Abstract Managing milkweed (Asclepias spp.) is of high conservation concern due to its association with monarch butterflies (Danaus plexippus L.), which are proposed for listing under the Endangered Species Act. To counteract monarch declines, conservation goals aim to establish ≥1.6 billion nonagricultural milkweed stems within the Midwestern United States. Rangelands offer a unique opportunity to promote milkweed within the eastern migratory monarch range, but in grazed rangelands, little is known about the influence of herbivory on milkweed. To learn more about cattle−milkweed interactions, we measured the abundances of ungrazed and grazed milkweed stems in North Dakota mixed‐grass prairie rangelands throughout the growing seasons of 2021 and 2022. We counted stems in three different grazing management strategies: (1) modified twice‐over rest‐rotation grazing (MTORG), (2) patch‐burn grazing (PBG), and (3) season‐long continuous grazing (SLG). We found that total available (ungrazed plus grazed) and grazed oval‐leaf milkweed (Asclepias ovalifolia Dcne.) were much rarer than other milkweeds, which included common (A. syriaca L.), showy (A. speciosa Torr.), and their hybrids (common/showy milkweed). Cattle grazed only 2% of oval‐leaf but 13% of common/showy milkweed stems across all grazing strategies. However, the amount of grazing increased as the growing season progressed, and common/showy milkweed went from 3% of stems being grazed to upwards of 30% of stems being grazed at the end of the season. Oval‐leaf and common/showy milkweed total availability was impacted by grazing strategy, with MTORG and PBG generally having greater abundances than SLG. Only the number of grazed common/showy milkweed was impacted by grazing strategy, with MTORG having more grazed stems compared to PBG and SLG. Our results indicate that consumption was not solely a function of stem availability, as herbivory of common/showy milkweed increased throughout the grazing season despite availability not changing. Overall, we found that cattle herbivory of milkweed differed by milkweed species and through the growing season, with some changes due to management. Reducing grazing pressure later in the summer where common/showy milkweed is abundant will improve monarch butterfly conservation in rangelands by moderating cattle−milkweed interactions.

Habitat fragmentation and destruction are driving widespread declines in ecosystem function, species abundance, and genetic diversity across the globe. Among the affected taxa are bumble bees (genus Bombus), which are essential pollinators. Bumble bee declines have been linked to anthropogenic pressures such as land-use change and climate change. To better understand how the environment is shaping bumble bee populations, we employed a landscape genetics approach to examine the genetic diversity, population structure, and potential local adaptation of two widespread species—Bombus ternarius and Bombus griseocollis—across North Dakota. From 2017–2020, 161 B. ternarius and 200 B. griseocollis bumble bees were sampled in ND across 13 and 17 sites, respectively. We found low levels of heterozygosity and inbreeding across all populations for both species, with no evidence of population structure or isolation by distance. Our results revealed signatures of potential local adaptation to climatic variables and land cover characteristics, suggesting that our species are adapted to environmental gradients across the state. Having similar results between both species across all analyses suggests that other wide-ranging bumble bees in the region may share these patterns. High connectivity can buffer short-term population losses, but low genetic diversity may constrain adaptive potential and reduce resilience to future environmental change and emerging threats. Our findings have broad applicability to other pollinators and taxa facing similar environmental pressures. Both species have populations that continually exchange genes creating widespread connectivity but are still locally shaped by adaptation.

Grasslands cover more than one-third of the world’s terrestrial surface and provide many important ecosystem services, and yet, are one of the least protected biomes. Threats include land-use conversion, woody plant encroachment, and invasive species which alter or limit many of the ecosystem services grasslands provide. Despite their significance, the conservation of grasslands remains a pressing challenge. The lack of protection for grassland ecosystems creates a need for targeted conservation and informed management on extant grasslands. As part of this effort, we discuss the role of herbaceous litter in promoting ecosystem function and providing ecosystem services. In this paper, we highlight both the positive and negative effects of litter and 1) summarize the multitude of ecosystem services it affects, 2) outline the environmental factors that influence litter accumulation and quality, and 3) discuss management practices that promote variable litter. Litter contributes to all ecosystem service categories defined by the Millennium Ecosystem Assessment including provisioning, cultural, regulating, and supporting services. While many of these services are indirect, such as improving livestock forage production through increased water infiltration and nutrient cycling, the cascading accumulation of these effects shape grassland ecosystems and should be a critical part of management decisions. Therefore, we emphasize the importance of litter management to improve grassland quality and enhance ecosystem function. While many of the drivers of litter accumulation are inherently difficult to alter, management practices aimed at achieving heterogeneity can restore diverse landscapes that enhance ecosystem services and agronomic benefits.

