Ambient urban N deposition drives increased biomass and total plant N in two native prairie grass species in the U.S. Southern Great Plains

Alexandra G. Ponette-González; Michelle L. Green; Justin McCullars; Laura Gough

doi:10.1371/journal.pone.0251089

Abstract

Remnants of native tallgrass prairie experience elevated atmospheric nitrogen (N) deposition in urban areas, with potential effects on species traits that are important for N cycling and species composition. We quantified bulk (primarily wet) inorganic N (NH₄⁺-N + NO₃^--N) deposition at six sites along an urban development gradient (6–64% urban) in the Dallas-Fort Worth metropolitan area from April 2014 to October 2015. In addition, we conducted a phytometer experiment with two common native prairie bunchgrass species––one well studied (Schizachyrium scoparium) and one little studied (Nasella leucotricha)––to investigate ambient N deposition effects on plant biomass and tissue quality. Bulk inorganic N deposition ranged from 6.1–9.9 kg ha^-1 yr^-1, peaked in spring, and did not vary consistently with proportion of urban land within 10 km of the sites. Total (wet + dry) inorganic N deposition estimated using bulk deposition measured in this study and modeled dry deposition was 12.9–18.2 kg ha^-1 yr^-1. Although the two plant species studied differ in photosynthetic pathway, biomass, and tissue N, they exhibited a maximum 2-3-fold and 2-4-fold increase in total biomass and total plant N, respectively, with 1.6-fold higher bulk N deposition. In addition, our findings indicate that while native prairie grasses may exhibit a positive biomass response to increased N deposition up to ~18 kg ha^-1 yr^-1, total inorganic N deposition is well above the estimated critical load for herbaceous plant species richness in the tallgrass prairie of the Great Plains ecoregion and thus may negatively affect these plant communities.

Citation: Ponette-González AG, Green ML, McCullars J, Gough L (2021) Ambient urban N deposition drives increased biomass and total plant N in two native prairie grass species in the U.S. Southern Great Plains. PLoS ONE 16(5): e0251089. https://doi.org/10.1371/journal.pone.0251089

Editor: RunGuo Zang, Chinese Academy of Forestry, CHINA

Received: December 19, 2020; Accepted: April 19, 2021; Published: May 6, 2021

Copyright: © 2021 Ponette-González et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: The data underlying this study are available on the KNB repository (DOI: 10.5063/6D5RDT).

Funding: MG—Beta Phi Chapter of the Phi Sigma Biological Honors Society at the University of Texas Arlington. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Introduction

Over the past decade, there has been a surge in research on nitrogen (N) deposition in cities around the world (e.g., [1–6]). Although there are many urban areas for which data are still sparse or nonexistent [7], research highlights three distinguishing characteristics of urban N deposition. First, compared to nearby rural and remote sites, wet or bulk N deposition in urban areas is, on average, twofold higher [3]. Second, N deposition can exhibit high intra-urban (e.g., [8]) and intra-annual variability (e.g., [9]). Third, responses to urban N deposition remain poorly documented: a recent meta-analysis found that just ~10% of studies concomitantly measured N deposition and some biogeochemical metric (e.g., N mineralization) that might be affected by N [3].

Indeed, much of the current understanding of plant responses to and recovery from N addition is derived from experimental field manipulations which are most often conducted in plant communities outside the influence of urban air pollution (e.g., [10–15]). These studies show that individual plants exposed to elevated levels of N deposition often exhibit changes in biomass, resource allocation (e.g., root:shoot ratio), and tissue quality in the form of decreased carbon (C) to N ratio. In turn, lower C:N ratios have the potential to affect energy transfer to higher trophic levels by increasing the palatability of tissues to herbivores (e.g., [16]).

While informative, experimental manipulations usually involve large N pulses (e.g., >75 kg N ha^-1 yr^-1; [17]), whereas natural ecosystems typically experience chronic N deposition at rates well below these values [3]. However, because N accumulates within ecosystems, even lower levels of N deposition can lead to ecological changes if N deposition is elevated above background and persists over time [18–20]. The quantitative threshold above which atmospheric N deposition is expected to have negative impacts on ecosystems is termed “critical load” [21]. Observational and experimental studies show that critical load exceedances drive altered plant community composition and decreased species richness across diverse biomes (e.g., [22]), with changes often conditional on soil and climate characteristics [20]. In urban areas, N deposition effects on ecosystems are likely also contingent on local gradients in heat, rainfall, ozone, carbon dioxide, and their interactions [23].

Compared to research on N deposition impacts on urban forests [6, 24–27], urban grassland responses to N deposition are less well understood and warrant further attention. Grasslands play important roles in carbon sequestration, water quality protection, non-native species suppression, and wildlife habitat provision [28, 29]. To begin to fill this gap, we quantified bulk inorganic N––ammonium (NH₄⁺-N) and nitrate (NO₃^--N)––deposition effects on two common native prairie grass species along an urban development gradient. We hypothesized that (1) N deposition would increase with proportion of urban land (within 10 km) and (2) plant biomass would increase, while root:shoot ratio and tissue C:N would decrease, over the urban-induced deposition gradient. Our results expand current understanding of urban N deposition and prairie grass responses to rising urban N; both types of observations are sparse in the Southern Great Plains ecoregion and in numerous regions worldwide.

Materials and methods

Urban development and tallgrass prairie in Dallas-Fort Worth

The research was conducted in the Dallas-Fort Worth (DFW) metropolitan area, Texas (Fig 1). Settlement of DFW began in the mid-19^th century, with ranching as the primary economic activity [30]. The first major period of population growth in the cities of Dallas and Fort Worth occurred in the late 1880s, while significant population growth in the intermediate cities did not occur until a half century later [31]. Since the 1960s, DFW has expanded rapidly: between 2010–2018, DFW was the metropolitan area with the largest numeric population growth in the U.S. [32]. Today, it is the fourth most populous metropolitan area, with a population of >7 million [32]. Regionally, DFW is part of the greater “Texas Triangle” (Houston-Austin-San Antonio-Dallas), one of several U.S. megapolitan regions (i.e., clustered networks of cities) identified as important for research on urbanization across societal and environmental gradients [7].

Download:

Fig 1. Study area map.

Sites where bulk inorganic N deposition was measured in the Dallas-Fort Worth metropolitan area (municipal areas in grey) and the L.B.J. National Grasslands National Atmospheric Deposition Program (NADP) site. Percent urban development within a 10-km radius buffer [39] is indicated in parentheses and ranges from low (light pink border) to high (crimson red border).

https://doi.org/10.1371/journal.pone.0251089.g001

Situated at the southern end of the Great Plains ecoregion, a semi-arid grassland extending from Canada through the central U.S. into Mexico, DFW straddles the Grand Prairie to the west and the Blackland Prairie to the east. Climate is humid sub-tropical with hot summers, cool winters, and intermediate rainfall (annual normal (1981–2010) ~918 mm yr^-1; [33]). Despite rapid urbanization, considerable land areas in DFW are being used for agriculture [34], especially surrounding Tarrant and Dallas counties where the cities of Fort Worth and Dallas, respectively, are located. Together, agriculture and urbanization have resulted in the contraction of native prairie to just 1–2% of the landscape [35, 36]. Remnants of late-successional tallgrass communities––often intermixed with grazed grasslands––contain little bluestem (Schizachyrium scoparium), big bluestem (Andropogon gerardii), and Indiangrass (Sorghastrum nutans) [37], with little bluestem the dominant plant species [38]. Associated species include side-oats grama (Bouteloua curtipendula), tall dropseed (Sporobolus compositus), and Texas wintergrass (Nasella leucotricha).

Site selection

Six sites were selected along an urban development gradient (Fig 1, Table 1) based on property owners’ willingness to participate, accessibility, and suitability to the research study. All sites were located in the Fort Worth Prairie, the northern portion of the larger vegetation unit known as the Grand Prairie [38], where pasture, grassland and herbaceous cover occur alongside and are inversely correlated with percent urban land. Three sites were located on college or county campuses with nearby buildings and groomed landscapes. These included Tarrant County College Northwest (TCNW), Tarrant County College Northeast (TCNE), and the Resource Connection of Tarrant County, a campus of county services buildings and a demonstration garden (TCSO). Two properties were located within designated natural areas with few nearby buildings and some restoration management on the landscape: Lewisville Lake Environmental Learning Area (LLELA) and Clear Creek Natural Heritage Center in Denton County (DENT). An additional agricultural site was located adjacent to a house and farm animals on private property in the community of Alvarado (ALVA). The National Atmospheric Deposition Program (NADP) monitoring site at Lyndon B. Johnson National Grasslands (L.B.J., TX56), located 78 km north-northwest of Fort Worth, was used as a non-urban reference site since NADP monitoring sites are located distant from local pollution sources. Thus, NADP measurements of wet N deposition underestimate deposition in urban-affected areas but serve as useful estimates of background deposition [6].

Download:

Table 1. Study site characteristics.

https://doi.org/10.1371/journal.pone.0251089.t001

Nitrogen deposition measurements

Bulk inorganic N (NH₄⁺-N + NO₃^--N) deposition was measured from 4 April 2014 to 9 October 2015 at the six sites described above in open areas with no canopy cover and >30 m from trees and buildings, with the exception of TCNW (~10 m). Two identical bulk collectors set on PVC tubes 1 meter aboveground were established three meters apart at each of the sites (n = 12 collectors total). Bulk collectors remain open between sampling periods and primarily collect N ions dissolved in rainwater and some amount of coarse particles heavy enough to settle on collector surfaces between rainfall events [42]. Relative to total dry N deposition, gaseous and particulate N deposition to bulk collectors is often low (e.g., [9]).

Following the design of Simkin et al. [43], bulk collectors consisted of a 20-cm diameter high-density polyethylene funnel attached to Tygon tubing, a HDPE connector, and a chromatograph column filled with 20 mL of ion-exchange resin. Before sampling, all components were rinsed and then soaked in double deionized water for 24 hours. Components were rinsed again and left to dry in a clean enclosed area. In this study, Amberlite IRN 150 mixed-bed ion exchange resin (Rohm & Haas Company, Philadelphia, PA) was used to capture both positively and negatively charged ions as rainfall passed through the collectors [44]. To prepare the resin, double-deionized water was added to the resin to create a slurry. Each column fitted with a 30-μm pore size filter at the bottom was filled with 20 mL of resin. Prepared columns were refrigerated before use.

We evaluated the efficiency of ion capture as well as the extraction efficiency of the resin after Fenn et al. [45]. Columns were loaded with 0, 101, 138, 332, 664, 1665, and 6652 μeq of N as NH₄Cl and 0, 32, 250, 104, 208, 517, and 2080 μeq of N as KNO₃. The efficiency of ion capture was >98% for NH₄⁺ and ~100% for NO₃^-. Minimum extraction efficiency, the percentage of ions loaded on the columns and recovered in sequential extractions, was 79% for NH₄⁺ and 86% for NO₃^-. We also used the fixed exchange capacity of the resin (cation = 1.9 eq L^-1, anion = 1.2 eq L^-1), rainfall amount, and chemical composition data (2011–2013) from the L.B.J. NADP site to estimate the potential range of cation plus anion loading at our study sites (S1 Text). Based on our calculations and previous studies (e.g., [46]), we determined that resin columns could be collected every three months.

