Grassland Research Articles

Correlations between root phosphorus acquisition and foliar phosphorus allocation reveal how grazing promotes plant phosphorus utilization

Overgrazing and phosphorus (P) deficiency are two major factors limiting the sustainable development of grassland ecosystems. Exploring plant P utilization and acquisition strategies under grazing can provide a solid basis for determining a reasonable grazing intensity. Both foliar P allocation and root P acquisition are crucial mechanisms for plants to adapt to environmental P availability; however, their changing characteristics and correlation under grazing remain unknown. Here, we investigated foliar P fractions, root P-acquisition traits and gene expression, as well as rhizosphere and bulk soil properties of two dominant plant species, Leymus chinensis (a rhizomatous grass) and Stipa grandis (a bunchgrass), in a field grazing intensity gradient site in Inner Mongolia. Grazing induced different degrees of compensatory growth in the two dominant plant species, increased rhizosphere P availability, and alleviated plant P limitation. Under grazing, the foliar metabolite P of L. chinensis increased, whereas the nucleic acid P of S. grandis increased. Increased P fractions in L. chinensis were positively correlated with increased root exudates and rapid inorganic P absorption. For S. grandis, increased foliar P fractions were positively correlated with more fine roots, more root exudates, and up-regulated expression of genes involved in defense and P metabolism. Overall, efficient root P mobilization and uptake traits, as well as increases in leaf metabolic activity-related P fractions, supported plant compensatory growth under grazing, a process that differed between tiller types. The highest plant productivity and leaf metabolic activity-related P concentrations under medium grazing intensity clarify the underlying basis for sustainable livestock production.

Decadal soil total carbon loss in northern hinterland of Tibetan Plateau

As the largest and highest plateau in the world, ecosystems on the Tibetan Plateau (TP) imply fundamental ecological significance to the globe. Among the variety, alpine grassland ecosystem on the TP forms a critical part of the global ecosystem and its soil carbon accounts over nine tenths of ecosystem carbon. Revealing soil carbon dynamics and the underlying driving forces is vital for clarifying ecosystem carbon sequestration capacity on the TP. By selecting northern TP, the core region of the TP, this study investigates spatiotemporal dynamics of soil total carbon and the driving forces based on two phases of soil sampling data from the 2010s and the 2020s. The research findings show that soil total carbon density (STCD) in total-surface (0–30 cm) in the 2010s (8.85 ± 3.08 kg C m−2) significantly decreased to the 2020s (7.15 ± 2.90 kg C m−2), with a decreasing rate (ΔSTCD) of −0.17 ± 0.39 kg C m−2 yr−1. Moreover, in both periods, STCD exhibited a gradual increase with soil depth deepening, while ΔSTCD loss was more apparent in top-surface and mid-surface than in sub-surface. Spatially, ΔSTCD loss in alpine desert grassland was −0.41 ± 0.48 kg C m−2 yr−1, which is significantly higher than that in alpine grassland (−0.11 ± 0.31 kg C m−2 yr−1) or alpine meadow (−0.04 ± 0.28 kg C m−2 yr−1). The STCD in 2010s explained >30 % of variances in ΔSTCD among the set of covariates. Moreover, rising temperature aggravates ΔSTCD loss in alpine desert grassland, while enhanced precipitation alleviates ΔSTCD loss in alpine meadow. This study sheds light on the influences of climate and background carbon on soil total carbon loss, which can be benchmark for predicting carbon dynamics under future climate change scenarios.

Extraction and Analysis of Grasshopper Potential Habitat in Hulunbuir Based on the Maximum Entropy Model

