Changing land management of lowland wet grasslands of the UK: impacts on snipe abundance and habitat quality

Snipe Gallinago gallinago breeding on lowland wet grasslands in England have undergone widespread and dramatic declines in abundance and distribution since at least the 1970s. There are many potential drivers of the decline but reductions in habitat quality, driven by land management, are often proposed as a contributing factor in the historical declines of breeding waders. Breeding snipe are now restricted to a few key places such as nature reserves and environmentally sensitive areas where management for breeding waders is implemented. On average, populations have continued to decline, even in these key areas, though population trends vary from a decline of 98% to an increase of 61% between the early 1990s and 2006. We examined the relationship between regional variation in snipe population trends and soil conditions, other habitat features and land management. Snipe were more likely to persist in fields where the soil conditions were wet and soft. Fields are wetter and softer now than in the early 1990s and management influenced these conditions. Soil softness increased with decreasing grazing pressure and increasing surface flooding. Soil moisture increased with surface flooding and was higher in organic soils. Changes in field condition were consistent with decreases in grazing pressure and increases in surface flooding. In spite of habitat condition being altered in a way that should have been beneficial to snipe, the numbers have continued to decline. Thus, it is unlikely that the measures of habitat condition examined here have been the driver of the decline and other factors must be involved. Research efforts should now focus on alternative explanations of the decline, for example, changes in other key aspects of habitat quality such as prey abundance, or changes in snipe productivity or mortality.     

Shrub expansion modulates belowground impacts of changing snow conditions in alpine grasslands

Climate change is disproportionately impacting mountain ecosystems, leading to large reductions in winter snow cover, earlier spring snowmelt and widespread shrub expansion into alpine grasslands. Yet, the combined effects of shrub expansion and changing snow conditions on abiotic and biotic soil properties remains poorly understood. We used complementary field experiments to show that reduced snow cover and earlier snowmelt have effects on soil microbial communities and functioning that persist into summer. However, ericaceous shrub expansion modulates a number of these impacts and has stronger belowground effects than changing snow conditions. Ericaceous shrub expansion did not alter snow depth or snowmelt timing but did increase the abundance of ericoid mycorrhizal fungi and oligotrophic bacteria, which was linked to decreased soil respiration and nitrogen availability. Our findings suggest that changing winter snow conditions have cross-seasonal impacts on soil properties, but shifts in vegetation can modulate belowground effects of future alpine climate change.     

Conversion of sagebrush shrublands to exotic annual grasslands negatively impacts small mammal communities

Aim The exotic annual cheatgrass (Bromus tectorum) is fast replacing sagebrush (Artemisia tridentata) communities throughout the Great Basin Desert and nearby regions in the Western United States, impacting native plant communities and altering fire regimes, which contributes to the long‐term persistence of this weedy species. The effect of this conversion on native faunal communities remains largely unexamined. We assess the impact of conversion from native perennial to exotic annual plant communities on desert rodent communities. Location Wyoming big sagebrush shrublands and nearby sites previously converted to cheatgrass‐dominated annual grasslands in the Great Basin Desert, Utah, USA. Methods At two sites in Tooele County, Utah, USA, we investigated with Sherman live trapping whether intact sagebrush vegetation and nearby converted Bromus tectorum‐dominated vegetation differed in rodent abundance, diversity and community composition. Results Rodent abundance and species richness were considerably greater in sagebrush plots than in cheatgrass‐dominated plots. Nine species were captured in sagebrush plots; five of these were also trapped in cheatgrass plots, all at lower abundances than in the sagebrush. In contrast, cheatgrass‐dominated plots had no species that were not found in sagebrush. In addition, the site that had been converted to cheatgrass longer had lower abundances of rodents than the site more recently converted to cheatgrass‐dominated plots. Despite large differences in abundances and species richness, Simpson’s D diversity and Shannon‐Wiener diversity and Brillouin evenness indices did not differ between sagebrush and cheatgrass‐dominated plots. Main conclusions This survey of rodent communities in native sagebrush and in converted cheatgrass‐dominated vegetation suggests that the abundances and community composition of rodents may be shifting, potentially at the larger spatial scale of the entire Great Basin, where cheatgrass continues to invade and dominate more landscape at a rapid rate.     

