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Plants make important contributions to green roof ecosystem service provision through evapotranspiration, canopy shading, and water retention. Because these plant communities are a critical component of green roof design and function, both seasonal and interspecific variation of these plant communities are important factors in evaluating green roof performance. This study examines variation in both species abundance and 9 leaf traits throughout the 2015 growing season of four New York City green roofs. While community composition varied significantly between each month (pANOSIM = 0.036), three major plant families (Asteraceae, Lamiaceae, and Poaceae) consistently had the greatest green cover and were present during the entirety of the growing season. For leaf traits, period of the growing season had a significant impact on most of the traits measured. Leaf thickness, leaf relative water content (RWC) and saturated water content (SWC) decreased as the growing season progressed, while leaf dry matter content (LDMC) and stomatal density increased, likely due to a seasonal decrease in rainfall as species-level variance in these water traits is low (7.40% and 0.88%, respectively). We also ranked planted and spontaneous species in accordance to both cover and functional trait values, and identified 11 species suitable for green roofs in NYC: Pycnanthemum tenuifolium (Lamiaceae), Symphiotrichum leave, Symphiotrichum pilosum, Rudbeckia hirta, Solidago odora (Asteraceae), Panicum virgatum, Sorghastrum nutrans, Schizachyrium scoparium, Dichanthelium clandestinum, Deschampsia flexuosa (Poaceae), and Oenothera biennis (Onagraceae). Understanding the temporal responses of plant communities and their constituent species is critical in optimizing green roof ecosystem services.

Coastal dunes are sensitive indicators of climate change: it is expected that higher precipitation and warmer temperature will promote vegetation growth and sand stabilization. Alternatively, dunes may become active during severe droughts, which would reduce plant cover and increase sand mobility. Consequently, it is relevant to explore community shifts and self-organization processes to better understand how coastal dunes vegetation will respond to these projected changes. Primary succession allows the exploration of community assembly and reorganization processes. We focused on three environmental variables (bare sand, temperature, and precipitation) and five successional groups (facilitators, colonizers, sand binders, nucleators, and competitors). For 25 years (from 1991 to 2016), species turnover was monitored in 150 permanent plots (4 × 4 m) placed on an initially mobile dune system located on the coast of the Gulf of Mexico. The spatiotemporal dynamics observed during primary succession were consistent with the facilitation nucleation model. As late colonizers grew and expanded, psammophytes became locally extinct. The spatial patterns revealed that ecological succession did not occur evenly on the dunes. In addition, the increased mean yearly temperature during the last decades seemed to be associated with the accelerated increment in plant cover and species richness, which had not been registered before in Mexico.

Elevated temperatures and drought may exacerbate invasion success of non-native grasses, as non-native species often possess traits favored by a warmer, drier world. In our study, we assessed plant traits potentially linked to invasion success under elevated temperature and drought, including biomass production, reproductive allocation, arbuscular mycorrhizal (AM) fungal root colonization, and germination of native grasses and non-native invasive grasses. We selected two caespitose warm-season grasses [native (Schizachyrium scoparium) and non-native (Bothriochloa ischaemum)] and two cool-season grasses [native (Pascopyrum smithii) and non-native (Bromus inermis)]. Plant biomass, reproductive effort, and AM fungal colonization were assessed at two temperatures (ambient or elevated) and four levels of soil water-availability; germination was assessed at two temperatures and three levels of soil water-availability. Non-native warm- and cool-season grasses produced greater vegetative biomass, initiated seed production more frequently, and displayed greater germination when grown under elevated temperature and drought, compared to their paired native counterparts. Percent AM fungal root colonization of the non-native grasses was generally greater than native grasses regardless of soil moisture or elevated temperature. Our results suggest that under warmer and drier conditions non-native grasses will continue to outperform native species, due to greater biomass production, germination capabilities, and colonization by AM fungi.

