Urban Grassland Research Articles

From lawns to meadows: spiders (Arachnida: Araneae) as indicators to measure urban grassland restoration success

In the present study, we investigate how spiders can be used to assess the effectiveness of restoring mesic grasslands on former urban lawns. We compile and analyze a comprehensive dataset, including both past and current data, focusing on the Aachen region. By systematically examining this data, we identify various indicators using different analytical methods. This approach allows us to distinguish distinct species communities, making them useful as diagnostic tools at various stages of habitat development. Additionally, we identify further parameters that are essential for evaluating meadow restoration in urban settings. We highlight the crucial importance of understanding the local species repertoire, as this knowledge is vital for setting realistic benchmarks for restoration projects.

Varying patterns of taxonomic and functional plant composition and diversity across different types of urban and rural grasslands

AbstractSemi‐natural grasslands are found predominantly in agricultural landscapes; however, their counterparts are also found in cities, referred to as urban grasslands. We sampled the most extensive patches of urban grasslands in Wrocław (Poland, Europe) in urban parks and along a river valley. We compared urban grasslands to broadly defined rural grasslands in terms of compositional gradients and both taxonomic and functional diversity. We also tested for relationships between rare species and different facets of diversity. Urban grasslands corresponded to three rural grassland habitat types: mesic pastures, mesic meadows, and alluvial meadows. We conducted analogous analyses, including and excluding habitat‐level assignment, to determine if emerging patterns between rural and urban grasslands are habitat‐dependent. Rural pastures and their urban counterparts showed high taxonomic and functional similarity, implying that short‐ and frequent‐cutting, applied in cities, mimics grazing management on agricultural sites. Rural mesic hay grasslands and alluvial meadows showed high taxonomic and functional dissimilarities from their urban counterparts. We found that rare species contribute to taxonomic diversity while only affecting functional diversity in a few cases. Varying patterns of taxonomic and functional similarity were observed across different habitats. Comparisons of grasslands without regard for habitat types mask diverging patterns in taxonomic and functional diversity. Despite high environmental and management pressures in urban areas (higher nutrient levels and temperatures, decreased moisture, and intensified management and soil disturbances), we showed that urban grasslands hold a considerable portion of the plant diversity found in rural grasslands.

Dry grasslands in urban areas can harbour arthropod species of local conservation concern and should be prioritised for biodiversity‐friendly mowing regimes

Abstract Although urbanisation is one of the greatest threats to biodiversity, its effect on particular invertebrate groups remains ambiguous on local and landscape scales. We aimed to analyse the effect of urban grassland management on spiders (Araneae) and carabids (Coleoptera: Carabidae), as well as other local and landscape parameters. We investigated 27 grasslands of two different management intensities (‘extensive’: one to two late cuts with removal of biomass [n = 18]; ‘intensive’: three to five mulching cuts [n = 9]) in the city of Karlsruhe, Germany. Pitfall trapping and sweep netting were performed to sample carabids and spiders. Results indicate that urban grasslands in Karlsruhe are inhabited by species‐rich assemblages, including several species of conservation concern (cc). Latter remain mostly restricted to dry grassland. The number of total specimens and of those belonging to species of cc were negatively affected by intensive management. The number of specimens of species of cc further decreased with increasing humidity and in spiders, additionally, by vegetation height. Landscape factors had limited effects, and only isolation of meadows negatively influenced the species richness of carabids (total and of species of cc). Our results demonstrate that conservation of dry grasslands in urban areas is crucial for sustaining local arthropod communities. Dry urban grassland may also act as a refugium for species of cc and mitigate the global insect crisis on a local and regional scale. In conclusion, biodiversity‐friendly mowing regimes should be applied on a broader scale in urban areas and target especially dry grassland plots. In addition, increasing connectivity and permeability of the urban matrix assist the colonisation by species of cc.

How to successfully improve the biodiversity of city grasslands?