The role of community-based wild resource management in Zimbabwe

Wildlife was in decline in Zimbabwe while the resource was being managed centrally by the State in terms of conventional protectionist legislation. The legislation was changed in 1960 and this led to cautious institutional reforms, whereby responsibility for wildlife was gradually devolved to landholders who were encouraged to use it profitably. This was achieved without the State abrogating its ultimate responsibility for the wellbeing of the resource.The CAMPFIRE programme was a response to the particular requirements of communally managed wild resources. Successful implementation required that appropriate institutions were in place. These allowed the peasants a meaningful say in the management of their wildlife and permitted them to use it profitably to generate a sufficient incentive to persuade them to conserve the resource on their land. As on large-scale commercial ranches, socio-economic factors proved more significant than ecological considerations in preserving wildlife on communally occupied land that is representative of much of Africa and the Third World.Former Director of National Parks and Wild Life Management, Zimbabwe.     

Past pasture management affects the land snail diversity in nutrient-poor calcareous grasslands

Changes in agriculture (intensification or abandonment) have resulted in a dramatical reduction of semi-natural grasslands in Central Europe in the 20th century. Recent management actions aim to restore overgrown and formerly fertilized nutrient-poor grasslands. Former land use is known to influence the present-day vegetation. Similar information is not available for animals with low dispersal ability. We investigated the effect of pasture management history over a period of 55 years on the present-day land snail diversity in 20 dry, nutrient-poor grasslands in the Swiss Jura mountains. Snails were recorded in pastures left unmanaged for 10–40 years but recently cleared from overgrowing shrubs, in pastures fertilized for 15–25 years but recently managed extensively (no fertilizer), and in pastures which have been extensively managed throughout (=control). Past shrub cover had a negative effect on the total number of snail species and the number of red-listed individuals. Former use of fertilizer reduced red-listed species and individuals and changed the snail community. Three species (Vitrina pellucida, Helicella itala and Abida secale) were found less frequently in formerly fertilized pastures than in extensive pastures. Our results show that changes in pasture use for a period of 10–40 years caused long-term alterations of the land snail fauna.     

Response of Orthoptera assemblages to management of montane grasslands in the Western Carpathians

Montane grassy habitats in the Western Carpathians are relatively well preserved, maintain high species richness and are often important in accordance to the nature conservation policy in Europe. However, knowledge about the impact of farming on the habitat quality there is rather poor. The influence of various management types (permanent sheep pen, irregular grazing, mowing) on Orthoptera diversity and species determining assemblages of these habitats were analysed on 72 plots in Poľana Mts Biosphere Reserve. Altogether, 36 Orthoptera species (15 Ensifera, 21 Caelifera) were found, whereas the highest number of species was found on plots with irregular grazing (28 species), followed by plots with mown grass (17) and permanent sheep pens (14). All four measures of the assemblages’ diversity confirmed significant differences. Using Discriminant Function Analysis, correct classification rate of Orthoptera assemblages was unambiguous according to the type of management. Each form of the management harboured several characteristic species. Thus implications regarding the biodiversity conservation and grassland management were given.     

Yield and species density of grasslands during restoration management

Abstract. The relation between the dry matter production and species density of 27 grasslands with different fertilization histories in the Netherlands was studied. The range in species density was 12–28 species on 150 m², the average annual dry matter production in 1983–1985 varied between 3.3 and 12.8 ton /ha. The results show an optimum curve and confirm the hump-backed model proposed by other researchers for a great variety of vegetation types. It is concluded that a high species density can be expected when the annual dry matter production above a stubble height of 5 cm, is between 4 and 6 ton/ha (ca. 4.6 - 6.0 ton seasonal maximum standing biomass). Species density can be expected to decrease when the dry matter production exceeds values of 6 - 7 ton ha^-1yr^-1 (ca. 6.0 - 6.7 ton seasonal maximum standing biomass). The implications of this relation for grassland restoration, aimed at an increase in species density, are discussed. The results agree with other grassland data based on the seasonal maximum standing biomass. The difference between annual production estimated by harvesting the biomass after mowing at 5 cm above the soil surface (mostly in two cuts), and the maximum seasonal standing biomass must be taken into account. It is proposed to compare data on the basis of the estimation that 62 ± 5% of the annual yield is harvested at the first cut, and that there is a linear relation between the total standing biomass, y (g/m²), and the biomass harvested above a stubble height of 5 cm, x (g/m²) that could be described by the regression line y = 1.10 x + 189.6 (r = 0.89, p < 0.01, n = 34).     

