Prairie Plant Research Articles

Vacant lot plant establishment techniques alter urban soil ecosystem services

Vacant residential lots are ubiquitous in cities. While there is increasing interest in enhancing the aboveground habitat and biodiversity of vacant lots via restoration, vacant lot restoration may also affect the properties of and ecosystem services provided by soil. We assessed the effects of four vacant lot plant community establishment techniques (seed bombing, broadcast seeding, plug planting, and intensive gardening) and unaltered lawn on three critical ecosystem services provided by urban soils: carbon sequestration, nutrient retention, and water infiltration. We found that aboveground-focused treatments had belowground consequences. Consistent with other “urban grassland” studies, lawns exhibited the highest carbon storage among our treatments. However, soil carbon may increase in our other treatments over time – a common phenomenon in disturbed urban soils. We also found that nutrient retention – particularly nitrogen retention – increased with treatment intensity, likely due to increased plant uptake and microbial immobilization in our plots with prairie plantings. Finally, our most investment-intensive treatment, intensive gardening, resulted in decreased water infiltration, likely due to soil disturbance and increased bare soil resulting from frequent watering and weeding. Thus, treatments did not have consistent positive or negative effects on soil ecosystem services, emphasizing the multifunctionality and trade-offs associated with urban soil ecosystem processes. However, assuming low soil carbon and organic matter pools in our broadcast seeding and plug planting treatments recover over time, these two treatments may optimize aboveground plant community establishment and belowground ecosystem service provision in urban vacant lots.

Variation in Insect Richness on Six Prairie Plant Species

Insects play a fundamental role in ecosystem stability by providing important ecological services such as pollination, biological pest control, and nutrition for other organisms. Recent human-caused declines in insect populations mandate that we better understand how to improve and sustain insect diversity and abundance. The goal of our study was to identify the insects associated with 6 prairie plant species. We spent 248 hours over 3 months during 1 year monitoring insect visits to 10 replicates of ∼1-m2 patches each of Verbena brasiliensis (Brazilian Vervain, Verbenaceae), Pycnanthemum muticum (Blunt Mountainmint, Lamiaceae), Monarda fistulosa (Wild Bergamot, Lamiaceae), Eryngium yuccifolium (Rattlesnake Master, Apiaceae), Silphium gracile (Slender Rosinweed, Asteraceae), and Rudbeckia texana (Texas Coneflower, Asteraceae). We identified 11 bee species and 100 non-bee species representing 9 orders and 57 families. Insect richness varied widely among plant species: More taxa (n = 75) visited Blunt Mountainmint than any other plant species. Wild Bergamot had the fewest visiting taxa (n = 23). The majority of insects visited multiple plants, although we observed 2 bee species and 44 non-bee species on only 1 plant species. The number of unique insect visitors of each plant species varied from 1 to 19 taxa. Total insect richness was significantly greater in the morning than afternoon (χ2 = 3.7, P = 0.054). That plant diversity begets insect diversity is widely accepted, and our work suggests that inclusion of plants that are strong insect attractors could be integral to insect conservation and restoration initiatives.

Creation of a Field Guide to Camas Prairie Plants with Undergraduates: Project-Based Learning Combined with Epistemological Decolonization

Remnant camas prairies and associated oak woodlands are the focus of contemporary Indigenous food sovereignty efforts in the Salish Sea (aka Puget Sound) region of western Washington. They are also the focus of research and restoration to conserve at-risk species of animals and plants protected under the United States Endangered Species Act. Currently there is little collaboration between tribes and restoration scientists. These conditions create an opportunity and ethical imperative for developing undergraduate curriculum that highlights the connections between biodiversity conservation and traditional Indigenous ecological knowledge. Patchy mosaic prairie-oak woodland vegetation visibly reflects the imprint of human activity, which includes past burning to foster native food plants including common camas (Camassia quamash) and Oregon white oak (Quercus garryana). Using a floristic research project focused on these cultural landscapes as a case study, this essay illustrates how interdisciplinary inquiry and service learning can enrich college-level plant taxonomy curriculum, while creating rich opportunities for students to link their botanical studies to a historically-grounded understanding of why the conservation challenges exist in the first place. Through this collaborative, multi-year research effort, students contribute to the production of needed resources useful to regional conservation efforts. Affiliated learning communities also consider what it might mean to decolonize botanical knowledge in the context of ecological restoration.