Irrigation of farmlands in xeric areas can increase soil salinity, reducing their suitability for food and fiber crops. One way to repurpose these lands is to convert them for use in grazing. To choose the best forage species, it is important to understand the impact of soil salinity on the growth and nutritional quality of potential forage grasses. Here, we grew four perennial C4 grasses: blue grama (Bouteloua gracilis), sideoats grama (Bouteloua curtipendula), little bluestem (Schizachyrium scoparium), and bermudagrass (Cynodon dactylon) in soil treated with four different concentrations (0, 8, 16, and 24 dS/m) of sodium chloride salt (NaCl). We then determined the effects of soil salinity on germination, biomass production, and plant tissue nitrogen content (an indicator of nutritional quality). We found a high degree of variability in salinity responses among species. S. scoparium performed poorly relative to the other species across all metrics. C. dactylon showed high biomass and low sensitivity to soil salinity for each index but had the lowest shoot nitrogen concentration of all species tested. This indicated a tradeoff of tissue quality for quantity. On the other hand, the two Bouteloua species showed opposite results, falling on the shoot quality end of the quantity-quality spectrum and even showing increased nitrogen concentration with increasing soil salinity. Given their complimentary traits, C. dactylon and Bouteloua spp. may be good candidates for interseeding on saline lands. These results indicate that species choice can help mitigate negative impacts of soil salinity on forage production and quality and should be carefully considered by land managers.

We integrated microscopy, spectroscopy, culturing and molecular biology, and aqueous chemistry techniques to evaluate arsenic (As) accumulation in hydroponically grown Schizachyrium scoparium inoculated with endophytic fungi. Schizachyrium scoparium grows in historically contaminated sediment in the Cheyenne River Watershed and was used for laboratory experiments with As(V) ranging from 0 to 2.5 mg L(−1) at circumneutral pH. Arsenic accumulation in regional plants has been a community concern for several decades, yet mechanisms affecting As accumulation in plants associated with endophytic fungi remain poorly understood. Colonization of roots by endophytic fungi supported better external and vascular cellular structure, increased biomass production, increased root lengths and increased P uptake, compared to noninoculated plants (p value

Although microbial participation in litter decomposition is widely known within terrestrial soils, the role and significance of microorganisms during the aerial standing litter phase of decomposition remains poorly investigated. We examined the fungi inhabiting standing leaf litter of Schizachyrium scoparium and Schizachyrium tenerum in a Longleaf Pine savanna ecosystem and estimated their contribution to litter decomposition. We identified fungal phylotypes associated with leaf litter and quantified leaf C mass loss, fungal biomass production, and microbial respiration during decomposition. These data were used to construct budgets estimating C flow into and through fungi. Significant losses in S. scoparium (55%) and S. tenerum (67%) leaf C mass were observed during standing decomposition along with concomitant increases in fungal biomass, which reached a maximum of 36 and 33 mgC/g detrital C, respectively. Cumulative fungal production during decomposition totaled 99 ± 6 mgC/g initial detrital C in S. scoparium and 73 ± 5 mgC/g initial detrital C in S. tenerum, indicating that 18 and 11% of the litter C was converted into fungal biomass, respectively. Corresponding estimates of cumulative fungal respiration totaled 106 ± 7 and 174 ± 11 mgC/g initial detrital C in S. scoparium and S. tenerum, respectively. Next generation sequencing identified several fungal phylotypes, with the majority of sequences belonging to the Ascomycota (Dothideomycetes) and Basidiomycota (Agaricomycetes). Fungal phylotypes were similar between litter species and changed over time, showing a successional pattern. These findings extend our understanding of fungal processes to standing litter in terrestrial ecosystems, and highlight the quantitative importance of fungi in C cycling processes.

Adult flies of Conioscinella nuda (Adams) were collected from four native grass species, big bluestem (Andropogon gerardii Vitman), little bluestem [Schizachyrium scoparium (Michx.) Nash], sand bluestem (Andropogon hallii Hack), and Indiangrass [Sorghastrum nutans (L.) Nash] to determine the insect's preference among these species. The mean number of insects collected varied from 9.7 to 27.0 adults per 15 plants, and the order of preference of C. nuda was big bluestem, little bluestem, sand bluestem, and Indiangrass. Differences did occur among plant species for C. nuda preference (P < 0.05) where big and little bluestem were different from sand bluestem and Indiangrass (P < 0.05). The observed differences between the species may be related to spikelet pubescent hairs. The spikelets of big bluestem and little bluestem are mostly glabrous compared to those of sand bluestem and Indiangrass which are covered with conspicuous hairs. Host plant resistance may offer the best approach for controlling C. nuda.