More salt,please: global patterns,responses and impacts of foliar sodium in grasslands

Sodium is unique among abundant elemental nutrients, because most plant species do not require it for growth or development, whereas animals physiologically require sodium. Foliar sodium influences consumption rates by animals and can structure herbivores across landscapes. We quantified foliar sodium in 201 locally abundant, herbaceous species representing 32 families and, at 26 sites on four continents, experimentally manipulated vertebrate herbivores and elemental nutrients to determine their effect on foliar sodium. Foliar sodium varied taxonomically and geographically, spanning five orders of magnitude. Site‐level foliar sodium increased most strongly with site aridity and soil sodium; nutrient addition weakened the relationship between aridity and mean foliar sodium. Within sites, high sodium plants declined in abundance with fertilisation, whereas low sodium plants increased. Herbivory provided an explanation: herbivores selectively reduced high nutrient, high sodium plants. Thus, interactions among climate, nutrients and the resulting nutritional value for herbivores determine foliar sodium biogeography in herbaceous‐dominated systems.     

Potential long-term impacts of livestock introduction on carbon and nitrogen cycling in grasslands of Southern South America

Empirical evidence based on grazing exclusion at the scale of years to decades shows that grazing modifies carbon (C) and nitrogen (N) cycling. However, long‐term effects at the scale of centuries are less known, yet highly relevant to understand local and global impacts of grazing. Additionally, most studies have focused on the isolated response of C and N, with little understanding of their interactions. Using CENTURY, a process‐based biogeochemical model, we analyzed the impacts of 370 years of livestock grazing (i.e. long term, from early European colonization to present) in 11 sites across the Río de la Plata grasslands and compared them with those resulting from two decades of grazing (i.e. mid‐term, typical exclosure experiment). In the long term, livestock grazing primarily altered the N cycle through faster N returns to the soil via urine and dung, which were offset by uninterrupted N outputs by volatilization and leaching. As a result, soil organic N decreased by ?880 kg ha^?1 or ?19%. Higher N outputs (mainly as NH₃) opened the N cycle, potentially decreasing N₂O and NO_x emissions and increasing N depositions over the region. These greater outputs of N constrained C accumulation in soils, reducing soil organic C by ?21 200 kg ha^?1 (?22%, a reduction of ?1.5 Pg of C for the whole region) and net primary production by ?2192 kg ha^?1 yr^?1 (?24%). Mid‐term simulations showed that the effects of livestock introduction in a decadal time scale were substantially different both in magnitude and direction from long‐term responses. Long‐term results were not substantially affected when atmospheric CO₂ content, species composition and fire regime were changed within plausible ranges, but highlighted fire‐grazing interactions as a major constraint of long‐term C and N dynamics in these grasslands.     

Optimizing prevention and community-based management of severe malnutrition in children

Zulfiqar A. Bhutta discusses prevention and treatment strategies for optimization of community-based management of severe acute malnutrition in children.