Grasshoppers have profound effects on both grassland ecosystems and livestock production. Despite commendable efforts made by China in grasshopper control, completely eradicating or preventing them still remains a distant prospect. This study aims to analyze the ecological distribution and patterns of grasshopper occurrences in order to provide more accurate monitoring techniques and preventive measures. By considering four types of environmental determinants—meteorology, vegetation, soil, and topography—we systematically identified 18 key influencing factors. These factors encompass various developmental stages of grasshoppers, including variables such as temperature, precipitation, vegetation coverage, vegetation type, soil moisture, soil salinity, soil type, and terrain characteristics. The MaxEnt model is employed in this study to comprehensively capture complex ecological interactions. Omission curves, Receiver Operating Characteristic curves (ROC curves), and the Area Under the Curve (AUC values) demonstrate the robustness and high accuracy of the MaxEnt model. Our research results indicate that meteorological factors are the primary influencing factors for the distribution of grasshoppers, surpassing the effects of vegetation, soil, and terrain. Precipitation and vegetation type emerge as key factors shaping their distributional patterns. Integrating the Sen-MK trend method, our findings identify the epicenter of damage primarily within the central, southern, and northeastern regions, notably affecting locales such as New Barag East County and the Ewenki Autonomous Banner. While their impact in 2012 was particularly severe, temporal trends indicate a decreasing risk of grasshoppers in specific regions, with escalated activity observed in other areas. The empirical insights from this study lay a solid foundation for the development of monitoring and control strategies concerning grasshoppers. Furthermore, the derived theoretical framework serves as a valuable foundation for future research endeavors addressing grasshopper infestations.

Leopards (Panthera pardus pardus) in Gashaka Gumti National Park, Nigeria: historical records and recent sightings

West-African populations of the African subspecies of leopards (Panthera pardus pardus) are very fragmented, particularly so in Nigeria, Africa’s most populous nation. We compile historical and recent information about the occurrence of these big cats in what is likely their last remaining stronghold: Gashaka Gumti National Park (GGNP) in Adamawa and Taraba States along the border with Cameroon. Leopards in GGNP’s northern Gumti sector are close to extinction, given that its open plains of savannah are heavily encroached upon by illegal cattle grazing. However, in GGNP’s southern Gashaka sector, leopards are better protected, given its often mountainous and densely forested landscape. We present specific data for a 30 km2 forest-savannah area around a research station at Kwano, which harbours sizeable populations of 35 species of prey species leopards target elsewhere. Here, direct evidence for leopard presence (e.g., footprints, scratchmarks, predation incidences, vocalizations, sightings, cameratrap images) amounts to 1 per year. Albeit this encounter rate is very low, it is relatively steady throughout the last 30 years and into the present. We assume that GGNP’s Gashaka sector represents one of the best chances for leopards to survive in Nigeria.

Factor analysis of hydrologic services in water-controlled grassland ecosystems by InVEST model and geodetector.

Water conservation is highly important for a successful desert grassland ecosystem, but there was no comprehensive view on how to assess influencing factors in managing and addressing water yield and water conservation in desert steppe. The Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model, which is specifically used for the assessment of ecosystem services, was combined with geographic detectors to identify the priority areas for water conservation function and analyze the driving factors of water conservation in the Tabu River Basin, Inner Mongolia Autonomous Region, China, using different meteorological data sources. (i) The InVEST model has the advantage of modeling water yield and water conservation at spatial scales by fusion downscaling data. High water yield mainly occurs in the southern hilly mountainous areas, low water yield in the northern desert and grassland areas, and between the two in the central agro-pastoral areas; the multi-year average water conservation and water yield based on the InVEST model are 3.3 and 16mm, respectively. (ii) Water yield and water conservation roughly show a transitional phenomenon of "high in the south and low in the north." The water yield and water conservation per unit area of the Tabu River Basin are relatively large for construction land, unused land, and cropland, relatively small for grassland and forestland, and basically zero for water bodies. Forest land has the strongest water conservation capacity, followed by grassland and farmland, while the order of water yield capacity is the opposite. (iii) Precipitation shows the strongest explanatory power for water yield (q = 0.427), followed by land use types (q = 0.411). The precipitation ∩ actual evapotranspiration has the strongest explanatory power for water yield (q = 0.87). The explanatory power of water yield on water conservation is the strongest (q = 0.752), followed by precipitation (q = 0.4), and the water yield ∩ soil has the greatest explanatory power on water conservation (q = 0.91). These findings are crucial for promoting regional hydrologic services and can provide a water resources management strategy for decision-makers.

