research articles about grasslands

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Recent advances in understanding grasslands

Carly j. stevens.

1 Lancaster Environment Centre, Lancaster University, Lancaster, UK

Grasslands are a vitally important ecosystem, supporting a wide range of ecosystem services and high levels of biodiversity. As a consequence, they have long been a focus for ecologists, playing host to some of the world’s longest-running ecological experiments and providing the inspiration for many long-standing theories and debates. Because the field of grassland ecology is broad, encompassing many areas of ecology, this article picks some areas of particular debate and development to look at recent advances. The areas include relationships between diversity and productivity, ecosystem stability and ecosystem service provision, global change threats from nutrient addition, invasive species, climate change, and plant soil interactions.

Introduction

Grasslands cover 40% of the world’s terrestrial surface 1 , and they are found on all continents except Antarctica, in a wide range of climates, and on a wide range of soil types. They can vary in their species richness from monocultures up to botanically species-rich habitats which support diverse animal communities. Grasslands are typically dominated by grasses ( Poaceae ) and other grass-like plants. Some grasslands occur naturally, whilst others must be maintained by active management such as cutting or grazing. They are also incredibly important to mankind, providing many different services. Unsurprisingly, given their importance, extent, and variation, grasslands have been a focus for many ecologists and the home of many ecological theories, some of which remain intensely debated. In this article, I will highlight some of the recent advances in understanding grasslands. The field of grassland ecology is broad and developing rapidly. A Web of Science search with grasslands as a key word reveals almost 9,000 papers published between January 2016 and May 2018. As a consequence, this is not an exhaustive review but rather focusses on some key causes and consequences of biodiversity declines in grasslands, picking out some areas of key developments, controversies, and findings that I believe have helped us to advance our understanding of how these complex, intriguing, and beautiful ecosystems work.

Variation in diversity between grasslands

Productivity–diversity relationships.

Grasslands across the world vary hugely in both physical and biological characteristics, and explaining relationships between them has led to much discussion. One of the fiercest ecological debates of recent decades has concerned the relationship between productivity and diversity. The humpbacked model 2 predicts that in extreme environments only a few stress-tolerant species survive and diversity is low. Both productivity and diversity increase until, when resource levels are high, diversity declines again, most likely due to competition or species pools. Grasslands account for as much as one-third of the net primary production on land 3 , and many of the original studies exploring the relationship between productivity and diversity originated in grasslands 2 , 4 . In 2011, Adler et al . 5 published a paper in Science that reignited the debate. Using a global dataset of 48 grasslands on five continents that were part of the Nutrient Network (NutNet), they found no consistent relationship between productivity and richness. Since then, we have seen publications that fall on both sides of the debate. Recently, Fraser et al . 6 collected data from 30 sites on six continents and performed a similar analysis to that employed by Adler et al . 5 . They found strong support for the humpbacked model, with 19 of 28 sites showing significant concave-down quadratic relationships between plant species richness and productivity 6 . They identified a number of hypotheses for why they found much stronger support for the humpbacked model than did Adler et al . Whilst the debate regarding whether there is a single hypothesis that can explain the relationship between plant diversity and productivity will likely rage for a long time, most authors can agree that there is a need to develop our understanding of the mechanisms that underlie the relationships identified. Grace et al . 7 recently made progress toward this objective by showing that integrative modelling, considering multiple potential drivers of both richness and diversity, has substantially higher explanatory power than bivariate analyses, arguing for more integration of ideas and simultaneous tests of their combined implications.

Threats to grasslands

Land-use change.

Globally, land-use change is a major driver of community change and habitat loss. The impacts of land-use change can be seen across trophic groups. A recent paper has taken a functional trait approach to examine shifts in invertebrate communities in response to land-use intensification. Working across 124 grasslands of differing intensities of land-use in Germany, Simons et al . 8 collected data on a range of traits in insect and spider species to demonstrate that higher-intensity landscapes favoured smaller, more mobile, and less-specialised species. The collection of functional trait data for invertebrates is labour intensive, but the authors argue it is essential for understanding the impacts of land-use change on invertebrates.

Response to nutrient additions

One of the most challenging issues we currently face is the extent to which we have perturbed nutrient cycles and the impact this is having on the environment. High levels of nutrient addition have long been recognised to reduce species richness. We expect that nutrient enrichment results in a switch from belowground competition for nutrients to aboveground competition for light. Because some plants are taller, they receive more light per unit size than do smaller plants, thus precipitating competitive exclusion. Up to now, there has been limited evidence to conclusively demonstrate this mechanism, but a recent study demonstrated that an increase in light asymmetry is the main cause of species loss under nutrient enrichment 9 . DeMalach et al . 9 used a combination of light measurements through the grassland canopy and plant height in fertilised and unfertilised grasslands to calculate light asymmetry and determine the competitive effect, demonstrating that it is an increase in the rate of light decay through the canopy rather than an increase in canopy height that is responsible for the competitive effect of grasses on forbs.

Another recent advance has been in the increased recognition of multiple factors limiting production in grasslands. Two recent papers from the NutNet 10 – 12 have demonstrated that, contrary to popular opinion, where nitrogen (or nitrogen and phosphorus) is deemed a key determinant of aboveground net primary productivity, other nutrients are important in determining production, and not only were many grasslands limited by multiple nutrients 10 but the number of added nutrients predicted diversity loss. Adding nutrients reduced niche dimensionality, increased productivity, and increased compositional turnover 11 . Nutrient addition is clearly a considerable threat to grassland biodiversity, yet in many parts of the world it does not receive sufficient attention in policy or research, meaning there are many knowledge gaps we need to address.

Invasive species

There are many different mechanisms that have been identified for the success and spread of invasive species in grasslands and other habitats. A recent paper by Broadbent et al . 13 highlighted the potential importance of root competition in the interactions between invasive and native grasses in New Zealand. This small-scale study only investigated the relationship between three species but demonstrated the importance of belowground competition, a mechanism that has received very little attention, in driving their interactions and highlights this as an area in need of future research. In contrast, a large meta-analysis was performed by Liu et al . 14 to test whether invasive species benefit more from global environmental change than do native species. They compiled a database of published studies that gave performance measures for 74 invasive plant species and 117 native plant species in response to global change drivers. They found that invasive species responded more strongly to carbon dioxide enrichment and elevated temperature (and did not respond significantly to nitrogen deposition and increased precipitation), indicating that the problems caused by invasive plant species are likely to get worse under a changing climate. This study suggested that drought may be detrimental for invasive species, as did a seedbank study in Californian annual grasslands, which found that seeds of exotic annual grasses declined whilst native annual forbs increased 15 . Invasive species have very large impacts on grassland communities in some parts of the world, meaning that understanding and predicting these impacts is a priority.

Climate change

Long-term experiments are critically important in ecology 16 , and as grassland ecologists we are lucky to host some of the longest-running experiments in the world, including the 150-year-old Park Grass Experiment 17 . For climate change research, long-term experiments are especially valuable, as it takes time for plant species to respond. One of the longest-running climate change experiments is the Buxton Climate Change Impacts Laboratory (BCCIL) in northern England 18 . Recent research at BCCIL has demonstrated that climate change (warming and rainfall manipulation) has rapid direct impacts on the soil microbial community but also indirect impacts mediated by changes in plant species composition, which occur over longer time scales 19 .

Shifts in species composition are likely as a result of climate change but do not necessarily result in changes to ecosystem stability 20 . Also, using a long-term investigation, Reich et al . 21 showed that whilst in the first 12 years of carbon dioxide enrichment C 3 plant biomass increased markedly, C 4 plant biomass did not. This is expected, since C 4 plants are thought to be less limited by carbon dioxide; however, in the latter 8 years of the experiment, the responses switched, with biomass depressed in C 3 plants but not in C4 plants. Fay et al . 22 demonstrated that carbon dioxide concentrations have a strong effect on flowering in four of the five grassland species they investigated. They utilised contrasting soil conditions to demonstrate that impacts were mediated by productivity and nutrient status. The impacts of climate change will be felt globally, but we are only just beginning to understand likely impacts. In the future, we need more research to understand not only likely impacts of climate change but also how climate change and other global change drivers are likely to interact; long-term experiments will be key to achieving this.

Effects of biodiversity loss

Diversity–stability relationships.

One of the main arguments for biodiversity conservation is that more-diverse communities will be more stable and better able to resist perturbation. A number of mechanisms have been suggested for this relationship between diversity and stability, including asynchrony (productivity of one species increases, compensating for declines in another species), portfolio effects (statistical averaging of fluctuations in species properties), and functional redundancy (species loss is compensated by other species fulfilling a similar function). A recent study of 2,671 species from 300 plots, across three regions in Germany, indicated that asynchrony was the primary driver of stability rather than diversity alone 23 . Evidence for this is mixed, but several recent papers, including two synthesis studies combining results from multiple experiments in grasslands, have provided strong evidence in support of the argument that diversity begets stability. Hautier et al . 24 used results from 12 multiyear experiments to show that changes in biodiversity caused by a range of environmental change drivers were a major factor in determining the impact on stability, whilst Isbell et al . 25 used data from 46 experiments that manipulated grassland diversity to show that diversity increased resistance to climate events. Further results from the NutNet collaborative experiment have shown that eutrophication weakens the relationship between diversity and stability. We would expect this to occur as a result of diversity losses, but in this case it was actually due to an increase in temporal variability of productivity 26 .

Diversity–service provision relationships

Another often-cited negative consequence of the loss of biodiversity is that more-diverse systems support more ecosystem services. Many of the early papers in this field were conducted in grasslands, and now there is a move towards testing these relationships in the “real-world” in natural or managed grasslands. Allan et al . 27 provided strong evidence to support this, using 150 grassland plots spread across three regions of Germany as part of the Biodiversity Exploratories experiment. Their results show that diversity loss and functional composition change, caused by land-use intensification, is just as important as the land-use intensification itself in terms of its impact on ecosystem service delivery. It is not just richness that is important though: Winfree et al . 28 compared composition, richness, and abundance of pollinators to determine their relative contributions to pollination services and found that the abundance of dominant species was the most important factor whereas richness was relatively unimportant because most of the species were not responsible for service delivery. Whilst this is interesting evidence in favour of considering the composition of communities, this study was focussed on one trophic group and one ecosystem service; other recent studies have demonstrated the need for multiple trophic groups to be considered. Results also from the Biodiversity Exploratories project demonstrated that high richness in multiple trophic groups had stronger positive effects on ecosystem service provision than did richness in any single group. This was particularly true for cultural and regulating services 29 and for the provision of multiple ecosystem services 30 .

