Understanding the array of financial and non-financial decision-making drivers of private landowners with vulnerable cropland for enrolling in the United States Department of Agriculture’s Conservation Reserve Program (CRP) is critical for the success and cost-effectiveness of agricultural policies that aim to create long-term agri-environmental security. Following the underpinnings of the Theory of Planned Behavior, we used Structural Equation Modeling to test the predictive validity and impacts of socio-cognitive variables: attitude, subjective norm, and perceived behavioral control, on landowners’ intent to enroll in CRP. We analyzed mailed survey data of landowners in the western High Plains of the United States, where irrigated agriculture is a major economic activity, and cropland consists of vulnerable wetlands that play a role in recharging the Ogallala Aquifer. Overall, landowners had a positive attitude towards the wetland conservation benefits of CRP enrollment and its benefits of preventing soil erosion and sedimentation. In addition, attitudes, subjective norms, and perceived behavior controls positively influenced landowners’ intentions to (re)enroll in CRP. Among the three predictors, subjective norms had the largest influence. Landowners’ understanding of CRP benefits in improving water quality and availability, and opinions from their neighbors and other landowners were the most significant measured variables affecting their intention to enroll. For enhanced outreach and long-term success, we suggest that policymakers recognize and respond to a range of non-financial motivations to better design programs that represent the conservation benefits of wetlands to leverage their willingness to participate. Furthermore, (re)enrollment acres could be enhanced by understanding local barriers related to landowners’ skills and knowledge and fostering collaboration and coordination among different federal conservation programs in the region.

In 2016, the annual value of all global crops dependent upon pollination was valued at $ 235–$ 577 billion (US$). Pollination service is threatened by habitat loss, pesticides, and climate change. We collected potential pollinators with blue vane traps in native grasslands, Conservation Reserve Program (CRP) lands, and cropland (land use), and their embedded playa wetlands (land type) in the Southern High Plains of Texas (SHP). We collected vegetation data that included floral cover, floral diversity, native grass cover, introduced grass cover, canopy gap, and duff cover. Our objective was to determine if individual vegetation characteristics influenced potential pollinator abundance and richness in addition to land use or land type as a whole. The top model explaining abundance was land use, land type, and floral cover. Floral cover had a positive influence on all land uses. The top model that explained insect richness was land use x floral cover, land type, canopy gap, and duff cover. Floral cover positively influenced insect richness in native grasslands but negatively influenced cropland and CRP richness. Percent of canopy gap had a slight negative influence on insect richness, and duff cover positively influenced richness. Our recommendations to land managers are to protect playas to preserve undisturbed areas and native floral resources and seed all future CRP contracts with floral rich plantings to provide for pollinators over the entire growing season. Our results show that vegetation characteristics shared by all land uses such as floral cover, canopy gap and duff cover influence pollinator abundance and richness. Therefore, conserving playa wetlands and programs such as the CRP have the potential for enhancing pollinator habitat in working landscapes of the SHP of Texas.

Habitat management efforts for multiple species with contrasting habitat requirements can be challenging, particularly on small landscapes where large-scale heterogeneity may not be a viable solution. We sought to utilize derivative functions from species-response curves to identify thresholds along an environmental gradient for two species with differing responses to juniper cover. We estimated percentages of one-seed juniper (Juniperus monosperma) cover around loggerhead shrike (Lanius ludovicianus) and gray vireo (Vireo vicinior) nests in central New Mexico in 2016-2020 to better understand tolerance of juniper expansion for these two species of con-servation concern. Species-response curves were derived from generalized additive mixed-effect models, with year as a random effect and a local regression smoother. Loggerhead shrike nests were more likely to occur in areas without junipers at the 170-m radius spatial scale. Nest-site selection declined as percent juniper cover increased. Gray vireo nests were most likely to be found in areas with approximately 11 % juniper cover at the 100-m radius spatial scale. Derivative functions were used to find juniper percentages where the rate of change in species' response was most negative for loggerhead shrikes and most positive for gray vireos. The rate of change in nest-site selection decreased the fastest at 13 % and increased the fastest at 4 % juniper cover for loggerhead shrike and gray vireo, respectively. These results suggest that maintaining juniper percentages between 4 and 13 % at relatively broad spatial scales would likely increase available nesting habitat both species. We demonstrate how derivative functions can be used to estimate the rate of change of species' response to environmental gra-dients and an application of such thresholds to resolve conflicting habitat management for two species of con-servation concern.

