrequently burned sites. Genotype composition of A. gerardii was not significantly different between the frequently burned sites (annual vs. 2 year) but did differ between frequently burned and infrequently burned sites (1 and 2 year vs. 4 and 20 year, etc.). Together, these results suggest site-level ecological sorting of genotypes in intact prairie across a broad gradient of disturbance frequencies, likely driven by alterations in environmental conditions. Frequent fire promotes the abundance of dominant grass species, reduces plant community diversity and impacts ecosystem processes such as productivity. Our study suggests that genetic diversity within dominant grass species also may be affected by disturbance frequency, which could have important implications for how species are able to respond to disturbance. [ABSTRACT FROM AUTHOR]

The article presents a study concerning the grasshopper sparrows' postfledging survival in grasslands managed with fire and grazing. It states that more precise prospects of survival after nestlings fledge are required for population models to be paraeterized and population dynamics to be realized during the delicate life stage. Moreover, the data show that the survival rate of Grasshopper Sparrow may be less compared with most models.

Aims In order to better understand how tornados structure the ecotone between eastern deciduous forest and tallgrass prairie, we sampled trees in a recent tornado blowdown area and in the adjacent undisturbed forest. Both are part of the Cross Timbers ecotone of Osage County, Northeastern Oklahoma, USA. Methods We set up a 1-ha square plot in each area and sampled all tree stems at least 50 cm tall where stems were identified to species and measured for size and spatial location in both plots. For the stems in the blowdown plot, we also scored damage and resprouting. We then used the spatial location data to compute the spatial heterogeneity and degree of clumping in both areas. Important Findings Significant clumping was observed in the control forest at the small spatial scale of 1-8 m and at the medium spatial scale of 30-36 m. The blowdown area: showed domination by post oak (Quercus stellata) with small stems, branch damage and stem resprouting above 1 m most common; had no trees that either lost their leaves without branch or stem damage or lived without some sort of resprouting, had a significant negative correlation between damage and resprouting and clumped only at small spatial scales for stems of medium size, for stems with branch damage and for stems that resprouted at or below 1 m height. We conclude that in addition to largely eliminating a forest's spatial heterogeneity, tornados may also structure this ecotone by increasing tree persistence through resprouting. [ABSTRACT FROM AUTHOR]

Despite fundamental importance to population dynamics, mating system evolution, and conservation management, the fitness consequences of breeding patterns in natural settings are rarely directly and rigorously evaluated. We experimentally crossed Echinacea angustifolia, a widespread, perennial prairie plant undergoing radical changes in distribution and abundance due to habitat fragmentation. We quantified the effects of both biparental inbreeding and crossing between remnant populations on progeny survival and reproduction in the field over the first eight years. Lifetime fitness is notoriously difficult to assess particularly for iteroparous species because of the long sequence and episodic nature of selection events. Even with fitness data in hand, analysis is typically plagued by nonnormal distributions of overall fitness that violate the assumptions of the usual parametric statistical approaches. We applied aster modeling, which integrates the measurements of separate, sequential, nonnormally distributed annual fitness components, and estimated current biparental inbreeding depression at 68% in progeny of sibling-mating. The effect of between-remnant crossing on fitness was negligible. Given that relatedness among individuals in remnant populations is already high and dispersal very limited, inbreeding depression may profoundly affect future dynamics and persistence of these populations, as well as their genetic composition. [ABSTRACT FROM AUTHOR]

Small mammals spend a majority of their lives in shelter sites such as belowground burrows. Understanding temporal patterns of burrow use would provide valuable information about the influence of physiological and environmental factors on activity patterns. To examine patterns of burrow use. we developed a system that automatically monitors activity of deer mice (Peromyscus maniculatus) at artificial burrows in tallgrass prairie. The automatic activity-monitoring system is composed of a passive integrated transponder (PIT)--tag transceiver that reads the identification tags of individuals and an infrared trail monitor that confirms movements in and out of artificial burrows. We PIT-tagged and monitored nightly activity of >90 deer mice on Konza Prairie Biological Station in northeastern Kansas from July 2003 to December 2004. The monitoring system allowed us to examine individual variation in activity relative to sex, parental attendance, and early exploration by young. We also discuss advantages and disadvantages of the system compared to other activity-monitoring techniques, so that researchers might develop similar systems for other study species. [ABSTRACT FROM AUTHOR]