Bulk ion-exchange resin collectors were assembled and installed at the sites on 4 April 2014. A polywool filter was inserted into the neck of each funnel to prevent debris and insects from falling into the resin column. Samples were collected on 11 July 2014, 11 October 2014, 9 January 2015, 10 April 2015, and 13 July 2015. The last columns were collected on 9 October 2015, for a total of six consecutive sampling seasons: Spring 2014 (Apr-Jun; 98 days), Summer 2014 (Jul-Sep; 92 days), Fall 2014 (Oct-Dec; 90 days), Winter 2014 (Jan-Mar; 91 days), Spring 2015 (Apr-Jun; 94 days), and Summer 2015 (Jul-Sep; 88 days). Upon collection, funnels, tubing, connectors, and polywool filters were replaced with new, clean components, and new ion-exchange resin columns were attached. In addition to field samples, two blank resin columns were prepared for each sampling period.

Resin columns were transported to the Ecosystem Geography Laboratory at the University of North Texas where they were refrigerated at 4°C until sample extraction. Bulk deposition and blank samples were extracted three times with 100 mL 2 M KCl [27, 44], frozen and then shipped to the Cary Institute of Ecosystem Studies where NH₄⁺-N and NO₃^--N were determined on a Lachat QuickChem Flow Injection Analyzer +8000 Series (Lachat Instruments, Loveland, Colorado). Ammonium concentrations were determined using the phenate method, while NO₃^--N concentrations were determined using the cadmium diazotization method. Detection limit for both methods was 0.02 mg L^-1. A series of standards was included with each instrument run.

Calculation of bulk deposition

Bulk NH₄⁺-N and NO₃^--N concentrations (mg L^-1) were multiplied by extractant volume (0.3 L), converted to kg, and then divided by collector surface area to obtain deposition rate (kg ha^-1 sampling period^-1). Lab blank concentrations were all below detection limit (<0.02 mg L^-1). At each site, values for the two bulk collectors were similar (S1 Fig) and averaged for each sampling period. Twelve samples (~15%) were deemed invalid because samplers: were knocked over, had visual evidence of bird droppings and samples with NH₄⁺-N values more than two times higher than those of the paired collector, were clogged, or were attached to columns with missing labels. In these cases, values from the remaining collector were used. For the NADP L.B.J. site, weekly wet deposition was calculated for each sample period by multiplying NH₄⁺-N and NO₃^--N concentrations times rainfall amount.

Accumulated deposition per site was calculated by summing the values for the six sample periods. Deposition values were also normalized (i.e., divided) by rainfall amount at each site to assess the relative effect of urban exposure (i.e., urban atmospheric N pollution) on N deposition. To obtain annual N deposition, accumulated deposition over the entire study period was divided by the total number of days sampled (553 days) and the daily deposition value multiplied by 365.

Phytometer experiment

A phytometer experiment was conducted to investigate the effects of N deposition on plant biomass and tissue quality of two native prairie grass species. Phytometer experiments involve placing plants from one population into multiple locations and then monitoring their growth [47]. The focal plant species were little bluestem (Schizachyrium scoparium) and Texas wintergrass (Nasella leucotricha). Little bluestem, a C₄ warm-season perennial, was selected because of its adaptation to the ecoregion and dominance in the native prairie landscape. Little bluestem begins active growth in late spring and grows through the summer until the first frost in fall [48]. Texas wintergrass is a cool-season C₃ perennial that thrives in disturbed areas. This species experiences the most rapid growth in early fall and grows through winter and spring [49]. Texas wintergrass was chosen to serve as counterpart to little bluestem for two reasons: (1) C₃ and C₄ plants may respond differently to N additions due to varying sensitivity to seasonal water and N availability [50] and (2) it is a little-studied species compared to little bluestem, but one that represents an important component of the Fort Worth prairie. Both little bluestem and Texas wintergrass are bunchgrasses, which reproduce vegetatively via the growth of new tillers from buds on existing tillers. This results in a dense bunch of grass with the oldest tillers towards the center. Sexual reproduction occurs in each grass species with the formation of specialized flowering tillers that are wind pollinated.

All plants for the phytometer experiment were obtained from one population grown at a local nursery in Mansfield, Texas. Clumps of little bluestem were divided into smaller clumps, each possessing 1–4 tillers and weighing between 0.5 g and 2 g. Texas wintergrass plants were divided into clumps of 2–10 tillers each and similarly weighed between 0.3 g and 1.5 g. Divided clumps were potted individually in black plastic pots (3785 cm³) with weed barrier on the bottom and sandy loam topsoil sourced from Mansfield.

A total of 20 little bluestem and 20 Texas wintergrass plants were randomly assigned to each of the N deposition measurement sites. Adjacent to the bulk deposition collectors, black weed barrier was attached to the ground in a 6 x 7.5 m rectangle to prevent competition from established plants and minimize weed invasion. A water barrel was installed at each site to facilitate watering. Little bluestem plants were placed at the sites between 27–29 September 2013, while Texas wintergrass plants were placed at the sites on 5–6 April 2014. During the experiment, all plants grew in full sun and were watered biweekly with 500 ml of water per pot. Local potable water was used and therefore did not represent a source of nitrogen for the plants. Little bluestem plants were harvested on 22 July 2014. Due to human disturbance and significant loss of plants at three sites, data for little bluestem are presented for the ALVA, TCNW, and TCSO sites only. Texas wintergrass plants were harvested between 20 May and 1 June 2015.

Following harvest, plants were returned to the lab where they were separated into tillers (vegetative and reproductive) and roots, dried at 52°C for 72 hours, and then weighed to obtain tiller (hereafter shoot) and root biomass. Biomass values were divided by the total number of days plants were in the ground to enable species comparisons. Subsamples (~5–10 g) of shoot and root biomass were ground using a Wiley Mill, weighed, placed in a tin capsule, and analyzed for total C and N on a Perkin-Elmer 2400 CHN analyzer. Total plant (shoot + root) N for little bluestem and Texas wintergrass was estimated by multiplying shoot and root biomass by percent N of each and then summing the values.

Statistical analyses

All variables were tested for normality using the Shapiro-Wilk test. Variables with non-normal distributions were log-transformed to meet assumptions of normality and homogeneity of variance. Nonparametric tests were used when sample data did not meet these assumptions.

We examined relationships of urban development with N deposition using simple linear regressions, and we tested for seasonal differences in N deposition using the Kruskal-Wallis Test with the Dunn Method for joint ranking. For each of the plant traits measured, t-tests were used to examine contrasts between species within each of the three sites (ALVA, TCNW, TCSO) along the gradient where both species were present. Site-to-site differences in little bluestem and Texas wintergrass traits were assessed using the Kruskal-Wallis test followed by the Steel-Dwass test for multiple comparisons. Plant trait relationships with N deposition from planting date to harvest date were also evaluated with simple linear regression. All statistical analyses were performed in JMP v.14 [51]. Significance was set at p < 0.1.

Results

Nitrogen deposition along an urban development gradient

Bulk inorganic N deposition measured in DFW ranged from 6.1 to 9.9 kg ha^-1 yr^-1 across sites (Table 1). Sites with ≥15% urban land received 30–100% more N than the L.B.J. reference site (5 kg ha^-1 yr^-1). Ammonium-N was higher than NO₃^--N deposition at all sites and during all seasons sampled. Ammonium-N constituted 63–70% of inorganic N.

Urban development was not correlated with absolute or normalized bulk NH₄⁺-N or inorganic N deposition (Fig 2; S1 Table). Nitrate-N deposition also did not increase with proportion of urban land (Fig 2). When normalized by rainfall, NO₃^--N deposition increased along the urban development gradient in Spring 2015 (p = 0.12) and Summer 2015 (p = 0.13), but the relationships were not significant.

Download:

Fig 2. Relationships between urban development, rainfall, and absolute and precipitation-normalized bulk nitrogen deposition for six consecutive sampling seasons.

Nitrogen deposition was sampled in Spring 2014 (Apr-Jun), Summer 2014 (Jul-Sep), Fall 2014 (Oct-Dec), Winter 2014 (Jan-Mar), Spring 2015 (Apr-Jun), and Summer 2015 (Jul-Sep). Percent urban development within 10 km of each site in the Dallas-Fort Worth metropolitan area ranges from low (light pink) to high (crimson red).

https://doi.org/10.1371/journal.pone.0251089.g002

Significant seasonal effects on N deposition were evident, with peaks in spring. In the spring of 2014 and 2015, bulk NH₄⁺-N deposition was 4-6-fold higher compared to Fall 2014 and 6-9-fold higher compared to Summer 2015. Similarly, in both years, Spring NO₃^--N deposition was 4–5 times the level measured in Summer 2015, and Spring 2015 NO₃^--N deposition was double that in Fall 2014. Nitrate-N deposition in Winter 2014 was also 2.5-fold higher than in Summer 2015. Seasonal differences in inorganic N deposition were identical to those of NH₄⁺-N deposition.

Little bluestem and Texas wintergrass plant traits

Little bluestem and Texas wintergrass plants growing at ALVA, TCNW, and TCSO differed in their root biomass accumulation, biomass allocation, tissue C and N, and total plant N. Shoot biomass was similar for both species, but little bluestem accumulated four to eight times more root biomass than Texas wintergrass, resulting in higher mean root:shoot ratios for little bluestem (Fig 3a). Shoot and root C differed significantly but less markedly between species (Fig 3b) than did shoot and root N. Shoot and root N were approximately two-fold higher in Texas wintergrass compared to little bluestem (Fig 3c). Given the higher tissue N, Texas wintergrass had lower tissue C:N ratios than little bluestem across all sites and higher overall total plant N at the two more urban sites (Table 2).

Download:

Fig 3. Little bluestem (LBS) and Texas wintergrass (TW) plant traits.

Differences in (a) mean (±1SE) biomass accumulation, allocation, (b) tissue C, and (c) tissue N between native prairie grass species at three sites characterized by low (pink) to high (crimson red) urban development in the Dallas-Fort Worth metropolitan area. *p < 0.1, ** p < 0.05, *** p < 0.001.

https://doi.org/10.1371/journal.pone.0251089.g003

Download:

Table 2. Plant traits (mean±1SE) for the six phytometer sites along an urban development gradient (indicated in parentheses).

https://doi.org/10.1371/journal.pone.0251089.t002

Prairie grass responses to nitrogen deposition

Both little bluestem and Texas wintergrass plants exhibited site-to-site differences in plant traits (Table 2). All measures of little bluestem biomass were highest at TCNW and lowest at TCSO. At harvest, plants at TCNW had twice the shoot and total biomass as plants at the other sites. Root C:N was also lowest at TCSO due to elevated root N compared to the other sites. Although little bluestem plants at TCNW did not have higher shoot or root N compared to the other sites, total plant N was nearly double that measured at other sites there given the higher total plant biomass.