Urban grasslands (UG) are among the most common types of urban green areas. They are usually species poor, and spontaneous plant migration, which can increase biodiversity, is limited. To improve the range of ecosystem services provided by UG, various seed mixtures are applied during the establishment and restoration of UG. These mixtures vary in content, quality, and cost. High-quality seed mixtures are expensive and are usually only available in small amounts. Meanwhile, alternative methods of seed introduction (e.g., fresh hay application, seeds harvested by brush) have not been well studied in UG restoration, and inexpensive commercial mixtures could have low quality and lead to poor restoration outcomes. Here, we tested the effectiveness of different seed sources to create high-quality UG at two study sites. Based on the results, all seed addition methods increased the species richness of restored grasslands. The outcome of seed addition was satisfactory regardless of differences in residual vegetation species composition and soil properties between the sites. The species richness on plots that received a commercial mixture of flower meadow plants dedicated to pollinators decreased after overwintering. The alternative seed sources (fresh hay and seed incidentally collected during mowing) yielded grassland quality that was comparable to that on plots that received high-quality mixtures with known seed origin (a seminatural meadow mixture and a mixture with the addition of grasses).

Both management practices and landscape influence plant communities in urban grasslands

The development of urban areas now requires the integration of biodiversity issues, and this leads to better consideration of their seminatural habitats. Among these habitats, urban grasslands subjected to mowing management practices are commonly promoted over lawns to enhance biodiversity in cities. Despite their ecological value, relatively little attention has been paid to the effects of urban grassland management regimes or the landscape contexts of these habitats in terms of biodiversity. This study aims to investigate the effects of mowing practices and the landscape context of urban grasslands on species diversity and composition and the ecological strategies of plant communities. In this study, 66 sites (mown grasslands) were selected in the Angers and Rennes conurbations of western France according to their management practices (regarding mowing) and landscape gradient (more or less urbanized). The results show that mowing practices and landscape composition did not affect the richness or diversity of plant species but significantly influenced the composition of communities. Partitioning analysis showed that landscape composition explained twice as much of the variance in plant species composition as mowing practices did. Landscape composition favors plant species according to their strategies, preferential habitats, and life spans. Furthermore, diversification of management practices limits the establishment of nonnative species and induces a wider range of functional strategies, as late mowing favors competitors and disfavors stress-tolerant species. Nevertheless, management practices need to be put into perspective in the context of urban grasslands. Thus, this research brings new perspectives to recommendations for the management of urban green spaces.

Spatial Variation and Influencing Factors of Optical Characteristic of Water Extractable Organic Matter in Soils of Urban Grassland Across Climatic Zones in China

Spatial Variation and Influencing Factors of Optical Characteristic of Water Extractable Organic Matter in Soils of Urban Grassland Across Climatic Zones in China

Genetic structure of Trifolium pratense populations in a cityscape.

Urban grasslands provide numerous ecosystem services, and their maintenance should be based on naturally regenerating plant populations. However, the urban environment is challenging for preserving viable populations, mostly because of their high fragmentation and small size, which can lead to genetic drift. We examined red clover (Trifolium pratense) in a medium-size city in Central Europe to test the cityscape effect on within- and among-population genetic diversity. We used eight inter-simple sequence repeat markers to examine the genetic structure of 16 populations, each represented by eight individuals. The isolation by resistance was analysed using a least cost patch approach, focusing on gene flow via pollinators. We found great variation among T. pratense populations, with no discernible geographic pattern in genetic diversity. We linked the diversity to the long history of the city and high stochasticity of land use changes that occurred with city development. In particular, we did not find that the Odra River (ca. 100 m wide) was a strong barrier to gene transfer. However, notable isolation was present due to resistance and distance, indicating that the populations are threatened by genetic drift. Therefore, gene movement between populations should be increased by appropriate management of urban green areas. We also found that small urban grassland (UG) patches with small populations can still hold rare alleles which significantly contribute to the overall genetic variation of T. pratense in the city.

Polycyclic aromatic hydrocarbons concentration and spatial distribution in the soils of Santiago de Compostela (northwestern Spain)

Organic pollutants are commonly accumulated in urban soils, interfering with the normal functions of soils and ecosystems, and representing potential risks for human health and well-being. Here we have studied the presence of polycyclic aromatic hydrocarbons (PAHs) in 55 soils from the city of Santiago de Compostela (Spain). The soils include different land uses: urban grasslands, urban forests, urban and periurban agricultural soils. Sample preparation was carried out by miniaturized ultrasound-assisted extraction and analytical determination was performed by gas chromatography-tandem mass spectrometry. Results revealed the presence in the soils of 17 out of the 18 PAHs analyzed, with total concentration levels up to μg g−1 in 28% of the analyzed soils. The sum of their concentrations varied widely, between 4 and 4728 ng g−1, with a mean value of 508 ng g−1 (median 217 ng g−1). The sum of the 16 EPA PAHs ranged from 4 to 4216 ng g−1, with a median of 193 ng g−1. The values found are similar to other similar-sized cities with low population densities. The study of PAHs distribution with depth in one soil showed that these compounds are mainly concentrated in the top 20 cm. Spatial distribution was very heterogeneous and without a clear pattern. In general, all PAHs were strongly intercorrelated except naphthalene, whereas no correlations have been found to soil physicochemical properties. Strong correlation of PAHs with Pb was observed, suggesting a common major source for these pollutants, probably combustion by traffic and households.