North American Prairie Is a Source of Pollen for Managed Honey Bees (Hymenoptera: Apidae).

Prairie was a dominant habitat within large portions of North America before European settlement. Conversion of prairies to farmland resulted in the loss of a large proportion of native floral resources, contributing to the decline of native pollinator populations. Efforts to reconstruct prairie could provide honey bees (Apis mellifera) a source of much-needed forage, especially in regions dominated by crop production. To what extent honey bees, which were introduced to North America by European settlers, use plants native to prairies is unclear. We placed colonies with pollen traps within reconstructed prairies in central Iowa to determine which and how much pollen is collected from prairie plants. Honey bee colonies collected more pollen from nonnative than native plants during June and July. During August and September, honey bee colonies collected more pollen from plants native to prairies. Our results suggest that honey bees’ use of native prairie plants may depend upon the seasonality of both native and nonnative plants present in the landscape. This finding may be useful for addressing the nutritional health of honey bees, as colonies in this region frequently suffer from a dearth of forage contributing to colony declines during August and September when crops and weedy plants cease blooming. These results suggest that prairie can be a significant source of forage for honey bees in the later part of the growing season in the Midwestern United States; we discuss this insight in the context of honey bee health and biodiversity conservation.

From the Ground Up: Prairies on Reclaimed Mine Land—Impacts on Soil and Vegetation

After strip mining, soils typically suffer from compaction, low nutrient availability, loss of soil organic carbon, and a compromised soil microbial community. Prairie restorations can improve ecosystem services on former agricultural lands, but prairie restorations on mine lands are relatively under-studied. This study investigated the impact of prairie restoration on mine lands, focusing on the plant community and soil properties. In southeast Ohio, 305 ha within a ~2000 ha area of former mine land was converted to native prairie through herbicide and planting between 1999–2016. Soil and vegetation sampling occurred from 2016–2018. Plant community composition shifted with prairie age, with highest native cover in the oldest prairie areas. Prairie plants were more abundant in older prairies. The oldest prairies had significantly more soil fungal biomass and higher soil microbial biomass. However, many soil properties (e.g., soil nutrients, β-glucosoidase activity, and soil organic carbon), as well as plant species diversity and richness trended higher in prairies, but were not significantly different from baseline cool-season grasslands. Overall, restoration with prairie plant communities slowly shifted soil properties, but mining disturbance was still the most significant driver in controlling soil properties. Prairie restoration on reclaimed mine land was effective in establishing a native plant community, with the associated ecosystem benefits.

Habitat-scale heterogeneity maintains fungal endophyte diversity in two native prairie legumes

ABSTRACT The assembly of fungal endophyte communities within plants depends on the complex interactions of fungal taxa, their host plants, and the abiotic environment. Prairie plant communities provide a unique avenue to explore the interplay of biotic and abiotic factors affecting endophyte communities, since the historical distribution of prairies spans a broad range of temperature and precipitation, while the distances between small fragments of contemporary prairie communities may challenge the dispersal capabilities of these otherwise ubiquitous fungi. We sampled foliar fungal endophytes from two native prairie legumes, purple and white prairie clovers (Dalea purpurea and D. candida), in 17 remnant prairie sites across Minnesota in order to evaluate the relative contributions of abiotic factors, host species, and dispersal limitation to the diversity and structure of these communities. We found that similarity of communities was significantly associated with their location along a temperature and precipitation gradient, and we showed a distance-decay relationship that suggests dispersal limitations only over very large spatial scales. Although the effect of host species was small relative to these other factors, the two Dalea species maintained distinct communities within sites where they co-occur. Our results illustrate the capacity of many of these endophyte taxa to disperse over large distances and across heterogeneous biotic and abiotic environments and suggest that the interplay of biotic and abiotic factors maintains high diversity observed in endophyte communities.