Similar to little bluestem, Texas wintergrass plants accumulated the most shoot, root, and total biomass at TCNW, as much as three times more than plants at the other sites. Plants grown at TCSO had the highest root:shoot ratio of all sites. Although patterns for tissue C and N were less clear, the highest shoot C, shoot C:N, root C, and root N were recorded at TCNE, the most urban site.

Both species showed a significant increase in total biomass (Fig 4) and total plant N with inorganic N deposition (Fig 4; S2 Table). For Texas wintergrass, changes in total biomass and plant N were most pronounced at sites receiving >0.025 kg ha^-1 d^-1 of inorganic N (~9 kg ha^-1 yr^-1).

Download:

Fig 4. Prairie grass responses to nitrogen deposition.

Increase in total plant biomass (g d^-1) and total plant N (g) with inorganic nitrogen deposition (kg ha^-1 d^-1) from planting date to harvest date for little bluestem and Texas wintergrass plants at six phytometer sites in the Dallas-Fort Worth metropolitan area.

https://doi.org/10.1371/journal.pone.0251089.g004

Discussion

Nitrogen deposition in Dallas-Fort Worth: Magnitude, seasonality, and form

Here we provide a first estimate of inorganic N deposition in Dallas-Fort Worth, the fourth largest U.S. metropolitan area and a major node in the Texas Triangle megapolitan area. We find that bulk inorganic N deposition in this semi-arid city is relatively high, 6.1–9.9 kg ha^-1 yr^-1, and more comparable to bulk N deposition measured in wetter cities such as Boston (5.2 kg ha^-1 yr^-1; [52]) than in arid cities such as Phoenix (1.9 kg ha^-1 yr^-1; [9]).

Moreover, N deposition in DFW varies seasonally with lower rates in fall and pulsed deposition in spring. Several factors contribute to temporal variability in urban atmospheric wet deposition, including changes in the source and strength of emissions, meteorological conditions, and the rate of chemical reactions in the atmosphere (e.g., [9, 53–56]). At our study sites, 43% of NH₄⁺-N, 34% of NO₃^--N, and 40% of the bulk inorganic N measured between April 2014 and March 2015 occurred in spring compared to 30% of rainfall, suggesting that both increased rainfall and N concentrations contributed to elevated deposition during this season. In 2015, we captured a month of record-breaking rainfall, in which DFW received nearly half its mean annual rainfall in May alone. As a result, spring N deposition was 1.5 to 4.5-fold higher compared to Spring 2014 depending on the site. Long-term data from the L.B.J. National Grasslands NADP site confirm that spring deposition peaks are typical for this region. From 1983 to 2019, spring accounted for 30% of annual rainfall and 40% of inorganic N at L.B.J. [40].

During all seasons and across all sites, the majority of N deposited was in the form of NH₄⁺-N (63–70%). This is in line with previous studies that show NH₄⁺-N comprising 70–77% of bulk inorganic N in Boston [6, 8], 69% of wet deposition in Providence [57], ~53% in Phoenix [9], ~59% of wet inorganic N deposition across the continental U.S. [58], and 60% of N in urban areas globally [3]. The dominance of NH₄⁺-N in the DFW area is consistent with an observed shift over time from NO₃^-- to NH₄⁺-dominated N deposition in U.S. urban areas likely resulting from increased NO_x regulations and lack of NH₃ regulations [8, 58, 59], as well as NO_x reduction technologies that produce NH₃ [60].

Myriad local emission sources contribute to elevated NH₄⁺-N deposition within urban areas. Lawn and greenspace fertilizer application [8, 53], industrial and fossil fuel combustion [58] and wastewater treatment [61] represent important sources of gaseous ammonia to the atmosphere. Off-site emissions from crop and livestock production also influence urban N deposition [9]. In a recent study, measured and estimated on-road and agricultural NH₃ emissions in Dallas and Tarrant counties––where the cities of Dallas and Fort Worth are located––were notably high [58]. Although we cannot apportion sources of N at our study sites, high levels of traffic congestion [62], intensive and extensive landscaping [63], and growing proportions of land under agriculture [64] likely contribute to the prevalence of NH₄⁺-N deposition in DFW.

Urban development effects on N deposition

Bulk inorganic N deposition in DFW was high compared to the L.B.J. reference site but did not, contrary to our hypothesis, increase with urban development within 10 km of the sites. We expected such a relationship given previous studies in arid cities, which show positive relationships between N deposition and urbanization proxies. For example, at sites in the Denver-Boulder metropolitan area and at oak savanna sites in central California, either bulk N concentrations or deposition exhibited positive relationships with population density [56] and proximity to urban core [55]. In contrast, Lohse et al. [54] found that neither distance to urban core nor land use were related to rainwater N concentrations, while Cook et al. [9] found little variation in bulk N deposition along an urban-rural gradient in the Phoenix metropolitan area.

There are several possible reasons why we did not detect a relationship between annual N deposition and urban development. First, estimates indicate that 74–84% and 51–61% of total (wet + dry) inorganic N deposition to our study sites in 2014 and 2015 [65, 66], respectively, was in the form of dry deposition. Although bulk collectors capture varying amounts of dry N deposition [67, 68], this amount is likely low relative to total dry inputs (e.g., [54]). Second, urban land within 10 km may not serve a good proxy for NH₄⁺-N or NO₃^--N deposition. Strong concentration gradients in atmospheric N due to localized emissions near roads and lower emissions in park areas [69] may have obscured spatial variation in N deposition. For example, one of the more urban (44%) sites sampled in this study was located within a designated natural area (LLELA) and had comparatively low deposition compared to most of the other sites. Gaseous ammonia has a short atmospheric lifetime (on the order of hours) and tends to deposit close to the source [70]. Thus, the location of this site relative to emissions source (e.g., roads) may have affected deposition rates there. In the case of NO₃^--N, the longer atmospheric lifetime (~1 day; [71]) and potential for long-range transport of NO_x in the troposphere [72] might prevent us from observing relationships between deposition and urban development within a 10-km buffer. Third, variation in atmospheric mixing processes due to variability in wind speed, surface roughness, and heat island effects could have contributed to heterogeneous patterns of N deposition [69].

Prairie grass responses to N deposition

Although the relationship between N deposition and level of urban development was not what we anticipated, our findings show that two common native prairie grass species in the Southern Great Plains exhibit a positive biomass response, and in turn higher plant N, with greater N deposition. This response is consistent with previous research indicating that N additions increase grassland primary productivity [73–75] and the expectation that as N becomes less limiting, plants allocate a greater proportion of biomass aboveground. In a global meta-analysis of 42 plots in the Nutrient Network Global Research Cooperative (http://www.nutnet.unm.edu), where N deposition ranged from <1 to 36 kg N ha^-1 yr^-1, Stevens et al. [75] found a 3% increase in aboveground net primary production with each additional unit of N deposition.

In this study, sites receiving 7.2–9.9 kg inorganic N ha^-1 yr^-1, the high end of the deposition range we found, exhibited the most pronounced changes in total biomass and plant N. As these values do not include dry deposition, we extracted wet and dry N deposition (2014–2015) from NADP total deposition maps. NADP total deposition estimates were developed using a hybrid approach that combines measured and modeled data [65]. The estimates indicate that our DFW sites receive a total (wet + dry) N deposition load of 11–13 kg N ha^-1 yr^-1. If we sum bulk deposition measured in this study with estimates of dry deposition from NADP total deposition maps, N deposition rates are even higher, 13–18 kg N ha^-1 yr^-1. Thus, native prairie grasses may exhibit a positive biomass response to increased urban N deposition up to ~18 kg ha^-1 yr^-1. Moreover, both ranges of total inorganic N deposition surpass the critical load limit for herbaceous plant species richness in the DFW area, which we estimated to be 8.9 kg N ha^-1 yr^-1 after Simkin et al. [20]. Nevertheless, larger scale and longer-term monitoring in the DFW are needed to assess the effects of N deposition on shifts in plant community composition.

Implications for native prairie grass species

At levels above N critical loads, grassland ecosystems experience changes in species composition which may include loss of N-sensitive and native species, shifts in dominance, and decreased species richness [18, 20, 76, 77]. Thus, increased rates of ambient urban N deposition could affect native prairie grass remnants in the Southern Great Plains. Consistent with previous studies [78, 79], little bluestem plants in our phytometer experiment had low tissue N compared to Texas wintergrass but allocated a higher proportion of biomass belowground. The high N-use efficiency and more extensive root network of little bluestem are traits that make this species a good competitor on N-poor soils [79]. In contrast, Texas wintergrass had higher tissue N but invested less in root biomass, potentially indicating a higher N uptake rate [80].

Texas wintergrass is unique among cool-season grasses in that its range is restricted south of 35° N latitude [81], yet it is an important component of the prairie in the Southern Great Plains. We know of only one study in which little bluestem and Texas wintergrass responses to light and nitrogen were assessed, both in monoculture and in mixture [81]. In that study, both species grew best under high light and high N––similar to our phytometer experiment in which both species accumulated the most biomass at the highest N deposition site. However, Texas wintergrass accumulated more biomass when grown in mixture, suggesting that this species may be able to better use additional N in a community setting. Little bluestem, on the other hand, is vulnerable to loss at high N levels [76]; a recent study reported a N critical load range of 9–14 kg ha^-1 yr^-1 for this species [18]. Using data specific to our study area and the model presented by Clark et al. [18], the critical load for little bluestem in DFW is 13.9 kg ha^-1 yr^-1. Little bluestem thus appears to be near or at the critical load limit for N, meaning this species is potentially vulnerable to loss.

Future work is needed to determine the effect of N on these species especially in the context of Great Plains drought [82], precipitation variability [83], and urban pollution and heat effects. In the Southern Great Plains ecoregion, little bluestem is the dominant while Texas wintergrass is a common component of late-successional tallgrass prairie communities. Loss of one or both of these species could therefore have significant negative implications for plant community composition and higher trophic levels. As urbanization continues to have multiple effects on local vegetation, the role of N deposition in affecting individual species and communities warrants additional study.