Pinyon jays (Gymnorhinus cyanocephalus) are experiencing range wide population declines primarily in response to habitat degradation. More studies examining pinyon jay nest site selection in pinyon-juniper woodlands would be helpful in determining potential habitat management prescriptions. Therefore, we conducted a nest site selection study in pinyon jay breeding habitat in central New Mexico. We compared size and foliage characteristics of pinyon and juniper trees in 42 17.5-m radius plots around pinyon jay nests to 41 same-sized vegetation plots in random locations using binomial generalized linear models. The strongest model indicated that pinyon jays preferred nesting in areas with fewer dead juniper trees within pinyon-juniper habitats. In contrast to previous studies, pinyon jays tended to nest in juniper-dominated areas as opposed to pinyon-dominated areas, possibly in response to widespread pinyon mortality at the study site. Results suggest that pinyon jays may be able to adapt to climate-related pinyon mortality by shifting to juniper dominated habitat.

Common approaches to estimating habitat quality are habitat suitability indices, which are often subjective. We propose a quantitative definition of habitat quality as the percentage of selected habitat that has a high probability of contributing to population growth. Using this definition, we created a habitat quality index based on spatial projections of habitat selection and survival probabilities, and the interaction of those probability gradients. We used nest-site selection and nest survival of Gray Vireos (Vireo vicinior) to represent habitat selection and survival probabilities of a sensitive life stage that is likely to increase population size. We used data from 173 Gray Vireo nests in central New Mexico to estimate selection and survival probabilities. Generalized linear mixed-effect models (GLMM) and logistic exposure models (LEM) were used to estimate nest-site selection and daily nest survival, respectively. We projected top-ranked GLMM and LEM models in a geographic information system (GIS) to spatially display relative probabilities of selection and survival. We converted these continuous probabilities into binary rasters representing high and low selection and survival. Multiplying these two rasters in ArcGIS provided us with a raster of four categories: areas with i) low selection and low survival, ii) low selection and high survival, iii) high selection and low survival, and iv) high selection and high survival. We determined the spatial area of each category and calculated percentage of selected habitat where survival was likely to occur, which we termed a habitat quality index (HQI). At our study site, Gray Vireos had a HQI of 0.85, suggesting that approximately 85% of the highly selected habitat had a high probability of contributing to Gray Vireo population growth through nest survival, and that few ecological traps exist in this landscape. These methods provide a quantifiable, continuous index of habitat quality, with spatial projections of potential ecological trap locations.

Understanding the interactions between behavior and habitat characteristics can have important implications for species of conservation concern. Gray vireos ( Vireo vicinior ) are one example of a species of conservation concern that is understudied in terms of nest survival probabilities and the habitat characteristics that influence them. Our objective was to determine if habitat features such as juniper density, juniper foliage density, or tree height influence nest survival probabilities, and if gray vireo nest placement can mitigate habitat risks. Based on previous work, we expected daily nest survival probabilities to be associated with nest height and surrounding vegetation. We monitored 89 nests in central New Mexico from 2016–2018 to estimate daily nest survival probabilities. We compared variation in nest placement, nest tree characteristics, and surrounding vegetation between failed and successful nests using logistic exposure models and Akaike Information Criteria. Daily and cumulative nest survival probability were 0.983 (95% CI [0.973–0.989]) and 0.575 (95% CI [0.444–0.702]), respectively. Top models predicting nest survival included a negative interaction between nest-tree foliage density and the distance of the nest from the edge of the nesting tree. This suggests that gray vireos can mitigate risks associated with low nest concealment by nesting closer to the interior of the nesting tree.