In this issue of PLOS Medicine, Matt Hitchings and colleagues detail the findings from their prospective cluster-randomized crossover trial conducted across 10 health centers in Sokoto, Nigeria, to assess the nutritional recovery in children with uncomplicated severe acute malnutrition (SAM) receiving monthly follow-up compared to the standard weekly follow-up schedules [1]. In almost 4,000 children so allocated, the nutritional recovery at 3 months’ follow-up was lower in the monthly follow-up group (52.4%) compared to the standard weekly group (58.8%), with higher cumulative mortality at 3 months (8.5% versus 6.2% with the standard weekly follow-up). In contrast, rates of default and relapse were significantly lower among SAM children allocated to monthly follow-up. The authors, while urging caution in adopting a modified schedule of monthly follow-up visits in such children, also recognize the trade-off of simplicity and ease of operations in some settings where weekly follow-up visits are not feasible.Despite global progress in improving maternal and child undernutrition, the high burden of severe malnutrition persists. Recent estimates show a small reduction (from 15.9% to 14.2%) in wasting prevalence in low-income countries, and a slight increase (from 3.3% to 4.7%) in middle-income countries, although overall almost 50 million children aged under 5 years still remain wasted worldwide [2]. This burden of SAM has most likely been exacerbated during the recent Coronavirus Disease 2019 (COVID-19) pandemic, with an estimated additional 6.7 million children becoming wasted in 2020 [3].Within this large number of wasted children are those with SAM who are triaged to facility-based nutritional rehabilitation if seriously ill, or community-based treatment regimens if stable. The development of standardized management protocols for children with SAM with ready-to-use therapeutic foods (RUTFs) represents one of the greatest advances in treating such children at scale and reducing the mortality associated with the condition [4]. However, given the general context where childhood SAM clusters, such as those affected by extreme poverty, climate change, conflict, and involving displaced populations, major challenges remain in optimizing SAM management. These include relatively high rates of relapse [5], and associated residual mortality with severe malnutrition, often exceeding 10% in some settings [6]. Strategies are thus needed to optimize community case management aimed at simplifying the treatment regimen for SAM, reducing defaults and relapse rates among affected children.Such real-life evaluations of management strategies for severe malnutrition among at-risk children are few and far between, and most welcome. The global evidence base for the management of SAM in various settings is still mixed, with wide variations in recovery or relapse rates and mortality. This is especially the case in complex emergencies and conflict settings [7] with obvious limitations of human resources and commodities. The challenges of managing SAM in different contexts and settings are directly related to available nutrition rehabilitation commodities and trained human resources, as well as the ability of poor and food-insecure households to follow complex regimen and follow-up schedules. For many poor households with daily wage laborers or workers, taking a day off to travel to ambulatory care settings is a weekly financial and logistic hardship that may be impossible to bear. Alternative approaches with community outreach workers providing care and commodities in domiciliary settings has also met with mixed success, with lower rates of uptake in effectiveness settings with busy public-sector workers [8,9].There are additional research questions related to the nutritional rehabilitation and management of SAM including dosage schedules and protocols for administering RUTF in outreach and ambulatory programs. Additional therapeutic challenges in managing children with SAM include the limited repertoire of options for interventions in children under 6 months of age, as well as strategies to manage children with concurrent stunting and wasting [1,10]. While the recommendations for facility-based management of unstable children with SAM are well recognized [11], corresponding protocols for ambulatory management of severely malnourished children with suspected infections and at risk of adverse outcomes are still a subject of much debate [12].The gains from potentially simplifying ambulatory management strategies for SAM are considerable but must be weighed against the best-possible and cost-effective strategies. Of great priority are strategies that integrate SAM management in community settings with additional child health and development interventions [13]. Given the close correlation and relationship between various forms of malnutrition (moderate and severe acute malnutrition), there is growing interest in common management protocols and simplified regimens for preventing and managing all forms of acute malnutrition. The sizeable subgroup of children with concurrent wasting and stunting represents a subgroup at much greater risk of adverse outcomes and mortality [14] and needs strategies that also integrate maternal and early child health and nutrition strategies.There has been a healthy increase in research related to prevention and management strategies for SAM in recent years, all adding to the evidence base for effective implementation in field settings. Corresponding processes for guidelines development by WHO are understandably cautious, but it is worth noting that the guidelines for the management of SAM by WHO are now almost a decade old [15] and need updating as well as flexibility in implementation. Studies such as those by Hitchings and colleagues [1] should show the way to optimize the screening and management of SAM in settings with limited facilities and community capacity for weekly follow-up. The recognition that such infants may be at higher risk of relapse or mortality could well require additional contacts, such as fortnightly follow-up or outreach services, areas that should be studied in future evaluations.     

Plant–plant interactions and soil moisture might be important in determining ozone impacts on grasslands

Ozone effects on plant species mixtures could depend on the characteristics of the species involved, their mixing ratio, or on environmental conditions. Predicting long-term effects on the dynamics of plant communities requires an understanding of the interactions involved. The present experiment was designed to determine the effects of ozone on grassland species in relation to mixing ratio and soil water content (irrigation) using binary mixtures. The grass Trisetum flavescens was grown in potted replacement-series mixtures with Centaurea jacea (Experiment A) or Trifolium pratense (Experiment B). The plants were exposed to three concentrations of ozone in open-top chambers in two irrigation treatments. Total above-ground dry weight over three growth periods was measured. The competitive ability of T. flavescens was expressed as the competitive ratio ( CR _T). In Experiment B, total above-ground dry weight was reduced by elevated ozone and by reduced soil moisture, and significant interactions were found for ozone × irrigation and ozone × ratio. In Experiment A these effects were not significant. Under well watered conditions, CR _T tended to be reduced by elevated ozone in Experiment A, but increased significantly in Experiment B, indicating the importance of the competing species in modifying the ozone effect on T. flavescens . In both experiments reduced irrigation decreased the magnitude of ozone effects on biomass production, which could be related to observed reductions in specific leaf conductance. The results suggest that under well watered conditions the effect of elevated ozone on the competitive balance between species depends on the species mixture, but that the mixing ratio is less important.     