Supporting information

S1 Table. Results of regression analyses, including regression coefficient, standard error, p-values, and goodness of fit.

https://doi.org/10.1371/journal.pone.0251089.s001

(DOCX)

S2 Table. Results of regression analyses, including regression coefficient, standard error, p-values, and goodness of fit.

https://doi.org/10.1371/journal.pone.0251089.s002

(DOCX)

S1 Text. Estimates of the potential range of cation plus anion loading.

https://doi.org/10.1371/journal.pone.0251089.s003

(DOCX)

S1 Fig. Nitrogen deposition rates per collection period for both samplers at each of the six urban sites sampled in the Dallas-Fort Worth metropolitan area from April 2014 to October 2015.

https://doi.org/10.1371/journal.pone.0251089.s004

(DOCX)

Acknowledgments

We are grateful to John Snowden for providing native prairie grasses, Dr. Thomas Chrzanowski for use of laboratory equipment, Jayme Walton of SWCA for assistance with GIS, and James Hobbs, Margaret Park, and Zane Winer for help in the field and laboratory. We thank Kathleen C. Weathers and the staff at the Cary Institute of Ecosystem Studies Analytical Laboratory for assistance with chemical analysis and Jennifer Ellis and Roman Rangel for assistance with land cover analysis. Our thanks to Tarrant County College District, Lewisville Lake Environmental Learning Area, Clear Creek Natural Heritage Center, Tarrant County Resource Connection, and the Stricklin Family for providing space for the phytometer experiments. Finally, we are indebted to Stephen Decina, John Van Stan III, Christopher Clark, and two anonymous reviewers for helpful feedback on the manuscript.

