Grassland Sites Research Articles

Evaluation of the ECOSSE Model for Estimating Soil Respiration from Eight European Permanent Grassland Sites

This study used the ECOSSE model (v. 5.0.1) to simulate soil respiration (Rs) fluxes estimated from ecosystem respiration (Reco) for eight European permanent grassland (PG) sites with varying grass species, soils, and management. The main aim was to evaluate the strengths and weaknesses of the model in estimating Rs from grasslands, and to gain a better understanding of the terrestrial carbon cycle and how Rs is affected by natural and anthropogenic drivers. Results revealed that the current version of the ECOSSE model might not be reliable for estimating daily Rs fluxes, particularly in dry sites. The daily estimated and simulated Rs ranged from 0.95 to 3.1 g CO2-C m−2, and from 0.72 to 1.58 g CO2-C m−2, respectively. However, ECOSSE could still be a valuable tool for predicting cumulative Rs from PG. The overall annual relative deviation (RD) value between the cumulative estimated and simulated annual Rs was 11.9%. Additionally, the model demonstrated accurate simulation of Rs in response to grass cutting and slurry application practices. The sensitivity analyses and attribution tests revealed that increased soil organic carbon (SOC), soil pH, temperature, reduced precipitation, and lower water table (WT) depth could lead to increased Rs from soils. The variability of Rs fluxes across sites and years was attributed to climate, weather, soil properties, and management practices. The study suggests the need for additional development and application of the ECOSSE model, specifically in dry and low input sites, to evaluate the impacts of various land management interventions on carbon sequestration and emissions in PG.

Insects benefit from agri-environmental schemes aiming at grassland extensification

One key target of agri-environmental schemes (AES) is maintaining biodiversity. However, if and how insect biomass and diversity benefit from grassland AES is not well known. Using Malaise trap samples from 72 grassland sites in four grassland dominated regions in Southern Germany, we investigated the effect of 1) local grassland AES (three levels: control, farm-wide, site-specific), and 2) an index of land use extensification (LEI, calculated for each site) on insect biomass and species richness of all insects, of five insect orders including all species (Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera), and two pollinator groups (Syrphidae, Apiformes). Moreover, the effect of grassland AES in the surrounding landscape was quantified. Insect samples were subjected to metabarcoding to create DNA barcode sequences which were then compared with reference libraries (BOLD; NCBI) and additionally classified using the Ribosomal Database Project (RDP) classifier. Resulting taxonomies were combined into a consensus taxonomy table and the potential minimum number of species per sample was estimated. Statistical analyses were carried out using Generalized linear mixed models and Bayesian inference. Our results indicated that species richness of many insect groups benefited from AES. As predicted by the regression model, presence of site-specific grassland AES increased the species richness of all insects (∼8%), Hymenoptera (∼27%), Lepidoptera (∼35%) and Syrphidae (∼26%). While Apiformes benefited most, we found an average increase of species richness in the presence of farm-wide AES by ∼82% and even more with site-specific AES ∼120%. We found that an increasing LEI, and thus more extensive management, positively affected insect diversity in grassland habitats. No effect of local AES and LEI on insect biomass was found. Moreover, the amount of grassland AES in the landscape was less important for insect diversity. We conclude that many grassland insects (especially pollinators) benefit from extensive management. However, we showed that the studied AES variants comprise variable management intensities hampering general AES recommendations for promoting insects. AES programs should, therefore, specifically reward extensification measures that were shown to benefit insect diversity. The integration of the land use extensification index (LEI) as a tool in the AES framework seems a promising approach to preserve and promote of insect diversity.

Spatial distribution of tree and grassland fine roots in an alley cropping system

Alley cropping systems are known as more sustainable land use alternatives compared to monoculture cropland. In addition to the improvement of above-ground structures and creation of biotopes relevant to nature conservation, the improvement of resource development through various root systems plays a major role. We studied the interaction of the root systems in an alley cropping system combining permanent grassland and willows and at a reference grassland site. The system was established 12 years prior to our study on a site with a shallow groundwater table at 130 cm depth. We measured carbon stocks in the topsoil and determined the share of root-bound carbon relative to the total carbon pool and extracted soil cores up to a depth of 150 cm along a distance gradient to the trees and at a reference grassland site with no tree influence. The maximal rooting depth of the grassland roots increased with increasing distance to the tree lines and total root biomass was higher than under the grassland reference up to a distance of 2.5 m from the tree line. Tree roots extended up to a distance of 5.5 m from the trees and we could distinguish zones of tree root dominance very close to the trees, zones of grassland root dominance at distances ≥ 8.5 m and an interaction zone in between those two extremes. We conclude that alley cropping increases belowground biomass as compared to grassland and has therefore a higher potential to store carbon in the subsoil.