Collembola (Isotomidae) and mowing management practices control distinct aspects of thatch decomposition in a lawn mesocosm experiment

Soil mesofauna, such as Collembola and mites, are important decomposers in many ecosystems. In lawns, soil mesofauna have been implicated in the decomposition of thatch, an unsightly and problematic by-product of management found in many urban grasslands. In this study, we utilized a model lawn mesocosm experiment and ubiquitous soil mesofauna (Collembola: Isotomidae) to understand their role in thatch decomposition under a variety of simulated lawn management conditions. Our results showed that Collembola enhanced thatch decomposition by 6–8% over Collembola-absent treatments, with clipping additions moderating, and in some cases diminishing the role of Collembola in thatch decomposition. This finding was likely caused by substrate switching in the presence of clippings, and Collembola and clipping additions favoring unique aspects of microbial decomposition: Collembola enhanced oxidative enzymes, enhanced microbial biomass carbon, and marginally reduced microbial respiration, which are associated with oligotrophic microbes. Clipping additions generally increased hydrolytic enzymes, had little effect on microbial biomass, and enhanced respiration, which are associated with copiotrophic microbes. These contrasting results highlight the nuanced effects of soil mesofauna in enhancing thatch decomposition and suggest that management decisions related to lawn mowing may be equally important in mitigating thatch in lawns.

How do urbanization and alien species affect the plant taxonomic, functional, and phylogenetic diversity in different types of urban green areas?

Human pressure on urban landscapes has serious consequences for urban plant species. Therefore, environmental and anthropogenic factors affect the assembly of urban wildlife in plant communities. For biodiversity conservation and ecosystem services in urban areas, it is crucial to understand the impacts of urbanization as well as the introduction of alien plant species on urban plant communities. On 47 sites in Poznań (W Poland), we studied variation within and between three management greenery habitats, i.e., urban parks, greenery associated with housing estates, and urban grasslands, as they relate to taxonomical, functional, and phylogenetic alpha and beta diversity. We also examined how urbanization (measured by ISA) and alien plant species relate to vegetation compositional differences. We found that both urbanization and alien plant species cover decreased alpha diversity, while urbanization had various impacts on beta diversity within each studied habitat. Our results suggest that human pressure leads to similarities in the urban flora, where plant species with specific functional traits adapted to the urban environment. To achieve sustainable urbanization, urban planners should not only create diverse green spaces but also eliminate alien plants, increasing the role of urban land management in promoting the wildness of plant biodiversity in cities.

Soil microbiomes in lawns reveal land-use legacy impacts on urban landscapes

Land-use change is highly dynamic globally and there is great uncertainty about the effects of land-use legacies on contemporary environmental performance. We used a chronosequence of urban grasslands (lawns) that were converted from agricultural and forested lands from 10 to over 130 years prior to determine if land-use legacy influences components of soil biodiversity and composition over time. We used historical aerial imagery to identify sites in Baltimore County, MD (USA) with agricultural versus forest land-use history. Soil samples were taken from these sites as well as from existing well-studied agricultural and forest sites used as historical references by the National Science Foundation Long-Term Ecological Research Baltimore Ecosystem Study program. We found that the microbiomes in lawns of agricultural origin were similar to those in agricultural reference sites, which suggests that the ecological parameters on lawns and reference agricultural systems are similar in how they influence soil microbial community dynamics. In contrast, lawns that were previously forest showed distinct shifts in soil bacterial composition upon recent conversion but reverted back in composition similar to forest soils as the lawns aged over decades. Soil fungal communities shifted after forested land was converted to lawns, but unlike bacterial communities, did not revert in composition over time. Our results show that components of bacterial biodiversity and composition are resistant to change in previously forested lawns despite urbanization processes. Therefore land-use legacy, depending on the prior use, is an important factor to consider when examining urban ecological homogenization.