Estimating vegetation water content from Sentinel-1 C-band SAR data over savanna and grassland ecosystems

Studying vegetation water content (VWC) dynamics is essential for understanding plant growth, water and carbon cycles, and ecosystem stability. However, acquiring field-based VWC estimates, consistently through space and time, is challenging due to time and resource constraints. This study investigates the potential of Sentinel-1 C-band Synthetic Aperture Radar (SAR) data for estimating VWC in natural ecosystems in central Brazil. We assessed (i) how well Sentinel-1 SAR data can capture variations in VWC over three different vegetation types (i.e. dry and waterlogged grasslands, and savannas) and (ii) how the studied vegetation types respond to seasonal dry periods in terms of water content. Field data from 82 plots, distributed across the three vegetation types and revisited in four different seasons, were used to calibrate and validate a model for VWC estimation. The calibrated model, with an R 2 of 0.52 and RMSE of 0.465 kg m−2, was then applied to Sentinel-1 SAR backscatter data to generate monthly VWC maps for grassland and savanna ecosystems at 30 m spatial resolution between April 2015 and September 2023. These maps, combined with rainfall and potential evapotranspiration data, provided insights into how the studied vegetation types respond to water shortage during the dry season at the community scale. More specifically, savannas showed to be better able to retain higher levels of water content during the dry season, probably due to a higher water holding capacity of the woody component together with its deep-root system ability to access deeper groundwater. This research demonstrates the potential of Sentinel-1 SAR data for monitoring VWC in natural ecosystems, allowing for future studies to assess ecosystems’ response to drought events and changes in their functioning, ultimately supporting land management decisions.

Biology of the invasive species Eragrostis plana in Southern Brazil: What have we learned and how may this help us manage it?

AbstractSince its accidental introduction in 1951, the South African species Eragrostis plana has invaded a large part of the Pampa biome in South America, a highly diverse grassland ecosystem that has coexisted with livestock since its introduction at the beginning of the 17th century. E. plana, a perennial tussock grass with a deep and abundant root system, is resistant to frost and cattle grazing, and a successful competitor for environmental resources. The species is diploid, C4 dispersed endozoochorically, and flowers in late spring and early summer, with optimal germination occurring at 35°C and viability up to 39–40°C. It is allelopathic because it produces several phenols and alkaloids. Extreme soil disturbance or intense grazing favours initial invasion. Nonetheless, grazing exclusion enhances E. plana competition and affects the grassland community and diversity. E. plana is highly tolerant to interspecific competition, especially with grasses exhibiting a similar growth habit. Under water stress, it responds faster by increasing its root system by 66% more than native grass. Moreover, antioxidant system activity increases, and the species recovers quickly through osmolyte production. In non‐invaded fields, avoiding soil disturbance and intensive grazing are key strategies to preserving Biome Pampa. Nonetheless, in fields where the invasion has already occurred, grazing must be maintained, cattle quarantined practiced, along with strategies that reduce cover and prevent the spread of E. plana. Liming and fertilising native grasslands improve their potential to compete with E. plana. The wiper applicator, a device that allows glyphosate herbicide application selectively to E. plana, is an important component of the integrated weed management system, especially with very severe infestations. Establishing strategies to contain or manage E. plana should be a priority to preserve the biodiversity of the Pampa. In the future, innovative options could also help prevent new invasions.

Understanding the effects of revegetated shrubs on fluxes of energy, water, and gross primary productivity in a desert steppe ecosystem using the STEMMUS–SCOPE model

Abstract. Revegetation is one of the most effective ways to combat desertification and soil erosion in semiarid and arid regions. However, the impact of the perturbation of revegetation on ecohydrological processes, particularly its effects on the interplay between hydrological processes and vegetation growth under water stress, requires further investigation. This study evaluated the effects of revegetation on the energy, water, and carbon fluxes in a desert steppe in Yanchi County, Ningxia Province, northwest China, by simulating two vegetated scenarios (shrub–grassland ecosystem and grassland ecosystem) using the STEMMUS–SCOPE (Simultaneous Transfer of Energy, Mass and Momentum in Unsaturated Soil–Soil Canopy Observation of Photosynthesis and Energy fluxes) model. The model was validated by field observations from May to September of 2016–2019. The evaluation of revegetation effects relied on comparing simulated fluxes between two vegetated scenarios in 2016 and 2019. In both scenarios, turbulent energy was dominated by latent heat flux, which was stronger in the shrub–grassland ecosystem (+7 %). A higher leaf area index and root water uptake of C3 shrubs (Caragana intermedia) resulted in increased carbon fixation (+83 %) and transpiration (+72 %) of the shrub–grassland ecosystem compared to the C3 grassland ecosystem. Accompanied by a marked increase in root water uptake (+123 %), revegetation intensified water consumption beyond the levels of received precipitation. These results highlight the critical importance of considering both energy and water budgets in water-limited ecosystems during ecological restoration to avert soil water depletion.