Understanding where animals graze and why they choose to graze there can be critical to rangeland and ecosystem management with misunderstandings of grazing distribution and behavior often being detrimental to management goals. Over time, grazing animals create grazing lawns that attract grazing animals due to ease of accessibility to more palatable regrowth. Similarly, fire can defoliate large areas of vegetation and promote new plant growth that is preferentially grazed by herbivores (i.e., pyric-herbivory in a patch-burn grazing framework). Grazer distribution in pyric-herbivory studies has been tracked through various metrics that produce valuable data. However, these data often lack precise information on what animals consume and do not account for differential plant production, limiting our ability to understand and apply pyric-herbivory to rangeland management through patch-burn grazing. Simultaneously monitoring plant biomass production and livestock grazing utilization would be the most comprehensive method to show site selection by grazing animals. To examine how previous grazing events influence grazing patterns, we collected data over 3 years on the utilization rate of patches by cattle in patch-burn grazing pastures and compared them to utilization rates in season-long grazed pastures. We found that regardless of management, grazing patterns were influenced by grazing in prior years. However, grazing in patch-burn pastures was more strongly influenced by fire than previous grazing events. Our results suggest that in the absence of additional disturbances, grazing patterns from previous years influence grazing patterns in the current year. However, disturbances that remove dead vegetation and promote regrowth, such as fire, override the influence of previous grazing patterns, modifying patch selection. Moving forward, these disturbances can be used to negate the effect of established grazing lawns and promote targeted grazing in areas with fresh regrowth, which benefits management goals. (c) 2025 The Author(s). Published by Elsevier Inc. on behalf of The Society for Range Management. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )

Rangelands globally are invaded by exotic species. In the northern Great Plains, Kentucky bluegrass (hereafter, “bluegrass”) invades rangelands by forming a thick thatch layer that alters water and nutrient cycling and prevents seed germination by native plants. Consequently, management actions that focus on reducing the bluegrass thatch layer have a greater chance of successfully promoting native plant diversity. To determine how different rangeland management practices impact bluegrass thatch, we measured thatch depth at multiple points across pastures invaded by bluegrass in south-central North Dakota. Each pasture was managed with either patch-burn grazing, modified twice-over rest-rotational grazing (MTORG), or season-long grazing. We also measured thatch in a control pasture that was neither burned nor grazed the previous 5 years. Both the patch-burn grazing and MTORG pastures were designed to increase landscape-level heterogeneity and promote biodiversity. We found that all forms of rangeland management resulted in a thinner thatch layer than our control pasture (3.92 ± 0.27 cm). However, pastures managed with patch-burn grazing had less thatch (1.79 ± 0.03 cm) than those managed with either MTORG (2.60 ± 0.03 cm) or season-long grazing (2.59 ± 0.05 cm). These results suggest that any form of cattle grazing can reduce bluegrass thatch, however fire followed by grazing can further reduce bluegrass thatch. A reduction in thatch resulting from interacting fire and grazing may lessen the impact of bluegrass on rangelands.