White-tailed Deer Fecal Matter Distribution and Nutrient Contribution in Tallgrass Prairie

Herbivores can have nonconsumptive effects on ecosystems, including the redistribution of nutrients in their waste. In tallgrass prairie bison (Bison bison) historically increased soil nitrogen availability via labile waste deposits. White-tailed deer (Odocoileus virginianus) are now the dominant native large herbivore in prairie and have been shown to consume higher nutrient-content plants than those preferred by bison. Deer are also edge-dwelling species that reuse the trails they make as they move and browse throughout the prairie. Therefore, deer may differ from bison in their spatial patterns of nutrient content and redistribution of fecal matter. We examined the nutrient content and spatial distribution of deer pellets by measuring the number of deer pellet piles along deer trails and transects that were systematically placed at the forest border and in open prairie. We also measured the nitrogen content of deer pellets. White-tailed deer pellets had twofold greater nitrogen concentrations (3.43% N and 40.8% C) compared to values reported for bison fecal matter. Deer pellet piles were more concentrated on deer trails compared to the transects, resulting in fourfold greater N inputs on deer trails compared to areas off of trails. As a result, White-tailed deer have the potential to create patches of increased nutrient availability through their clumped distribution of nutrient rich fecal matter, with potential consequences for prairie plant communities.

Strips of prairie vegetation placed within row crops can sustain native bee communities.

As landscapes have become increasingly dominated by intensive agricultural production, plant diversity has declined steeply along with communities of pollinating insects including bees. Semi-natural habitats, such as field edge meadows and hedgerows, can be maintained to provide a diversity of flowering plants that can increase floral resources required by bees. An additional habitat enhancement practice is that of sowing strips of native prairie vegetation within row-cropped fields. In this study, conducted in Iowa, USA, we found that increases in both the abundance and diversity of floral resources in strips of native prairie vegetation within agricultural production fields greatly and positively influenced the bee community. The benefits to the bee community were important for both common and uncommon species and the effect may be strongest early in the season. Using networks of co-occurrence between plant and bee species, we were able to identify two native prairie plants, Ratibida pinnata and Zizia aurea, as potentially keystone resources that can be used to support native bees. When we evaluated the effect of reconstructed prairie strips on bees in the context of the surrounding landscape, we found that these conservation practices had positive effects on bees in agriculturally-dominated areas and that these effects were detectable in low to high complexity landscapes with 8–69% natural habitat. In landscapes dominated by crops with few pollen and nectar resources the inclusion of native prairie strips can buffer the decline of bees and effectively increase bee abundance and diversity.

White-tailed Deer Fecal Matter Distribution and Nutrient Contribution in Tallgrass Prairie

Herbivores can have nonconsumptive effects on ecosystems, including the redistribution of nutrients in their waste. In tallgrass prairie bison (Bison bison) historically increased soil nitrogen availability via labile waste deposits. White-tailed deer (Odocoileus virginianus) are now the dominant native large herbivore in prairie and have been shown to consume higher nutrient-content plants than those preferred by bison. Deer are also edge-dwelling species that reuse the trails they make as they move and browse throughout the prairie. Therefore, deer may differ from bison in their spatial patterns of nutrient content and redistribution of fecal matter. We examined the nutrient content and spatial distribution of deer pellets by measuring the number of deer pellet piles along deer trails and transects that were systematically placed at the forest border and in open prairie. We also measured the nitrogen content of deer pellets. White-tailed deer pellets had twofold greater nitrogen concentrations (3.43% N and 40.8% C) compared to values reported for bison fecal matter. Deer pellet piles were more concentrated on deer trails compared to the transects, resulting in fourfold greater N inputs on deer trails compared to areas off of trails. As a result, White-tailed deer have the potential to create patches of increased nutrient availability through their clumped distribution of nutrient rich fecal matter, with potential consequences for prairie plant communities.