References

1. Carnelos DA., Portela SI, Jobbágy EG, Jackson RB, Di Bella CM, Panario D, et al. A first record of bulk atmospheric deposition patterns of major ions in southern South America. Biogeochemistry. 2019; 144: 261–271. https://doi.org/10.1007/s10533-019-00584-3
- View Article
- Google Scholar
2. de Souza PA, Ponette-González AG, de Mello WZ, Weathers KC, Santos IA. Atmospheric organic and inorganic nitrogen inputs to coastal urban and montane Atlantic Forest sites in southeastern Brazil. Atmos Res. 2015; 160(15): 126–137. https://doi.org/10.1016/j.atmosres.2015.03.011
- View Article
- Google Scholar
3. Decina SM, Hutyra LR, Templer PH. Hotspots of nitrogen deposition in the world’s urban areas: a global data synthesis. Front Ecol Environ. 2020; 18(2), 92–100. https://doi.org/10.1002/fee.2143
- View Article
- Google Scholar
4. Du E, De Vries W, Liu X, Fang J, Galloway JN, Jiang Y. Spatial boundary of urban ‘acid islands’ in southern China. Sci Rep-UK. 2015; 5, 12625. https://doi.org/10.1038/srep12625 pmid:26211880
- View Article
- PubMed/NCBI
- Google Scholar
5. Ponette-González AG, Weathers KC, Curran LM. Tropical land‐cover change alters biogeochemical inputs to ecosystems in a Mexican montane landscape. Ecol Appl. 2010; 20(7), 1820–1837. https://doi.org/10.1890/09-1125.1 pmid:21049872
- View Article
- PubMed/NCBI
- Google Scholar
6. Rao P, Hutyra LR, Raciti SM, Templer PH. Atmospheric nitrogen inputs and losses along an urbanization gradient from Boston to Harvard Forest, MA. Biogeochemistry. 2014; 121: 229–245. https://doi.org/10.1007/s10533-013-9861-1
- View Article
- Google Scholar
7. Grimm NB, Foster D, Groffman P, Grove JM, Hopkinson CS, Nadelhoffer KJ, et al. The changing landscape: ecosystem responses to urbanization and pollution across climatic and societal gradients. Front Ecol Environ. 2008; 6(5): 264–272. https://doi.org/10.1890/070147
- View Article
- Google Scholar
8. Decina SM, Templer PH, Hutyra LR, Gately CK, Rao P. Variability, drivers, and effects of atmospheric nitrogen inputs across an urban area: emerging patterns among human activities, the atmosphere, and soils. Sci Total Environ. 2017; 609:1524–1534. https://doi.org/10.1016/j.scitotenv.2017.07.166 pmid:28800694
- View Article
- PubMed/NCBI
- Google Scholar
9. Cook EM, Sponseller R, Grimm NB, Hall SJ. Mixed method approach to assess atmospheric nitrogen deposition in arid and semi-arid ecosystems. Environ Pollut. 2018; 239: 617–30. https://doi.org/10.1016/j.envpol.2018.04.013 pmid:29705717
- View Article
- PubMed/NCBI
- Google Scholar
10. Borer ET, Grace JB, Harpole WS, MacDougall AS, Seabloom EW. A decade of insights into grassland ecosystem responses to global environmental change. Nat Ecol Evol. 2017; 1, 0118. https://doi.org/10.1038/s41559-017-0118 pmid:28812706
- View Article
- PubMed/NCBI
- Google Scholar
11. Bowman WD, Ayyad A, Bueno de Mesquita CP, Fierer N, Potter TS, Sternagel S. Limited ecosystem recovery from simulated chronic nitrogen deposition. Ecol Appl. 2018; 28(7), 1762–1772. https://doi.org/10.1002/eap.1783 pmid:30179279
- View Article
- PubMed/NCBI
- Google Scholar
12. Clark CM, Cleland EE, Collins SL, Fargione JE, Gough L, Gross KL, et al. Environmental and plant community determinants of species loss following nitrogen enrichment. Ecol Lett. 2007; 10: 596–607. https://doi.org/10.1111/j.1461-0248.2007.01053.x pmid:17542938
- View Article
- PubMed/NCBI
- Google Scholar
13. Reich PB, Tilman D, Craine J, Ellsworth D, Tjoelker MG, Knops J, et al. Do species and functional groups differ in acquisition and use of C, N and water under varying atmospheric CO₂ and N availability regimes? A field test with 16 grassland species. New Phytol. 2001; 150: 435–448. https://doi.org/10.1046/j.1469-8137.2001.00114.x
- View Article
- Google Scholar
14. Storkey J, Macdonald AJ, Poulton PR, Scott T, Köhler IH, Schnyder H, et al. Grassland biodiversity bounces back from long-term nitrogen addition. Nature. 2015; 528(7582), 401–404. https://doi.org/10.1038/nature16444 pmid:26633635
- View Article
- PubMed/NCBI
- Google Scholar
15. Wedin DA, Tilman D. Influence of nitrogen loading and species composition on the carbon balance of grasslands. Science. 1996; 274:1720–1723. https://doi.org/10.1126/science.274.5293.1720 pmid:8939865
- View Article
- PubMed/NCBI
- Google Scholar
16. Throop HL, Lerdau MT. Effects of nitrogen deposition on insect herbivory: implications for community and ecosystem processes. Ecosystems. 2004; 7(2), 109–133. https://doi.org/10.1007/s10021-003-0225-x
- View Article
- Google Scholar
17. Bejarano-Castillo M, Campo J, Roa-Fuentes LL. Effects of increased nitrogen availability on C and N cycles in tropical forests: a meta-analysis. PLoS ONE 10(12): e0144253. https://doi.org/10.1371/journal.pone.0144253 pmid:26633681
- View Article
- PubMed/NCBI
- Google Scholar
18. Clark CM, Simkin SM, Allen EB, Bowman WD, Belnap J, Brooks ML, et al. Potential vulnerability of 348 herbaceous species to atmospheric deposition of nitrogen and sulfur in the United States. Nat Plants. 2019; 5(7), 697–705. https://doi.org/10.1038/s41477-019-0442-8 pmid:31263243
- View Article
- PubMed/NCBI
- Google Scholar
19. Phoenix GK, Emmett BA, Britton AJ, Caporn SJ, Dise NB, Helliwell R, et al. Impacts of atmospheric nitrogen deposition: responses of multiple plant and soil parameters across contrasting ecosystems in long-term field experiments. Glob Change Biol. 2012; 18: 1197–1215. https://doi.org/10.1111/j.1365-2486.2011.02590.x
- View Article
- Google Scholar
20. Simkin SM, Allen EB, Bowman WD, Clark CM, Belnap J, Brooks ML, et al. Conditional vulnerability of plant diversity to atmospheric nitrogen deposition across the United States. P Natl Acad Sci USA. 2016; 113: 4086–4091. https://doi.org/10.1073/pnas.1515241113 pmid:27035943
- View Article
- PubMed/NCBI
- Google Scholar
21. Nilsson J. Critical loads for sulphur and nitrogen. In: Mathy P, editors. Air Pollution and Ecosystems. Dordrecht: Springer; 1988. pp. 85–91. https://doi.org/10.1007/978-94-009-4003-1_11
22. Bobbink R, Hicks K, Galloway J, Spranger T, Alkemade R, Ashmore M, et al. Global assessment of nitrogen deposition effects on terrestrial plant diversity: a synthesis. Ecol Appl. 2010; 20: 30–59. https://doi.org/10.1890/08-1140.1 pmid:20349829
- View Article
- PubMed/NCBI
- Google Scholar
23. Carreiro MM, Tripler CE. Forest remnants along urban-rural gradients: examining their potential for global change research. Ecosystems. 2005; 8(5), 568–582. https://doi.org/10.1007/s10021-003-0172-6
- View Article
- Google Scholar
24. Fang Y, Yoh M, Koba K, Zhu W, Takebayashi Y, Xiao Y, et al. Nitrogen deposition and forest nitrogen cycling along an urban-rural transect in southern China. Glob Change Biol. 2011; 17: 872–885. https://doi.org/10.1111/j.1365-2486.2010.02283.x
- View Article
- Google Scholar
25. Fenn ME, Baron JS, Allen EB, Rueth HM, Nydick KR, Geiser L, et al. Ecological effects of nitrogen deposition in the western United States. BioScience. 2003; 53(4), 404–420. https://doi.org/10.1641/0006-3568(2003)053[0404:EEONDI]2.0.CO;2
- View Article
- Google Scholar
26. Gregg JW, Jones CG, Dawson TE. Urbanization effects on tree growth in the vicinity of New York City. Nature. 2003; 424: 183–187. http://dx.doi.org/10.1038/nature01728 pmid:12853954
- View Article
- PubMed/NCBI
- Google Scholar
27. Ponette-González AG, Perroni Y, Weathers KC, de Souza PA, García-Oliva F, de Mello WZ. Nitrogen cycling in tropical Atlantic Forest differing in exposure to urban atmospheric nitrogen deposition. Plant Soil. 2017; 420: 451–465. https://doi.org/10.1007/s11104-017-3421-8
- View Article
- Google Scholar
28. Dass P, Houlton BZ, Wang Y, Warlind D. Grasslands may be more reliable carbon sinks than forests in California. Environ Res Letters. 2018; 13: 074027. https://doi.org/10.1088/1748-9326/aacb39
- View Article
- Google Scholar
29. Sala OE, Paruelo JM. Ecosystem services in grasslands. In: Daily GC, editor. Nature’s services: societal dependence on natural ecosystems. Washington DC: Island Press; 1997. pp 237–251
30. Smeins FE. Echoes of the Chisholm Trail: Texas: a biological crossroads. Rangelands. 2004; 26: 15–21. https://doi.org/10.2111/1551-501X(2004)026:5[0015:EOTCT]2.0.CO;2
- View Article
- Google Scholar
31. Vision North Texas [Internet]. Regional Choices for North Texas. 2008. http://www.visionnorthtexas.org
32. US Census Bureau. New Census Bureau Estimates Show Counties in South and West Lead Nation in Population Growth, Census Bureau Reports. Press release # CB19-55, 2019 https://www.census.gov/newsroom/press-releases/2019/estimates-county-metro.html.
33. National Weather Service. Dallas/Fort Worth–Normals (1981–2010), Means, and Extremes [Internet]. 2020. https://www.weather.gov/fwd/dfwann.
34. Zhao C, Jensen J, Weng Q, Currit N, Weaver R. Application of airborne remote sensing data on mapping local climate zones: Cases of three metropolitan areas of Texas, US. Comput Environ Urban Syst. 2019; 74, 175–193. https://doi.org/10.1016/j.compenvurbsys.2018.11.002
- View Article
- Google Scholar
35. Diggs GM, Lipscomb BL, O’Kennon RJ, Mahler WF, Shinners LH. Shinners’ and Mahler’s illustrated flora of North Central Texas. Botanical Research Institute of Texas; 1999.
36. Taylor J, Acevedo W, Auch R, Drummond M. Status and trends of land change in the Great Plains of the United States––1973 to 2000. US Geological Survey Professional Paper. 2015; 1794-B:180. http://dx.doi.org/10.3133/pp1794B
- View Article
- Google Scholar
37. Diamond DD, Smeins FE. Composition, classification and species response patterns of remnant tallgrass prairies in Texas. Am Midl Nat. 1985; 113(2); 294–308. https://doi.org/10.2307/2425575
- View Article
- Google Scholar
38. Dyksterhuis EJ. The vegetation of the Fort Worth prairie. Ecol Monogr. 1946; 16(1): 2–29.https://doi.org/10.2307/1943572
- View Article
- Google Scholar
39. Dewitz J. National Land Cover Database (NLCD) 2016 Products: U.S. Geological Survey data release, https://doi.org/10.5066/P96HHBIE
40. National Atmospheric Deposition Program. Madison (WI): National Trends Network. 2020a. http://nadp.slh.wisc.edu/data/NTN/ntnAllsites.aspx
41. Weather Underground. wunderground [Online] https://www.wunderground.com
42. Staelens J, De Schrijver A, Van Avermaet P, Genouw G, Verhoest N. A comparison of bulk and wet-only deposition at two adjacent sites in Melle (Belgium). Atmos Environ. 2005; 39(1): 7–15. https://doi.org/10.1016/j.atmosenv.2004.09.055
- View Article
- Google Scholar
43. Simkin SM, Lewis DN, Weathers KC, Lovett GM, Schwarz K. Determination of sulfate, nitrate, and chloride in throughfall using ion-exchange resins. Water Air Soil Poll. 2004; 153(1–4): 343–54. https://doi.org/10.1023/B:WATE.0000019958.59277.ed
- View Article
- Google Scholar
44. Fenn ME, Poth MA, Arbaugh MJ. A throughfall collection method using mixed bed ion exchange resin columns. Sci World J. 2002; 2:122–130 pmid:12806045
- View Article
- PubMed/NCBI
- Google Scholar
45. Fenn M, Blubaugh T, Alexander D, Jones D. Using Ion Exchange Resin Columns to Measure Throughfall and Bulk Deposition to Forests. 2006. USDA Forest Service, Pacific Southwest Research Station, Forest Fire Laboratory.
46. Fenn ME, Poth MA. Monitoring nitrogen deposition in throughfall using ion exchange resin columns: a field test in the San Bernardino Mountains. J Environ Qual. 2004; 33(6): 2007–2014. pmid:15537922
- View Article
- PubMed/NCBI
- Google Scholar
47. Clements FE, Goldsmith GW. The phytometer method in ecology: the plant and community as instruments. Washington: Carnegie Institution of Washington; 1924.
48. Tober D, Jensen N. Plant guide for little bluestem (Schizachyrium scoparium). USDA Natural Resources Conservation Service, Plant Materials Center, Bismarck, ND. 2013.
49. Leithead HL, Yarlett LL, Shiflett TN. 100 native forage grasses in 11 southern states. USDA SCS. Agriculture Handbook No. 1976; 389.
- View Article
- Google Scholar
50. Niu S, Liu W, Wan S. Different growth responses of C₃ and C₄ grasses to seasonal water and nitrogen regimes and competition in a pot experiment. J Exp Bot. 2008; 59: 1431–1439. https://doi.org/10.1093/jxb/ern051 pmid:18356144
- View Article
- PubMed/NCBI
- Google Scholar
51. SAS Institute Inc. JMP^®, Version 14 [software]. https://www.jmp.com/global-geo-redirects/geohome.html
52. Decina SM, Templer PH, Hutyra LR. Atmospheric inputs of nitrogen, carbon, and phosphorus across an urban area: unaccounted fluxes and canopy influences. Earth’s Future. 2018; 6: 134–148. http://doi.org/10.1002/eft2.282
- View Article
- Google Scholar
53. Ayars J, Gao Y. Atmospheric nitrogen deposition to the Mullica River-Great Bay estuary. Mar Environ Res. 2007; 64(5): 590–600. https://doi.org/10.1016/j.marenvres.2007.06.004 pmid:17714775
- View Article
- PubMed/NCBI
- Google Scholar
54. Lohse KA, Hope D, Sponseller R, Allen JO, Grimm NB. Atmospheric deposition of carbon and nutrients across an arid metropolitan area. Sci Total Environ. 2008; 402(1):95–105. https://doi.org/10.1016/j.scitotenv.2008.04.044 pmid:18550152
- View Article
- PubMed/NCBI
- Google Scholar
55. Tulloss EM, Cadenasso ML. Nitrogen deposition across scales: Hotspots and gradients in a California savanna landscape. Ecosphere. 2015; 6(9):1–2. https://doi.org/10.1890/ES14-00440.1
- View Article
- Google Scholar
56. Wetherbee GA, Benedict KB, Murphy SF, Elliott EM. Inorganic nitrogen wet deposition gradients in the Denver-Boulder metropolitan area and Colorado Front Range–Preliminary implications for Rocky Mountain National Park and interpolated deposition maps. Sci Total Environ. 2019; 691:1027–42. https://doi.org/10.1016/j.scitotenv.2019.06.528 pmid:31326795
- View Article
- PubMed/NCBI
- Google Scholar
57. Joyce EE, Walters WW, Le Roy E, Clark SC, Schiebel H, Hastings MG. Highly concentrated atmospheric inorganic nitrogen deposition in an urban, coastal region in the US. Environ Res Comm. 2020; 2(8): 081001. https://doi.org/10.1088/2515-7620/aba637
- View Article
- Google Scholar
58. Fenn ME, Bytnerowicz A, Schilling SL, Vallano DM, Zavaleta ES, Weiss SB, et al. On-road emissions of ammonia: an underappreciated source of atmospheric nitrogen deposition. Sci Total Environ. 2018. 625: 909–919. https://doi.org/10.1016/j.scitotenv.2017.12.313 pmid:29996462
- View Article
- PubMed/NCBI
- Google Scholar
59. Li Y, Schichtel BA, Walker JT, Schwede DB, Chen X, Lehmann CMB, et al. Increasing importance of deposition of reduced nitrogen in the United States. P Natl Acad Sci USA. 2016; 113: 5874–5879. http://doi.org/10.1073/pnas.1525736113 pmid:27162336
- View Article
- PubMed/NCBI
- Google Scholar
60. Heeb NV, Forss AM, Brühlmann S, Lüscher R, Saxer CJ, Hug P. Three-way catalyst-induced formation of ammonia—velocity-and acceleration-dependent emission factors. Atmos Environ. 2006; 40(31): 5986–97. https://doi.org/10.1016/j.atmosenv.2005.12.035
- View Article
- Google Scholar
61. Reche C, Viana M, Karanasiou A, Cusack M, Alastuey A, Artiñano B, et al. Urban NH₃ levels and sources in six major Spanish cities. Chemosphere. 2015; 119: 769–77. https://doi.org/10.1016/j.chemosphere.2014.07.097 pmid:25194477
- View Article
- PubMed/NCBI
- Google Scholar
62. US Department of Transportation. Transportation Statistics Annual Report. Washington DC: Bureau of Transportation Statistics. 2018. https://doi.org/10.21949/1502596153:343-354
63. US Department of Labor. Washington D.C.: Bureau of Labor Statistics. May 2019 National Industry-Specific Occupational Employment and Wage Estimates. 2019. https://www.bls.gov/oes/current/naics5_561730.htm
64. Bennett B, Hanselka D. The impact of agribusiness in the Dallas-Fort Worth Metroplex. Texas A&M AgriLife Extension, Texas A&M University System. 2013.
65. Schwede DB, Lear GG. A novel hybrid approach for estimating total deposition in the United States. Atmos Environ. 2014; 92: 207–20. https://doi.org/10.1016/j.atmosenv.2014.04.008
- View Article
- Google Scholar
66. National Atmospheric Deposition Program. Total Deposition Maps, v2018. 02. http://nadp.slh.wisc.edu/committees/tdep/tdepmaps/.
67. Cape JN, van Dijk N, Tang YS. Measurement of dry deposition to bulk precipitation collectors using a novel flushing sampler. J Environ Monitor. 2009; 11(2): 353–8. https://doi.org/10.1039/B813812E pmid:19212593
- View Article
- PubMed/NCBI
- Google Scholar
68. Fenn ME, Sickman JO, Bytnerowicz A, Clow DW, Molotch NP, Pleim JE, et al. Methods for measuring atmospheric nitrogen deposition inputs in arid and montane ecosystems of western North America. Dev Environ Sci. 2009; 9: 179–228. https://doi.org/10.1016/S1474-8177(08)00208-8
- View Article
- Google Scholar
69. Harrison RM. Urban atmospheric chemistry: A very special case for study. npj Clim Atmos Sci. 2018; 1(1): 1–5. https://doi.org/10.1038/s41612-017-0010-8
- View Article
- Google Scholar
70. Asman WA, Sutton MA, Schjørring JK. Ammonia: emission, atmospheric transport, and deposition. New Phytol. 1998; 139(1); 27–48. https://doi.org/10.1046/j.1469-8137.1998.00180.x
- View Article
- Google Scholar
71. Jacob DJ. Introduction to Atmospheric Chemistry. Princeton University Press; 1999 Dec 21.
72. Nelson DM, Tsunogai U, Ding D, Ohyama T, Komatsu DD, Nakagawa F, et al. Triple oxygen isotopes indicate urbanization affects sources of nitrate in wet and dry atmospheric deposition. Atmos Chem Phys. 2018; 18(9): 6381. https://doi.org/10.5194/acp-18-6381-2018
- View Article
- Google Scholar
73. Anderson TM, Griffith DM, Grace JB, Lind EM, Adler PB, Biederman LA, et al. Herbivory and eutrophication mediate grassland plant nutrient responses across a global climatic gradient. Ecology. 2018; 99(4): 822–31. https://doi.org/10.1002/ecy.2175 pmid:29603733
- View Article
- PubMed/NCBI
- Google Scholar
74. Fay PA, Prober SM, Harpole WS, Knops JM, Bakker JD, Borer ET, et al. Grassland productivity limited by multiple nutrients. Nature Plants. 2015; 1(7): 1–5. https://doi.org/10.1038/nplants.2015.80 pmid:27250253
- View Article
- PubMed/NCBI
- Google Scholar
75. Stevens CJ, Lind EM, Hautier Y, Harpole WS, Borer ET, Hobbie S, et al. Anthropogenic nitrogen deposition predicts local grassland primary production worldwide. Ecology. 2015; 96(6): 1459–1465. https://doi.org/10.1890/14-1902.1
- View Article
- Google Scholar
76. Clark CM, Tilman D. Loss of plant species after chronic low-level nitrogen deposition to prairie grasslands. Nature. 2008; 451(7179): 712–5. https://doi.org/10.1038/nature06503 pmid:18256670
- View Article
- PubMed/NCBI
- Google Scholar
77. Pardo LH, Fenn ME, Goodale CL, Geiser LH, Driscoll CT, Allen EB, et al. Effects of nitrogen deposition and empirical nitrogen critical loads for ecoregions of the United States. Ecol Appl. 2011; 21(8): 3049–3082.
- View Article
- Google Scholar
78. Tilman D, Wedin D. Plant traits and resource reduction for five grasses growing on a nitrogen gradient. Ecology. 1991; 72(2): 685–700. https://doi.org/10.2307/2937208
- View Article
- Google Scholar
79. Wedin DA, Tilman D. Nitrogen cycling, plant competition, and the stability of tallgrass prairie. Proceedings of the Twelfth North American Prairie Conference; 1992; Cedar Falls, Iowa. Iowa: University of Northern Iowa Press.
80. Lane DR, BassiriRad H. Differential responses of tallgrass prairie species to nitrogen loading and varying ratios of NO3– to NH4+. Funct Plant Biol. 2002; 29(10): 1227–35. https://doi.org/10.1071/PP01225 pmid:32689575
- View Article
- PubMed/NCBI
- Google Scholar
81. White JJ, Auken OV. Germination, light requirements, and competitive interactions of Stipa leucotricha (Gramineae). Southwest Nat. 1996; 41(1), 27–34. https://www.jstor.org/stable/30054437
- View Article
- Google Scholar
82. Bharath S, Borer ET, Biederman LA, Blumenthal DM, Fay PA, Gherardi LA, et al. Nutrient addition increases grassland sensitivity to droughts. Ecology. 2020; 101(5): e02981. https://doi.org/10.1002/ecy.2981 pmid:31960948
- View Article
- PubMed/NCBI
- Google Scholar
83. La Pierre KJ, Blumenthal DM, Brown CS, Klein JA, Smith MD. Drivers of variation in aboveground net primary productivity and plant community composition differ across a broad precipitation gradient. Ecosystems. 2016; 19(3): 521–33. https://doi.org/10.1007/s10021-015-9949-7
- View Article
- Google Scholar