Depressional wetlands in the Great Plains are experiencing watershed alterations that impact the provisioning of important ecosystem services, which are unmonitored on a large scale (Smith et al. 2011). The Natural Resources Conservation Service’s (NRCS) Conservation Effects Assessment Project (CEAP) determines the effects of conservation programs on ecosystem service provisioning across the nation (Tomer et al. 2014). CEAP–Wetlands has focused on the effects of conservation programs and land use on ecosystem service provisioning in areas dominated by different wetland types. The High Plains region (HPR) primarily contains playa wetlands. The dominant land uses are native grassland, cropland, and conservation program land (Brinson and Eckels 2011). Predictive models were developed from CEAP–Wetlands data and can be used to estimate services by identifying playa wetlands and measuring variables required to populate the models (Duriancik et al. 2008). We developed a sampling manual that can be used to remotely classify playa function and ecosystem service provisioning. The manual and models can be used to monitor ecosystem services and inform USDA conservation decisions. Playas are depressional recharge wetlands that exist within western portions of Texas, Oklahoma, and Kansas, western and central Nebraska, the eastern plains of Colorado and New Mexico, and southeast Wyoming (Smith 2003) (figure 1). Playas exist within closed watersheds and receive water only through precipitation and overland flow (Bolen et al. 1989). Playa hydrology is similar among basins, allowing application of CEAP–Wetlands models to estimate service provisioning (Smith et al. 2015). Playas provide ecosystem services including habitat provisioning, floodwater storage, and carbon (C) sequestration (Smith et al. 2011). When cultivation occurs in …

There are many gaps in our understanding of Gray Vireo (Vireo vicinior) life history especially as it relates to nesting ecology. Our objective was to determine habitat features selected by Gray Vireos for nesting to improve management strategies for breeding populations. We searched for Gray Vireo nests on Kirtland Air Force Base in Albuquerque, New Mexico from 2016 to 2017. We estimated Gray Vireo nest-site selection at the tree level, the surrounding vegetation, and at two broader scales corresponding to selection within territories. Nest-site selection was estimated for 99 Gray Vireo nests. For tree-level selection, we compared characteristics of nesting trees with mean characteristics from groups of six randomly selected one-seed junipers (Juniperus monosperma) within a 25-m radius. We also compared overall vegetation characteristics at the 25-m scale for nesting plots and 66 randomly selected plots. Broad-scale cover proportions of nest sites and random points were estimated at 50- and 100-m radius spatial scales using a geographic information system. Gray Vireos selected nesting trees that were taller and wider than other adjacent junipers. Selection of vegetation characteristics surrounding nests showed a similar pattern, where Gray Vireos nested in areas where junipers were taller, wider, and had greater foliage density than was randomly available. Broad-scale analyses suggested that Gray Vireos selected nest sites in areas with higher proportions of junipers at low elevations (< 1954 m), and lower proportions of junipers in higher elevations (> 1954 m); however, juniper proportions at nest sites consistently ranged from 15 to 30% of available cover. Gray Vireos also tended to select areas with less pinyon pine than what was randomly available at the 100-m radius scale. Future management strategies should provide large patches of old-growth juniper to optimize Gray Vireo nesting habitat.