The Canadian Prairie Plant Thermopsis rhombifolia Contains Luteolin, a Flavone that Inhibits Cyclin Dependent Kinase 9 and Arrest Cells in the G1-Phase of the Cell Cycle

Introduction: Plant species within the prairie ecological zone of Canada are a source of natural products with important bio-activities. Investigation of these plants and the secondary metabolites that they produce will provide insight into their biology, and identify sources of natural products that may become new medicines or scientific tools. Methods: We investigated a G1 phase arrest activity in extracts from the prairie plant, Thermopsis rhombifolia (Buffalo bean) by biology-guided fractionation and isolated luteolin. Cell based assays and CETSA were used to identify a cyclin-dependent kinase 9 inhibitory activity. Results and Discussion: Luteolin treated cells showed decreased phosphorylation of the carboxy terminal domain of RNA polymerase II, and low levels of Mcl-1. Plant extracts or luteolin inhibited Cdk9 (cyclin dependent kinase) in tests in vitro, stabilized Cdk9 as determined by the cellular thermal shift assay (CETSA), and arrested cells in the G1 phase of the cell cycle. Conclusions: Luteolin joins an increasing number of flavonoid inhibitors that make convenient cell biology tools and contribute to our understanding of natural product biology in plants.

Adaptation of plant‐mycorrhizal interactions to moisture availability in prairie restoration

The strength and direction of plant response to inoculation with arbuscular mycorrhizal fungi (AM fungi) is dependent on both abiotic and biotic contexts, often generating patterns of AM fungal mediation of plant adaptation. However, knowledge of plant‐community level effects of these interactions in grassland restoration is limited. We conducted a field inoculation experiment by inoculating five plant species native to a drier prairie and five plant species native to a moister prairie with mycorrhizal fungal communities from each prairie type. Species were paired by genus or family to account for phylogenetic effects. The inoculated plants were transplanted to study plots seeded with a restoration seed mix. Plots were manipulated to create either moister or drier conditions similar to environments of the plant species and mycorrhizal communities. In both transplanted and seeded plant species, we found that only drier prairie‐range species benefited from moisture‐regime matched AM fungal inoculum. Other seeded prairie plant species demonstrated a negative response to inoculation, likely due to the earlier successional stage of these species. Additionally, nonseeded plants benefited from inoculation in different ways: native nonseeded plants had highest cover with drier prairie inoculum in drier conditions, while nonnative plants had highest cover with moister prairie‐origin inoculum. These results suggest that use of local AM fungi may be particularly important in restorations at drier sites, even at relatively small differences in moisture availability. Further, specific knowledge of relative responsiveness of seeded plant species and nonseeded plant species to AM fungal inoculation will be useful in planning restorations.

Climate warming alters photosynthetic responses to elevated CO2 in prairie plants.

The impact of elevated CO2 concentration ([CO2 ]) and climate warming on plant productivity in dryland ecosystems is influenced strongly by soil moisture availability. We predicted that the influence of warming on the stimulation of photosynthesis by elevated [CO2 ] in prairie plants would operate primarily through direct and indirect effects on soil water. We measured light-saturated photosynthesis (Anet ), stomatal conductance (gs ), maximum Rubisco carboxylation rate (Vcmax ), maximum electron transport capacity (Jmax ) and related variables in four C3 plant species in the Prairie Heating and CO2 Enrichment (PHACE) experiment in southeastern Wyoming. Measurements were conducted over two growing seasons that differed in the amount of precipitation and soil moisture content. Anet in the C3 subshrub Artemisia frigida and the C3 forb Sphaeralcea coccinea was stimulated by elevated [CO2 ] under ambient and warmed temperature treatments. Warming by itself reduced Anet in all species during the dry year, but stimulated photosynthesis in S. coccinea in the wet year. In contrast, Anet in the C3 grass Pascopyrum smithii was not stimulated by elevated [CO2 ] or warming under wet or dry conditions. Photosynthetic downregulation under elevated [CO2 ] in this species countered the potential stimulatory effect under improved water relations. Warming also reduced the magnitude of CO2 -induced down-regulation in this grass, possibly by sustaining high levels of carbon utilization. Direct and indirect effects of elevated [CO2 ] and warming on soil water was an overriding factor influencing patterns of Anet in this semi-arid temperate grassland, emphasizing the important role of water relations in driving grassland responses to global change.