[ref1] 1. Carnelos DA., Portela SI, Jobbágy EG, Jackson RB, Di Bella CM, Panario D, et al. A first record of bulk atmospheric deposition patterns of major ions in southern South America. Biogeochemistry. 2019; 144: 261–271. https://doi.org/10.1007/s10533-019-00584-3
View Article
Google Scholar

[2] View Article

[3] Google Scholar

[ref2] 2. de Souza PA, Ponette-González AG, de Mello WZ, Weathers KC, Santos IA. Atmospheric organic and inorganic nitrogen inputs to coastal urban and montane Atlantic Forest sites in southeastern Brazil. Atmos Res. 2015; 160(15): 126–137. https://doi.org/10.1016/j.atmosres.2015.03.011
View Article
Google Scholar

[5] View Article

[6] Google Scholar

[ref3] 3. Decina SM, Hutyra LR, Templer PH. Hotspots of nitrogen deposition in the world’s urban areas: a global data synthesis. Front Ecol Environ. 2020; 18(2), 92–100. https://doi.org/10.1002/fee.2143
View Article
Google Scholar

[8] View Article

[9] Google Scholar

[ref4] 4. Du E, De Vries W, Liu X, Fang J, Galloway JN, Jiang Y. Spatial boundary of urban ‘acid islands’ in southern China. Sci Rep-UK. 2015; 5, 12625. https://doi.org/10.1038/srep12625 pmid:26211880
View Article
PubMed/NCBI
Google Scholar

[11] View Article

[12] PubMed/NCBI

[13] Google Scholar

[ref5] 5. Ponette-González AG, Weathers KC, Curran LM. Tropical land‐cover change alters biogeochemical inputs to ecosystems in a Mexican montane landscape. Ecol Appl. 2010; 20(7), 1820–1837. https://doi.org/10.1890/09-1125.1 pmid:21049872
View Article
PubMed/NCBI
Google Scholar

[15] View Article

[16] PubMed/NCBI

[17] Google Scholar

[ref6] 6. Rao P, Hutyra LR, Raciti SM, Templer PH. Atmospheric nitrogen inputs and losses along an urbanization gradient from Boston to Harvard Forest, MA. Biogeochemistry. 2014; 121: 229–245. https://doi.org/10.1007/s10533-013-9861-1
View Article
Google Scholar

[19] View Article

[20] Google Scholar

[ref7] 7. Grimm NB, Foster D, Groffman P, Grove JM, Hopkinson CS, Nadelhoffer KJ, et al. The changing landscape: ecosystem responses to urbanization and pollution across climatic and societal gradients. Front Ecol Environ. 2008; 6(5): 264–272. https://doi.org/10.1890/070147
View Article
Google Scholar

[22] View Article

[23] Google Scholar

[ref8] 8. Decina SM, Templer PH, Hutyra LR, Gately CK, Rao P. Variability, drivers, and effects of atmospheric nitrogen inputs across an urban area: emerging patterns among human activities, the atmosphere, and soils. Sci Total Environ. 2017; 609:1524–1534. https://doi.org/10.1016/j.scitotenv.2017.07.166 pmid:28800694
View Article
PubMed/NCBI
Google Scholar

[25] View Article

[26] PubMed/NCBI

[27] Google Scholar

[ref9] 9. Cook EM, Sponseller R, Grimm NB, Hall SJ. Mixed method approach to assess atmospheric nitrogen deposition in arid and semi-arid ecosystems. Environ Pollut. 2018; 239: 617–30. https://doi.org/10.1016/j.envpol.2018.04.013 pmid:29705717
View Article
PubMed/NCBI
Google Scholar

[29] View Article

[30] PubMed/NCBI

[31] Google Scholar

[ref10] 10. Borer ET, Grace JB, Harpole WS, MacDougall AS, Seabloom EW. A decade of insights into grassland ecosystem responses to global environmental change. Nat Ecol Evol. 2017; 1, 0118. https://doi.org/10.1038/s41559-017-0118 pmid:28812706
View Article
PubMed/NCBI
Google Scholar

[33] View Article

[34] PubMed/NCBI

[35] Google Scholar

[ref11] 11. Bowman WD, Ayyad A, Bueno de Mesquita CP, Fierer N, Potter TS, Sternagel S. Limited ecosystem recovery from simulated chronic nitrogen deposition. Ecol Appl. 2018; 28(7), 1762–1772. https://doi.org/10.1002/eap.1783 pmid:30179279
View Article
PubMed/NCBI
Google Scholar

[37] View Article

[38] PubMed/NCBI

[39] Google Scholar

[ref12] 12. Clark CM, Cleland EE, Collins SL, Fargione JE, Gough L, Gross KL, et al. Environmental and plant community determinants of species loss following nitrogen enrichment. Ecol Lett. 2007; 10: 596–607. https://doi.org/10.1111/j.1461-0248.2007.01053.x pmid:17542938
View Article
PubMed/NCBI
Google Scholar

[41] View Article

[42] PubMed/NCBI

[43] Google Scholar

[ref13] 13. Reich PB, Tilman D, Craine J, Ellsworth D, Tjoelker MG, Knops J, et al. Do species and functional groups differ in acquisition and use of C, N and water under varying atmospheric CO₂ and N availability regimes? A field test with 16 grassland species. New Phytol. 2001; 150: 435–448. https://doi.org/10.1046/j.1469-8137.2001.00114.x
View Article
Google Scholar

[45] View Article

[46] Google Scholar

[ref14] 14. Storkey J, Macdonald AJ, Poulton PR, Scott T, Köhler IH, Schnyder H, et al. Grassland biodiversity bounces back from long-term nitrogen addition. Nature. 2015; 528(7582), 401–404. https://doi.org/10.1038/nature16444 pmid:26633635
View Article
PubMed/NCBI
Google Scholar

[48] View Article

[49] PubMed/NCBI

[50] Google Scholar

[ref15] 15. Wedin DA, Tilman D. Influence of nitrogen loading and species composition on the carbon balance of grasslands. Science. 1996; 274:1720–1723. https://doi.org/10.1126/science.274.5293.1720 pmid:8939865
View Article
PubMed/NCBI
Google Scholar

[52] View Article

[53] PubMed/NCBI

[54] Google Scholar

[ref16] 16. Throop HL, Lerdau MT. Effects of nitrogen deposition on insect herbivory: implications for community and ecosystem processes. Ecosystems. 2004; 7(2), 109–133. https://doi.org/10.1007/s10021-003-0225-x
View Article
Google Scholar

[56] View Article

[57] Google Scholar

[ref17] 17. Bejarano-Castillo M, Campo J, Roa-Fuentes LL. Effects of increased nitrogen availability on C and N cycles in tropical forests: a meta-analysis. PLoS ONE 10(12): e0144253. https://doi.org/10.1371/journal.pone.0144253 pmid:26633681
View Article
PubMed/NCBI
Google Scholar

[59] View Article

[60] PubMed/NCBI

[61] Google Scholar

[ref18] 18. Clark CM, Simkin SM, Allen EB, Bowman WD, Belnap J, Brooks ML, et al. Potential vulnerability of 348 herbaceous species to atmospheric deposition of nitrogen and sulfur in the United States. Nat Plants. 2019; 5(7), 697–705. https://doi.org/10.1038/s41477-019-0442-8 pmid:31263243
View Article
PubMed/NCBI
Google Scholar

[63] View Article

[64] PubMed/NCBI

[65] Google Scholar

[ref19] 19. Phoenix GK, Emmett BA, Britton AJ, Caporn SJ, Dise NB, Helliwell R, et al. Impacts of atmospheric nitrogen deposition: responses of multiple plant and soil parameters across contrasting ecosystems in long-term field experiments. Glob Change Biol. 2012; 18: 1197–1215. https://doi.org/10.1111/j.1365-2486.2011.02590.x
View Article
Google Scholar