Conclusions

Grassland ecology, and the broader field of ecology, are rapidly moving fields. Developing analytical and statistical techniques combined with innovative approaches and co-ordinated networks are allowing us to address questions which we were not previously able to. However, many questions remain, and there are rarely, if ever, definitive answers to questions in ecology. Luckily, in much of grassland ecology, there is a willingness to embrace change and accept that rules are there to be broken. There are, however, unprecedented threats to grassland habitats through climate change, nutrient deposition, invasive species, and habitat loss, to name a few, so the need to understand impacts and protect valuable habitats is more pressing than ever.

Abbreviations

BCCIL, Buxton Climate Change Impacts Laboratory; NutNet, Nutrient Network

Acknowledgements

I would like to acknowledge the helpful input of reviewers Eric Allan, Till Kleinebecker, and Jin-Sheng He.

[version 1; referees: 2 approved]

Funding Statement

The author(s) declared that no grants were involved in supporting this work.

Editorial Note on the Review Process

F1000 Faculty Reviews are commissioned from members of the prestigious F1000 Faculty and are edited as a service to readers. In order to make these reviews as comprehensive and accessible as possible, the referees provide input before publication and only the final, revised version is published. The referees who approved the final version are listed with their names and affiliations but without their reports on earlier versions (any comments will already have been addressed in the published version).

The referees who approved this article are:

• Till Kleinebecker , Division of Landscape Ecology and Landscape Planning, Gießen University, Gießen, Germany No competing interests were disclosed.
• Eric Allan , Institute of Plant Sciences, University of Bern, Bern, Switzerland No competing interests were disclosed.

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Peer-reviewed

Research Article

Rapid Decline of a Grassland System and Its Ecological and Conservation Implications

* E-mail: [email protected]

Affiliation Instituto de Ecología, Universidad Nacional Autónoma de México, México D.F., México

Affiliation Facultad de Ciencias, Universidad Nacional Autónoma de México, México D.F. México

• Gerardo Ceballos, 
• Ana Davidson, 
• Rurik List, 
• Jesús Pacheco, 
• Patricia Manzano-Fischer, 
• Georgina Santos-Barrera, 
• Juan Cruzado

• Published: January 6, 2010
• https://doi.org/10.1371/journal.pone.0008562
• Reader Comments

One of the most important conservation issues in ecology is the imperiled state of grassland ecosystems worldwide due to land conversion, desertification, and the loss of native populations and species. The Janos region of northwestern Mexico maintains one of the largest remaining black-tailed prairie dog ( Cynomys ludovicianus ) colony complexes in North America and supports a high diversity of threatened and endangered species. Yet, cattle grazing, agriculture, and drought have greatly impacted the region. We evaluated the impact of human activities on the Janos grasslands, comparing changes in the vertebrate community over the last two decades. Our results reveal profound, rapid changes in the Janos grassland community, demonstrating large declines in vertebrate abundance across all taxonomic groups. We also found that the 55,000 ha prairie dog colony complex has declined by 73% since 1988. The prairie dog complex has become increasingly fragmented, and their densities have shown a precipitous decline over the years, from an average density of 25 per ha in 1988 to 2 per ha in 2004. We demonstrated that prairie dogs strongly suppressed woody plant encroachment as well as created open grassland habitat by clearing woody vegetation, and found rapid invasion of shrubland once the prairie dogs disappeared from the grasslands. Comparison of grasslands and shrublands showed markedly different species compositions, with species richness being greatest when both habitats were considered together. Our data demonstrate the rapid decline of a grassland ecosystem, and documents the dramatic loss in biodiversity over a very short time period concomitant with anthropogenic grassland degradation and the decline of a keystone species.

Citation: Ceballos G, Davidson A, List R, Pacheco J, Manzano-Fischer P, Santos-Barrera G, et al. (2010) Rapid Decline of a Grassland System and Its Ecological and Conservation Implications. PLoS ONE 5(1): e8562. https://doi.org/10.1371/journal.pone.0008562

Editor: Dennis Marinus Hansen, Stanford University, United States of America

Received: October 8, 2008; Accepted: October 26, 2009; Published: January 6, 2010

Copyright: © 2010 Ceballos 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.

Funding: This research was supported by the J.M. Kaplan Fund, Dirección General de Asuntos del Personal Académico - Universidad Nacional Autónoma de México, Ecociencia S.C., Consejo Nacional de Ciencia y Teconologí­a (CONACyT), Whitley Fund for Nature, Comisión Nacional para el Conocimiento y Uso de la Biodiversidad, Defenders of Wildlife, the Dutch Embassy in Mexico, The Nature Conservancy, Environmental Flying Services, Foundation for Deep Ecology, National Black-footed Ferret Recovery Foundation, National Fish and Wildlife Foundation, National Wildlife Federation, Naturalia A.C., People's Trust for Endangered Species, Phoenix Zoo, Research Ranch Foundation, U.S. Agency for International Development, Sky Island Alliance, British Council, Wildlands Project, and Turner Foundation. ADD was supported by a postdoctoral scholarship by the Universidad Nacional Autónoma de México and the National Science Foundation Grant OISE-0653296. 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

Global environmental problems have become more acute as a consequence of ever-increasing pressures from human activities, resulting in an alarming loss of biological diversity. These losses are rapidly reducing Earth's life support systems and the services that nature provides, such as the clean air and water we all depend on [1] , [2] . Grasslands have become one of the most imperiled ecosystems in the world, and are facing increasing threats by multiple anthropogenic activities. Their future depends greatly on the future of agriculture and grazing [3] , [4] . Indeed, humans depend greatly on grasslands for overall food production, which is projected to increase by more than 75% over the next 30 years to support the projected doubling of the human population and its growing need for food [5] . Throughout the world, grasslands are being converted either to croplands or desertified shrublands from overgrazing by livestock [6] , [7] . The loss and fragmentation of grasslands is causing the extinction of uncounted populations and species, changes in the structure and function of ecosystems, depletion of environmental services, and decline in human well-being [e.g.] , [7] , [8,9] .

Only around 20% of North America's central grasslands have not yet been developed or converted to cropland, and much of what remains is utilized for cattle grazing [7] , [10] . Widespread desertification of North America's semi-arid grasslands has already occurred [11] , [12] , [13] , [14] . Overgrazing results in the removal of perennial grasses and leads to shrub invasion, with the result that these grasslands have been replaced by desert shrub communities often dominated by unpalatable plants such as ephedra (long-leaf jointfir, Ephedra trifurca ), and palatable ones such as mesquite ( Prosopis glandulosa ) whose seeds are readily eaten by cattle [6] , [11] , [14] . In some regions, overgrazing has resulted in the widespread replacement of perennial grasses by forbs and annual grasses [15] . Perennial grasslands are characterized by relatively stable grass cover, uniform distribution of available resources, and stable soils. In contrast, desertified grasslands dominated by annual grasses have more temporally variable vegetation and resources, and are subject to severe soil erosion [11] , [16] , [17] .

The semi-arid grasslands of the Janos region of northern Chihuahua, Mexico, have been subject to intensive cattle grazing and some exceptionally dry periods over the last decade, providing an ideal opportunity to study the ecological consequences of grassland degradation. These grasslands support one of the largest remaining black-tailed prairie dog ( Cynomys ludovicianus ) complexes on the continent (14,796 ha), and the only significant complex remaining in the semi-arid grassland system of the American Southwest/northern Mexico region [15] . Prairie dogs are fossorial rodents that live in large colonies and are considered to be keystone species and ecosystem engineers, as they transform grassland ecosystems through their burrowing and herbivory [18] , [19] , [20] . They create important habitats for other animals and are key prey for many predators, increasing heterogeneity and biodiversity in grasslands [19] , [21] , [22] , [23] , [24] , [25] . Prairie dogs also play an important role in preventing shrub invasion by consuming the seeds and seedlings of shrubs, in turn helping to maintain grassland ecosystems [26] .

While anthropogenic activities are transforming the globe, few studies have documented the effects of the decline of a grassland ecosystem due to human activities and the consequential effects on plant and animal communities. Here, we document the effects of the rapid decline of a grassland ecosystem on vertebrate biodiversity in the Janos region. We also assess human land use changes and long-term weather (i.e., precipitation) to better understand the large-scale factors driving the observed changes over time. Little is known about how unique these prairie dog grassland communities are, how fast land degradation can impact biodiversity, and what the main conservation lessons are. Specifically, we address the following questions: i) Have there been large landscape-scale changes in area covered by native plant communities, concomitant with intensive human land use (i.e., grazing and agriculture)? ii) If so, have those changes affected the area covered by the prairie dog complex in the same period? iii) Do prairie dogs reduce the invasion of shrubland and thus promote the maintenance of semi-arid grasslands? iv) Do grasslands and shrublands differ in vertebrate biodiversity, and if so, what is their combined contribution to regional biodiversity? v) Have there been concomitant declines in vertebrate diversity parallel to the decline in prairie dog colonies over a short-term (i.e., ca. 10-year) period? Finally, we discuss specific conservation strategies to restore the prairie dog colonies and the grassland ecosystem.

Landscape scale changes over time

The Janos region covers 1 million ha of grasslands, shrublands, and mountain plant communities ( Figure 1 ). We observed anthropogenic degradation of the native vegetation over the course of our research, leading to surprisingly extensive and rapid changes, especially those due to overgrazing and intensive agriculture. In only a decade, from 1990 to 2000, around 6% (46,493 ha) of the grasslands were completely transformed, and there also was a large, 142-fold increase (from 6,645 to 52,123 ha) in bare ground cover, in areas that used to have grasslands. Similarly, the area used for intensive agriculture, especially by center-pivot crop fields, showed a 1,757-fold (731 ha to 12,845 ha) increase from 1993 to 2008, all of which were plowed in either prairie dog colonies or native grasslands. Compounding the impacts of intensive land use, the region experienced a prolonged drought, with a period of below average precipitation between 1993–1996 and 1998–2003. The years from 1993–2005 represent the driest period in the last 50 years ( Figure S1 ). The effects of drought were very severe when coupled with overgrazing, and were one of the leading causes of the conversion of grasslands to bare ground. For example, the communal grasslands of Ejido Casa de Janos, supported the largest prairie dog colony in Janos in 1993 (35,000 ha). The cattle grazing carrying capacity of this land was estimated at 200 head of cattle (M. Rollo, personal communication). However, they had 2000 animals during most of the time from 1993 to 2005. By 2005, most of the former prairie dog colony was abandoned with very few prairie dogs remaining ( Figure 2 ).