Stepping Carefully: Thinking Through the Potential Pitfalls of Integrated STEM

In light of discussions about the benefits and tradeoffs of integrated STEM education, we present a case that focuses on an apparently promising context for integrating mathematics and science. First- and second-graders observed changes in prairie plants over a year and sought a way to locate their plants in the prairie, as a planned prairie burn would soon destroy the top growth. They agreed to use compasses and pacing to write directions from a common landmark to the plants. Later, the class attempted to reinterpret their conceptions of location and wayfinding in the context of two new representations: a 2-dimensional map and a hoop on the floor that depicted the outline of the prairie. During this conversation, children struggled to integrate their memories of distance and unit-length, experienced within the prairie, to inscriptions that presented an external perspective of the same space. Some problems appeared to stem from the authenticity of the task, which inspired solutions that disrupted the teacher’s mathematical agenda. To promote STEM education, educators need to be aware of the task solutions that children are likely to invent, thoroughly address children’s understanding of representational conventions, and select tasks in which model-test and revision play a prominent role.

Milkweed Establishment in Restored Central Missouri Prairie

ABSTRACTThe decline of the Eastern North American monarch butterfly (Danaus plexippus) population continues to be a major concern among conservationists. Numerous publications and organizations suggest that establishing milkweed (Asclepias spp.), at a landscape scale, is necessary to increase the monarch population. The translocation of commercially grown containerized plugs is commonly recommended to establish milkweed. During 2017, we used a split‐plot design to examine the factors of age of prairie restoration, plant type, and land preparation method on survival of translocated milkweed in restored prairie in central Missouri, USA. Milkweeds were translocated to 16 0.81‐ha sites, half classified as young (<8 yr) and half as old (>9 yr) prairie restorations. We randomly selected 8 sites to establish bare‐root milkweed seedlings and 8 sites were planted with milkweed seedling plugs. Each site contained paired 0.4‐ha plots. At the plot level we tested 2 land preparation techniques, disking with the application of pre‐emergent herbicide and application of a grass herbicide. Milkweeds were planted at the density of 200 milkweeds/0.40 ha as suggested by the Missouri Monarch and Pollinator Conservation Plan. We conducted a census to determine milkweed survival 2 growing seasons after establishment. Two‐year survival of translocated bare‐root milkweed ( = 0.26, 95% CI = 0.12–0.49) was nearly 5 times greater than that of milkweed seedling plugs ( = 0.05, 95% CI = 0.02–0.13). Milkweed in disked plots had greater survival ( = 0.18, 95% CI = 0.10–0.31) than in plots treated with grass herbicide ( = 0.08, 95% CI = 0.04–0.16). Milkweed survival in older restored prairies ( = 0.07, 95% CI = 0.03–0.18) was lower than that in newer prairie plantings ( = 0.21, 95% CI = 0.09–0.41). Our results suggest translocation of bare‐root milkweed seedlings, combined with disking and application of pre‐emergent herbicide, is the preferred alternative. We suggest translocation of milkweed may be a feasible method of enhancing monarch habitat. However, meeting the challenge of restoring milkweed at recommended densities in established grasslands may be limited if milkweed seedling plugs are used. © 2020 The Wildlife Society.

Three Decades of Divergent Land Use and Plant Community Change Alters Soil C and N Content in Tallgrass Prairie

AbstractFrequent fire and grazing by megafauna are important determinants of tallgrass prairie plant community structure. However, fire suppression and removal of native grazers have altered these natural disturbance regimes and changed grassland plant communities with potential long‐term consequences for soil carbon (C) and nitrogen (N) storage. We investigated multidecade changes in soil C and N pools in response to contrasting long‐term burning and grazing treatments. Fire suppression with or without grazers and exclusion of grazers in annually burned prairie increased soil C content and shifted the δ13C signature of soil C over time, concomitant with changes in plant community composition. Soil δ13C values indicated that increased soil C content was associated with an increased contribution from plants using a C3 photosynthetic pathway (i.e., woody shrubs) under fire suppression. Soil N content also increased when fire was suppressed, relative to frequently burned grassland, but the rate of increase was slower when grazers were present. Additionally, changes in δ15N values suggested that grazing increased the openness of the N cycle, presumably due to greater N losses. By coupling long‐term fire and grazing treatments with plant community data and soil samples archived over three decades, we demonstrate that human‐caused changes to natural disturbance regimes in a tallgrass prairie significantly alter soil C and N cycles through belowground changes associated with shifts in the plant community. Since natural disturbance regimes have been altered in grasslands across the world, our results are relevant for understanding the long‐term biogeochemical consequences of these ongoing land use changes.