An Integrated Grassland Fire-Danger-Assessment System for a Mountainous National Park Using Geospatial Modelling Techniques

Grasslands are key to the Earth’s system and provide crucial ecosystem services. The degradation of the grassland ecosystem in South Africa is increasing alarmingly, and fire is regarded as one of the major culprits. Globally, anthropogenic climate changes have altered fire regimes in the grassland biome. Integrated fire-risk assessment systems provide an integral approach to fire prevention and mitigate the negative impacts of fire. However, fire risk-assessment is extremely challenging, owing to the myriad of factors that influence fire ignition and behaviour. Most fire danger systems do not consider fire causes; therefore, they are inadequate in validating the estimation of fire danger. Thus, fire danger assessment models should comprise the potential causes of fire. Understanding the key drivers of fire occurrence is key to the sustainable management of South Africa’s grassland ecosystems. Therefore, this study explored six statistical and machine learning models—the frequency ratio (FR), weight of evidence (WoE), logistic regression (LR), decision tree (DT), random forest (RF), and support vector machine (SVM) in Google Earth Engine (GEE) to assess fire danger in an Afromontane grassland protected area (PA). The area under the receiver operating characteristic curve results (ROC/AUC) revealed that DT showed the highest precision on model fit and success rate, while the WoE was used to record the highest prediction rate (AUC = 0.74). The WoE model showed that 53% of the study area is susceptible to fire. The land surface temperature (LST) and vegetation condition index (VCI) were the most influential factors. Corresponding analysis suggested that the fire regime of the study area is fuel-dominated. Thus, fire danger management strategies within the Golden Gate Highlands National Park (GGHNP) should include fuel management aiming at correctly weighing the effects of fuel in fire ignition and spread.

Desertification, Water and Women in Banni Grasslands of India

Land degradation is one of the most serious ecological issues we face today. From the Rio+20 Summit through the 15th Conference of the Parties to the United Nations Convention to Combat Desertification (UNCCD-COP15), many countries have made significant commitments to combat desertification. For its part, India also established goals in this area. UNCCD acknowledges the intricate relationship between land degradation and its impacts on women. The convention actively promotes gender-sensitive approaches to addressing environmental issues. The main aim of this study is to assess the present condition of desertification and degradation in the Banni grasslands ecosystem located in Kutch, India. The grasslands in question have undergone a prolonged period of degradation, desertification and droughts spanning several decades. However, a limited number of academic studies have been conducted in relation to this matter. The evaluation of the consequences of Banni’s degradation on the local communities, with a particular focus on women, has been motivated by Sustainable Development Goal 15 and the UNCCD. The researchers conducted an empirical study in the Banni region that integrated both qualitative and quantitative methodologies, utilising structured and unstructured questionnaires as well as interviews. The researchers have utilised inductive reasoning in the process.

Military Activity Impact on Vegetation in Pannonian Dry Sandy Grasslands

The conservation of dry sandy grasslands is a global issue because of the restoration and conservation of endangered ecosystems to provide a sufficient amount of forage under warming and drying climatic conditions. Our aim was to explore the impact of military activity on sandy grasslands in Hungary. The sample areas chosen were the Little Hungarian Plain (I. and II.) and the Great Hungarian Plain (III.), consisting abandoned, restored areas; still-active military exercise fields; and shooting ranges. In each sample area, six to ten coenological surveys were made. Based on our survey, the closed natural sandy grassland was documented only in the Little Hungarian Plain and were found rich in species. The open sandy grassland was described in all studied sites, Festuca vaginata appeared in all of them, while Festuca pseudovaginata was observed only in the Great Hungarian Plain. In the open sandy grassland, the natural vegetation had the highest cover value (78.8%), the sowed grassland area had the least cover value (53.3%), while the III. sample area was also poor in coverage (56.5%) but consisted of a natural species composition favorable for restoration. Our results confirmed the indirect role of military activity in the successful habitat conservation of Pannonian dry sandy grassland ecosystems.