Urban Grassland Afforestation as a Public Land Management Tool for Environmental Improvement: The Example of Krakow (Poland)

Afforestation can play a significant role in greenhouse gas emission reduction through increased carbon (C) sequestration in the biomass and soil. However, its environmental effects, especially through changes in soil characteristics as a result of afforestation, are still poorly understood. In this work, we studied the response of grassland soils derived from two different parent materials to afforestation. We measured the basic soil properties, including pH, C accumulation, nutrient contents and enzyme activity, in soils from grasslands and mature forests. We focused on the parameters associated with organic matter and the changes resulting from afforestation. We established that in the humus layers, habitat played a more important role in creating the soil properties, including organic-C accumulation, than land use (forest vs. grassland). We created models to explain the C storage in the soils, which indicated the substantial role of certain conditions in promoting the stabilisation of the organic matter, such as pH, and the amount of clay, humines and residue. We determined negative changes in the soil properties when compared with grassland and forest soils, but we found increased C storage, which counteracts the increased emission of carbon dioxide into the atmosphere. The results of our work may be of use for afforestation planners and urban managers.

Root traits of grasslands rapidly respond to climate change, while community biomass mainly depends on functional composition

Abstract Current challenges of functional responses in plant communities to climate change call for multi‐factorial experiments. Moreover, studies on climate change should focus on below‐ground responses since absorptive roots largely control soil C allocation and resource acquisition. Thus, we aimed to understand biomass allocation and traits of absorptive roots in young mesocosm grasslands subjected to simultaneous manipulation of three components of climate change. We tested grassland biomass and root traits under climate change while manipulating functional composition. Using 64 mesocosms with designed grasslands within four chambers of a controlled‐environment facility (‘ecotron’), we simulated two contrasting IPCC climate change scenarios for elevated [CO2] and temperature (‘eCO2’ and ‘eT’). We applied normal vs. reduced precipitation of early summer in Central Europe. We also tested the effect of functional composition by varying the proportion of grasses and forbs in the communities. Specifically, we quantified above‐ and below‐ground biomass, root diameter (RD), root tissue density (RTD), specific root length (SRL), and root length density (RLD). Functional composition played a significant role in biomass allocation of the grasslands, with grass‐dominated communities producing more below‐ground biomass than forb‐dominated ones, and the opposite pattern registered above‐ground. Below‐ground biomass did not respond to climate change factors, whereas root trait values responded significantly during early establishment of the grasslands. A higher RD indicated a more conservative strategy under reduced precipitation, while eT and eCO2 led to higher RTD. We detected interactive effects between climate change and functional composition on root traits. Moreover, root biomass primarily occupied the upper soil layer, while a warm and CO2‐rich environment promoted root allocation to the lower soil layer. Grass‐dominated communities quickly colonized all available soil volume, while forb‐dominated ones accumulated more root biomass in the upper soil layer. In the mesocosm grasslands, root trait variation rather than root biomass reflected below‐ground adjustments to climate change. Furthermore, functional composition and the associated trait diversity modulated biomass allocation. Thus, establishing plant communities that are more resilient to climate change must consider the functional and taxonomic composition of the seed mixtures designed to restore urban grasslands. Read the free Plain Language Summary for this article on the Journal blog.

Response of Bare Soil Respiration to Air and Soil Temperature Variations According to Different Models: A Case Study of an Urban Grassland

Soil respiration is an important component of the global carbon cycle and is highly responsive to disturbances in the environment. Human impacts on the terrestrial ecosystem lead to changes in the environmental conditions, and following this, changes in soil respiration. Predicting soil respiration and its changes under future climatic and land-use conditions requires a clear understanding of the processes involved. The observation of CO2 fluxes was conducted at an urban grassland, where plants were removed and respiration from bare soil was measured. Nine soil respiration models were applied to describe the temperature dependence of heterotrophic soil respiration. Modified models were suggested, including a linear relationship of the temperature sensitivity and base respiration coefficients with soil temperature at various depths. We demonstrate that modification improves the simulated soil respiration. The exponential and logistic models with linear dependences on the model parameters from the soil temperatures were the best models describing soil respiration fluxes. Variability of the apparent temperature sensitivity coefficient (Q10) was demonstrated, depending on the model used. The Q10 value can be extremely high and does not reflect the actual relationships between soil respiration and temperature. Our findings have important implications for better understanding and accurately assessing the carbon cycling characteristics of terrestrial ecosystems in response to climate change in a temporal perspective.