Ecologists consider biological invasions one of the primary drivers of global change. Many remaining grasslands in North America have extensive invasions of exotic grass species that have replaced native plant species. In the Northern Great Plains, exotic cool-season grasses Kentucky bluegrass (Poa pratensis) and smooth brome (Bromus inermis), paired with human alterations to the landscape and historical disturbance regimes, have resulted in functionally and structurally altered grassland plant communities. These changes may extend to impact species that rely on these plant communities, such as bees. Bees are ecologically diverse and serve important pollinator roles but are at risk from the loss and change of floral and nesting resources in plant communities. Our objectives were to determine whether Kentucky bluegrass and smooth brome alter the bee and forb species richness in invaded Northern Great Plains grasslands and how litter accumulation, grass cover, the amount of bare ground, and forb species richness interact with bee functional traits. To do this, we surveyed 67 grassland sites from 2017 to 2020 with two bee-sampling methods (268 netting and bee bowl surveys total) and vegetation cover surveys at each site. We collected 20,559 bees from 201 bee species and observed 249 forb and shrub species in vegetation surveys. Bee richness and Shannon diversity were associated with greater forb richness while forb richness was significantly lower with thicker litter depths and higher with a greater coverage of all grasses other than Kentucky bluegrass and smooth brome. Bee trait analyses showed varying relationships with plant community variables. Of these, litter depth and Kentucky bluegrass cover were associated with lower ground-nesting bee abundance while small-bodied bee abundance was positively associated with increasing bare ground. While our results support the close relationship between bee and plant diversity, we also found litter depth, in particular, contributed to the structure of these two communities. Specifically, Kentucky bluegrass and smooth brome are two exotic grass species associated with thatch-forming litter layers, especially under idle management that appear to simplify bee and forb communities. Our results make apparent the importance in maintaining structural and compositional diversity in invaded grasslands to support diverse bee communities.

Understanding the resources bees use is essential because we depend greatly on their ecosystem services, and this information could help guide conservation efforts. One way to identify the flowers that bees visit is to collect pollen directly from the bee and then identify the pollen with plant taxa. However, the current method for processing such pollen samples, acetolysis, is designed for samples such as those collected across individuals (e.g., pollen trap), bee nests, or, at the very least, from pollen pellets collected from live bees or from the exhaustive removal of pollen from lethally collected individuals. Smaller samples, including those down to just a few pollen grains sampled from live bees, could facilitate additional opportunities for bee-pollen research, if they can be processed effectively. We present a revised acetolysis methodology designed specifically for processing small pollen samples, so that they can then be used for more accurate identification. Using pollen samples from cotton swabs directly applied to live bees in the field, we demonstrate the effectiveness of our methodology for processing small pollen samples, including samples too small to be visually detected. This methodology can permit nonlethal collections in the field from a greater number of bee species.

1. Anthropogenic pressures on native ecosystems have resulted in numerous functional and compositional changes, creating novel ecosystems with new interactions between native and exotic species. How native species utilize these resources is crucial for their management in altered landscapes and the promotion of their essential ecosystem services. 2. We compared seasonal floral selection between European honey bees and their most phylogenetically similar native component in our study region, bumble bees, in North American grasslands with high densities of exotic plant species. Additionally, we determined whether floral species richness, total flowering density, native floral density or exotic floral density best explained the abundance of both groups. 3. Selection analyses revealed that honey bees and native bumble bees differed in selection between native and non-native floral resource availability, with any significant selection of honey bees being for exotic plants while native bumble bees selected for native plants. 4. Native forb presence and floral richness best explained the variation in bumble bee abundance, while honey bee abundance was associated with flowering densities in the early and mid-seasons and floral richness in both the early and late seasons. 5. Despite their generalist diets, we emphasize the importance of native floral availability for bumble bee foraging in novel grassland landscapes and the importance of exotic plants to support honey bee production. 6. Synthesis and applications. Our results indicate that pollinator forage management should differ for non-native and native species, despite morphological and life-history similarities. However, greater floral diversity provides a common management focus that can benefit honey bees and bumble bees in particular seasonal periods. Our results suggest that management actions promoting resource diversity can benefit functionally different species. In grasslands, implementing disturbance processes that can favour floral expression (e.g. fire; grazing) can support bumble bees of conservation concern and agriculturally important bees simultaneously.