• PPT PowerPoint slide
• PNG larger image
• TIFF original image

The Janos region covers 1 millon hectares in northern Mexico, bordering the United States. The main plant communities are grasslands, shrublands, and temperate forests. This region still maintains one of the largest prairie dog complexes in the world, and the Janos Biosphere Reserve has been designated to protect this biologically important region.

https://doi.org/10.1371/journal.pone.0008562.g001

These photos show the rapid loss of prairie dogs within the largest colony of the Janos grasslands, following two decades of intensive land use and drought. Note the sparse coverage of annual grasses and forbs and the lack of perennial grasses, which is characteristic of degraded grasslands in Janos. These plants are only available during the rainy season and most of the year the area is bare ground.

https://doi.org/10.1371/journal.pone.0008562.g002

Prairie dog decline and shrubland expansion

The decline of the natural vegetation at a landscape level in Janos had a severe impact on the prairie dog colony complex. The 55,000 hectares of grassland occupied by prairie dogs in 1988 experienced a 73% decline by 2005, representing a loss of around 40,000 ha ( Figure 2 and 3 ). The original eight colonies, with an average size of 6,250 ha, were converted into more and smaller (437 ha on average) colonies (31). The remaining colonies were scattered along the original geographic distribution area. A few very large colonies still remain such as El Cuervo (6,300 ha) and Monte Verde (3,250 ha).

Extent of prairie dog colonies in 1988 and 2005, and location of the sampling sites 1992–2004: pitfall trap grids and transects for herpetofauna, point count transects for birds, Sherman trap grids for small mammals, and spotlighting transects for medium and large mammals (see Table A3 for specific sampling periods for each group).

https://doi.org/10.1371/journal.pone.0008562.g003

The loss of prairie dogs had profound negative impacts on the maintenance of grasslands and the expansion of shrublands. We documented major changes in the grassland – shrubland landscape composition, related in part to the presence of prairie dogs that strongly suppress woody plant encroachment and create open habitat through their foraging and clipping behavior ( Figures 4A and B ). Here, we took advantage of an (un-)natural experiment where prairie dogs had been poisoned or had recolonized the landscape, providing us the opportunity to assess changes in grassland and mesquite cover in relation to the presence or absence of prairie dogs. In one case, prairie dogs were poisoned in the 1,588 ha Los Ratones colony between 1988 and 1990. The effects of prairie dog removal on the grassland were already visible by 1996. Thirty four percent (1,653 ha) of the previous open grassland was invaded by either mesquite (14%, 693 ha) or ephedra (20%, 960 ha) shrubland in just eight years ( Figure 4C ). In the second case, between 2000–2005, the La Bascula prairie dog colony expanded 16% (208 ha/1,270 ha) into closed ephedra shrubland through the physical removal of shrubs ( Figure 4D ). Additionally, ephedra shrubs were 55% shorter (34.1 cm vs 75.5 cm) in the prairie dog colony, and 81% of them had signs of prairie dog clipping; in comparison, ephedra shrubs only 50 m away from the colony were taller and only 3% had signs of clipping ( Figure 4B , Table S1 ). The edge of the colony advanced up to 546 m into the shrubland during this five-year period, converting the area back into an open grassland habitat. In summary, our data clearly indicates the effects of prairie dogs in maintaining the presence of open grasslands and limiting the expansion of shrubland.

A) Prairie dog colony in Janos, Chihuahua, Mexico, note the absence of woody plants. B) Prairie dog expansion into ephedra shrubland by physically damaging the invading shrubs. Visible in the picture is the extensive browsing of shrubs, and several burrows at the base of the shrub which exposes the roots (see also map in Fig. 2D ). C) Polygon of the southern portion of the prairie dog colony of Los Ratones, which was covered by grassland in 1988, showing a 43% advance of honey mesquite (Prosopis grandulosa) and ephedra (Ephedra trifurca) shrubland after the colony was poisoned between 1988 and 1990. D) Sixteen percent expansion of the La Báscula prairie dog colony into ephedra shrubland between 2000 and 2005.

https://doi.org/10.1371/journal.pone.0008562.g004

Comparison of grassland and shrubland vertebrate communities

The prairie dog colony grasslands and the shrublands had differences in vertebrate species richness, composition, and abundance in the four vertebrate classes evaluated. As we predicted, species richness was greater when both habitats were considered together, but shrublands had greater species diversity across all vertebrate classes, except large carnivores ( Figure 5 ). However, simply comparing species richness to assess differences can be misleading, so we compared species composition and found that the two plant communities exhibited markedly different compositions, with many species being unique to each habitat type ( Figures 5 , 6 and 7 , Table S2 ). Indeed, herpetofauna, birds, and small mammal assemblages differed strongly between the two plant communities, when analysed with both a Detrended Correspondence Analysis (DCA) and a Multi-Response Permutation Procedure (MRPP) ( P <0.0002, for all tests) ( Figure 6 ).

Total number of shared and unique species of all vertebrate groups combined, birds, small mammals (including lagomorphs), herpetofauna, and carnivores on the grassland and shrubland habitats over all sample periods (1994, 1995, 1996, 2000, 2001, 2002, 2003, and 2004; see Table A3 for specific sampling periods for each group).

https://doi.org/10.1371/journal.pone.0008562.g005

Total abundance of herpetofauna, birds, small mammals, rabbits, and carnivores on the prairie dog grassland and shrubland habitats over all sample periods (1994, 1995, 1996, 2000, 2001, 2002; N = 8 for each sample period). Asterisks (*) indicate significant differences in abundance between the habiats at P<0.01.

https://doi.org/10.1371/journal.pone.0008562.g006

Detrended Correspondence Analysis (DCA) ordinations based on species composition of herpetofauna, birds, and small mammals. Multi-Response Permutation Procedure (MRPP) demonstrates that the species compositions of these vertebrate groups is significantly different between the prairie dog grasslands and the shrublands (1994, 1995, 1996, 2000, 2001, 2002; N = 8 for each sample period).

https://doi.org/10.1371/journal.pone.0008562.g007

Large differences in relative abundance and dominance of vertebrate species also were present between the two habitats ( Figures 7 and 8 ). While total vertebrate species richness and abundance were greater in shrublands, there was considerable variation among the vertebrate groups ( Figure 8 ). Total abundance of birds did not differ significantly between the two habitat types. Yet, birds were almost twice as species rich in the shrubland than in the grassland habitat (W: C  = 38.0, P  = 0.0037), and of the 24 different families of birds observed, 20 showed significant differences in abundance between the two habitat types (W: P <0.05, for all tests). At a species level, grasslands were dominated by Horned Larks ( Eremophila alpestris ) and Chihuahuan Ravens ( Corvus cryptoleucus ), while shrublands were dominated by Lark Buntings ( Calamospiza melanocorys ) and Mourning Doves ( Zenaida macroura ) ( Figure 7 and Table S2 ).

Relative abundance of herpetofauna, bird, and small mammal species on the prairie dog colony grasslands and the shrublands over all sample periods (1994, 1995, 1996, 2000, 2001, 2002; N = 8 for each sample period). Asterisks (*) indicate significant differences in abundance between the habitats at P<0.05.

https://doi.org/10.1371/journal.pone.0008562.g008

Species richness of small mammals and total abundance of both small mammals and lagomorphs were significantly higher in shrublands than grasslands (species richness W: C  = 36.0, P  = 0.0002; abundance W: C  = 36.0, P  = 0.0008; Chi-Square: x 2  = 20, df = 7, P  = 0.007, respectively; Figure 5 , 7 , and 8 ). Most species and all trophic and family groups of small mammals were significantly more abundant in the shrubland habitat (W: P <0.01, for all tests; Figure 7 and Table S2 ). Silky pocket mice ( Perognathus flavus ) and Mearn's grasshopper mice ( Onychomys arenicola ) showed a strong association with grasslands, while Merriam's kangaroo rats ( Dipodomys merriami ) were more associated with the shrublands. Of the two lagomorph species, the black-tailed jackrabbits ( Lepus californicus ) were more than ten-times more abundant in the shrublands than in the grasslands (Chi-Square: x 2  = 22, df = 7, P  = 0.003), while the desert cottontails ( Sylvilagus audubonii ) did not show differences.

Abundance ( N  = 52) and richness ( N  = 5) of carnivores were greater in the grasslands than in the shrublands (abundance N  = 8, richness N  = 1; Figures 7 , and 8 ). The relatively higher number of carnivore species observed in the grasslands versus the shrublands could have been influenced by the greater sampling visibility in the grasslands versus the shrublands, but Program Distance adjusts for sighting distance making the overall effect of visibility minor. Trends among species were somewhat varied ( Figure 7 and Table S2 ). For example, the relative density of coyotes ( Canis latrans ) was greater in the shrubland habitat ( D  = 0.002) than in the grassland ( D  = 0.001), but kit foxes ( Vulpes macrotis ), skunks ( Mephitis spp.), and badgers ( Taxidea taxus ) all had higher densities in the grasslands ( D  = 0.014, D  = 0.001, D  = 0.1, respectively) than in the shrublands ( D  = 0, for all three species). One black-footed ferret ( Mustela nigripes ) also was observed in the grassland where they were reintroduced in 2001.

As expected, reptiles and amphibians were more diverse in the shrublands when compared to the grasslands, with two-fold increases in both species richness (W: C  = 42.5, P  = 0.009) and abundance (W: C  = 46.5, P  = 0.02; Figure 5 and 7 ). Toads and lizards were significantly more associated with shrublands than grasslands (W: C  = 42.5, P  = 0.009; C  = 48.0, P  = 0.03, respectively; Figure 7 and Table S2 ).

Importantly, the prairie dog grasslands harbored many more priority conservation species compared to the shrublands. There were more endangered, threatened, and/or keystone species, and in larger numbers, in the grasslands as compared to the shrublands, including Burrowing Owls ( Athene cunicularia ), Ferruginous Hawks ( Buteo regalis ), Bald Eagles ( Haliaeetus leucocephalus ), Curlews ( Numenius americanus ), kit foxes and black-footed ferrets ( Figure 7 , Table S2 ).