Nitrous oxide fluxes over establishing biofuel crops: Characterization of temporal variability using the cross‐wavelet analysis

AbstractEmissions of nitrous oxide (N2O) over croplands are a major source of greenhouse gases to the atmosphere. The precise accounting of sources of N2O is essential to national and global budgets, as well as the understanding of the spatial and temporal relationships with environmental variables such as rainfall, air and soil temperature, and soil moisture. The objective of this work was to investigate the temporal correlations of N2O fluxes with soil and air temperatures, as well as soil moisture. N2O fluxes were measured over four biofuel crops in Central Illinois during their establishment phase. Measurements were carried out from 2009 to 2011 using a trace gas analyzer (TGA) with tunable laser technology. Measurements of concentrations of N2O and CO2 were taken at the center of four plots of maize/soybean rotation, miscanthus (Miscanthus × giganteus), switchgrass (Panicum virgatum) and a mixture of native prairie plants. Cumulative fluxes indicate an average emission of nitrogen via N2O fluxes on the order of 1.5 kg N ha−1 year−1, in agreement with chamber measurements previously reported for the site. N2O fluxes were associated with peaks in soil and air temperature, and soil moisture, particularly during spring and winter thaws. Cross‐wavelet analysis was used to investigate the correlation between N2O fluxes and those variables. Results indicate that N2O fluxes and meteorological variables have significant covariance in time scales ranging from 4 to 32 days. In addition, temporal delays of 1–8 days were found in those relationships. Cross‐wavelet patterns were similar when relating N2O fluxes with soil temperature, air temperature and soil moisture. The temporal patterns of fluxes and environmental variables reported here support the modeling of emissions and highlight the importance of considering the timing of fluxes in relation to trends in meteorological variables.

Pipeline Impacts and Recovery of Dry Mixed-Grass Prairie Soil and Plant Communities

Agricultural practices have historically dominated disturbance on North American grasslands. Disturbances from oil and gas have become increasingly common and problematic for grassland conservation. With growing demand for oil and gas, industry is actively implementing minimal disturbance techniques during construction to reduce impacts on grasslands. This study aimed to determine impacts of a large-diameter pipeline right of way (ROW) on dry mixed-grass prairie to determine if and how far these impacts extended beyond the ROW and the effect of time on grassland recovery on and off ROW. Soil and vegetation on the ROW and on transects extending 300 m on either side of the ROW were assessed over a 10-yr period, starting the yr of construction, at six sites along a pipeline route in southern Alberta, Canada. There were significant impacts to soil and vegetation on the ROW and within 5 m of the ROW in the first yr. The trench was most impacted, followed by work and storage areas. Within 2 yr, soil and plant communities were on a trajectory toward reference prairie conditions. Ten yr following construction, only soil pH and bare ground were greater, and litter was less, on the trench than on work and storage areas, and relative to reference prairie. While native grass richness, dominance, and cover were similar on and off ROW, abundance of some native forb species was less on ROW. Non-native species cover was < 2% in all yr and locations. Although ruderal weed species were abundant on ROW the yr following construction, they disappeared by the following yr. Use of minimal-disturbance construction techniques reduced the size and intensity of the disturbance footprint, allowing for even sensitive arid habitat to recover within a short period of time. Similar approaches to other grassland disturbances can increase ecosystem resiliency.