Globally, large herbivores (e.g., cattle, elk) graze over 2.6 billion hectares of land. These lands can also be used to conserve pollinators that rely on similar resources, specifically diverse plant communities. Pollinator conservation will benefit from management in lands that are used for livestock grazing and wildlife conservation. However, maximizing ecosystem services provided in these areas is often nuanced and difficult. To improve our ability to support multiple ecosystem services in grazing lands, we reviewed published literature to investigate the mechanisms of indirect effects of large herbivores on pollinators via their resources (food plants, nesting sites). We used a framework from previous research on indirect effects of insect herbivores to explore and interpret how plant responses mediate large herbivore effects on pollinators through three mechanistic categories: resource abundance and availability, plant appearance, and plant chemistry. Using the broader conceptual model, we conducted a targeted literature review that found ~ 95% of studies investigating pollinators and large herbivores focused on resource abundance and availability. Consequently, more research is necessary to understand how large herbivores impact pollinators through multiple mechanisms. Future research could also test responses with both large herbivores and insect herbivores to determine their combined ecological consequences. This research will provide insights for managing large herbivores and pollinators simultaneously, while connecting concepts of pollinator ecology and grazing ecology. Filling research gaps on the mechanisms of indirect effects of large herbivores on pollinators will ultimately improve management of multiple ecosystem services and our ability to conserve declining pollinator species.

Abstract Pollinator declines have driven research and increased monitoring efforts. Within North Dakota, USA, our research group initiated research in 2015 on pollinator conservation and management. We synthesized results across five projects, producing 12 publications and providing baseline data on pollinator diversity and rangeland management to improve conservation efforts while land‐sharing with livestock. We detected 76 species of butterflies and ∼318 bee species. Butterfly diversity and relative abundance were driven by floral resources and less exotic plant invasions, with a positive relationship between flowers and pollinators. Invasive forbs were visited by pollinators, primarily honey bees. We also found management influenced vegetation characteristics within pastures, but landscape context was important for determining the specific outcome. Although pollinator abundance did not distinctly respond to management, diversity was affected by regime and grazer type. Using fire and grazing may benefit flowers to support pollinators. Our research will help guide rangeland management decisions that promote land sharing and benefit pollinator conservation efforts. Core Ideas We synthesized pollinator data from research conducted over six years in North Dakota. Pollinator diversity correlated with more forb diversity and less invasive plant species cover. Pollinator diversity, not abundance, has variable responses to management regime and grazer type. Fire and grazing may benefit vegetation communities to conserve pollinators in some landscapes.

Abstract Land‐use and land‐cover change associated with agriculture is one of the main drivers of biodiversity loss. In heavily modified agricultural landscapes, grazing lands may be the only areas that can provide essential resources for native grassland species. Management decisions, such as choice of livestock species, affect the extent to which grazing lands provide suitable habitat for native species such as pollinators. Our study compared how sheep versus cattle herbivory affected floral resources and butterfly abundance across low‐diversity, former Conservation Reserve Program (CRP) pastures managed with patch‐burn grazing. Across all years (2017–2019), flowering species richness and abundance were significantly higher in cattle pastures than sheep pastures. On average, we recorded 6.9 flowering species/transect in cattle pastures and 3.8 flowering species/transect in sheep pastures. The average floral abundance per transect was 1278 stems/transect in cattle pastures and 116 stems/transect in pastures grazed by sheep. Similarly, we observed higher butterfly species richness, diversity, and abundance in cattle than in sheep pastures. In cattle pastures, we observed an average of 75 butterflies and 6.75 species per transect, compared with an average of 52 butterflies and 3.37 species per transect in sheep pastures. However, the butterfly community composition did not significantly differ between grazing treatments likely because agricultural‐tolerant, habitat generalists comprised the majority of the butterfly community. Five generalist butterflies comprised 92.3% of observations; Colias philodice was the most abundant (61% of observations). Speyeria idalia and Danaus plexippus, two butterflies of conservation concern, comprised less than 0.5% of butterfly observations. Our results, which are among the first attempt quantifying butterfly use of post‐CRP fields grazed by livestock, show that increased precipitation and cattle grazing promoted higher forb abundance and richness. However, additional interventions may be needed to enhance floral resources to sustain and improve pollinator diversity in these landscapes.