Temporal variation in vertebrate community diversity

To assess whether the comparisons of current vertebrate diversity in the Janos region were the outcome of the land use changes that have occurred in the last two decades, we compared the vertebrate species assemblages in Janos over a ca. 10-year period. The results indicate that the vertebrate community structure and diversity has showed a much more complex, dynamic scenario than when only comparing current diversity data. In the absence of experimental data we cannot determine specific causes of these changes with certainty, but there was a pervasive correspondence among land use changes and vertebrate community changes. Dramatic declines have occurred in both grassland birds and mammals over the ca. 10-year period concomitant with the large declines in area covered by grasslands ( Figure 9 ). Birds showed a two-fold decline in density from 1994 to 2004. Unsurprisingly, species most typical of grasslands showed the largest declines, such as Horned Larks that experienced four-fold declines. Cottontail rabbits and small mammals also showed large declines with their densities decreasing by more than 50%. Prairie dogs exhibited the second greatest decline among small mammals with an 8-fold decrease in density just over the course of this study, from 16 per ha in 1994 to 2/ha in 2004. Medium and large mammals showed an overall 12-fold decline in abundance, ranging from more than a 20-fold decline in coyotes and skunks, to an eight-fold decline in the threatened kit foxes, and a five-fold decline in badgers.

Mammal and bird species in the Janos prairie dog grasslands showing dramatic declines in densities over time. (Note prairie dog densities are compared from 1994–2004.) Of the 33 bird species that were sampled, only those that exhibited a 2-fold or greater change over time are shown here.

https://doi.org/10.1371/journal.pone.0008562.g009

Our results reveal profound, rapid changes in the Janos grassland ecosystem. We documented large declines in the distribution of prairie dog colonies as well as in vertebrate abundance across all taxonomic groups evaluated, concomitant with severe land degradation. Further, the grassland and mesquite shrubland provided habitats for two markedly different vertebrate communities. Herpetofauna, mammals, and birds all differed greatly in community structure between the two habitats, and many were unique to only one of the habitat types. A few decades ago, the Janos region was a mosaic of grasslands mostly occupied by prairie dog colonies, shrublands, and riparian vegetation [27] . Under these rapid environmental changes, the grasslands are being transformed to shrublands, leading to desertification and biodiversity loss, as has been shown in other regions of the southwestern United States [28] . The transformation of the grasslands is clearly linked to prairie dog loss and intensive land use practices, exacerbated by drought.

The results follow the broader trend of over 95% decline in prairie dog populations throughout their range [29] . The decline in prairie dogs is known to have cascading effects on other animals, as many species associate with the open habitats and burrows that prairie dogs create and depend on prairie dogs as prey, such as black-footed ferrets, Mountain Plovers ( Charadrius montanus ), kit foxes, coyotes, badgers, raptors, and Burrowing Owls [e.g.] , [8] , [23] , [30] , [31,32] . As such, the decline in prairie dogs has likely contributed to the overall decline in the vertebrate community observed in our study. Our research also demonstrates that prairie dogs engineer grasslands by clipping shrubs, converting an invading shrubland back to open grassland. Conversely, the consequence of their loss results in shrub invasion. These results are consistent with Weltzin et al. [26] who found that prairie dogs eat the seeds and seedlings of mesquite shrubs and that shrub establishment occurs following their removal. They also surmised that the mass extermination efforts designed to eliminate prairie dogs over the last century in the United States likely contributed to the widespread expansion of mesquite shrubland.

Differences in vertebrate community structure between the prairie dog grasslands and the shrublands were expected. Yet, the differences we found were unexpected when compared to previous research in the region as well as reported ecological associations between species and their habitats. For example, although the mesquite shrublands were richer in bird species than the prairie dog colony grasslands, as would be predicted for structurally more complex habitats [33] , [34] , [35] , this result was the opposite from previous research in the area where bird species were three-times more rich in the grasslands than in the shrublands [36] . Another example is the bunchgrass lizard ( Sceloporus scalaris ), a species highly associated with perennial grassland habitat [37] , but which was more abundant in the shrublands in our study. This species may have preferred the more structurally complex shrublands compared to the heavily grazed grasslands, as it has been found to be ten-times more abundant in ungrazed perennial grassland than grazed grassland [38] . Even some small mammals common to grasslands, such as Ord's kangaroo rats ( D. ordii ) and hispid pocket mice ( Chaetodipus hispidus ), were significantly more common in the shrublands in our study.

These unexpected results and the rapid, large declines in grassland vertebrates are undoubtedly related to the overall grassland deterioration. After years of below-average precipitation and continuous overgrazing by domestic cattle, the Janos grasslands have become desertified annual grasslands and shrublands with extensive areas of bare ground [39] , [40] . In this degraded system, productivity is reduced and important resources, like food and refuge, are scarcer and less dependable. Indeed, grassland productivity declined in the Janos region from a 0.162 Normalized Difference Vegetation Index (NDVI) in 1990 to 0.068 in 2000 [39] . Cattle management practices in the region have not adapted to the productivity change, and much of the land is communally owned, referred to as Ejido lands, which has resulted in the tragedy of the commons [41] . Shrubs have expanded not only in Janos, but throughout the Chihuahuan Desert grassland since the late 1800's, a consequence of livestock grazing and seed dispersal, the disruption of fire regimes, and drought conditions [42] , [43] , [44] , [45] .

The contraction of prairie dog colonies between 1988 and 1996 was due to poisoning, and between 1996 and 2005 was a consequence of the synergistic effect of drought and overgrazing as well as increasing land conversion to agriculture primed by the expansion of utility lines [46] , [47] . While we only report the change in prairie dog colony sizes from 1988 and 2005, intermediate mapping efforts in 1996 and 2000 showed that the loss of prairie dog colonies was a continuous process [46] , [48] . To date, no plague events, which have been the cause of prairie dog declines elsewhere, have been recorded in the Janos prairie dog complex. Our findings on the decline of the grassland system in Janos are likely taking place in other areas of the Chihuahuan Desert and even in other drylands of the world [6] , [11] , [49] . The implication of the rapid loss in biodiversity to the overall conservation of grassland systems is dramatic, as grasslands cover about 40% of the planet's land surface and provide a large proportion of the world's food supply [7] , [12] . Such losses in biodiversity impact the provision of ecosystem services that grasslands provide. Indeed, as shown by our data, the loss of prairie dogs and inadequate land management practices are resulting in shrub encroachment, reducing the capability of the grasslands to provide forage for cattle, carbon sequestration, soil stability, water infiltration, and other ecosystem services. Our study provides evidence of the ecological decline of an ecosystem, as a consequence of the loss of a keystone species and extreme environmental pressures imposed by overgrazing, intensive agriculture, and drought. Global warming is further predicted to increase the frequency of droughts and aridity of the Chihuahuan Desert, causing up to 40% species turnover by 2055 [50] , which we can expect to exacerbate the current ecological conditions in the Janos region, unless major changes in land management are made.

Conservation implications

The rapid deterioration of the Janos grassland ecosystem has led us to propose conservation and management solutions that can be applied at a landscape level [14] . To do this, we designed a half million hectare biosphere reserve in the Janos region to help conserve the grasslands, prairie dogs, and regional biodiversity in a way that is compatible with human economic activities, especially grazing and agriculture ( Figure 1 ). The Janos Biosphere Reserve has now been announced in the Official Registry of the Federal Government of Mexico and will become official later in 2009.

We are now working on a new paradigm in conservation for the Janos region that incorporates human activities as part of a large-scale conservation strategy, and avoids fighting the powerful cattle and agricultural industries to instead use them at a local scale as agents of restoration. We are designing management plans for using grazing and agriculture to maintain the grassland. For example, we are using cattle grazing to open grasslands and allow prairie dogs to re-colonize them more rapidly, and in turn helping the long-term maintenance of the grassland ecosystem. Reducing grazing pressure can allow grasses to grow and help restore the now absent fire. Fire and prairie dogs can limit shrubland encroachment and expand the more productive grasslands for the benefit of cattle ranching, and cattle and fire can reduce vegetation height that allows prairie dog colonies to expand into the grassland.

Similarly, we plan to use intensive agriculture to restore grassland that has been desertified to shrubland. Eliminating mesquite shrubland is extremely expensive, and therefore, usually impossible to do as a large-scale restoration approach. In Janos, there are thousands of hectares of such shrublands that can be reconverted to grasslands if industrial agriculture is first used to clear the invasive mesquite and plant commercial crops for a set period. After that period, these areas will be planted with perennial native grasses and converted into grasslands. There are incentives for both intensive agriculture and conservation to employ such a strategy. On one hand, the land for new agricultural fields is now limited because of the reserve, so using it as a restoration technique will allow the generation of a local income through agriculture to continue in the coming decades. On the other hand, using the economic power of agricultural groups to eliminate the invasive mesquite shrubs, a now impractical conservation strategy because of the cost, will be a major achievement for the long-term ecological restoration of the region. These are just a sample of the many possible human-ecological strategies that could be employed to restore and maintain native ecosystems in the Janos area and elsewhere.

Ultimately, for sound, long-term ecosystem conservation in the face of increasing global challenges, it is urgent to complement traditional land use and endangered species conservation approaches with novel strategies that couple the human dimension (e.g., culture) and ecological systems. As scientists, this is one of the most critical challenges of our time, and our responsibility includes finding answers for the problems.

This study was conducted in the Janos Casas Grandes prairie dog complex, a mosaic of native grasslands and shrublands in northwestern Chihuahua, Mexico (30° 50′N, 108° 24′W) ( Figure 1 ). The grasslands are presently dominated by the annual grasses, sixweeks threeawn ( Aristida adscensionis ), needle grama ( Bouteloua aristidoides ), and sixweeks grama ( B. barbata ), and numerous forbs. Perennial grasses present include poverty threeawn ( A. divaricata ), ear muhly ( Muhlenbergia arenacea ), burrograss ( Scleropogon brevifolius ), vine mesquite ( Panicum obtusum ), tobosagrass ( Pleuraphis mutica ), blue grama ( B. gracilis ), black grama ( B. eriopoda ), and red grama ( B. trifida ). The shrublands are dominated by mesquite, ephedra, and cholla ( Opuntia imbricata ). The climate is semi-arid, with hot summers and cold winters ( X  = 15.7°C, range  = −12 to 50°C). Most of the precipitation occurs during the summer, with an average annual rainfall of 287 mm, although during most of our study rainfall was below average (1993–1996 and 1998–2003, Figure S1 ).