Fire and bison (Bison bison) are thought to be historically responsible for shaping prairie vegetation in North America. Interactions between temporal--spatial distributions of bison and prescribed burning protocols are important in current restoration of tallgrass prairies. We examined dynamics of bison distribution in a patch-burned tallgrass prairie in the south-central United Stales relative to bison group size and composition, and burn age and temporal distribution. Bison formed larger mixed groups during summer and smaller sexually segregated groups the rest of the year, and bison selected dormant-season burn patches in the 1st postfire growing season most often during spring and summer. Large bison herds selecting recently burned areas resulted in seasonally variable and concentrated grazing pressure that may substantially alter site specific vegetation. These dynamics must be considered when reintroducing bison and fire into tallgrass prairie because variable outcomes of floral richness and structural complexity are likely depending on temporal--spatial distribution of bison. [ABSTRACT FROM AUTHOR]

Small and relatively isolated populations that occupy fragmented habitat are at risk of local extinction. However, fitness consequences of fragmentation related to mating distance, such as inbreeding depression following increased self- and near-neighbor mating, may not follow standard expectations in species with specialized genetic systems. We investigated the effect of mating distance on progeny fitness in Calylophus serrulatus, a primarily autogamous, permanent translocation heterozygote that is restricted to prairie fragments in the North American tallgrass prairie region. We pollinated flowers by hand in the field with pollen sampled at various distances from the maternal parent within and between three populations in southeastern Minnesota. We raised the progeny in a greenhouse and measured fitness-related characters. Because their genetic system prevents loss of heterozygosity throughout much of the genome, regardless of inbreeding, permanent translocation heterozygmes are not expected to exhibit inbreeding depression. Consistent with this expectation, in no case did progeny of self matings suffer significantly reduced mean fitness compared to progeny from crosses between plants. Crosses between plants in the two closely situated (2 km) populations yielded progeny with fitness intermediate to their parents, but crosses between each of those populations and the more distant (20 km) population yielded progeny with reduced fitness, suggesting outbreeding depression at this largest spatial scale. Similarly, fitness of self-pollinated progeny and progeny from "near" crosses («2 m) within populations tended to be higher than "mid" (10-25 m) and "far" (»35 m) cross-progeny fitness. Under the current conditions of fragmentation, it seems likely that the distant matings that produce outbreeding depression are rave. It appears that mean fitness in this species is maintained in the context of severe fragmentation of its populations, largely because of its genetic system. [ABSTRACT FROM AUTHOR]

Changes in landscape cover in the Great Plains are resulting from the range expansion and invasion of eastern red cedar (Juniperus virginiana). By altering the landscape and local vegetation, red cedar is changing the structure and function of habitat for small mammals. We examined effects of invasion by eastern red cedar on small mammals in 3 plant communities (taligrass prairie, old field, and cross-timbers forest) in the cross-timbers ecoregion in Oklahoma. We sampled small mammals seasonally from May 2001 to August 2002 by using Sherman live traps and mark-recapture techniques on 3.24-ha, 450-trap grids in each plant community. We sampled vegetation in two hundred twenty-five 12 x 12-m cells within each grid. The structure of the small-mammal community differed among the 3 habitat types, with higher species diversity and richness in the tallgrass-prairie and old-field sites. Overall, the small-mammal community shifted along a gradient of increasing eastern red cedar. In the old-field and tallgrass-prairie plots, occurrence of grassland mammals decreased with increasing red cedar, whereas only 1 woodland mammal species increased. In the cross-timbers forest site, percent woody cover (<1 m in height), rather than cover of red cedar, was the most important factor affecting woodland mammal species. Examination of our data suggests that an increase in overstory cover from 0% to 30% red cedar can change a species-rich prairie community to a depauperate community dominated by 1 species, Peromyscus leucopus. Losses in species diversity and changes in mammal distribution paralleled those seen in avian communities invaded by eastern red cedar. Our results highlight ecological effects of invasion by eastern red cedar on diversity and function at multiple trophic levels. [ABSTRACT FROM AUTHOR]