Numerous studies have documented that invertebrate pollinator services are critical to the world economy. Factors including habitat loss and agricultural practices, however, threaten pollinator populations. Many counties in the Southern High Plains were identified as at risk for a shortage of pollination service from wild bees. This region also has one of the highest concentrations of Conservation Reserve Program (CRP) contracts in the US. The CRP is the largest, voluntary, private lands conservation program in the US and was targeted as a program to improve pollinator habitat. Our objective was to determine how the predominant land uses in the SHP (native grassland, CRP, and cropland) affect pollinator abundance and species richness, and more specifically if the CRP can provide quality habitat for pollinators. We also examined how the keystone habitat, playa wetlands, embedded within these land uses contribute to pollinator habitat (land type: uplands vs. wetland). We used blue vane traps placed in playa basins and adjacent uplands to determine Hymenoptera abundance and richness from April to October in 2013 and 2014. The CRP had lower abundance than cropland and native grassland, and generally less richness. Uplands and playa wetlands had little difference in Hymenoptera abundance and richness. Patch size negatively influenced abundance but had a positive influence on richness. The interaction of vegetation height and percent bare ground positively influenced abundance in cropland and native grasslands, and positively influenced richness in all land uses. In the CRP, vegetation height negatively influenced Hymenoptera abundance and percent bare ground had a positive influence. The years sampled in this study were during a severe extended drought; therefore, these results may be reflective of poor floral resources. The CRP has potential to create valuable habitat for pollinators if land managers incorporate a diversity of native grasses and native forbs into plantings to enhance pollinator foraging and nesting habitat.

Abstract. Winter conditions impose hardships on waterfowl, impacting how they apportion energy and time. Human disturbances may affect this energetic balance, influence lipid reserves, and potentially survival. Objectives of this study were to determine effects of environmental and anthropogenic factors on energetic expenditure (kcal/day) of Northern Pintails (Anas acuta) in behaviors commonly associated with a disturbance response (alert, locomotion, and flight) during winter 2008-2009 and 2009-2010 at Bosque del Apache National Wildlife Refuge in central New Mexico, USA. The refuge is a frequently visited ecotourism destination with over 170,000 visitors each winter. Thermoregulatory cost, time-of-winter, amount of natural and anthropogenic disturbances, and forage availability were examined to determine their influence on pintail energetic response (e.g., flight, locomotion, alert behavior). Average number of pintails ranged from 7,524-15,769. Using Akaike Information Criteria, the top-ranked model indicated that increased thermoregulatory cost, and by association decreased temperature, may cause a decline in energetic response of pintails to disturbances. Modeled values for energetic response had a mean (± SE) of 175 ± 11.5 kcal/day in year 1, and 111.7 ± 7.22 kcal/day in year 2. Neither the amount of disturbance nor forage availability strongly influenced energetic response. Results of this study raise questions about the efficacy of using behavior or energy expenditure data, alone, to assess anthropogenic disturbance effects on waterfowl.

The economic value of insect pollination to the world economy is tremendous, and pollination service is critical for our food supply and persistence of native plants. Little data are currently available on pollinator occurrence in the Southern High Plains (SHP) of Texas. Past studies on hybrid cottonseed production in the region documented high abundance of six species of Agapostemon and lower abundance of Diadasia spp., Melissodes spp., and Perdita spp. Historical records indicated the presence of Bombus fraternus and B. pensylvanicus which now have Endangered and Vulnerable IUCN status respectively. In 2013 and 2014, we used blue vane traps and targeted netting to collect insect pollinators and anthophiles on the three dominant land uses in the region; cropland, Conservation Reserve Program (CRP), and native grasslands. With capture methods combined, we collected 74,215 insect specimens; 63% of the specimens were Hymenoptera (289 taxa), 28.61% were Coleoptera (150 taxa), 4.48% were Diptera (115 taxa), 2.34% were Lepidoptera (60 taxa), and 1.61% were of other orders (15 taxa). Our capture included all previously documented bee genera, but we did not detect B. fraternus. Studies support that blue vane traps are an effective method of trapping bees and our results demonstrated that they are also effective in attracting some families of anthophilous Coleoptera and Diptera. However, we captured several species of Hymenoptera, Diptera, and Lepidoptera with aerial nets that we did not capture in blue vane traps. This study documents pollinator and anthophile species present in a highly altered landscape and is the most comprehensive list of pollinators and anthophiles in this region to date.