Landscape-scale changes over time

To determine the large-scale vegetation changes over time in the Janos region, a supervised classification of satellite imagery (Landsat TM for 1990 and Lansat ETM+ for 2000) at a 25 m×25 m resolution, using ENVI software (ITT Visual Information Solutions v. 4.5) was made, using the resulting algorithms from a decision tree generated by the program See5 for Windows (Rulequest Research Data Mining Tools) [39] . The area of prairie dog colonies transformed to agricultural land was determined by counting the number of center pivot crops and measuring their diameter to determine area from a real color satellite image from 1993 [51] and from Google Earth in 2008 [52] , over a 4,250 km 2 area.

Prairie dog decline and shrub control

To assess the change in area occupied by prairie dogs, the entire Janos prairie dog colony complex was mapped by following the contour of each colony in 1988 on horseback, walking, or flying, using a theodolite and topographic maps (1∶250 000). The complex was mapped again in 2005 by walking, cycling, or riding an ATV and taking coordinates with a Global Positioning System receiver (GPS) every 150 m. A prairie dog burrow was considered as being part of the same colony if it was <150 m from a previously mapped burrow, which represents roughly 1.5 times the distance prairie dogs have been observed moving away from their burrows in their foraging activities in the area.

Using the above methods, we followed parts of two colonies over time to evaluate the change in shrub expansion/contraction in response to prairie dog removal/colonization. One of the colonies originally mapped in 1988 (4,930 ha) was poisoned from 1988–1990, and the vegetation types on 2,500 ha of this colony were mapped in 1996 as part of another study [31] , [46] , which allowed us to document the expansion of shrubs into the area originally occupied by prairie dogs. Prairie dogs were observed building burrows and chewing ephedra at the edge of prairie dog colonies that were surrounded by shrublands. In one particular colony, mapped in 2000 (1,270 ha), the expansion was evident, so it was re-mapped in 2005 to document this expansion. To determine the impact of prairie dogs on ephedra shrubs, 100 individual shrubs were examined along a transect at the edge of the colony where it was expanding, and along an adjacent transect extending 50 m away from the colony. The height of each shrub was measured, and it was examined for presence or absence of prairie dog teeth signs, exposure of the roots by prairie dog burrows, and clipping of stems and branches.

Prairie dog densities were determined in 1994 (420 transects), 1995 (384 transects), 1996 (304 transects), and 1999 (234 transects) by counting the number of active and inactive burrows along 1 km×3 m wide transects within the prairie dog colony grasslands following methods described in Biggins et al. [53] . Parallel transects were established, each separated by 40 m. To reduce the observer error in assigning burrows as active or inactive, or other biases of the method [54] , density estimates in 2001 onwards were based on maximum number of prairie dogs aboveground at any one time observed from 12 4.5 ha quadrants (triangles). The triangle method consisted of three triangles measuring 150 m per side (4.5 ha) around an observer located at the center. The vortices of the triangles were 50 m from the observer, so by turning around, the observer could record the number of prairie dogs within each triangle every 10 minutes.

Vertebrate diversity in grasslands with prairie dog colonies and in mesquite shrubland was assessed by establishing 4 replicate plots in grassland habitat and 4 replicate plots in shrubland habitat within a mosaic of a ca. 15,000 ha prairie dog colony and mesquite shrubland ( Figure 2 ). Ten field trips, covering all 4 seasons, were conducted for all vertebrate groups between November 2000 and June 2002 ( Table S3 ). While our previous studies have compared vertebrate diversity in prairie dog colonies and adjacent grasslands in this area between 1992–1996 [21] , [55] , [56] , the grassland without prairie dogs is a transient vegetation type. It often is rapidly invaded by woody plants, mainly mesquite and ephedra, converting it into shrubland. Thus, our objective was to determine if the overall vertebrate diversity would decline when grasslands become desertified shrublands, losing species exclusive to the grasslands/prairie dog colonies [45] , [57] . Reptile and amphibian diversity was compared with pitfall traps [58] . From 2000–2004, pitfall traps were established in a 3×3 grid array, with traps separated by 30 m in each of the 4 grassland study sites and 4 shrubland study sites (overlapping with the mammal grids and bird surveys during the same period, Figure 2 , Table S3 ). Each trap consisted of a standard 20 liter plastic bucket [59] . The traps remained opened for three consecutive days in each sampling period. Each site was checked every morning or twice a day on extremely hot days.

Bird diversity was assessed with point count transects [60] from 1994–1995 in various colonies of the prairie dog complex including the 4 grassland study sites ( Figure 2 , Table S3 ), and in 2000–2004 the transects were sampled in each of the 4 grassland and 4 shrubland sites. In 1994–1995, each transect was 2.5 km long and paired with a parallel replicate transect located 1 km away. Each transect had 10 point counts at 250 m intervals (160 point counts total) [56] . In 2000–2004, each transect was 1.2 km long and paired with a parallel replicate transect located 1 km away. Each transect had 5 point counts at 300 m intervals (160 point counts total). For all point counts, the radius was 50 m and sampling time was 5 minutes. The number of individuals of each species and their distance from the center of each point count at 50 m, 100 m and >100 m intervals were recorded.

Small mammal diversity was estimated from 7×7 grids, with 49 Sherman traps each separated by 10 m. In 1992–1996, the sampling took place in two sites in a 15,000 ha colony and one 194 ha colony ( Figure 2 , Table S3 ). In each site a grid was established in the interior of the colony, one at the edge, and one in the shrubland 150 m from the edge of the colony. In 2000–2002 the small mammal trapping grids were established in the 4 grassland and 4 shrubland sites ( Figure 2 , Table S3 ). Traps were opened for two consecutive nights on each grid. The small mammal trapping grids established on the prairie dog colony grasslands in 2000–2002 were in a different location than those established in 1992–1996 to accommodate different sampling designs.

Lagomorphs and carnivores were sampled along all available roads within the shrubland and prairie dog colony grassland study sites from 1994–1996 and 2000–2002 ( Figure 2 and Table S3 ). Lagomorphs were estimated by spotlighting at night from a vehicle with two 1-million candle searchlights at 8 km/hr, expressed as number of individuals seen per km of transect to standardize transects of variable length [46] ( Figure 2 , Table S3 ). During each sighting, species were identified as either desert cottontail or black-tailed jackrabbit and the number of individuals was recorded. Carnivore density was determined on the same road transects, taking the perpendicular distance and angle, with respect to the transect's center, for each carnivore sighted [61] .

Data Analysis

For data analysis of comparisons between vertebrate communities in the shrubland and grassland habitats, we used non-parametric statistics on all data sets, and data for each vertebrate group were pooled across seasons. Statistical significance was set at P<0.05. Wilcoxon Two-Sample (W) tests were used to analyze differences in herpetofauna, birds, and small mammals between the grassland and shrubland habitats [62] . Separate analyses were then conducted for each vertebrate group to evaluate differences in total abundance, species richness, functional groups, trophic groups, and each species between the grassland and shrubland habitats. DCA was used to test for potential differences between the grassland and shrubland sites based on simultaneous analysis of all species of vertebrates [63] , [64] . MRPP was used to provide a multivariate test of significance based on Euclidean distances [64] , [65] . For the DCA and MRPP, very rare species were removed from the data sets [64] , [65] . Chi-square tests then were used to compare the relative abundance of lagomorphs between the grassland and shrubland sites. Carnivore densities were estimated using the program Transect, which compensates for differences in sighting distance between the grassland and shrubland habitats [66] . Given the small sample size, no statistical tests were conducted on the carnivore data. Comparisons were made between prairie dog grasslands over time by calculating the difference in the density of each vertebrate species over time.

Supporting Information

Signs of prairie dog impact on 100 Ephedra trifurca shrubs at the edge of an expanding prairie dog colony, and 50 m away from the colony into the shrubland.

https://doi.org/10.1371/journal.pone.0008562.s001

(0.03 MB DOC)

Species associated with the prairie dog colony grassland habitat, based on total abundance for herpetofauna, birds, and small mammals and total densities for carnivores over all sample periods in the grassland (Grass) and shurbland (Shrub) habitats. Statistical results for herpetofauna, birds, and small mammals are based on Wilcoxon Two-Sample tests (N = 8). Conservation status in Mexico: SP - Subject to Special Protection, T - Threatened, E - Endangered [67] (SEMARNAT 2002).

https://doi.org/10.1371/journal.pone.0008562.s002

(0.06 MB DOC)

Sampling periods and effort (in days) for herpetofauna, birds, and small mammals, and kilometers of transect for medium and large mammals in the Janos region of northern Chihuahua.

https://doi.org/10.1371/journal.pone.0008562.s003

Mean annual precipitation from 1957–2005 in the Janos-Casas Grandes region. The dotted line indicates the long-term mean annual precipitation for the region (287 mm). The Janos prairie dog colony complex was first mapped in 1988 and then re-mapped in 2005. The vertebrate communities were first sampled in 1994–1996 and then in 2000–2003. Comparisons between the shrubland and grassland communities were made in 2000–2003. The change in land cover was obtained from satellite images from 1990 and 2000.

https://doi.org/10.1371/journal.pone.0008562.s004

(0.14 MB DOC)

Acknowledgments

We thank Yolanda Domínguez, Mark Doughty, Mark Eaton, Elsa Figueroa, Andrés García, Héctor Gómez de Silva, Manuel Grosselet, Loe Hanebury, Beatriz Hernández, the Janos Christmas Bird Count crews (1995–2004), Everardo Jiménez, Glenn Johnson, Sandy Lanham, Guadalupe Mondragón, Erika Marcé, Cynthia Melcher, Gisselle Oliva, Cengiz Philcox, Eduardo Ponce, Hugo Rivas, Rodrigo Sierra, and Bejamín Vieyra for data collection, Rafael Ávila-Flores and Alejandra de Villa Meza for sharing their land cover data, and Heliot Zarza for creating the maps. David Macdonald and Conn Nugent provided invaluable support to the project over the years. Charles Curtin offered helpful comments on a previous version of the manuscript.

Author Contributions

Conceived and designed the experiments: GC RL JP PMF GSB. Performed the experiments: GC RL JP PMF GSB JC. Analyzed the data: GC ADD. Wrote the paper: GC ADD RL.