[67] View Article

[68] Google Scholar

[ref20] 20. Simkin SM, Allen EB, Bowman WD, Clark CM, Belnap J, Brooks ML, et al. Conditional vulnerability of plant diversity to atmospheric nitrogen deposition across the United States. P Natl Acad Sci USA. 2016; 113: 4086–4091. https://doi.org/10.1073/pnas.1515241113 pmid:27035943
View Article
PubMed/NCBI
Google Scholar

[70] View Article

[71] PubMed/NCBI

[72] Google Scholar

[ref21] 21. Nilsson J. Critical loads for sulphur and nitrogen. In: Mathy P, editors. Air Pollution and Ecosystems. Dordrecht: Springer; 1988. pp. 85–91. https://doi.org/10.1007/978-94-009-4003-1_11

[ref22] 22. Bobbink R, Hicks K, Galloway J, Spranger T, Alkemade R, Ashmore M, et al. Global assessment of nitrogen deposition effects on terrestrial plant diversity: a synthesis. Ecol Appl. 2010; 20: 30–59. https://doi.org/10.1890/08-1140.1 pmid:20349829
View Article
PubMed/NCBI
Google Scholar

[75] View Article

[76] PubMed/NCBI

[77] Google Scholar

[ref23] 23. Carreiro MM, Tripler CE. Forest remnants along urban-rural gradients: examining their potential for global change research. Ecosystems. 2005; 8(5), 568–582. https://doi.org/10.1007/s10021-003-0172-6
View Article
Google Scholar

[79] View Article

[80] Google Scholar

[ref24] 24. Fang Y, Yoh M, Koba K, Zhu W, Takebayashi Y, Xiao Y, et al. Nitrogen deposition and forest nitrogen cycling along an urban-rural transect in southern China. Glob Change Biol. 2011; 17: 872–885. https://doi.org/10.1111/j.1365-2486.2010.02283.x
View Article
Google Scholar

[82] View Article

[83] Google Scholar

[ref25] 25. Fenn ME, Baron JS, Allen EB, Rueth HM, Nydick KR, Geiser L, et al. Ecological effects of nitrogen deposition in the western United States. BioScience. 2003; 53(4), 404–420. https://doi.org/10.1641/0006-3568(2003)053[0404:EEONDI]2.0.CO;2
View Article
Google Scholar

[85] View Article

[86] Google Scholar

[ref26] 26. Gregg JW, Jones CG, Dawson TE. Urbanization effects on tree growth in the vicinity of New York City. Nature. 2003; 424: 183–187. http://dx.doi.org/10.1038/nature01728 pmid:12853954
View Article
PubMed/NCBI
Google Scholar

[88] View Article

[89] PubMed/NCBI

[90] Google Scholar

[ref27] 27. Ponette-González AG, Perroni Y, Weathers KC, de Souza PA, García-Oliva F, de Mello WZ. Nitrogen cycling in tropical Atlantic Forest differing in exposure to urban atmospheric nitrogen deposition. Plant Soil. 2017; 420: 451–465. https://doi.org/10.1007/s11104-017-3421-8
View Article
Google Scholar

[92] View Article

[93] Google Scholar

[ref28] 28. Dass P, Houlton BZ, Wang Y, Warlind D. Grasslands may be more reliable carbon sinks than forests in California. Environ Res Letters. 2018; 13: 074027. https://doi.org/10.1088/1748-9326/aacb39
View Article
Google Scholar

[95] View Article

[96] Google Scholar

[ref29] 29. Sala OE, Paruelo JM. Ecosystem services in grasslands. In: Daily GC, editor. Nature’s services: societal dependence on natural ecosystems. Washington DC: Island Press; 1997. pp 237–251

[ref30] 30. Smeins FE. Echoes of the Chisholm Trail: Texas: a biological crossroads. Rangelands. 2004; 26: 15–21. https://doi.org/10.2111/1551-501X(2004)026:5[0015:EOTCT]2.0.CO;2
View Article
Google Scholar

[99] View Article

[100] Google Scholar

[ref31] 31. Vision North Texas [Internet]. Regional Choices for North Texas. 2008. http://www.visionnorthtexas.org

[ref32] 32. US Census Bureau. New Census Bureau Estimates Show Counties in South and West Lead Nation in Population Growth, Census Bureau Reports. Press release # CB19-55, 2019 https://www.census.gov/newsroom/press-releases/2019/estimates-county-metro.html.

[ref33] 33. National Weather Service. Dallas/Fort Worth–Normals (1981–2010), Means, and Extremes [Internet]. 2020. https://www.weather.gov/fwd/dfwann.

[ref34] 34. Zhao C, Jensen J, Weng Q, Currit N, Weaver R. Application of airborne remote sensing data on mapping local climate zones: Cases of three metropolitan areas of Texas, US. Comput Environ Urban Syst. 2019; 74, 175–193. https://doi.org/10.1016/j.compenvurbsys.2018.11.002
View Article
Google Scholar

[105] View Article

[106] Google Scholar

[ref35] 35. Diggs GM, Lipscomb BL, O’Kennon RJ, Mahler WF, Shinners LH. Shinners’ and Mahler’s illustrated flora of North Central Texas. Botanical Research Institute of Texas; 1999.

[ref36] 36. Taylor J, Acevedo W, Auch R, Drummond M. Status and trends of land change in the Great Plains of the United States––1973 to 2000. US Geological Survey Professional Paper. 2015; 1794-B:180. http://dx.doi.org/10.3133/pp1794B
View Article
Google Scholar

[109] View Article

[110] Google Scholar

[ref37] 37. Diamond DD, Smeins FE. Composition, classification and species response patterns of remnant tallgrass prairies in Texas. Am Midl Nat. 1985; 113(2); 294–308. https://doi.org/10.2307/2425575
View Article
Google Scholar

[112] View Article

[113] Google Scholar

[ref38] 38. Dyksterhuis EJ. The vegetation of the Fort Worth prairie. Ecol Monogr. 1946; 16(1): 2–29.https://doi.org/10.2307/1943572
View Article
Google Scholar

[115] View Article

[116] Google Scholar

[ref39] 39. Dewitz J. National Land Cover Database (NLCD) 2016 Products: U.S. Geological Survey data release, https://doi.org/10.5066/P96HHBIE

[ref40] 40. National Atmospheric Deposition Program. Madison (WI): National Trends Network. 2020a. http://nadp.slh.wisc.edu/data/NTN/ntnAllsites.aspx

[ref41] 41. Weather Underground. wunderground [Online] https://www.wunderground.com

[ref42] 42. Staelens J, De Schrijver A, Van Avermaet P, Genouw G, Verhoest N. A comparison of bulk and wet-only deposition at two adjacent sites in Melle (Belgium). Atmos Environ. 2005; 39(1): 7–15. https://doi.org/10.1016/j.atmosenv.2004.09.055
View Article
Google Scholar

[121] View Article

[122] Google Scholar

[ref43] 43. Simkin SM, Lewis DN, Weathers KC, Lovett GM, Schwarz K. Determination of sulfate, nitrate, and chloride in throughfall using ion-exchange resins. Water Air Soil Poll. 2004; 153(1–4): 343–54. https://doi.org/10.1023/B:WATE.0000019958.59277.ed
View Article
Google Scholar

[124] View Article

[125] Google Scholar

[ref44] 44. Fenn ME, Poth MA, Arbaugh MJ. A throughfall collection method using mixed bed ion exchange resin columns. Sci World J. 2002; 2:122–130 pmid:12806045
View Article
PubMed/NCBI
Google Scholar

[127] View Article

[128] PubMed/NCBI

[129] Google Scholar

[ref45] 45. Fenn M, Blubaugh T, Alexander D, Jones D. Using Ion Exchange Resin Columns to Measure Throughfall and Bulk Deposition to Forests. 2006. USDA Forest Service, Pacific Southwest Research Station, Forest Fire Laboratory.

[ref46] 46. Fenn ME, Poth MA. Monitoring nitrogen deposition in throughfall using ion exchange resin columns: a field test in the San Bernardino Mountains. J Environ Qual. 2004; 33(6): 2007–2014. pmid:15537922
View Article
PubMed/NCBI
Google Scholar

[132] View Article

[133] PubMed/NCBI

[134] Google Scholar

[ref47] 47. Clements FE, Goldsmith GW. The phytometer method in ecology: the plant and community as instruments. Washington: Carnegie Institution of Washington; 1924.

[ref48] 48. Tober D, Jensen N. Plant guide for little bluestem (Schizachyrium scoparium). USDA Natural Resources Conservation Service, Plant Materials Center, Bismarck, ND. 2013.

[ref49] 49. Leithead HL, Yarlett LL, Shiflett TN. 100 native forage grasses in 11 southern states. USDA SCS. Agriculture Handbook No. 1976; 389.
View Article
Google Scholar

[138] View Article

[139] Google Scholar

[ref50] 50. Niu S, Liu W, Wan S. Different growth responses of C₃ and C₄ grasses to seasonal water and nitrogen regimes and competition in a pot experiment. J Exp Bot. 2008; 59: 1431–1439. https://doi.org/10.1093/jxb/ern051 pmid:18356144
View Article
PubMed/NCBI
Google Scholar

[141] View Article

[142] PubMed/NCBI

[143] Google Scholar

[ref51] 51. SAS Institute Inc. JMP^®, Version 14 [software]. https://www.jmp.com/global-geo-redirects/geohome.html

[ref52] 52. Decina SM, Templer PH, Hutyra LR. Atmospheric inputs of nitrogen, carbon, and phosphorus across an urban area: unaccounted fluxes and canopy influences. Earth’s Future. 2018; 6: 134–148. http://doi.org/10.1002/eft2.282
View Article
Google Scholar

[146] View Article

[147] Google Scholar

[ref53] 53. Ayars J, Gao Y. Atmospheric nitrogen deposition to the Mullica River-Great Bay estuary. Mar Environ Res. 2007; 64(5): 590–600. https://doi.org/10.1016/j.marenvres.2007.06.004 pmid:17714775
View Article
PubMed/NCBI
Google Scholar

[149] View Article

[150] PubMed/NCBI

[151] Google Scholar

[ref54] 54. Lohse KA, Hope D, Sponseller R, Allen JO, Grimm NB. Atmospheric deposition of carbon and nutrients across an arid metropolitan area. Sci Total Environ. 2008; 402(1):95–105. https://doi.org/10.1016/j.scitotenv.2008.04.044 pmid:18550152
View Article
PubMed/NCBI
Google Scholar

[153] View Article

[154] PubMed/NCBI

[155] Google Scholar

[ref55] 55. Tulloss EM, Cadenasso ML. Nitrogen deposition across scales: Hotspots and gradients in a California savanna landscape. Ecosphere. 2015; 6(9):1–2. https://doi.org/10.1890/ES14-00440.1
View Article
Google Scholar