Vertical canopy structure of Dutch chalk grasslands in relation to their management

Analysis of leaf canopy overtopping relationships was carried out using a non-destructive point quadrat method followed by a destructive stratified harvest of the above-ground phytomass in Dutch chalk grasslands with different management: summer sheep grazing and annual autumn mowing. The two methods of analysis are compared: e.g. relative leaf overtopping can be recorded by the point quadrat method but it is obscured in vertical vegetation profiles based on stratified phytomass distribution. However the stratified harvest method describes the relationship between canopy phytomass and light microclimate, recorded by measuring Photosynthetically Active Radiation (PAR) at different heights in the vegetation. Plant growth form during peak standing crop is of greater significance than Raunkiaerian life form in determining structure of chalk grassland vegetation. In annually mown grasslands, the tall graminoid growth form, shown by Brachypodium pinnatum, reduces PAR in the lower canopy and suppresses most other growth forms except those which can reach the higher canopy levels, e.g. clumped herbs such as Origanum vulgare. In contrast, grazing can result in a reduction of dominance from the tall graminoids and reduction of the abundance of taller, grazing-sensitive herbs, e.g. clumped and climbing herbs such as Origanum and Lathyrus pratensis, and an increase in grazing-tolerant species, e.g. smaller rosette herb growth forms, e.g. Leontodon hispidus and shorter rhizomatous or stoloniferous graminoids, e.g. Carex flacca and Briza media. Changes in both the overtopping hierarchy at the peak of the growing season and the intensity of overtopping in the course of a growing season are of conclusive importance in determining the relative abundance of species in the vegetation.     

Satellite remote sensing of grasslands: from observation to management

Aims Grasslands are the world's most extensive terrestrial ecosystem, and are a major feed source for livestock. Meeting increasing demand for meat and other dairy products in a sustainable manner is a big challenge. At a field scale, Global Positioning System and ground-based sensor technologies provide promising tools for grassland and herd management with high precision. With the growth in availability of spaceborne remote sensing data, it is therefore important to revisit the relevant methods and applications that can exploit this imagery. In this article, we have reviewed the (i) current status of grassland monitoring/observation methods and applications based on satellite remote sensing data, (ii) the technological and methodological developments to retrieve different grassland biophysical parameters and management characteristics (i.e. degradation, grazing intensity) and (iii) identified the key remaining challenges and some new upcoming trends for future development.Important findings The retrieval of grassland biophysical parameters have evolved in recent years from classical regression analysis to more complex, efficient and robust modeling approaches, driven by satellite data, and are likely to continue to be the most robust method for deriving grassland information, however these require more high quality calibration and validation data. We found that the hypertemporal satellite data are widely used for time series generation, and particularly to overcome cloud contamination issues, but the current low spatial resolution of these instruments precludes their use for field-scale application in many countries. This trend may change with the current rise in launch of satellite constellations, such as RapidEye, Sentinel-2 and even the microsatellites such as those operated by Skybox Imaging. Microwave imagery has not been widely used for grassland applications, and a better understanding of the backscatter behaviour from different phenological stages is needed for more reliable products in cloudy regions. The development of hyperspectral satellite instrumentation and analytical methods will help for more detailed discrimination of habitat types, and the development of tools for greater end-user operation.     