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Grasslands Explained

Savanna, steppe, prairie, or pampas: They're all grasslands, the globe's most agriculturally useful habitats.

Biology, Ecology, Conservation, Earth Science, Climatology

Little Missouri National Grassland

Grasslands, like the Little Missouri National Grassland in the United States, fill the ecological niche between forests and deserts, often bordering the two.

Photograph by Phil Schermeister

Grasslands go by many names. In the United States Midwest, they're often called prairies . In South America, they're known as pampas . Central Eurasian grasslands are referred to as steppes , while African grasslands are savannas . What they all have in common are grasses, their naturally dominant vegetation. Grasslands are found where there is not enough regular rainfall to support the growth of a forest, but not so little that a desert forms. In fact, grasslands often lie between forests and deserts. Depending on how they’re defined, grasslands account for between 20 and 40 percent of the world's land area. They are generally open and fairly flat, and they exist on every continent except Antarctica, which makes them vulnerable to pressure from human populations. Threats to natural grasslands, as well as the wildlife that live on them, include farming, overgrazing, invasive species, illegal hunting, and climate change . At the same time, grasslands could help mitigate climate change: One study found California's grasslands and rangelands could store more carbon than forests because they are less susceptible to wildfires and drought. Still, only a small percentage—less than 10 percent—of the world's grassland is protected. Types of Grasslands There are two main kinds of grasslands: tropical and temperate . Examples of temperate grasslands include Eurasian steppes, North American prairies, and Argentine pampas. Tropical grasslands include the hot savannas of sub-Saharan Africa and northern Australia. Rainfall can vary across grasslands from season to season and year to year, ranging from 25.4 too 101.6 centimeters (10 to 40 inches) annually. Temperatures can go below freezing in temperate grasslands to above 32.2 degrees Celsius (90 degrees Fahrenheit). The height of vegetation on grasslands varies with the amount of rainfall. Some grasses might be under 0.3 meters (one foot) tall, while others can grow as high as 2.1 meters (seven feet). Their roots can extend 0.9 to 1.8 meters (three to six feet) deep into the soil. The combination of underground biomass with moderate rainfall—heavy rain can wash away nutrients—tends to make grassland soils very fertile and appealing for agricultural use. Much of the North American prairielands have been converted into land for crops, posing threats to species that depend on those habitats, as well as drinking water sources for people who live nearby. Grassland Plants and Animals Grasslands support a variety of species. Vegetation on the African savannas, for example, feeds animals including zebras, wildebeest, gazelles, and giraffes. On temperate grasslands, you might find prairie dogs, badgers, coyotes, swift foxes, and a variety of birds. There can be up to 25 species of large plant-eaters in a given grassland habitat, comprising a sort of buffet where different grasses appeal to different species. Some grass species in these habitats include red oat grass ( Themeda triandra ) and Rhodes grass ( Chloris gayana ) in tropical savannas, and purple needlegrass ( Nassella pulchra ) and galleta in temperate areas. When rainy season arrives, many grasslands become coated with wildflowers such as yarrow ( Achiella millefolium ), hyssop, and milkweed. The plants on grasslands have adapted to the drought, fires, and grazing common to that habitat. Fires, both natural and human-caused, are important factors shaping grasslands. In the U.S. Midwest, for example, Native Americans set fires to help maintain grasslands for game species, such as bison. Fire can also help prevent fire-intolerant trees and shrubs from taking over while increasing the diversity of wildflowers that support pollinators.

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• Environment

Amid “Rewilding” Trend, a 2,800-Acre English Farm Will Turn to Grassland

“the soil wants to be abundant, it wants to be rich with wildlife.”, patrick barkham.

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A view of the Wiltshire countryside outside Devizes. Andrew Parsons Media / ZUMA

This story was originally published by   the   Guardian   and is reproduced here as part of the  Climate Desk   collaboration.

The rolling hills south of Salisbury Plain are a bleak scene of vast arable fields and tightly grazed pasture dotted with scores of sheep.

In recent decades,  Lower Pertwood farm  has embraced organic growing, producing oats, barley and other crops, while boosting numbers of rare corn buntings and other wildlife with wildflower banks and newly planted trees.

But as wildlife continues to decline in  Wiltshire  and the farm’s profits plummet amid an increasingly unpredictable climate, the owners are turning to farming nature instead.

The 2,800-acre arable farm begins its transformation this spring into the biggest grassland rewilding project in southern  England , in an attempt to restore declining plants, insects and endangered species including cuckoos, grasshopper warblers, and turtle doves.

The “Pertwood Plain” project, masterminded by Restore, a land management company  specializing in large-scale restoration  led by the naturalist Benedict Macdonald, will ultimately see low densities of pigs and cattle roaming free to recreate flower-rich chalk grassland. This naturalistic grazing, alongside interventions such as adding green hay and brash piles where birds perch and excrete seeds into the soil, will give rise to a mosaic of grass and scrubland teeming with invertebrate life.

In the future, visitors could enjoy the return of extinct species including the  great bustard , which has been reintroduced on to nearby Salisbury Plain, and the charismatic  red-backed shrike , which became effectively extinct as a breeding bird in Britain in the 1990s.

“It’s enormously exciting,” said Macdonald. “Salisbury Plain on the horizon is like a giant, free seed bank of species, some of which—such as the reintroduced great bustard—might naturally explore Pertwood as it begins to recover.”

Tamara Webster, the director of the family-owned farm, said: “We have been looking, almost subconsciously, for a long time for an all-embracing blueprint for the future. One that can deliver environmental restoration, truly sustainable food production and achieve financial stability and profitability. This is why we commissioned the holistic research by Restore and we are extremely excited about what we hope to achieve together.”

In 2022, this large arable farm on  grade 3 farmland (a measure of good to moderate growing soils) made £179,000 profit (about $226,000). The following year, it posted a £180,000 loss ($227,300), spending £135,000 on fertilizer, £65,000 on muck and slurry, £43,000 on red diesel and losing £113,000 on farm machinery depreciation.

The rewilded farm will cut fertilizer and these other costs to virtually zero and sell off its expensive machinery. Staff numbers are expected to remain the same with some retained for new roles such as grazier. Typically,  rewilded estates employ more people  than conventional agriculture.

An increasing number of traditional farms are  turning to nature  regeneration as investors bank on speculative future revenues from carbon and biodiversity credits and payments for  biodiversity net gain (BNG) . This is where developers are legally obliged to “buy” or create natural areas to ensure every new housing estate leads to an uplift in nature.

Pertwood is setting aside a modest 50 acres for BNG and will continue to produce food—organic beef and pork—but its transition has been made financially straightforward by a  “wood pasture” funding option in the government’s countryside stewardship scheme. This guarantees the farm annual payments of £300,0000 ($379,000) for 10 years.

The wood pasture funding is proving popular with farmers who have been reluctant to completely stop farming and turn land over to forestry to sequester carbon. To create wood pasture, farmers can continue low-density livestock farming but allow scrub and woods to naturally regenerate and expand over fields to create a mosaic, which benefits a wide range of species and sequesters carbon.

Matt Collis, the lead ecologist at Restore who is measuring soil health and biodiversity at Pertwood, said: “Calcareous grassland is always the most diverse and botanically rich soil type, with 50 or 60 plant species in a few square meters. To get that into its ecological peak is very exciting. The opportunity for surprises is very high here. The soil wants to be abundant, it wants to be rich with wildlife.”

Is Big Agriculture Finally Having a “Come to Jesus” Moment?

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The Secret to Successful Rewilding Isn’t Trees—It’s People

Phoebe Weston

Rewilding the American West

King Corn Mowed Down 2 Million Acres of Grassland in 5 Years Flat

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Experts expanding the reach of engineering research

Between the roles of students learning in labs and the faculty who chart the course of that research, a group of specialists give the research enterprise incredible strength.

• Alex Parrish
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Addressing global challenges requires a strong team, and the work that occurs between the formation of an idea and the presentation of a solution demands skilled hands.

Many of the research faculty who direct labs at Virginia Tech have projects in motion with the potential of making a better world, but that research requires extensive trial and error. To best complete the work that happens between the beginning and the end of those projects, the engagement of skilled experts is essential. 

Those same skilled experts also bring mastery into the sphere of educating, standing beside students at a lab bench or lending their knowledge to the next generation of engineers and scientists. 

A little more than 5 percent of all employees at Virginia Tech are identified as a postdoctoral associate, research associate, research assistant professor, or postdoctoral associate. Some are attached to specific projects; others work broadly with faculty who are managing a large portfolio.  

In most cases, the work comes after acquiring a doctorate in the field, so expertise is firmly established. These are critical positions in the Department of Mechanical Engineering , which hosts more than 30 labs that push the boundaries of innovation through funded research from agencies both domestic and international. Two people working in that realm are Amanda Leong and Sibin Kunhi Purayil.

The nuclear option: Amanda Leong 

The nuclear engineering program within the mechanical engineering department has several labs in Blacksburg, and two of them house the work of Professor Jinsuo Zhang. To manage multiple projects and students at two sites, Zhang relies on Research Assistant Professor Amanda Leong. 

Leong came to Virginia Tech after finishing her bachelor’s degree in mechanical engineering at Ohio State, jumping straight into the doctoral program in the College of Engineering with Zhang. She had started with Zhang’s lab when both were in Ohio, where she first started working in nuclear engineering. 

She followed the research to Virginia, completing her Ph.D. and learning her way around Blacksburg labs. Her own research focus is on energy, particularly the area of material corrosion in advanced nuclear reactors and the use of molten salt as a fuel or coolant in energy plants.  

In her role as a research assistant professor, Leong mentors two senior design teams with projects in her area of expertise, one in the Department of Mechanical Engineering and one in the Department of Material Science and Engineering . In addition to those teams, she co-supervises the lab’s students’ and postdocs’ research and helps address questions as they arise. She also serves as main advisor to an undergraduate research team. 

“Dr. Leong does the work of the lab directly,” said Zhang. “Because of her work, we are able to get solutions more quickly when students have issues or problems or when they develop new ideas and new research directions." 

She also has continued her own investigations and an increase in the number of published papers that she has produced has followed. 

“When you’re a student, you usually just work on one project,” Leong said. “I oversee several.” 

With her background in the field, Leong also helps analyze the data coming from the team’s research, quickly filtering issues that could derail the learning process so that students can more easily interpret what they’re seeing. 