Little bluestem is a North American grass species found in native prairie remnants which is used for range, pasture, CRP, and restoration planting. In this study we asked whether the distance between planting site and seed source influenced the growth and survival of little bluestem. In a collaborative project with high school teachers and students, we planted seed at 2 sites in central Kansas, from 7 sources ranging from 6.9 to 814 km distant from the planting sites. We found that our measures of fitness (survival and tiller number) together declined significantly with the distance of the seed source from the site. Our results suggest that local adaptation is important to little bluestem survival and productivity and therefore recommend that land managers seek local sources of seed for range or prairie plantings.

Recent research demonstrated that mid- or late-summer prescribed fires can be employed to manage sericea lespedeza (Lespedeza cuneata) infestations in the Kansas Flint Hills. The effects of prescribed fire applied during the growing season (i.e., August to October) on grazing performance of yearling cattle have not been evaluated. Native pastures (n = 18; 22 ± 4.0 ha) were grouped by watershed and assigned randomly to one of three prescribed-fire treatments: spring (7 April ± 2.1 d), summer (21 August ± 5.7 d), or autumn (2 October ± 9.9 d). Yearling beef cattle were grazed from May to August at a targeted stocking density of 280 kg live-weight/ha following prescribed-fire application. Forage biomass accumulations, soil cover, plant species composition, and root carbohydrate concentrations in four native plant species were evaluated. Total body weight (BW) gains and average daily gain were greater (P = 0.01) for cattle that grazed the spring and summer prescribed-fire treatments compared with those that grazed the autumn prescribed-fire treatment. As a result, final BW were greater (P = 0.04) in the spring and summer treatments than the autumn treatment. Conversely, forage biomass accumulations did not differ (P = 0.91) between fire regimes. Proportions of bare soil were greater (P < 0.01) in the spring treatment compared with the summer and autumn treatments, whereas proportions of litter on the soil surface were greater (P < 0.01) in summer- and autumn-burned pastures compared with spring-burned pastures. Total basal cover of graminoids and forbs did not differ (P ≤ 0.15) between prescribed fire treatments. Likewise, total basal cover of C3 or C4 perennial grasses did not differ (P ≥ 0.23) between prescribed-fire treatments. No treatment differences (P = 0.24) in root starch or root water-soluble carbohydrate concentrations in big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium), Indiangrass (Sorghastrum nutans), or purple prairieclover (Dalea purpurea) were detected. These data were interpreted to suggest that summer or autumn prescribed fire can be applied without reducing forage biomass accumulations, root carbohydrate concentrations in key native plant species, or considerably altering native plant populations compared with conventional spring-season prescribed fire; however, summer prescribed fire could be favored over spring or autumn prescribed fire both to maintain stocker cattle growth performance and to achieve control over sericea lespedeza.

Dominant species can act as a biotic filter in structuring plant communities by constraining the establishment and survival of subordinate species. The effect of intraspecific trait variability of dominant species on the functional response of subordinate species, however, is not well understood. We quantified intraspecific variation in four functional traits of 26 subordinate species in an experimental grassland established with two population sources (i.e. cultivars and local ecotypes) of three dominant grasses (Sorghastrum nutans, Andropogon gerardii and Schizachyrium scoparium) and three pools of subordinate species (each from one origin) within each of the dominant grass source treatments. Twenty of the 26 subordinate species exhibited intraspecific trait variability for one trait or more in response to dominant species population source, and variation among population sources of the dominant species was non‐random. Dominant grass population source affected intraspecific variability in functional traits of multiple subordinate species. Cultivar sources of the dominant grasses and some of the subordinate species that established with them had higher and generally more variable functional leaf area and leaf nitrogen content compared to local ecotypes of the dominant grasses and the subordinate species that established with them. Local ecotype sources of the dominant grasses increased leaf area based functional diversity of subordinate species. Synthesis. This study provides evidence that intraspecific trait variability in dominant species acts as a biotic filter to constrain niche availability and dimensionality affecting trait variation of subordinate species during community assembly.