Rangeland simplification is a global threat to biodiversity. Historically, rangelands exhibited varied vegetation structure, which provided a diverse wildlife habitat. Vegetation heterogeneity resulted from interactions between topoedaphic (inherent heterogeneity) and disturbance factors (imposed heterogeneity). Until recently, these interactive sources of heterogeneity have been ignored in rangeland management and study. Under an emerging paradigm that embraces heterogeneity, contributions of disturbance and topoedaphic conditions to rangeland biodiversity remain largely unknown. Using the avian community, we assessed the effects of wetland area, ecological site, and topographic roughness (inherent heterogeneity) and four grazing strategies (imposed heterogeneity; patch-burn grazing with one or two seasons of fire, season-long grazing, and modified twice-over rotational grazing with variably stocked paddocks) on vegetation structure, avian diversity, avian community composition, and avian densities. The interaction between inherent and imposed heterogeneity influenced avian community composition but not species-specific densities. The effects of management on vegetation structural heterogeneity varied over years, though patch-burn management generated heterogeneity and temporal stability in vegetation structure compared to season-long grazing and modified twice-over rotational grazing. Patch-burn and season-long grazing pastures had higher diversity than modified twice-over rotational grazing. Community composition was sensitive to ecological site, topographic roughness, and wetland area, suggesting that both the fire-grazing interaction and inherent heterogeneity maintain biodiversity. Out of our six grassland obligate focal bird species, two responded to inherent heterogeneity, while three were most sensitive to imposed heterogeneity. One species, western meadowlark (Sturnella neglecta), did not respond to either source of heterogeneity, potentially indicating responsiveness to factors outside our study, such as annual precipitation or heterogeneity at fine scales. Our results indicate that both inherent and imposed heterogeneity are important in shaping grassland bird abundance, diversity, and community composition and that conserving rangeland biodiversity in the future will require managing for greater imposed heterogeneity while embracing existing landscape variability.

Grasslands provide essential floral resources for both managed and wild pollinators. However, grassland flowers in remaining native landscapes are threatened due to non-native plant invasions and alterations to historic disturbance regimes such as fire and grazing. The potential for managed disturbance to promote grassland floral resources remains unclear. Fire and grazing historically occurred interactively, but uniform application of each may be a detriment to floral resources and the pollinators depending on them. Though fire can increase resources available to plants and stimulate flowering, it initially destroys floral resources and may delay flower availability. Similarly, grazing removes competitors of flowering plants, but destroys flower heads. To address this knowledge gap, we investigated the impacts of rotational fire and cattle grazing (patch-burn grazing with one and two seasons of fire per year) versus traditional season-long grazing with no fire on floral resources in mixed-grass prairie. In patch-burn treatments, part of each pasture is burned each year, which focuses grazing activity due to the high-quality regrowth. We aimed to use fire to remove litter around flowering plants while also sheltering established flower heads from grazing pressure by directing cattle away from regenerating forbs in unburned portions of the landscape. Over two summers, we performed weekly flower surveys in season-long grazing and patch-burn grazing pastures. We analysed total seasonal floral resources, maximum floral abundance and seasonal species richness between treatments. Over 2 years, we surveyed 1,238,241 ramets of 160 species, focusing on 36 common species for individual analysis. We found broad positive associations between patch-burn grazing and total seasonal flower abundance, maximum flower abundance and species richness compared to traditional management. In most cases, patch-burn grazing with dormant and growing season fires produced higher floral abundance, total seasonal floral resources and species richness than patch-burning with dormant season fires alone, suggesting benefits of increased levels of pyrodiversity. Synthesis and applications. Under increasing pressure to manage for declining pollinators, rangeland managers must consider strategies to enhance floral resources within the context of livestock production goals. The spatiotemporal interaction of cattle grazing and fire shows promise for promoting floral resource abundance and diversity.

Insect communities with diverse life histories and morphologies, such as bees (Hymenoptera: Apoidea), are difficult to representatively sample. Methodological comparison studies have increased our knowledge of bee-sampling method biases. However, further understanding of how sampling methodologies are biased with respect to functional traits and the surrounding environment is needed. We examined the differences in taxonomic and functional trait representation of sampled bee communities between an active netting and passive bee bowl methodology. We also determined the influence of surrounding floral resources on each method's ability to capture bee abundance, richness, and diversity. We captured bees at 32 sites across North Dakota, USA using both methods. Netting and bee bowl methods reflected different bee communities defined by taxonomic families, genera, diet breadth, sociality, and body size. Bee bowls reflected more solitary and small-bodied bees while the netting method selected a greater representation of generalist, social, and large-bodied taxa. Bee bowls captured fewer bees as floral abundance increased, while bee abundance, richness, and diversity captured with the netting method showed the opposite trend with increasing floral resource availability. In addition, the netting method generally captured more varied samples than bee bowl surveys. Our results indicate the importance of using multiple types of sampling methods and of understanding how surrounding floral availability affects sampling of the target bee communities. Methodological biases influence how ecological studies interpret target communities, making it essential for future bee-sampling to incorporate multiple methods and to interpret their results carefully in the context of chosen methodologies and study systems. Implications for insect conservation The essential ecological services many bees provide, coupled with the concern over declines in bee populations and diversity, fuels the increased interest in bees and studies involving bee-sampling. Management and conservation policy for declining bee populations depend on data that is representative of the sampled bee communities. Therefore, it is important to understand systematic biases in our sampling methods as well as the effects of surrounding habitat on these biases.