Epigaeic invertebrate diversity of post‐mining revegetation evaluated by comparison with adjacent remnant woodlands

This study evaluated the validity of invertebrate diversity for evaluating the condition of minesite rehabilitation. Because the aim of rehabilitation of mined lands in this region is to establish a self‐sustaining ecosystem that resembles “bushland,” a variety of remnant woodlands in the vicinity of the minesite were selected as reference sites. Reference sites encompassed a range of soil types (alluvial, coarse‐textured, or clay) and understorey structural types (grassy, grass, and shrub or shrubby). Grassland sites (cleared woodlands) were also sampled to provide a negative control. Epigaeic invertebrates of three rehabilitation sites were compared with five reference sites and three grassland sites using pitfall traps over 6 years. Sites were sampled annually and the annual data within each of two time periods (T1: 2008–2010 and T2: 2011–2013) were pooled. Ants, beetles, and springtails were identified as morphospecies, providing site species richness and composition data. Springtail metrics of all three habitats, reference, rehabilitation, and grassland, resembled each other in T1 as well as T2, indicating that rehabilitation rapidly provided suitable conditions for this group. In contrast, the ant and beetle composition of rehabilitation sites differed significantly from that of reference sites in T1 but not T2, although only ants matched the expected negative control with grassland sites remaining distinct from reference sites in both time periods. Thus, ant assemblages of rehabilitation sites show a positive trajectory toward native woodlands and away from grasslands. These findings demonstrate that rehabilitation sites are developing diverse invertebrate assemblages comparable to local remnant woodlands in relatively short time frames.

Globally consistent response of plant microbiome diversity across hosts and continents to soil nutrients and herbivores

All multicellular organisms host a diverse microbiome composed of microbial pathogens, mutualists, and commensals, and changes in microbiome diversity or composition can alter host fitness and function. Nonetheless, we lack a general understanding of the drivers of microbiome diversity, in part because it is regulated by concurrent processes spanning scales from global to local. Global-scale environmental gradients can determine variation in microbiome diversity among sites, however an individual host’s microbiome also may reflect its local micro-environment. We fill this knowledge gap by experimentally manipulating two potential mediators of plant microbiome diversity (soil nutrient supply and herbivore density) at 23 grassland sites spanning global-scale gradients in soil nutrients, climate, and plant biomass. Here we show that leaf-scale microbiome diversity in unmanipulated plots depended on the total microbiome diversity at each site, which was highest at sites with high soil nutrients and plant biomass. We also found that experimentally adding soil nutrients and excluding herbivores produced concordant results across sites, increasing microbiome diversity by increasing plant biomass, which created a shaded microclimate. This demonstration of consistent responses of microbiome diversity across a wide range of host species and environmental conditions suggests the possibility of a general, predictive understanding of microbiome diversity.

Simulation-based assessment of the soil organic carbon sequestration in grasslands in relation to management and climate change scenarios

Soil organic carbon (SOC) is crucial for the quality and productivity of terrestrial ecosystems and its sequestration plays an important role in mitigating climate change. Understanding the effects of agricultural management under future climate on the SOC balance helps decision making in environmental policies. Thereby, grasslands will play a key role, since future climate change may prolong the vegetation period.We used 24 representative grassland sites in Germany to assess the SOC balance obtained from the CANDY model in relation to ten management regimes, 18 future climate change scenarios and different soil types. Simulations were conducted over a period of 110 years.For most of the selected grassland sites an increase in both air temperature and precipitation was observed in the future climate. The effect of management on the SOC balance largely exceeded the effect of soil type and climate. An increasing management intensity (i.e. three to five cuts) generally increased the SOC balance, while extensive management (i.e. two or fewer cuts) lead to SOC losses. The seasonal variation of precipitation was the most important climate metric, with increased SOC sequestration rates being observed with increasing growing season precipitation. Clay soils had the potential for both highest gains and highest losses depending on management and precipitation. Given an overall lower SOC storage potential in sands and loams, the SOC balance in those soil types varied the least in response to climate change.We conclude that fostering SOC sequestration is possible in grassland soils by increasing management intensity, which involves increased fertilizer input and field traffic. This however may stand in conflict with other policy aims, such as preserving biodiversity. Multicriterial assessments are required to estimate the nett greenhouse gas balance and other aspects associated with these management practices at a farm scale.