Analysis of temporal variation characteristics in water resources in typical ecosystems of the Genhe River Basin

The Genhe River Basin is an ecological barrier and water conservation area in northern China, but its hydrological process has undergone significant changes due to climate change and human activities, endangering ecosystem functions and water resource security. Systematic research on the influencing mechanisms and laws of hydrological processes in different ecosystems in this region remains lacking. Therefore, this study analyzed the effects of different anthropogenic factors on the hydrological processes of typical ecosystems in the Genhe River Basin. The Soil and Water Assessment Tool distributed hydrological model was used to simulate the surface runoff, evapotranspiration, and soil water content of the three ecosystems of forest, grassland, and farmland in four different periods of 1980, 1990, 2000, and 2010. The spatial and temporal changes in water resources in typical ecosystems under the influence of historical climate change were demonstrated. Results showed that under different land use scenarios, the surface runoff of the farmland ecosystem increased, the evapotranspiration remained unchanged, and the soil water content decreased. The surface runoff of forest and grassland ecosystems did not change significantly, the evapotranspiration increased, and the soil water content decreased. This study reveals the influence of different human factors on the hydrological processes of typical ecosystems in the Genhe River Basin and provides a scientific basis for water resources management and ecological protection in the region.

Spatiotemporal variability of evapotranspiration in Alpine grasslands and its biotic and abiotic drivers

AbstractTo gain a deeper understanding of the water balances of Alpine grassland ecosystems, it is crucial to know the abiotic and biotic drivers of evapotranspiration. The abiotic drivers are very heterogeneous in mountain regions because elevation, slope and aspect control incoming Rs, and atmospheric layering affect air temperature, humidity and wind distribution. In a study with 24 lysimeter plots distributed over a study area of approx. 300 km2 in the Eastern Alps, we covered a wide range of topographic conditions. We investigated the effects of abiotic drivers on evapotranspiration by measuring evaporation from a free‐water body (Ew). For the biological modulation of crop evapotranspiration (ETc), we analysed two different grassland types (at peak biomass and at low biomass) and calculated the respective crop coefficients (Kc). Results showed that primarily physical drivers such as the accumulated solar radiation from sunrise to measurement (Rs_acc), followed by atmospheric pressure (P), wind speed (u) and vapour pressure deficit (VPD) influence both Ew and ETc. Moreover, ETc is also significantly influenced by standing biomass and the grassland type (i.e., resource use strategies of the vegetation types) and by the geographic location along the valley (i.e., entrance, middle and head of the valley). We suppose plant stress and/or ground winds to be the underlying factor for the significance of the geographic location, yet further research is needed. The current study helps towards a better understanding of the water balance in alpine grassland ecosystems, but we also show that some spatial drivers cannot yet be adequately addressed.

Vicuña antipredator diel movement drives spatial nutrient subsidies in a high Andean ecosystem.

Large animals could be important drivers of spatial nutrient subsidies when they ingest resources in some habitats and release them in others, even moving nutrients against elevational gradients. In high Andean deserts, vicuñas (Vicugna vicugna) move daily between nutrient-rich wet meadows, where there is abundant water and forage but high risk of predation by pumas (Puma concolor), and nutrient-poor open plains with lower risk of predation. In all habitats, vicuñas defecate and urinate in communal latrines. We investigated how these latrines impacted soil and plant nutrient concentrations across three habitats in the Andean ecosystem (meadows, plains, and canyons) and used stable isotope analysis to explore the source of fecal nutrients in latrines. Latrine soils had higher concentrations of nitrogen, carbon, and other nutrients than did nonlatrine soils across all habitats. These inputs corresponded with an increase in plant quality (lower C:N) at latrine sites in plains and canyons, but not in meadows. Stable isotope mixing models suggest that ~7% of nutrients in plains latrines originated from vegetation in meadows, which is disproportionately higher than the relative proportion of meadow habitat (2.6%) in the study area. In contrast, ~68% of nutrients in meadow latrines appear to originate from plains and canyon vegetation, though these habitats made up nearly 98% of the study area. Vicuña diel movements thus appear to concentrate nutrients in latrines within habitats and to drive cross-habitat nutrient subsidies, with disproportionate transport from low-lying, nutrient-rich meadows to more elevated, nutrient-poor plains. When these results are scaled up to the landscape scale, the amount of nitrogen and phosphorus subsidized in soil at plains latrines was of the same order of magnitude as estimates of annual atmospheric nitrogen and phosphorus deposition for this region (albeit far more localized and patchy). Thus, vicuña-mediated nutrient redistribution and deposition appears to be an important process impacting ecosystem functioning in arid Andean environments, on par with other major inputs of nutrients to the system.