In the High Plains, U.S., native prairie conversion to cropland agriculture has resulted in a loss of service delivery capabilities from most depressional wetlands as a result of sedimentation. Restoring historic hydrological conditions to affected wetlands may rejuvenate some services, however, there may be tradeoffs due to emissions of CH4 and N2O. We evaluated the influence of two predominant conservation programs (Wetlands Reserve Program, WRP and Conservation Reserve Program, CRP) on gas emissions (CO2, CH4, N2O) from 42 playas and uplands in the High Plains of Nebraska. Because playa restoration through the WRP is most prevalent in the Rainwater Basin (RWB), we studied 27 playas/uplands among reference condition, cropland, and WRP land uses. We studied 15 playas/uplands within native grassland, cropland, and CRP land uses in the Western High Plains (WHP) of Nebraska. Emissions were collected bi-weekly from April-October of 2012 and 2013 from four landscape positions extending outward from the wetland center into upland. In RWB playas, CH4 and N2O emissions were similar among land uses but CO2 was 28% higher in cropland than WRP wetlands. Cropland uplands emitted 648% more N2O than reference and WRP uplands. Overall, net CO2-equiv emissions were lower in playas/uplands in WRP, suggesting that benefits of playa restoration may include climate mitigation services as well as increased water storage capacity and biodiversity provisioning. In the WHP, cropland and grassland playas emitted 46 and 23 times more CH4, respectively, than CRP in 2013. Playas in CRP emitted 43% less N2O than cropland playas. In 2013, net emissions for cropland and native grassland playas were 75% and 39% greater, respectively, than CRP playas. In the WHP, the benefits of lower gas emissions must be appropriately weighted against tradeoffs of ecosystem services related to shorter hydroperiods as a result of reduced runoff into playas in CRP.

Pollination is an ecosystem service that is in jeopardy globally. Decreasing trends in wild pollinator populations are primarily attributed to habitat loss and degradation. These concerns are especially apparent in the Rainwater Basin of Nebraska, USA where more than 90% of the land has been cultivated and 90% of the wetlands have been lost. We compared hymenopteran and dipteran pollinator abundance, richness, and diversity in 28 wetlands and their adjacent uplands within 3 dominant land-condition types: cropped, restored, and reference state. We used vane traps to capture local pollinator insects and sweep nets to collect insect pollinators on flowers. Vane-trap captures revealed a greater abundance, richness, and diversity of hymenopteran pollinators in uplands as compared to wetlands over the entire growing season in all land-condition types. However, net collections showed that hymenopterans foraged more in wetlands than in uplands, especially in restored wetlands. The exception was September when hymenopterans were captured in uplands more than wetlands while feeding on late season forbs. Dipteran vane-trap and sweep-net captures primarily consisted of hoverflies (Syrphidae). Hoverflies were more abundant in wetlands than uplands. All pollinators used both wetlands and uplands for resources. Thus, insect-pollinator conservation can be enhanced by promoting native forb communities and pollinator habitat through wetland restoration and the planting of buffer strips.

We estimated northern bobwhite (Colinus virginianus) densities in 4-and 8-year-old burned and unburned redberry juniper (Juniperus pinchottii) dominated pastures.The 4-year-old burned (800 ha), 8-year-old burned (1,200 ha), and unburned (1,200 ha) treatment sites had 8.6, 14.4, and 22.3% woody canopy coverage, respectively.Fall bobwhite densities were estimated from 122 flushes of quail coveys on 592.8 km of transects.Data histograms indicated that bobwhite were harder to detect in the unburned area than in the 8-year-old burn or the 4-year-old burn.Probability detection functions were smaller in the old burn than the new burn (P = 0.05) or unburned area (P = 0.02).Bobwhite densities of 43.3, 55.1, and 60.5 birds/100 ha in the 4-year-old burn, 8-year-old burn, and unburned sites, respectively, were similar (P > 0.10).Prescribed burning to control redberry juniper and manage bobwhite should be designed to maintain intermittent shrub coverage.