Effects of white‐tailed deer exclusion on the plant community composition of an upland tallgrass prairie ecosystem

AbstractQuestionsGrasslands support ecosystem services, promote diversity, and assist in carbon sequestration. However, grasslands worldwide are diminishing in area, and understanding the drivers shaping the remaining grasslands is critical for their maintenance. The North American tallgrass prairie covers approximately 13% of its historical range and is shaped by fire and herbivory. Fire frequency negatively correlates with plant species richness, while bison (Bos bison) — the historical grazers — offset this effect. However, bison populations have declined, and large browsers are increasing in density. Few studies though have examined the role of large browsers — particularly white‐tailed deer (Odocoileus virginianus) — and their interaction with fire frequency in tallgrass prairies. Here, we addressed two questions: (a) What are the impacts of deer on plant diversity, species identities, and relative abundances; and (b) is there an interactive effect between the pressures exerted by deer and the well‐documented effects of fire in driving plant community responses?LocationThis study took place at the Konza Prairie Biological Station in northeastern Kansas, USA.MethodsUsing a 22‐year deer exclosure experiment, we examined differences in plant species richness, evenness, and plant community composition between plots that were either accessible or inaccessible to deer, in areas burned annually or once every four years.ResultsWe did not find significant effects of deer or interactive effects between deer and burning frequency on any metric of the plant community measured, including plant species richness, evenness, and plant community composition.ConclusionsContrary to the impact that deer have in other ecosystems (e.g. forests), our results indicate that deer do not affect the plant community of herbaceous‐dominated tallgrass prairies. These results indicate that while the loss of bison‐grazers has shifted tallgrass prairie plant communities to C4grass‐dominated systems, the shift to browsing‐dominated herbivore pressure from deer has a minimal effect on the plant community.

Effects of Lespedeza cuneata invasion on tallgrass prairie plant and arthropod communities

We examined effects of the invasive species Lespedeza cuneata on native plants and foliar arthropod communities in a tallgrass prairie. Through observational and manipulative experiments, we examined plant and arthropod responses to L. cuneata over one growing season. The observational study found little impact of the invasive plant on arthropods. By the end of the manipulative experiment, the combined biomass of native grasses and forbs was reduced by approximately 50% in Lespedeza-present plots, while total arthropod numbers were only about 15% lower. Seasonal differences were evident; L. cuneata-absent plots showed lower arthropod numbers in May, but higher abundances in June. Some feeding groups, notably carnivorous arthropods, appeared unaffected by L. cuneata. We tested three hypotheses (one bottom-up and two top-down processes) to explain the relatively weak response of the arthropod community to the invasive plant. Nitrogen content of native plants adjacent to L. cuneata areas was significantly higher compared to plants more distant. Ground arthropod predators were higher during mid-summer in L. cuneata areas, which may partially explain seasonal variation in foliar arthropods. Insectivorous birds were unaffected by L. cuneata abundance, suggesting that arthropod predation rates by birds are unchanged. We suggest that while L. cuneata has strong effects on native plants, its ability to increase neighboring plant quality compensates for the lower biomass of native plants in L. cuneata areas, moderating the arthropod response. While management of this invasive species remains a priority, tallgrass prairie food webs may be partly resistant to L. cuneata invasion.

Reintroduced bison diet changes throughout the season in restored prairie

Grazing as a management tool is often intended to alter plant community dynamics through preferential foraging. Bison diet in the western United States has been well studied, especially in short and mixed grass remnant prairies. However, there is little known about what bison consume in restored and tallgrass prairies. As bison reintroductions are used more commonly in eastern tallgrass prairies, it is important to understand their diet to predict future impacts on prairie plant communities. This study aims to understand bison diet across different seasons, and asks whether diet differs among male and female, and differently aged bison. We used stable isotope analysis to quantify δ13C and δ15N in plants and used a Bayesian isotope mixing model to estimate bison diet. We found bulls relied more heavily on C4 plants and wetland plants than cows, which relied more heavily on forbs, but no differences in diet between ages. Our analysis shows that bison primarily grazed on C4 grasses throughout the late spring and summer. However, bison foraged more on wetland species and forbs in the late summer and fall. This change in diet could have implications for wetland species and habitats, through dung inputs and trampling. The relatively high reliance on forbs for nearly one‐third of bison diet could mean intended impacts of reintroduced bison such as increased plant diversity through preferential grazing on grasses could be dampened. Managers reintroducing bison to restored prairie ecosystems should ensure adequate wetland and forb species, in addition to a mix of grasses.