Seeds exhibit the most stable elemental composition with nitrogen addition in an Inner Mongolian grassland

Variation in biomass elemental composition of grassland plants may have important implications for ecosystem functioning in response to global change. However, relevant studies have mostly focused on variation of nitrogen (N) and phosphorus (P) concentrations in plant leaves, while few studies have evaluated other elements and plant organs of grassland species. Here, we examined the effects of N addition on multi-element concentrations, and analyzed their patterns across different organs (leaf, stem, root and seed) of five plant species in a steppe community of the Inner Mongolian grassland. Our results showed that seeds exhibited the most stable elemental composition with N addition, and that manganese (Mn) and iron (Fe) concentrations were substantially more variable than macro-elements in response to N addition. In particular, we identified a set of significant negative relationships between elemental concentrations and their corresponding CVs (coefficients of variation) for all plant organs as a whole and for each individual organ. We further found that changes in soil pH and the availability of soil nutrients contributed mostly to variation in the biomass elemental composition of major plants in this community. These findings are important for accurately assessing the effects of N deposition on the biochemical cycling of nutrient elements in grassland ecosystems, and provide critical clues for developing effective approaches to adaptively managing grassland resources as well as mitigating the impact of global change on the dryland ecosystems in the Mongolia Plateau.

A drying climate and habitat availability drive extirpations of a southward advancing ground squirrel

Abstract Ground squirrels act as important members of grassland ecosystems by serving as both ecosystem engineers and as a prey base for carnivores. There is mounting evidence that climate change is driving ground squirrel population declines. We resurveyed 54 historical localities throughout the Wyoming Basin and western Colorado where Wyoming Ground Squirrel (Urocitellus elegans) specimens were collected to investigate if climate change was driving extirpations at these historically occupied sites. We detected extirpations at 12 sites and used binomial generalized linear models in an information-theoretic framework to investigate if climate change was associated with these extirpations. Additionally, we investigated if land cover change was associated with persistence and if land cover ameliorated or exacerbated the effects of climate change. We found that changes in climate, especially increasingly dry summer air and increasing mean summer temperatures, were associated with a reduced probability that U. elegans persisted at a historically occupied site. In addition, we found that current forest cover at a site and increasing rangeland cover at the regional level were associated with reduced probability that U. elegans persisted, although these associations were weaker than the climate associations. The effects of climate change and land cover change did not interact. Our findings build on mounting evidence that montane-associated ground squirrels throughout the Western United States are negatively impacted by climate change. The reduction in ground squirrel abundance or their extirpation due to climate change could lead to changes in ecosystem structure or reductions in trophic complexity.

Effects of grazing in different intensities and 10‐year grazing exclusion on soil bacterial community composition and interaction complexity in alpine grasslands of the Qinghai‐Tibet Plateau

AbstractTo decrease the detrimental consequences of overgrazing on the sustainability of grassland ecosystems, many countries have developed policies on grazing exclusions. However, compared with grazing, how grazing exclusion modifies soil bacterial community and the associated environmental drivers is inadequately understood. Here, we studied the effects of grazing in different intensities (no grazing, light, moderate, and heavy grazing) and 10 years' grazing exclusion on soil bacteria community and associated environmental factors in the grassland of the Qinghai‐Tibet Plateau. The results showed significant changes in soil bacterial composition among all the treatments. After 10 years' grazing exclusion, the composition of the bacterial community rather than bacterial diversity was significantly different from that in grassland without grazing treatment. Under grazing exclusion, bacterial community composition was regulated by the total nitrogen and nitrate nitrogen. Grazing treatments decreased the complexity of the bacterial co‐occurrence network, but 10 years' grazing exclusion increased the complexity. This study found that grazing in different intensities substantially affected bacterial community structure and diversity, but 10 years' grazing exclusion hardly alleviated the historical grazing effects on the bacterial community structure. The findings of the study extended the understanding of how bacterial communities in grasslands respond to grazing in different intensities and grazing exclusion, providing a crucial scientific foundation for evaluating sustainable grazing management.