Our objective was to document potential wild pollinating insects in south central Nebraska. This intensively cultivated region is known as the Rainwater Basin and contains some of the most endangered wetland systems in North America. We used blue vane traps to passively collect insects and insect nets to actively collect on flowering plants from April through October in 2014 and 2015. Habitat types included playa wetlands, adjacent mixed and tallgrass prairies, and agricultural fields. Over 112,000 insects were collected; Hymenoptera represented 78% of the total, and the families Apidae and Halictidae comprised 99% of the total melittofauna. Insects from 13 orders were collected, but Hymenoptera, Diptera, and Coleoptera were the most abundant potential pollinators.

Eroded soil from cropland watersheds is deposited as sediment into depressional wetlands such as playas degrading their ability to provide ecosystem services. Sediment removal from these degraded playa wetlands restores water storage volume. However, the effects of this restoration practice on carbon (C) and nitrogen (N) concentrations and C sequestration potential in playas has not been determined. One of the most important wetland systems and intensively cultivated regions in North America, the Rainwater Basin (RWB) of Nebraska, contained over 4000 playas but has lost 90% of them due to agricultural activities. Our objective was to examine the effects of sediment removal on wetland C and N concentrations and determine subsequent C sequestration potential. We also were interested in determining the importance of the presence of wetlands on the landscape to C sequestration given the loss of wetlands that has occurred. We hypothesized that sediment removal might decrease C sequestration potential and that the presence of wetlands on the landscape provides important C sequestration sites. To accomplish these objectives we sampled 60 playas and their immediate watersheds (20 each from reference condition, cropland, and restored through sediment removal) in 2013 and 2014 by coring soil/sediments (mollisols) to a depth of 50 cm. Restored playas contained 29% lower C and N in the top 5 cm than in reference and cropland land uses. The C in the top 5 cm was also 36% higher in the wetland than in the watershed. There were no differences in C and N among land uses/landscape positions at depths > 5 cm. However, because restored playas had sediment removed, in some cases down to the clay pan of the historic playa soil surface, on an areal basis, restored playas stored 21% more soil organic carbon (SOC) in deeper horizons (25-50 cm) than reference or cropland conditions. Overall, SOC was similar among restored, cropland and reference wetlands to a 50 cm depth, indicating that sediment removal does not have a negative effect on C sequestration potential. On average, SOC was 15% higher in playas than in adjacent uplands, demonstrating the importance of playa wetlands on the landscape to C sequestration. Results of this study have widespread applicability because depressional wetlands are the dominant wetland type in temperate agroecosystems.

Wetlands provide a wide variety of ecosystem services including water quality remediation, biodiversity refugia, groundwater recharge, and floodwater storage. Realistic estimation of ecosystem service benefits associated with wetlands requires reasonable simulation of the hydrology of each site and realistic simulation of the upland and wetland plant growth cycles. Objectives of this study were to quantify leaf area index (LAI), light extinction coefficient (k), and plant nitrogen (N), phosphorus (P), and potassium (K) concentrations in natural stands of representative plant species for some major plant functional groups in the United States. Functional groups in this study were based on these parameters and plant growth types to enable process-based modeling. We collected data at four locations representing some of the main wetland regions of the United States. At each site, we collected on-the-ground measurements of fraction of light intercepted, LAI, and dry matter within the 2013-2015 growing seasons. Maximum LAI and k variables showed noticeable variations among sites and years, while overall averages and functional group averages give useful estimates for multisite simulation modeling. Variation within each species gives an indication of what can be expected in such natural ecosystems. For P and K, the concentrations from highest to lowest were spikerush (Eleocharis macrostachya), reed canary grass (Phalaris arundinacea), smartweed (Polygonum spp.), cattail (Typha spp.), and hardstem bulrush (Schoenoplectus acutus). Spikerush had the highest N concentration, followed by smartweed, bulrush, reed canary grass, and then cattail. These parameters will be useful for the actual wetland species measured and for the wetland plant functional groups they represent. These parameters and the associated process-based models offer promise as valuable tools for evaluating environmental benefits of wetlands and for evaluating impacts of various agronomic practices in adjacent areas as they affect wetlands.