The effect of grassland type and proximity to the city center on urban soil and vegetation coverage

Urban soils with associated vegetation are important components of urban ecosystems, providing multiple regulating and supporting ecosystem services. This study aimed to analyze the differences in the soil chemistry and vegetation of urban grasslands considering urbanization gradient and urban grassland type (UGT). We hypothesized that the chemical properties of soil, such as metal content, as well as vegetation traits, differ according to grassland type (lawns, grasslands in parks, grasslands on river embankments, and roadsides) and the location of grassland patches (city center versus peripheries). Our samples included 94 UGT patches which each patch represented by four square sampling plots sized 1 m2. The results showed high differentiation of measured traits unrelated to UGT and location. The exception was K content, with a relatively high concentration in lawns, and some metals (Cd, Cu, Pb, Zn), with higher concentrations in the city center than in the peripheries. We found two grassland patches located in the city center where the concentrations of Pb, Zn, and Cu exceeded the level authorized by Polish standards. In the case of vegetation traits, the variability was not structured considering the UGT and location of the patches, except for bare soil cover, which was higher in lawns in the city center compared to embankments in the peripheries. We observed correlations between vegetation traits and soil chemical properties. The vascular plant species richness decreased when N, P, and C content, along with an increase in grass cover and a decrease in herbs.

Fungal-bacterial associations in urban allotment garden soils

The soil microbiome in urban agriculture has not received much attention to date despite its important role in soil functionality. In this work, we evaluated the composition and diversity of fungal and bacterial communities through DNA extraction and ITS/16S marker gene sequencing in 40 soil samples collected from 10 urban allotment garden areas in the city of Santiago de Compostela (northwestern Spain). Despite anthropogenic activities are expected to affect negatively the microbial diversity, the richness of both fungal and bacterial communities was comparable to that of soils from other urban land-use categories with lower anthropogenic influence, i.e., urban forests, urban grasslands, and urban agricultural fields. However, the deterministic effect of soil properties and geographical distances was almost negligible in the surveyed allotment gardens. Neutral community models confirmed that the fungal and bacterial communities followed a random distribution (pseudo-R2fungi|bacteria = 0.653 | 0.898) and that they were more random (tNSTfungi|bacteria = 0.54 | 0.74) compared to the other abovementioned land-use categories (tNSTfungi|bacteria = 0.46 | 0.67, p ≪ 0.001). Network analysis showed that in contrast to natural soils with lower anthropogenic influence, microbial associations formed very small modules; and frequently, microbial units remained unconnected. Taken together, our findings provide evidence that the soil microbial communities in the studied urban allotment gardens comprised a random assortment of microbes and their interactions, thereby supporting potential implications of anthropogenic activity for soil health and ultimately ecosystem functionality.

Urban grassland restorations have reduced plant fitness but not pollinator limitation

Native grasslands worldwide have been greatly reduced due to anthropogenic activities. Grassland restoration efforts strive to increase biodiversity and ecosystem services of these habitats, but often fall short of management goals. This is especially true for small-scale restoration efforts in urban areas, which face unique challenges including increased surface temperatures, increased pollution, decreased habitat connectivity, and decreased pollinator availability. In 2019–2020, we conducted a seed-addition field experiment in four restoration sites near Louisville, KY USA to examine how urbanization influenced survival, growth, and reproduction of a common native forb, Chamaecrista fasciculata. We also conducted observations twice per week to characterize the active pollinator community in each site. We found that plants in urban restoration sites had reduced growth, flowering period, and reproduction compared to those in rural restoration sites. However, pollination rates (visits/flower) in urban sites did not differ from those in rural sites, and urban sites even tended to have greater pollinator effectiveness (seeds/flower) than rural sites. Our results suggest that pollination services are adequate in urban restorations, but that other factors associated with urbanization, such as increased drought stress, can reduce growth and fitness of native plants. Further work is needed to better characterize environmental stresses associated with urban grassland restoration in order to minimize fitness effects on target plant species.