Biodiversity enhances a variety of ecosystem processes, and yet the underlying mechanisms through which these relationships occur remain a critical knowledge gap. Here, we used the natural abundance of stable isotopes to measure depth of water uptake in five common grassland species (Asclepias tuberosa, Lespedeza capitata, Liatris aspera, Schizachyrium scoparium and Sorghastrum nutans) growing across an experimental grassland diversity gradient. Using this approach, we addressed the following questions: 1) does the depth‐specific provenance of water uptake differ among species and/or do interspecific differences in water source manifest with increasing community diversity? 2) Does the isotopic niche space occupied by plants change with increasing diversity? 3) Is plasticity in water uptake depth across a diversity gradient associated with functional plant responses? We found that the depth of soil water used by plants was inherently different among species when grown in monocultures. All species used less shallow soil water and more intermediate‐depth soil water in mixed assemblages than in monocultures, resulting in similar interspecific differences in water source across the diversity gradient. However, plasticity in the locations of water used were positively associated with increases in plant growth in higher diversity treatments. These results indicate that plasticity in water‐use may contribute to positive biodiversity–productivity relationships commonly observed in temperate grasslands.

Clavibacter nebraskensis is the causal agent of Goss’s leaf blight and wilt, an important disease of maize in the United States and Canada. The epidemiology and ecology of this bacterial pathogen are poorly understood. Infested maize residue is often considered to be the primary source of inoculum for maize; however, the potential for many other plant species to be infected and serve as inoculum sources is unknown. The goal of this study was to determine if C. nebraskensis could infect, survive, and grow on common weed, crop, and grass species. Seedling leaves of 18 plant species that grow in maize production areas in the United States were inoculated with this pathogen in a controlled environment and in the field. Lesion development, bacterial streaming, and pathogen population size on leaves were then determined and used as criteria to evaluate host–pathogen interactions. Woolly cupgrass (Eriochloa villosa) and the native prairie grasses big bluestem (Andropogon gerardii) and little bluestem (Schizachyrium scoparium) developed lesions and bacterial streaming, identifying them as hosts and susceptible to infection. To our knowledge, this is the first report of these grass species being hosts of C. nebraskensis. Ten other grass species, including wheat and oats, were identified as potential sustaining hosts that maintained epiphytic or endophytic pathogen populations >106 colony forming units per leaf sample but displayed no evidence of infection. Five broadleaf species tested were nonhosts based on the three criteria. This study suggests that multiple plant species support infection and growth of C. nebraskensis and further elucidates the ecology of this pathogen and the epidemiology of Goss’s wilt.

Native grasses are increasingly used in the landscape. Little bluestem (Schizachyrium scoparium L.), a perennial bunchgrass native to most of the United States, has ornamental traits, such as variation in leaf color, differences in growth morphology, and attractive seed heads. Traditionally, cultivars of little bluestem are propagated by division, which limits the production of new plants. Our objective in this study was to develop an improved micropropagation protocol for little bluestem that would produce true-to-type plants. In 2016, we cultured immature inflorescences of eight genotypes of little bluestem on Murashige and Skoog (MS) medium with four combinations of kinetin (1.0 or 2.0 mg·L−1) and 2,4-D (0.5 or 1.0 mg·L−1) under three levels of light (dark, semilight, full light) to initiate callus. Cultures were evaluated 30 days after initiation and those that had initiated callus were subcultured. Media for subculturing and rooting contained either 0.1 mg·L−1 or no 1-Naphthaleneacetic acid (NAA). Light level had no effect on callus initiation. Initiation media with 1.0 mg·L−1 kinetin and either level of 2,4-D induced callus at almost twice the rate of media with 2.0 mg·L−1 kinetin, and cultures initiated on those media also produced almost twice the number of rooted plants over all genotypes. Genotype affected the number of rooted plants produced. The addition of NAA to medium for subculturing and rooting did not increase the number of rooted plants. In 2017, we cultured immature inflorescences of four genotypes of little bluestem on MS medium with 0.5 mg·L−1 2,4-D and either 1.0 mg·L−1 kinetin or 6-benzylaminopurine (BAP) under full light. Cultures were evaluated 30 days after initiation. Cultures that had initiated callus were subcultured onto MS medium with the same growth regulators as the initiation medium but without 2,4-D. Cultures were cycled between subculture medium with growth regulator and subculture medium with no additional growth regulator until rooted. Cultures initiated and subcultured on medium with BAP initiated two to three times more callus than those on kinetin and produced twice as many rooted plants. Our recommendation for rapid micropropagation of little bluestem is to initiate cultures on MS medium with 1.0 mg·L−1 BAP and 0.5 mg·L−1 2,4-D. After callus initiation, cultures should be subcultured to medium with BAP but no 2,4-D, alternating with medium with no additional growth regulators, until rooted.