Amphibians are susceptible to exposure from contaminants via multiple pathways. Pyraclostrobin fungicides have been shown to be toxic to terrestrial amphibians at environmentally relevant concentrations; however, these studies did not account for factors that may influence exposure and effects, such as fungicide formulation, age of the individual, exposure route, and physiological state of the individual. We examined Headline (R) and Headline AMP (R) fungicide toxicity to adult Anaxyrus cognatus and Anaxyrus woodhousii by direct overspray, as well as acute toxicity of Headline AMP to juvenile A. cognatus through direct overspray, previously exposed soils, and diet. We also assessed effects of hydration state on fungicide toxicity in juvenile A. cognatus and sublethal effects of fungicide exposure on prey-orientation ability of juvenile A. cognatus. Neither formulation of Headline caused mortality of adult A. cognatus and A. woodhousii at up to 5 times the maximum label rate in North American corn (1052 and 879 mL formulation/ha for Headline AMP and Headline fungicides, respectively, corresponding to 1.52 and 2.2 mu g pyraclostrobin/cm(2), respectively). Exposures of juvenile A. cognatus to Headline AMP via direct overspray and previously exposed soils (2 types) resulted in median lethal rate (LR50) values of 2.4, 3.34, and 3.61 mu g pyraclostrobin/cm(2), respectively. Dietary Headline AMP exposure was not toxic, prey-orientations were not influenced by exposure, and effects were similar between dehydrated and hydrated treatments (LR50 = 2.4 and 2.3 mg pyraclostrobin/cm2, respectively). These results, combined with exposure concentrations reported in previous studies, suggest that risk of acute mortality for amphibians in terrestrial environments is low and is dictated by body size and site-specific factors influencing exposure. (C) 2017 SETAC

Soil organic carbon (SOC) is an important reservoir for atmospheric CO2 associated with climate warming. The High Plains, USA, lacks region-wide SOC estimates within playa wetlands and their adjacent watershed. Croplands often have less SOC than grasslands, and the Conservation Reserve Program (CRP; former croplands planted to grass) may return SOC. Our goals were to estimate SOC within playa wetlands and investigate small scale differences within wetland catchments across a broad agriculturally modified landscape. We estimated SOC (kg m(-2)) to 50 cm depth from 4 soil cores/catchment (in playas and 10,40 and 100 m into uplands) at 56, 52, and 54 sites in native grassland, CRP and cropland, respectively. At a subset of sample locations within each land use type, we estimated SOC to 1 m depth to characterize SOC missed by shallow sampling. In playa wetlands, CRP SOC from 0 to 50 cm was 18% greater than croplands, but native grassland playa SOC did not differ from other land-uses. From 0 to 1 m, SOC in native grassland wetlands and uplands was 20% greater than the same habitats within croplands, while CRP lands were intermediate. Native grassland playa SOC also was 16% greater than in surrounding native short grass prairie. Playas therefore represent an important SOC repository in the High Plains ecoregion. CRP playas and uplands may require an additional 10-30 years to resemble native grassland SOC. SOC increased with playa area throughout CRP and native grassland catchments, suggesting playa hydrogeomorphology influences adjacent upland SOC. High Plains playas store 20.8 Tg C and cropland conversion caused a cumulative loss of 2.0 Tg C from 82,000 ha of playas. Currently, CRP enrollment on over 25,000 ha of playas has returned 0.2 Tg C (95% CI: 0.1-0.3), only half the historic SOC lost by cropland conversion within CRP playas. To promote SOC storage, native grasslands and large playas should be preserved and CRP enrollments should be maintained over long timescales. (C) 2015 Elsevier B.V. All rights reserved.