Low precipitation due to climate change consistently reduces multifunctionality of urban grasslands in mesocosms.

Urban grasslands are crucial for biodiversity and ecosystem services in cities, while little is known about their multifunctionality under climate change. Thus, we investigated the effects of simulated climate change, i.e., increased [CO2] and temperature, and reduced precipitation, on individual functions and overall multifunctionality in mesocosm grasslands sown with forbs and grasses in four different proportions aiming at mimicking road verge grassland patches. Climate change scenarios RCP2.6 (control) and RCP8.5 (worst-case) were simulated in walk-in climate chambers of an ecotron facility, and watering was manipulated for normal vs. reduced precipitation. We measured eight indicator variables of ecosystem functions based on below- and aboveground characteristics. The young grassland communities responded to higher [CO2] and warmer conditions with increased vegetation cover, height, flower production, and soil respiration. Lower precipitation affected carbon cycling in the ecosystem by reducing biomass production and soil respiration. In turn, the water regulation capacity of the grasslands depended on precipitation interacting with climate change scenario, given the enhanced water efficiency resulting from increased [CO2] under RCP8.5. Multifunctionality was negatively affected by reduced precipitation, especially under RCP2.6. Trade-offs arose among single functions that performed best in either grass- or forb-dominated grasslands. Grasslands with an even ratio of plant functional types coped better with climate change and thus are good options for increasing the benefits of urban green infrastructure. Overall, the study provides experimental evidence of the effects of climate change on the functionality of urban ecosystems. Designing the composition of urban grasslands based on ecological theory may increase their resilience to global change.

High‐, medium‐, and low‐dispersal animal taxa communities in fragmented urban grasslands

AbstractUrbanized areas are rapidly expanding into a variety of habitats. Urbanization and suburbanization are often associated with changes in biodiversity, which are naturally influenced by biotic interactions and abiotic habitat characteristics. The main cause of changes caused by suburbanization is fragmentation. Its impacts vary between animals with different dispersal abilities. We focused on studying the responses of three taxa with different dispersal abilities: birds as a relatively high‐dispersal taxon, medium‐dispersal butterflies, and low‐dispersal land snails. We studied how biotic factors as well as habitat structural and fragmentation characteristics explain the community composition of the three study taxa in urban grasslands in the city of Pardubice (Czech Republic). Birds were the most species‐rich taxon followed by butterflies. Land snails had species‐poor grassland communities. Species composition analysis indicated species overlap among the studied taxa. Bird species composition covaried with butterfly species richness and reciprocally. Both taxa were significantly influenced by the amount of woody vegetation within the grassland. Bird community composition was also influenced by fragmentation characteristics, namely the distance to the nearest built‐up area. Urban growth most likely leads to changes in the characteristics of animal communities associated with former lowland natural grasslands, deteriorating the communities of low‐dispersal land snails while allowing birds that have generally higher dispersal abilities to thrive. Our results show that in assessing the impact of urbanization on biodiversity, attention should also be paid to low‐dispersal animal taxa.

Local and Landscape Factors Influence Plant-Pollinator Networks and Bee Foraging Behavior across an Urban Corridor

Given widespread concerns over human-mediated bee declines in abundance and species richness, conservation efforts are increasingly focused on maintaining natural habitats to support bee diversity in otherwise resource-poor environments. However, natural habitat patches can vary in composition, impacting landscape-level heterogeneity and affecting plant-pollinator interactions. Plant-pollinator networks, especially those based on pollen loads, can provide valuable insight into mutualistic relationships, such as revealing the degree of pollination specialization in a community; yet, local and landscape drivers of these network indices remain understudied within urbanizing landscapes. Beyond networks, analyzing pollen collection can reveal key information about species-level pollen preferences, providing plant restoration information for urban ecosystems. Through bee collection, vegetation surveys, and pollen load identification across ~350 km of urban habitat, we studied the impact of local and landscape-level management on plant-pollinator networks. We also quantified pollinator preferences for plants within urban grasslands. Bees exhibited higher foraging specialization with increasing habitat heterogeneity and visited fewer flowering species (decreased generality) with increasing semi-natural habitat cover. We also found strong pollinator species-specific flower foraging preferences, particularly for Asteraceae plants. We posit that maintaining native forbs and supporting landscape-level natural habitat cover and heterogeneity can provide pollinators with critical food resources across urbanizing ecosystems.