Climate change impacts animal abundances, distributions, and behaviors, frequently at the detriment to individuals. However, for many animals, including butterflies, current research focuses primarily on estimating abundance and distribution without observing behavior. Because behaviors often respond to climate change before other metrics, understanding behavioral change is critical for future climate change research and projections. Therefore, we investigated weather related changes in adult butterfly behavior using snapshot behavioral observations taken as part of a four year study of butterfly abundance throughout North Dakota, USA. Across 1,107 site-visits, we categorized adult butterfly behavior using 146,610 observations while also recording local weather variables with each site visit. We found patterns in butterfly behavior within years, including more flying and less resting at sites that were warmer during that site visit. We also observed differences across years, including more flying overall and a weaker behavioral response to temperature in a year that was particularly cool and wet. Further incorporating such behavioral observations into abundance surveys can help lead to better insights about weather-related variation in behavioral patterns and their consequences for animals facing climate change.

Within agricultural landscapes, native bees often rely on limited natural and seminatural lands to provide the majority of the food and nesting resources that sustain them. To understand better how management can affect pollinators in these seminatural areas, we compared how sheep or cattle herbivory influenced floral resources and bee communities in low-diversity, former Conservation Reserve Program (CRP) pastures managed with patch-burn grazing. We sampled bee communities and floral resources three times per season in 2017, 2018, and 2019. We used plant-pollinator line transect sampling and collected bees and counted all flowering stems within 1 m. Across all years, we found that floral abundance, floral richness, floral diversity (Simpson's) and bee richness and abundance were significantly higher in cattle pastures compared to sheep. In cattle pastures, 46 native bee species plus honey bees interacted with 25 of 68 available flowering forbs. In sheep pastures, we recorded 14 native bee species and honey bees interacted with 10 of 34 flowering species. Native bee abundance and native bee richness were best explained by models that included an interaction of floral richness and year. Overall, our results suggest that season-long sheep grazing in low-diversity grasslands greatly reduces available floral resources and correlates with much lower bee abundance and native bee diversity. Given the importance of pollinators to natural and agricultural systems, it is imperative that we take proactive actions to increase forb richness and native flower abundance in seminatural lands to maintain a more diverse and resilient bee community that can continue to support pollination services and global food security.

Many methods are used to survey butterfly populations, with line transect and area surveys being prominent. Observers are typically limited to search within 5 or 10 m from the line, while observers are unrestricted in larger specified search regions in area surveys. Although methods differ slightly, the selection is often based on producing defendable data for conservation, maximizing data quality, and minimizing effort. To guide method selection, we compared butterfly surveys using 1) line versus area methods and 2) varying width transects (5 m, 10 m, or unrestricted) using count data from surveys in North Dakota from 2015 to 2018. Between line and area surveys, we detected more individuals with area surveys, even when accounting for effort. However, both methods accumulated new species at similar rates. When comparing transect methodology, we detected nearly 60% more individuals and nine more species when transect width increased from 5 m to unrestricted, despite similar effort across methodology. Overall, we found line surveys slightly less efficient at detecting individuals, but they collected similar species richness to area surveys when accounting for effort. Additionally, line surveys allow the use of unrestricted-width transects with distance sampling procedures, which were more effective at detecting species and individuals while providing a means to correct count data over the same transect length. Methods that reduce effort and accurately depict communities are especially important for conservation when long-term datasets are unavailable.