Due to their different physiological effects, elevated carbon dioxide and elevated ozone might have interactive impacts on plants, and differentially so on plants differing in photosynthetic pathway and growth rate. To test several hypotheses related to these issues, we examined the physiological, morphological and growth responses of six perennial species grown at various atmospheric concentrations of carbon dioxide and ozone. The species involved (two C3 trees: Populus tremuloides Michx., Quercus rubra L.; two C3 grasses: Agropyron smithii Rybd., Koeleria cristata L.; two C4 grasses: Bouteloua curtipendula Michx., Schizachyrium scoparium Michx.) differed in growth form, stomatal conductance and photosynthetic pathway. In situ photosynthesis, relative growth rate (RGR) and its determinants (leaf area ratio, specific leaf area, leaf weight ratio and root weight ratio) were determined via sequential harvests of seedlings that were grown in all combinations of 366 or 672 μmol mol−1 CO2 and 3 or 95 nmol mol−1 O3 over a 101-d period. Elevated CO2 had minimal effect on either photosynthesis or RGR. By contrast, RGR for all six species was lower in high O3 concentrations at ambient CO2, significantly so in A. smithii and P. tremuloides. Five of the six species also exhibited reductions in in situ photosynthesis at ambient CO2 in high-O3-grown compared with low-O3-grown plants. For all species, these O3-induced reductions in RGR and photosynthesis were absent in the elevated CO2 environment. Root weight ratio was significantly reduced by elevated O3 in A. smithii and P. tremuloides in ambient but not elevated CO2. Species with high stomatal conductance were the most susceptible to oxidant injury, while those with low stomatal conductance, such as the C4 species and Q. rubra, were not as detrimentally affected by O3. Elevated levels of CO2 will reduce stomatal conductance and O3 uptake, and might therefore reduce the potential for oxidant damage. However, there was a stronger relationship of the percent reduction in whole-plant mass due to O3, related to the ratio of photosynthesis to stomatal conductance. In general, results of this study of six functionally diverse plant species suggest that O3 pollution effects on carbon balance and growth are likely to be ameliorated by elevated concentrations of atmospheric CO2.

Forage management and environmental conditions affect water soluble carbohydrate (WSC) storage, and, in turn, influence ruminant forage utilization in silvopastoral systems. The objective was to determine effects of four dependent variables: forage species [(non-native, C3 (orchardgrass (Dactylis glomerata L.)) and native C4 mix (8:1:1 big bluestem (Andropogon gerardii Vitman), little bluestem (Schizachyrium scoparium Michx. Nash) and indiangrass (Sorghastrum nutans L.))], fertility (poultry litter and an unfertilized control), forage sampling date (mid-May, late-May, early-June, mid-June, and late-June), and hour of day (0800, 1100, 1400, and 1700 h) on WSC accumulation in a silvopasture. Concentrations of WSC (g kg DM−1) were greater (p ≤ 0.05) for C3 forages, with poultry litter not impacting WSC accumulation. Overall, WSC was greatest in mid-June, with the lowest WSC concentration observed at 0800 compared to 1100, 1400, and 1700 h (p ≤ 0.05). Therefore, harvesting forages later in the day resulted in greater WSC. A stepwise regression model indicated acid detergent fiber, ash, and forage P concentration were the best predictors (R2 = 0.85, p ≤ 0.05) of forage WSC. These results may be useful in future studies aimed at explaining diurnal cattle grazing preference and optimum forage harvest timing in silvopastoral systems.