“Because I was exposed to research earlier, I pick up some things that newer people might not be able to see,” she said. “I really enjoy teaching students, seeing their light bulbs come on. I love solving problems together.” 

Leong is enjoying the work she has found in Zhang’s lab, and her hopeful long-term plan is to find her way to a tenure-track research and teaching position. 

Bringing solar energy home: Sibin Kunhi Purayil

Sometimes, a research scientist with specialized skills is needed for a specific project. This is how Sibin Kunhi Purayil came to work for Ranga Pitchumani , the George R. Goodson Professor of Mechanical Engineering, in the Advanced Materials and Technologies Laboratory . 

Purayil earned his Ph.D. in India and worked at the National Aerospace Laboratory before being recruited for Pitchumani’s solar energy research at Virginia Tech. Pitchumani is  editor-in-chief of the peer-reviewed journal Solar Energy  and was  chief scientist of the SunShot Initiative , a federal grant challenge aimed at making solar energy more widely instituted. 

Pitchumani received funding in 2018 from the U.S. Department of Energy for a new project to develop high efficiency solar absorber coatings viable at high temperatures, and it was a perfect fit for Purayil’s skill set.  

The young scientist spent a lot of time during his 2019 postdoctoral work developing nanometer-thick flexible, transparent, and conductive coatings. These could be used for space, flexible electronics, and solar energy applications employing sophisticated thin film deposition techniques, and he was eager for new opportunities. 

Purayil sought a position that would allow him to continue making contributions to the greater environmental good: reduce the carbon dioxide emissions that can result from energy production.  

“My goal was to, in my way, reduce carbon emission and work toward global carbon neutrality,” Purayil said. “This project has a lot of possibilities, and if we can improve the solar absorber’s efficiency, it could make a significant contribution to that cause.” 

Pitchumani’s project – involving harvesting solar thermal energy at high temperatures with high efficiency - was a great match for Purayil’s goal. Purayil used a novel approach utilizing highly textured, high-temperature-stable solar absorber coatings designed to operate at temperatures exceeding 750 degrees celsius in an air atmosphere. The coatings they chose were made through cost-effective and industrially viable deposition techniques, meaning the technology will be more readily transferable from lab to practice.  

Purayil’s prior work with coatings and materials had equipped him with the experience Pitchumani needed. Together they have created the most efficient absorber of solar energy for high temperature solar thermal processes, be it power generation, providing industrial process heat, or producing solar fuels, all contributing to a decarbonized future — and to Purayil’s professional goals. Pitchumani and Purayil have filed for a patent on this innovation. 

Better results through expert teams 

One of the advantages of the research enterprise at Virginia Tech lies in its blend of experts with budding inventors. By employing specialists who both innovate and teach, a full body of knowledge is being passed on to the next generation of engineers. 

In the cases of Leong and Purayil, both have had the opportunity to take their proven acumen in academics to the next level, giving back to learning, and building their own body of work. Working beside professors with long histories in their fields provides insights for how that body of work fits into the bigger picture while finding solutions to the world’s most complex problems.

Chelsea Seeber

540-231-2108

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• Science and Technology Directorate
• Feature Article: New Geo-Tracking Buoys Live Test Events

Feature Article: New Geo-Tracking Buoys Make a Splash During Live Test Events

New rugged buoy technologies equipped with Automatic Identification Systems aim to help the U.S. Coast Guard mark and track objects in the water.

Recent years have seen an uptick in the use of geo-tracking technology, which has become so widespread and affordable that we are able to attach small trackers to car keys or luggage to find them with our smartphones. The Science and Technology Directorate (S&T) is working with the U.S. Coast Guard (USCG) to develop buoys with improved geo-tracking technology for mission specific field use.

Instead of looking for car keys, USCG crews can use this technology to find and mark critical locations or objects in the water using buoys deployed from air or surface vessels. These could include stranded boats, contraband, or hazardous waste that are required to be reidentified after initial search and rescue or interdiction efforts are complete. The two new buoy systems, created by S&T industry partners, are moving into the final round of testing this year after successfully completing functional tests in 2023.

Building a Better Buoy

The USCG handles thousands of cases each year , each potentially involving the deployment of numerous supporting assets necessary to complete those missions. After the initial response efforts, ocean currents and associated weather conditions can carry away watercraft or other manmade materials from the original incident site. This presents a challenge for USCG crews since those materials left behind can become navigation hazards in busy shipping lanes or involve illegal goods. During a drug interdiction, for example, suspects will often throw contraband overboard while fleeing. Determining where these illegal materials are located is an essential part of gathering evidence and protecting the nation’s coasts; therefore, finding them quickly is key.

“The availability of accurate, real-time geo-position data is critical in verifying the drift and motion of items of interest and assisting in the planning of a search and rescue or other response mission,” said Edwin Thiedeman of the USCG Office of C4 & Sensors Capabilities.

“S&T is working closely with the vendors, USCG subject matter experts, and operators to deliver more capable buoys to support multiple USCG missions. These new improved buoys will provide the USCG with much improved accuracy and reliability to execute their important maritime missions,” stated Ron McNeal, S&T Silicon Valley Innovation Program (SVIP) transition director.

While the USCG currently has geo-tracking buoys, the existing systems do not have a secondary locator that is visible at sea level day and night in case of geo-tracking failure. The existing systems are not reusable or rechargeable, so they have to be replaced frequently, representing a significant cost and a potential loss in data. S&T’s SVIP put out a call to industry through the Maritime Object Tracking Technology (MOTT) solicitation for rugged geo-tracking buoys that could be quickly deployed from both air and surface vessels traveling at high speeds. The buoys needed to transmit Automatic Identification System (AIS) and Global Positioning System (GPS) data, which large ships use to share and receive location data while traversing the world’s waterways. Having AIS/GPS capabilities built into the buoy helps ensure USCG crews would be able to quickly pick up signals using their existing communications equipment.

“The ability to link small innovative businesses directly with the government to provide new technologies to fit government needs has a wide range of benefits for all parties. With all of this in mind, MOTT’s goal was to find a start-up company with a new or existing buoy system that could be tailored to the USCG’s needs, resulting in more efficient technology transition and acquisition processes,“ said CDR Rebecca Fosha, deputy of the USCG Research, Development, Test & Evaluation and Innovation Program .

Following the solicitation’s initial launch in March 2020, SVIP awarded funds to two companies: Kenautics, Inc. and Morcom International, Inc . Each business had an existing system they could adapt to the USCG’s requirements: the Kenautics Global Positioning System AIS Navigation and Tracking Buoy and the Morcom Tracking Unit for Navigational Aid. Both companies reached Phase 3 of the SVIP funding lifecycle in 2023, which required functional tests in a real-world setting.

“Startups typically don’t have the human or financial capital to champion large R&D projects,” said Melissa Oh, SVIP managing director. “Using the SVIP phased approach, we are quickly able to assess if a technology will have the ability to respond to the given need and transition the technology to the operators on a timeline that allows smaller businesses to be competitive.”

Go For Test Launch

In August and November 2023, staff from SVIP and the USCG Research, Development, Test & Evaluation and Innovation Program traveled to USCG Base Elizabeth City, North Carolina, to conduct separate test runs for each of the new MOTT buoys. The tests focused on how the buoys operated when dropped from different altitudes and velocities, which involved deploying the systems from an MH-60T helicopter and an HC-130J fixed wing aircraft traveling at various speeds and altitudes. Evaluators were interested in how the rugged designs held up upon impact, given that one version of the buoy has a parachute and the other does not.

It was also important to see whether the buoys successfully continued to function when they impacted the water, while at the same time determining whether the buoy went too deep under the surface of the water. Going too deep underwater could risk the system striking the bottom, where it might potentially get stuck or malfunction once it resurfaced. Participants conducted 10 drops over the course of four days, which provided valuable feedback on improvements that Kenautics and Morcom International can incorporate into the next version of their prototypes.

“It was important to test the buoys in a realistic, operational environment—in this case Base Elizabeth City—to evaluate the structure, functions, and software integrity. Observation from USCG personnel and the companies provided valuable feedback to modify the buoys’ performance to better fit USCG missions,” noted Jason Pharr from the Tactical/Navigation Program Office in the Engineering Support Branch of the USCG Aviation Logistics Center.

In addition to testing the buoys’ ability to withstand water impact, S&T and USCG staff also evaluated their battery life and cybersecurity. Rechargeable batteries are one of the design components that will help make the new buoys more cost effective than current models, so it was important to see how long they could operate in an open ocean environment.

Test sessions were conducted over several flights lasting approximately two hours for each sortie, which gave a realistic scenario of how long it might take USCG crews to return to an incident site once conditions were safe. During operational deployment, the buoys utilized strobe lights, radio beacons and transmitted AIS information approximately every 10 minutes so crews could pick up the signals on both visual and radio frequency scanners. Separate from the drop tests but related to the buoys’ communications capabilities, S&T also conducted Red Team testing with a third party to determine whether there were any cybersecurity issues for either system. The goal was to see whether the buoy signals could be vulnerable to detection or hacking by civilian systems, since this could represent a potential risk.

The Next Wave

Last year’s Phase 3 test sessions provided critical insight into how the MOTT buoys could be improved moving forward. The next rounds of operational evaluations are scheduled to take place later in 2024. The MOTT buoy is one of S&T’s joint projects between S&T and the USCG through SVIP, which also includes a Language Translation device that operates offline in a zero-connectivity environment. These systems could potentially join a growing list of solutions that empower our nation’s homeland security operations while promoting more efficient technology transition-to-market.

For additional information about S&T’s maritime security work and the SVIP program, contact [email protected] .

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• Vehicle Technologies Office
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Office: Vehicle Technologies Office FOA number:  DE-FOA-0003248 Link to apply:  Apply on EERE Exchange FOA Amount: $45,800,000

Today, the Department of Energy (DOE) announced $45.8 million in new funding for projects that will advance research, development, demonstration, and deployment (RDD&D) critical to achieving net-zero greenhouse gas emissions in the transportation sector. The funding will drive innovation in equitable clean transportation and is aligned with strategies detailed in the U.S. National Blueprint for Transportation Decarbonization . 