[157] View Article

[158] Google Scholar

[ref56] 56. Wetherbee GA, Benedict KB, Murphy SF, Elliott EM. Inorganic nitrogen wet deposition gradients in the Denver-Boulder metropolitan area and Colorado Front Range–Preliminary implications for Rocky Mountain National Park and interpolated deposition maps. Sci Total Environ. 2019; 691:1027–42. https://doi.org/10.1016/j.scitotenv.2019.06.528 pmid:31326795
View Article
PubMed/NCBI
Google Scholar

[160] View Article

[161] PubMed/NCBI

[162] Google Scholar

[ref57] 57. Joyce EE, Walters WW, Le Roy E, Clark SC, Schiebel H, Hastings MG. Highly concentrated atmospheric inorganic nitrogen deposition in an urban, coastal region in the US. Environ Res Comm. 2020; 2(8): 081001. https://doi.org/10.1088/2515-7620/aba637
View Article
Google Scholar

[164] View Article

[165] Google Scholar

[ref58] 58. Fenn ME, Bytnerowicz A, Schilling SL, Vallano DM, Zavaleta ES, Weiss SB, et al. On-road emissions of ammonia: an underappreciated source of atmospheric nitrogen deposition. Sci Total Environ. 2018. 625: 909–919. https://doi.org/10.1016/j.scitotenv.2017.12.313 pmid:29996462
View Article
PubMed/NCBI
Google Scholar

[167] View Article

[168] PubMed/NCBI

[169] Google Scholar

[ref59] 59. Li Y, Schichtel BA, Walker JT, Schwede DB, Chen X, Lehmann CMB, et al. Increasing importance of deposition of reduced nitrogen in the United States. P Natl Acad Sci USA. 2016; 113: 5874–5879. http://doi.org/10.1073/pnas.1525736113 pmid:27162336
View Article
PubMed/NCBI
Google Scholar

[171] View Article

[172] PubMed/NCBI

[173] Google Scholar

[ref60] 60. Heeb NV, Forss AM, Brühlmann S, Lüscher R, Saxer CJ, Hug P. Three-way catalyst-induced formation of ammonia—velocity-and acceleration-dependent emission factors. Atmos Environ. 2006; 40(31): 5986–97. https://doi.org/10.1016/j.atmosenv.2005.12.035
View Article
Google Scholar

[175] View Article

[176] Google Scholar

[ref61] 61. Reche C, Viana M, Karanasiou A, Cusack M, Alastuey A, Artiñano B, et al. Urban NH₃ levels and sources in six major Spanish cities. Chemosphere. 2015; 119: 769–77. https://doi.org/10.1016/j.chemosphere.2014.07.097 pmid:25194477
View Article
PubMed/NCBI
Google Scholar

[178] View Article

[179] PubMed/NCBI

[180] Google Scholar

[ref62] 62. US Department of Transportation. Transportation Statistics Annual Report. Washington DC: Bureau of Transportation Statistics. 2018. https://doi.org/10.21949/1502596153:343-354

[ref63] 63. US Department of Labor. Washington D.C.: Bureau of Labor Statistics. May 2019 National Industry-Specific Occupational Employment and Wage Estimates. 2019. https://www.bls.gov/oes/current/naics5_561730.htm

[ref64] 64. Bennett B, Hanselka D. The impact of agribusiness in the Dallas-Fort Worth Metroplex. Texas A&M AgriLife Extension, Texas A&M University System. 2013.

[ref65] 65. Schwede DB, Lear GG. A novel hybrid approach for estimating total deposition in the United States. Atmos Environ. 2014; 92: 207–20. https://doi.org/10.1016/j.atmosenv.2014.04.008
View Article
Google Scholar

[185] View Article

[186] Google Scholar

[ref66] 66. National Atmospheric Deposition Program. Total Deposition Maps, v2018. 02. http://nadp.slh.wisc.edu/committees/tdep/tdepmaps/.

[ref67] 67. Cape JN, van Dijk N, Tang YS. Measurement of dry deposition to bulk precipitation collectors using a novel flushing sampler. J Environ Monitor. 2009; 11(2): 353–8. https://doi.org/10.1039/B813812E pmid:19212593
View Article
PubMed/NCBI
Google Scholar

[189] View Article

[190] PubMed/NCBI

[191] Google Scholar

[ref68] 68. Fenn ME, Sickman JO, Bytnerowicz A, Clow DW, Molotch NP, Pleim JE, et al. Methods for measuring atmospheric nitrogen deposition inputs in arid and montane ecosystems of western North America. Dev Environ Sci. 2009; 9: 179–228. https://doi.org/10.1016/S1474-8177(08)00208-8
View Article
Google Scholar

[193] View Article

[194] Google Scholar

[ref69] 69. Harrison RM. Urban atmospheric chemistry: A very special case for study. npj Clim Atmos Sci. 2018; 1(1): 1–5. https://doi.org/10.1038/s41612-017-0010-8
View Article
Google Scholar

[196] View Article

[197] Google Scholar

[ref70] 70. Asman WA, Sutton MA, Schjørring JK. Ammonia: emission, atmospheric transport, and deposition. New Phytol. 1998; 139(1); 27–48. https://doi.org/10.1046/j.1469-8137.1998.00180.x
View Article
Google Scholar

[199] View Article

[200] Google Scholar

[ref71] 71. Jacob DJ. Introduction to Atmospheric Chemistry. Princeton University Press; 1999 Dec 21.

[ref72] 72. Nelson DM, Tsunogai U, Ding D, Ohyama T, Komatsu DD, Nakagawa F, et al. Triple oxygen isotopes indicate urbanization affects sources of nitrate in wet and dry atmospheric deposition. Atmos Chem Phys. 2018; 18(9): 6381. https://doi.org/10.5194/acp-18-6381-2018
View Article
Google Scholar

[203] View Article

[204] Google Scholar

[ref73] 73. Anderson TM, Griffith DM, Grace JB, Lind EM, Adler PB, Biederman LA, et al. Herbivory and eutrophication mediate grassland plant nutrient responses across a global climatic gradient. Ecology. 2018; 99(4): 822–31. https://doi.org/10.1002/ecy.2175 pmid:29603733
View Article
PubMed/NCBI
Google Scholar

[206] View Article

[207] PubMed/NCBI

[208] Google Scholar

[ref74] 74. Fay PA, Prober SM, Harpole WS, Knops JM, Bakker JD, Borer ET, et al. Grassland productivity limited by multiple nutrients. Nature Plants. 2015; 1(7): 1–5. https://doi.org/10.1038/nplants.2015.80 pmid:27250253
View Article
PubMed/NCBI
Google Scholar

[210] View Article

[211] PubMed/NCBI

[212] Google Scholar

[ref75] 75. Stevens CJ, Lind EM, Hautier Y, Harpole WS, Borer ET, Hobbie S, et al. Anthropogenic nitrogen deposition predicts local grassland primary production worldwide. Ecology. 2015; 96(6): 1459–1465. https://doi.org/10.1890/14-1902.1
View Article
Google Scholar

[214] View Article

[215] Google Scholar

[ref76] 76. Clark CM, Tilman D. Loss of plant species after chronic low-level nitrogen deposition to prairie grasslands. Nature. 2008; 451(7179): 712–5. https://doi.org/10.1038/nature06503 pmid:18256670
View Article
PubMed/NCBI
Google Scholar

[217] View Article

[218] PubMed/NCBI

[219] Google Scholar

[ref77] 77. Pardo LH, Fenn ME, Goodale CL, Geiser LH, Driscoll CT, Allen EB, et al. Effects of nitrogen deposition and empirical nitrogen critical loads for ecoregions of the United States. Ecol Appl. 2011; 21(8): 3049–3082.
View Article
Google Scholar

[221] View Article

[222] Google Scholar

[ref78] 78. Tilman D, Wedin D. Plant traits and resource reduction for five grasses growing on a nitrogen gradient. Ecology. 1991; 72(2): 685–700. https://doi.org/10.2307/2937208
View Article
Google Scholar

[224] View Article

[225] Google Scholar

[ref79] 79. Wedin DA, Tilman D. Nitrogen cycling, plant competition, and the stability of tallgrass prairie. Proceedings of the Twelfth North American Prairie Conference; 1992; Cedar Falls, Iowa. Iowa: University of Northern Iowa Press.

[ref80] 80. Lane DR, BassiriRad H. Differential responses of tallgrass prairie species to nitrogen loading and varying ratios of NO3– to NH4+. Funct Plant Biol. 2002; 29(10): 1227–35. https://doi.org/10.1071/PP01225 pmid:32689575
View Article
PubMed/NCBI
Google Scholar

[228] View Article

[229] PubMed/NCBI

[230] Google Scholar

[ref81] 81. White JJ, Auken OV. Germination, light requirements, and competitive interactions of Stipa leucotricha (Gramineae). Southwest Nat. 1996; 41(1), 27–34. https://www.jstor.org/stable/30054437
View Article
Google Scholar

[232] View Article

[233] Google Scholar

[ref82] 82. Bharath S, Borer ET, Biederman LA, Blumenthal DM, Fay PA, Gherardi LA, et al. Nutrient addition increases grassland sensitivity to droughts. Ecology. 2020; 101(5): e02981. https://doi.org/10.1002/ecy.2981 pmid:31960948
View Article
PubMed/NCBI
Google Scholar

[235] View Article

[236] PubMed/NCBI

[237] Google Scholar

[ref83] 83. La Pierre KJ, Blumenthal DM, Brown CS, Klein JA, Smith MD. Drivers of variation in aboveground net primary productivity and plant community composition differ across a broad precipitation gradient. Ecosystems. 2016; 19(3): 521–33. https://doi.org/10.1007/s10021-015-9949-7
View Article
Google Scholar

[239] View Article

[240] Google Scholar

Figures

Abstract

Introduction

Materials and methods

Urban development and tallgrass prairie in Dallas-Fort Worth

Site selection

Nitrogen deposition measurements

Calculation of bulk deposition

Phytometer experiment

Statistical analyses

Results

Nitrogen deposition along an urban development gradient

Little bluestem and Texas wintergrass plant traits

Prairie grass responses to nitrogen deposition

Discussion

Nitrogen deposition in Dallas-Fort Worth: Magnitude, seasonality, and form

Urban development effects on N deposition

Prairie grass responses to N deposition

Implications for native prairie grass species

Supporting information

S1 Table. Results of regression analyses, including regression coefficient, standard error, p-values, and goodness of fit.

S2 Table. Results of regression analyses, including regression coefficient, standard error, p-values, and goodness of fit.

S1 Text. Estimates of the potential range of cation plus anion loading.

S1 Fig. Nitrogen deposition rates per collection period for both samplers at each of the six urban sites sampled in the Dallas-Fort Worth metropolitan area from April 2014 to October 2015.

Acknowledgments

References