Influence of management and precipitation on carbon fluxes in great plains grasslands

Suitable management and sufficient precipitation on grasslands can provide carbon sinks. The net carbon accumulation of a site from the atmosphere, modeled as the Net Ecosystem Productivity (NEP), is a useful means to gauge carbon balance. Previous research has developed methods to integrate flux tower data with satellite biophysical datasets to estimate NEP across large regions. A related method uses the Ecosystem Performance Anomaly (EPA) as a satellite-derived indicator of disturbance intensity (e.g., livestock stocking rate, fire, and insect damage). To better understand the interactions among management, climate, and carbon dynamics, we evaluated the relationship between EPA and NEP data at the 250 m scale for grasslands in the Central Great Plains, USA (ranging from semi-arid to mesic). We also used weekly estimates of NEP to evaluate the phenology of carbon dynamics, classified by EPA (i.e., by level of disturbance impact). Results show that the cumulative carbon balance over these grasslands from 2000 to 2008 was a weak net sink of 13.7 g C m⁻² yr⁻¹. Overall, NEP increased with precipitation (R² = 0.39, P < 0.05) from west to east. Disturbance influenced NEP phenology; however, climate and biophysical conditions were usually more important. The NEP response to disturbance varies by ecoregion, and more generally by grassland type, where the shortgrass prairie NEP is most sensitive to disturbance, the mixed-grass prairie displays a moderate response, and tallgrass prairie is the least impacted by disturbance (as measured by EPA). Sustainable management practices in the tallgrass and mixed-grass prairie may potentially induce a period of average net carbon sink until a new equilibrium soil organic carbon is achieved. In the shortgrass prairie, management should be considered sustainable if carbon stocks are simply maintained. The consideration of site carbon balance adds to the already difficult task of managing grasslands appropriately to site conditions. Results clarify the seasonal and interannual dynamics of NEP, specifically the influence of disturbance and moisture availability.     

Effects of herd management and the use of ivermectin on dung arthropod communities in grasslands

Agroecosystems represent a large geographical footprint in most terrestrial landscapes, and management decisions within these systems affect their function in species conservation. We evaluated the effects that rangeland management systems (based on stocking density, rotation frequency, and the number of avermectin applications) have on conserving the dung arthropod community in the Northern Great Plains of North America. Comprehensive bioinventories of arthropods were collected from 16 rangelands using core samples of dung pats. Ivermectin was quantified in pats from each ranch using enzyme-linked immunosorbant assay (ELISA). Arthropods in dung were abundant (116,244 specimens) and diverse in eastern South Dakota (172 morphospecies). Rangelands managed with more regenerative practices (frequent rotation at high stocking densities and lack of ivermectin applications) had greater species richness, diversity, predator species abundance, and dung beetle abundance than more conventionally managed rangelands. Ivermectin quantity in cattle pats was negatively correlated with dung beetle abundance and diversity. This work shows that herd management (specifically high-intensity, frequent rotational grazing and eliminating prophylactic ivermectin use) that aims to mimic intensive grazing of large migrating herds of ruminants can foster dung arthropod community structure, a key trait correlated with nutrient cycling, pest suppression, and productivity of cattle-grazed rangelands.     

Impact of grazing management on hibernating caterpillars of the butterfly Melitaea cinxia in calcareous grasslands

Semi-natural grasslands are increasingly grazed by large herbivores for nature conservation purposes. For many insects such grazing is essential for the conservation of their habitat, but at the same time, populations decrease at high grazing intensity. We hypothesised that grazing management may cause increased butterfly mortality, especially for life-stages with low mobility, such as hibernating caterpillars. To test this, we measured the effect of sheep grazing on overwinter larval survival. We used the Glanville fritillary (Melitaea cinxia), which has gregarious caterpillars hibernating in silk nests, as a model species. Caterpillar nests were monitored throughout the hibernating period in calcareous grassland reserves with low and high intensity sheep grazing and in an ungrazed control treatment. After grazing, 64?% of the nests at the high intensity grazing treatment were damaged or missing, compared to 8 and 12?% at the ungrazed and low intensity grazing treatment, respectively. Nest volume and caterpillar survival were 50?% lower at the high intensity grazing treatment compared to both ungrazed and low intensity grazing treatments. Nest damage and increased mortality were mainly caused by incidental ingestion of the caterpillars by the sheep. It is likely that grazing similarly affects other invertebrates, depending on their location within the vegetation and their ability to actively avoid herbivores. This implies that the impact of grazing strongly depends on the timing of this management in relation to the phenology of the species. A greater focus on immature and inactive life-stages in conservation policy in general and particularly in action plans for endangered species is required to effectively preserve invertebrate diversity.