The funding is through DOE’s Office of Energy Efficiency and Renewable Energy (EERE). Topic areas in the Vehicle Technologies Office (VTO) Fiscal Year (FY) 2024 R&D funding opportunity include:

• Next-generation phosphate-based cathodes.
• Advancing the state of the art for sodium-ion batteries.
• Developing concepts for decreasing greenhouse gas emissions from off-road vehicles such as construction, agriculture, mining, and forestry vehicles.
• Developing and deploying vehicle-to-everything technologies that can lead to meaningful savings at the vehicle and transportation system level.
• Developing high-performance, domestically produced electrical steels (E-steels) for use in electrified powertrains.
• Addressing critical cybersecurity needs for smart and secure electric vehicle charging.

As part of the Biden-Harris Administration’s commitment to ensuring the benefits of a clean transportation system are shared equally, the funding seeks the participation of underserved communities and underrepresented groups. Applicants are required to describe how diversity, equity, and inclusion objectives will be incorporated into their project. 

VTO provides a series of funding opportunity announcement (FOA) information session videos , which help applicants understand VTO’s FOA process and requirements. The recently released, Session 3: Tips for a Strong FOA Application, includes best practices for incorporating Diversity, Equity, Inclusion, and Accessibility in a project.

Learn more about this and other funding opportunities on VTO’s funding webpage . 

Topic Areas

Topic Area 1: Next-Generation Phosphate-Based Cathodes

This topic area targets the development of phosphate-based cathode materials that surpass the performance of state-of-the-art lithium iron phosphate (LFP) cathode materials, which are currently gaining traction as an alternative low-cost solution. The primary objective of this area of interest is to develop high energy density battery cells containing phosphate-based cathodes at the material and cell level.

Topic Area 2: Na-ion Battery Seedling Projects for Electric Vehicle Applications

While shifting to alternative cathode materials like LFP can alleviate the impact of nickel and cobalt, the impact of lithium has not been adequately addressed. One alternative to lithium is sodium (Na). While there is much promise for Na-ion chemistries, key issues still limit their adoption. This objective of this topic area is to advance the state of the art for Na-ion batteries by solving key challenges for the cathode, anode, or electrolyte through the development of 1 Ah full cells utilizing cell chemistries that are significant advancements over current industry state-of-the-art Na-ion technology.

Topic Area 3: Low-GHG Concepts for Off-Road Vehicles

The objective of this topic area is to develop and validate technology concepts capable of significantly decreasing greenhouse gas emissions, energy use, harmful criteria emissions, and total cost of ownership across the entire off-road vehicle sector, including construction, agriculture, mining, forestry, ports, warehouses, etc. Concepts must demonstrate they can meet the unique requirements for off-road vehicles and gain customer acceptance.

Topic Area 4: Saving Energy with Connectivity

Research has shown that vehicle-to-everything (V2X) communications can lead to meaningful energy savings at the vehicle and transportation system level by integrating interoperable vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), and vehicle-to-pedestrian (V2P) communications. The objective of this topic area is to develop and deploy V2X technologies with a focus on the efficiency and convenience of the mobility ecosystem, while reducing transportation’s environmental impacts. Examples could include but are not limited to eco-driving along connected corridors, transit or freight priority, integrated corridor management, or passenger or freight trip-chaining optimization.

Topic Area 5: Domestically Produced Electrical Steels (E-Steels)

The US transportation sector is in a technology revolution where light-duty vehicles are rapidly transitioning from internal combustion engines to electrified powertrains. Although most of the vehicles are produced in the US, many of the powertrain components rely on imports and foreign supply chains. Of particular interest are traction motors and their components. The objective of this topic are is to develop E-Steels meeting properties including frequency, thickness, ductility, cost, and manufacturability. 

Topic Area 6: Cybersecurity for Smart and Secure Electric Vehicle Charging

This topic area is addressing critical cybersecurity needs to address through two subtopics: 

• Subtopic 6.a: Enabling Wide-scale, Cybersecure EV/EVSE Aggregation for Grid Services :  To support the integration of electric vehicles (EVs) and their charging requirements with the electric grid, both government and the private sector have made significant investments in the development of smart charge management (SCM) systems and technologies for EV charging infrastructure. The objective of this subtopic area is to research, develop, and demonstrate systems, technologies, and tools necessary for the cybersecure aggregation of EVs and charging infrastructure to provide widescale, cybersecure grid services.
• Subtopic 6.b: Tools to Assess EV/EVSE/Charging System Cybersecurity Posture and Compliance with Standards and Protocols for Communications, Controls, and Monitoring :   Testing and evaluation of Electric Vehicle Supply Equipment (EVSE) by DOE national laboratories has clearly indicated a lack of compliance by many vendors with certified and/or regulated EV charging standards and protocols. In addition to creating cybersecurity vulnerabilities, this non-compliance greatly inhibits interoperability, supplier-managed SCM, and right-to-repair. The objective of this subtopic is to research, develop, and validate a suite of tools and associated procedures to comprehensively assess EV/EVSE/charging system compliance with relevant standards and protocols and cybersecurity posture.

Additional Information

• Download the full funding opportunity  on the EERE Exchange website.
• For FOA-specific support, contact  [email protected] . 
• Sign up for the  Office of Energy Efficiency and Renewable Energy (EERE) funding email list  to get notified of new EERE funding opportunities. Also sign up for  VTO’s newsletter to stay current with the latest news.
• Watch the VTO Funding Opportunity Announcement information series webinars.

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Use of Abortion Pills Has Risen Significantly Post Roe, Research Shows

By Pam Belluck

Pam Belluck has been reporting about reproductive health for over a decade.

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On the eve of oral arguments in a Supreme Court case that could affect future access to abortion pills, new research shows the fast-growing use of medication abortion nationally and the many ways women have obtained access to the method since Roe v. Wade was overturned in June 2022.

The Details

A study, published on Monday in the medical journal JAMA , found that the number of abortions using pills obtained outside the formal health system soared in the six months after the national right to abortion was overturned. Another report, published last week by the Guttmacher Institute , a research organization that supports abortion rights, found that medication abortions now account for nearly two-thirds of all abortions provided by the country’s formal health system, which includes clinics and telemedicine abortion services.

The JAMA study evaluated data from overseas telemedicine organizations, online vendors and networks of community volunteers that generally obtain pills from outside the United States. Before Roe was overturned, these avenues provided abortion pills to about 1,400 women per month, but in the six months afterward, the average jumped to 5,900 per month, the study reported.

Overall, the study found that while abortions in the formal health care system declined by about 32,000 from July through December 2022, much of that decline was offset by about 26,000 medication abortions from pills provided by sources outside the formal health system.

“We see what we see elsewhere in the world in the U.S. — that when anti-abortion laws go into effect, oftentimes outside of the formal health care setting is where people look, and the locus of care gets shifted,” said Dr. Abigail Aiken, who is an associate professor at the University of Texas at Austin and the lead author of the JAMA study.

The co-authors were a statistics professor at the university; the founder of Aid Access, a Europe-based organization that helped pioneer telemedicine abortion in the United States; and a leader of Plan C, an organization that provides consumers with information about medication abortion. Before publication, the study went through the rigorous peer review process required by a major medical journal.

The telemedicine organizations in the study evaluated prospective patients using written medical questionnaires, issued prescriptions from doctors who were typically in Europe and had pills shipped from pharmacies in India, generally charging about $100. Community networks typically asked for some information about the pregnancy and either delivered or mailed pills with detailed instructions, often for free.

Online vendors, which supplied a small percentage of the pills in the study and charged between $39 and $470, generally did not ask for women’s medical history and shipped the pills with the least detailed instructions. Vendors in the study were vetted by Plan C and found to be providing genuine abortion pills, Dr. Aiken said.

The Guttmacher report, focusing on the formal health care system, included data from clinics and telemedicine abortion services within the United States that provided abortion to patients who lived in or traveled to states with legal abortion between January and December 2023.

It found that pills accounted for 63 percent of those abortions, up from 53 percent in 2020. The total number of abortions in the report was over a million for the first time in more than a decade.

Why This Matters

Overall, the new reports suggest how rapidly the provision of abortion has adjusted amid post-Roe abortion bans in 14 states and tight restrictions in others.

The numbers may be an undercount and do not reflect the most recent shift: shield laws in six states allowing abortion providers to prescribe and mail pills to tens of thousands of women in states with bans without requiring them to travel. Since last summer, for example, Aid Access has stopped shipping medication from overseas and operating outside the formal health system; it is instead mailing pills to states with bans from within the United States with the protection of shield laws.

What’s Next

In the case that will be argued before the Supreme Court on Tuesday, the plaintiffs, who oppose abortion, are suing the Food and Drug Administration, seeking to block or drastically limit the availability of mifepristone, the first pill in the two-drug medication abortion regimen.

The JAMA study suggests that such a ruling could prompt more women to use avenues outside the formal American health care system, such as pills from other countries.

“There’s so many unknowns about what will happen with the decision,” Dr. Aiken said.

She added: “It’s possible that a decision by the Supreme Court in favor of the plaintiffs could have a knock-on effect where more people are looking to access outside the formal health care setting, either because they’re worried that access is going away or they’re having more trouble accessing the medications.”

Pam Belluck is a health and science reporter, covering a range of subjects, including reproductive health, long Covid, brain science, neurological disorders, mental health and genetics. More about Pam Belluck

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South Korean computer chipmaker plans $3.87 billion Indiana semiconductor plant and research center

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WEST LAFAYETTE, Ind. (AP) — A major South Korean computer chipmaker said Wednesday it plans to spend more than $3.87 billion in Indiana to build a semiconductor packaging plant and research and development center.

SK Hynix expects the campus to create as many as 800 high-wage jobs in engineering, technical support, administration and maintenance by the end of 2030.

The investment will move Indiana to the forefront of artificial intelligence in America, said Purdue University President Mung Chiang said. The new plant will be built at the Purdue Research Park, an economic development incubator at the university.

The company said the plant will produce high-bandwidth memory chips that will help meet U.S. demand for semiconductors, develop future generations of chips and house an advanced packaging research and development line at the 430,000-square-foot plant (nearly 40,000-square-meter) around 100 miles (160 kilometers) southeast of Chicago.

“We believe this project will lay the foundation for a new Silicon Heartland, a semiconductor ecosystem centered in the Midwest,” company CEO Kwak Noh-Jung said in a news release.

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The Indiana Economic Development Corp. offered the company of up to $3 million in incentive-based training grants, up to $3 million in manufacturing readiness grants, up to $80 million in performance payments, up to $554.7 million in tax rebates and other incentives. The cities of West Lafayette and Lafayette, Tippecanoe County and Duke Energy offered additional Incentives.