Worldwide atmospheric N deposition varies in both quantity and composition of inorganic N forms (NO3– and NH4+). Many studies designed to assess the potential consequences of N pollution, however, pay little attention to the relative abundance of N forms. We hypothesized that native species with different physiological properties will show varying responses to different forms and amounts of N deposition. Here, we assessed the responses of six herbaceous species native to tallgrass prairies in North America to increased N loading at differing ratios of NO3– : NH4+. Individual plants of each species were grown for roughly 80 d in a sand culture under field conditions, three N levels (0.1, 1, 3 mM N), and three ratios of NO3– : NH4+ (1:1, 4:1, 1:3). Analysis of total biomass and relative growth rate revealed a significant 3-way interaction between N level, NO3– : NH4+ ratio, and species. We found that the C3 grasses showed a greater relative response to increasing N addition than did C4 grasses or forbs. We also found a strong correlation between specific root uptake capacity for N and growth response to N level, for five of the six species. Specific leaf area of green leaves and % N of senesced leaves both showed a significant N-level by ratio interaction. Cautiously interpreted, these species-specific responses in growth and tissue quality could lead to changes in community-level and ecosystem dynamics as atmospheric N deposition continues to rise. We suggest that future studies addressing the potential impacts of N loading on natural communities use inorganic N compositions that are consistent with those expected from atmospheric deposition.

The pooling of soil samples in plant-microbe interaction studies is commonly employed, but the impact of sample handling has rarely been explored experimentally. Concerns have been raised that sample pooling may reduce biological variation leading to inflated type I errors or may alter the magnitude of microbial effects observed, invalidating the results achieved. To assess the impact of inocula pooling on plant-microbe interactions, we examined the reciprocal influence of unpooled and pooled soil microbial inocula on growth of Solidago altissima and Schizachyrium scoparium, with and without inoculum sterilization. Soil pooling had no effect on the variance among replicates in either plant species. However, pooling dramatically altered the magnitude and direction of microbial impacts on plant performance. Pooling of Solidago altissima soil increased the antagonistic effects on growth of both target species. In contrast, pooling of Schizachyrium scoparium soil shifted impacts on Solidago altissima from effectively neutral to slightly positive. Pooling in this system altered both the strength and direction of plant-microbe interactions relative to unpooled soils. Therefore soil mixing should be avoided when the research goal is to determine naturally occurring interaction strengths, even within a single habitat.

A model is constructed of two tufted C4 grasses, Schizachyrium scoparium and Paspalum plicatulum, growing in mono and mixed culture. Two types of vegetative growth are included: the upward growth of the shoots and the lateral growth of the crown. Two types of competition are modeled: “fair” competition for resources and “direct” inter-species competition. Model parameters are derived from published experimental data. Inter-species competition based only on resource sharing is found to be insufficient to explain experimental results, and a direct competition term is required. The model suggests that both species directly inhibit the growth of the other one, with Paspalum plicatulum having the larger inhibitory effect on Schizachyrium scoparium.

The plant-soil feedback framework allows researchers to target the interaction of plants and root-associated microbes and to determine its interplay on plant-plant interactions. Plant-soil feedbacks in terrestrial ecology are well documented, but the strength and direction of feedbacks as influenced by abiotic environmental factors, such as temperature and soil moisture, has not been fully explored. In our study, we examined plant-soil feedback responses of both cool- and warm-season native and non-native grasses to elevated temperatures (ambient and +5° C) and soil moisture (100% and 75% field capacity). In a previous experiment, grasses were grown under temperature and soil moisture conditions similar to our current study. The resultant trained soil communities served as the inoculum sources for our current experiment. We found that consistent training and experimental temperatures resulted in negative PSF, where plants produced greater biomass in soils conditioned by heterospecifics. However, the direction of PSF was reversed when training and experimental conditions were mismatched. That is, when training and experimental temperatures mirrored one another, negative PSF occurred, suggesting coexistence between the two species is likely under these conditions. However, when only training or testing temperatures were elevated, positive PSF were detected, favoring the non-native species. These alterations in plant-soil feedbacks were relatively consistent across pairings of warm- and cool-season grasses. Overall, our results indicate inconsistent year-to-year environmental conditions, such as extreme temperatures, may undermine the stabilizing forces of negative PSF and favor of non-native grasses.