Soils in the Northern Great Plains of North America can host high salt concentrations, resulting from geologic origin, and strongly tied to landscape climate and hydrology patterns. Salt concentrations in topsoil can be elevated with intensive management for row crop production. We know that high salt concentrations in topsoil directly impact plant productivity and crop yield; however, our investigations indicate that belowground communities and processes do not necessarily align with patterns of plant productivity. Multiple years of field surveys have revealed that communities and functions of saline soils are distinctly different than non-saline soils. As expected, soils within saline patches tend to have reduced structural development, higher water content, lower surface residues and organic matter incorporation, and elevated soil nutrient concentrations. Thus, the habitat for soil organisms is physically and chemically different than nearby non-saline soils. We have observed that these habitat changes are associated with shifts in soil biological communities (microbial groups, nematodes, arthropods, and earthworms) and their activities (greenhouse gas production and decomposition) in unexpected ways. While total microorganism abundance is fairly stable across the saline and non-saline soils, arthropod, nematode, and earthworm counts are reduced in saline soils. Due to the abundance of microbes, soil water, and labile nutrients in saline soils, we observed elevated greenhouse gas emissions in saline soils. Decomposition rates are stable across salinity levels, providing further evidence that saline soils are microbiologically active despite a paucity of plant production. Given that soil salinity occurs within a suite of soil conditions that influence soil functions, and that these shifts happen over short distances, salinity appears to be an important driver of spatial heterogeneity in soil properties. These observations have implications for intensive, targeted management for mitigating the agroecosystem impacts of salts.

Abstract Previous exploration has found that bee visitation tends to benefit yields of many pollinator-independent crops. However, the reverse of this relationship—if pollinator-independent crops benefit bees—has not been extensively studied or explicitly reviewed. Therefore, we initiated a review of the literature using Web of Science and EBSCOhost to determine whether: 1) bees collect pollen from pollinator-independent crops, and 2) pollinator-independent crops provided adequate nutrition for bees.These factors help establish if pollinator-independent crops could benefit bees. We found 45 peer-review articles that included bee pollen trap data on 13 pollinator-independent crops (self-pollinating and wind-pollinated plants), with Zea mays, Brassica napus, and Glycine max pollen most often found in pollen traps. Pollinator-independent crops averaged 12% of total pollen loads, but due to high variability, the median was only 1.6%. Pollen from pollinator-independent crops increased in landscapes with more agricultural cover, but our data was heavily skewed towards honey bees (Apis mellifera). We found the average crude protein for B. napus and G. max was high enough to support honey bee requirements (>20%), along with providing essential amino acids; however, average crude protein and essential amino acids may be lacking in Z. mays. Although some pollinator-independent crops are found in pollen traps and provide adequate resources for bees, they may fail to provide temporally stable resources and chemical-free space. For improved health and reproduction, bees need access to semi-natural landscapes within diverse cropping systems to increase diet mixing. This will help amplify the mutualistic relationship between bees and pollinator-independent crops.

Global biodiversity declines are attributed to many factors, including landscape fragmentation and vegetation homogenization. These patterns may be exacerbated by the intensification of management in agroecosystems, as management to meet the increasing demand for food, fuel, and fiber often comes at the cost of biodiversity and subsequent ecosystem functions and services. Conserving biodiversity will be necessary to create sustainable agroecosystems capable of optimizing both production and services such as pollination. We conducted a meta-analysis with 109 studies to examine the relationship between plant species richness and pollinator species richness to determine whether higher plant species richness supports higher pollinator species richness, especially in areas prone to biodiversity losses. We found most groups of insect pollinators, including bees, butterflies, flies, moths, and wasps, responded positively to increasing plant species richness, irrespective of location or land use, suggesting the capacity to increase pollinator richness through management strategies that increase plant species richness. However, we found pollinators in manipulated studies did not consistently respond to increasing plant species richness despite the overall positive relationships in observational and experimental studies, highlighting the importance of plant selection when making management decisions aiming to improve pollinator richness. Additional studies in regions such as Africa and South America will help fill in latitudinal gradients and provide greater coverage necessary to refine patterns. Increasing plant species richness through management changes or restorations will likely increase pollinator richness and be beneficial in agroecosystems to support biodiversity.