We studied patterns of and factors influencing abundance of hispid cotton rats (Sigmodon hispidus) in tallgrass prairie habitats from autumn 1981 to spring 2001 at the Konza Prairie Biological Station, Kansas. Abundance of cotton rats was low during autumn (X¯ = 0.57 individuals/trapline) and extremely low in spring (X¯ = 0.04 individuals/trapline). Autumn abundance varied widely in 20 years (range: 0.00-2.50 individuals/trapline) and among 14 sites (0.05-1.35 individuals/trapline). Spring prairie fires had a positive influence on cotton rats during the 1st (X¯ = 0.8 individuals/trapline) and 2nd autumns (X¯ = 1.0 individuals/trapline), but not during the 3rd or later autumns (X¯ = 0.2 individuals/trapline). Cotton rats were associated strongly with lowland prairie relative to breaks and upland prairie. Autumn abundance was correlated positively with previous winter (December-February) average maximum temperature, but was not correlated with previous winter precipitation, summer (June-August) average maximum temperature, summer precipitation, or aboveground net primary productivity. Although previous winter maximum temperature accounted for only 32% of interautumn variation in abundance, winter harshness appears to be the major factor driving temporal variation in autumn abundance of hispid cotton rats. [ABSTRACT FROM AUTHOR]

Woody plant expansion is one of the greatest contemporary threats to mesic grasslands of the central United States. In this article, we synthesize more than 20 years of research to elucidate the causes and consequences of the ongoing transition of C4-dominated grasslands lo savanna-like ecosystems codominated by grasses and woody plants. This transition is contingent on fire-free intervals, which provide the opportunity for recruitment both of new individuals and of additional shrub and tree species into this grassland. Once shrubs establish, their cover increases regardless of fire frequency, and infrequent fires accelerate the spread of some shrub species. This process has resulted in a new dynamic state of shrub-grass coexistence in the mesic grasslands of North America. Important consequences of this shift in plant life-form abundance include alterations in plant productivity, species diversity, and carbon storage. Without drastic measures such as mechanical removal of shrubs, it is unlikely that management of fire and grazing regimes alone wilt be sufficient to restore historic grass dominance in these ecosystems. [ABSTRACT FROM AUTHOR]

Only tiny remnants of unplowed natural meadows remain in the eastern part of the state of North Dakota, and in Canada from eastern Saskatchewan to Manitoba. Those west of Lake Manitoba and the Red River Valley are characterized by their distinctive fauna of insects, principally leafhoppers and planthoppers (Homoptera: Auchenorrhyncha). These true bugs include hundreds of species invariably associated with North American grasslands. The distributions of those with the most limited dispersal abilities reflect long-term patterns of dominance and contiguity of native grass stands in prairies. These bug distributions indicate that bluestem-dominated grasslands in Canada, which usually are under 0.5 meter (20 inches) in height, are equivalent to tallgrass prairie from Illinois. This prairie once extended as much as 400 kilometers (250 miles) northwest of its previously known distribution. These bugs help differentiate tallgrass prairie from sites in southwestern Manitoba and adjacent North Dakota, which are more arid, and from sites east of Lake Manitoba and southward in the Red River Valley, which were formerly oak savanna. [ABSTRACT FROM AUTHOR]

Long-distance movements may play an important role in regulating populations of small mammals. To examine such movements, we livetrapped 1,712 deer mice (Peromyscus maniculatus) on 14-28 permanent traplines from autumn 1981 to spring 1990 on the Konza Prairie Biological Station, Kansas. These data were collected under a variety of climatic and biotic conditions that resulted in detection of >100 long-distance movements by deer mice between traplines (moves of 50-1,320 m). Males made more moves than females, but distance moved did not differ by sex. Age did not affect the number or distance of movements. On average, more long-distance moves occurred in spring and summer than in autumn, but distance did not differ by season. Proportion of the population making intertrapline movements was inversely related to abundance of deer mice. Deer mice did not exhibit a fire-positive response in long-distance movement. Our results indicate that deer mice may be more mobile than originally thought. Researchers should incorporate improved methods for detecting longer movements to better understand causes and consequences of these movements. [ABSTRACT FROM AUTHOR]