The Dakota skipper,Hesperia dacotae(Skinner, 1911) (Lepidoptera: Hesperiidae), is an at-risk butterfly that inhabits mesic mixed-grass prairie. Loss of native prairie is the main factor driving declines in Dakota skipper abundance. Currently, there is little knowledge on the environmental and habitat requirements of Saskatchewan, Canada populations. Our objective was to determine environmental associations of Dakota skipper in Saskatchewan through landscape, vegetation, soil, climate, microclimate, and Hesperiidae butterfly occupancy. Data collection was conducted in 2015 and 2016; a total of 46 sites were surveyed; nine of these were Dakota skipper positive (i.e., present) sites and 37 were negative (i.e., non-detected) sites. Results indicate that plant composition is not a significant predictor of Dakota skipper presence, but three plant species are significantly associated with the species;Pediomelum argophyllum(Pursh) Grimes (Fabaceae),Zizia aptera(Gray) Fernald (Apiaceae), andSchizachyrium scoparium(Michaux) Nash (Poaceae). No soil or climate variables were significant predictors of Dakota skipper presence; however it is significantly associated with steep slopes. Warmer maximum and average ground-level temperatures are also associated with Dakota skipper presence. Findings indicate that additional Dakota skipper populations are likely in Saskatchewan and future targeted surveys will allow for a full evaluation of the distribution of this species and conservation status.

Large expanses of loess hill prairie were once common along the bluffs of the Mississippi and Illinois rivers of Illinois. These communities occur in forest openings on thick loess deposits overlying bedrock and frequently have expanses of exposed limestone at their margins (glades). Warm season, clump-forming grasses dominate the herbaceous vegetation along with a mixture of prairie and open forest species. Miles Hill Prairie, Monroe County, Illinois is located about 20 km west of Waterloo in the Northern Section of the Ozark Natural Division. Within the prairie, 148 vascular plant species were recorded with 40 species found in the survey plots. Schizachyrium scoparium dominated followed by Andropogon gerardii, Solidago speciosa, Sorghastrum nutans, and Bouteloua curtipendula. Common forbs include Pycnanthemum pilosum, Symphotrichum patens, and Symphotrichum oolentangiense with Cornus drummondii the most abundant shrub, and Torilis japonica the only exotic species in plots. This is a high-qualit...

Arbuscular mycorrhizal fungi (AMF) are important for plant nutrient and water acquisition. Much is known about how nutrient addition and environment affect AMF, but little is known about nutrient by environment interactions. We measured AMF colonization with nutrient additions and along an environmental gradient to assess these interactions. We measured AMF colonization in roots of little bluestem (Schizachyrium scoparium (Michx) Nash) with nutrient addition and across an environmental gradient. We assessed how AMF colonization changed across different fertilization treatments, and used ridge regression to determine nutrient, environment, and nutrient by environment interaction variables that predicted AMF colonization. The addition of nitrogen decreased AMF colonization, while mean annual temperature (MAT) and soil pH both positively predicted the percentage of AMF colonization in Schizachyrium scoparium. Additionally, we found an interaction term between MAT and phosphorus treatments that significantly affected percent AMF colonization. Our results show the importance of understanding environmental conditions on AMF as well as nutrient by environment interactions when assessing how AMF respond to nutrient addition. Here we present a full-factorial nutrient addition study along an environmental gradient to assess how AMF root colonization is influenced by abiotic factors in addition to nutrients.

The bluestem gall midge (Stenodiplosis wattsii Gagne) is native to the grasslands of North America. It feeds on the developing seeds of warm-season grasses during a portion of its lifecycle, but little is known of the biology and extent of gall midge infestations in native warm-season grasses in the USA. We investigated the infestations of the bluestem gall midge in big bluestem (Andropogon gerardii Vitman), sand bluestem (Andropogon gerardii var paucipilus), little bluestem [Schizachyrium scoparium (Michx.) Nash], and indiangrass [Sorghastrum nutans (L.) Nash] commercial seed production fields during 2001 through 2004. Our objectives were to determine the annual production cycle of the bluestem gall midge, the range of the infestation in Nebraska, and estimate its impact on seed production. In eastern Nebraska, the midge goes through four generations with the fourth entering a larval diapause, overwintering in seeds and emerging in mid-June of the following year. The bluestem gall midge damaged from 31% of the little bluestem seed to 67% of the big bluestem seed, and, on average, reduced the production of viable seed by 54% across the four grass species in eastern Nebraska. Additionally, the warm-season prairie grasses were surveyed in nine other counties in Nebraska and the bluestem gall midge was found in each species surveyed from all nine counties. This study is the first to document the negative effects of the bluestem gall midge on the production of viable seed in sand bluestem and indiangrass.