Assessing changes in global fire regimes

BackgroundThe global human footprint has fundamentally altered wildfire regimes, creating serious consequences for human health, biodiversity, and climate. However, it remains difficult to project how long-term interactions among land use, management, and climate change will affect fire behavior, representing a key knowledge gap for sustainable management. We used expert assessment to combine opinions about past and future fire regimes from 99 wildfire researchers. We asked for quantitative and qualitative assessments of the frequency, type, and implications of fire regime change from the beginning of the Holocene through the year 2300.ResultsRespondents indicated some direct human influence on wildfire since at least ~ 12,000 years BP, though natural climate variability remained the dominant driver of fire regime change until around 5,000 years BP, for most study regions. Responses suggested a ten-fold increase in the frequency of fire regime change during the last 250 years compared with the rest of the Holocene, corresponding first with the intensification and extensification of land use and later with anthropogenic climate change. Looking to the future, fire regimes were predicted to intensify, with increases in frequency, severity, and size in all biomes except grassland ecosystems. Fire regimes showed different climate sensitivities across biomes, but the likelihood of fire regime change increased with higher warming scenarios for all biomes. Biodiversity, carbon storage, and other ecosystem services were predicted to decrease for most biomes under higher emission scenarios. We present recommendations for adaptation and mitigation under emerging fire regimes, while recognizing that management options are constrained under higher emission scenarios.ConclusionThe influence of humans on wildfire regimes has increased over the last two centuries. The perspective gained from past fires should be considered in land and fire management strategies, but novel fire behavior is likely given the unprecedented human disruption of plant communities, climate, and other factors. Future fire regimes are likely to degrade key ecosystem services, unless climate change is aggressively mitigated. Expert assessment complements empirical data and modeling, providing a broader perspective of fire science to inform decision making and future research priorities.

Understanding the Dynamics of Sex-Specific Responses Driven by Grassland Management: Using Syrphids as a Model Insect Group

Grassland ecosystems, managed by various grassland managements strategies, are the world’s most important land use. However, insect’s sex-specific responses within the context of grassland management have never been considered before. Therefore, our aim was to expand the understanding to the dynamics of grassland managements that drive sex-specific responses by using syrphids as a model insect group. We hypothesize that (1) male and female syrphids exhibit differential habitat preferences in grassland managements, (2) abundance and activity of male and female syrphid levels are influenced by vegetation structure in grassland habitats. Extensive and intensive grassland exhibited significantly different male and female syrphid abundance compared to abandoned grassland. Surprisingly, grassland management had a significant impact on male syrphids richness only, not on female. Flower cover significantly increased male and female syrphid abundance and richness. However, plant height significantly increased female syrphid abundance and richness only. Interestingly, abandoned grassland supports a higher amount of unique female syrphids than male syrphids. The dynamics of grassland management are not unidirectional, but they are multifaceted and multidirectional. Considering the importance of sex-specific responses by insects can provide a more comprehensive understanding of dynamics of grassland managements.

Effects of grazing on soil respiration in global grassland ecosystems

Soil respiration is an important process in the global carbon cycle, one that plays a crucial role in altering carbon dioxide levels in the atmosphere. However, the effects of grazing on soil respiration at the global scale remain unclear. Here, we analyzed 688 paired observations from 69 studies worldwide and found that grazing substantially suppresses soil respiration (including autotrophic respiration and heterotrophic respiration). Moreover, these negative effects on soil respiration were amplified at higher grazing intensity, longer grazing duration (> 10 years) and higher temperature (> 5 °C). Importantly, changes in belowground biomass drive soil respiration in response to grazing in grassland ecosystems worldwide. Overall, accurately predicting the soil respiration pattern in grazed grasslands allows us to minimize the impact of grazing on grassland functional structure and improve the sustainability of livestock production.