Seasonal variation of ecosystem photosynthetic capacity and its environmental drivers in global grasslands

Ecosystem maximum photosynthetic rate (Amax) is an important ecosystem functional property, as it is critical for ecosystem productivity modeling. However, little is known about the mechanisms that regulate the seasonal variation of Amax in grasslands, one of the dominant vegetation types worldwide. In this study, we analyzed the seasonal variability of Amax of grassland sites across the globe and its environmental drivers. We found that grassland Amax had strong seasonal variations, which were influenced by the climate and agricultural management, such as grass cutting and grazing. Second, the seasonal variation of Amax at all arid grasslands [mean annual vapor pressure deficit (VPD) > 10 hPa] was driven more by changes in canopy physiological property (i.e., maximum photosynthetic rate per leaf area Amaxa) than canopy structural property (i.e., leaf area, presented by LAI), because Amaxa had stronger temporal variability than LAI in these ecosystems. Third, temperature and VPD were the most influential factors for the seasonal variability of Amax and LAI, but environmental variables only explained a small proportion of the seasonal variation of Amaxa, which was probably because Amaxa was more related to plant traits. Our findings provide new ideas for better parameterizations of Amax in terrestrial ecosystem models.

Application of isotopic labels optimised for large scale plot experiments

AbstractIsotopic tracer methods using 15N or other isotopes provide insights into the sources and underlying N transformations leading to N2O emissions from agricultural soils. However, homogeneous labelling of naturally structured soil in the field is challenging since macropore flow must be avoided while the application must be performed in a limited timeframe. Therefore, we tested the infiltration pattern of several application methods and consequently developed drip application (DA) for larger scales using individual dropper bottles. We performed a proof of concept test, followed by an evaluation experiment in-situ with a manual sprinkler as control at an undisturbed grassland site using 15NH415NO3 (80 kg N ha-1, 10 at.%, 15 mm precipitation equiv.). 15N-NH4+ and 15N-NO3- recovery rates and corresponding correlation coefficients were calculated to examine horizontal and vertical homogeneity. The proof of concept test showed the negative effect of very dry topsoil on homogeneous infiltration. DA achieved significantly larger 15N recovery rates than sprinkler application and led to a more homogeneous horizontal label distribution. For DA, coefficients of variation of 15N recovery rates were smaller than with sprinklers for most depths, yet for both methods 15N recovery rates especially of 15N-NH4+ decreased vertically. Besides optimised label distribution, the DA method offers high flexibility in application patterns while offering reproducibility, feasibility and a reasonable application speed also at undisturbed sites at the plot scale. Moreover, DA causes no change in soil structure or soil diffusivity. Thus, the drip application method was found suitable for tracer application to field sites.

Soil microbial carbon and activity along with land use and geographic gradients

AbstractChanges in microbial biomass carbon (MBC) and microbial respiration in soils under five different land‐use systems were evaluated at a regional scale in Santa Catarina State, Southern Brazil, to assess the effects of land‐use change and geographical distribution on the microbial and environmental patterns related to soil carbon (C) dynamics. Results showed that, in the West mesoregion, changes in MBC were correlated to the sampling season in forest and pasture systems. In the Plateau mesoregion, however, a land‐use effect was observed, with MBC decreasing in no‐till and crop‐livestock integration systems. Forest and grassland sites presented the highest values of MBC and microbial activity, while grassland sites showed lower values of the metabolic quotient (qCO2) and higher values of the microbial quotient. The qCO2 was also lower in winter for all land‐use systems. The highest total and particulate organic carbon values were found in forest sites. Chemical–physical characteristics were also observed to be significantly correlated with microbiological variables related to soil microbial C dynamics. In conclusion, land‐use intensity, season, and location were found to be the main drivers of changes in microbial C dynamics.

Environmental changes drive soil microbial community assembly across arid alpine grasslands on the Qinghai-Tibetan Plateau, China

Soil microbes play a key role in regulating ecosystem functions in arid alpine grasslands, which are extremely sensitive to environmental changes. However, the exact mechanism by which multiple environmental factors interact to shape local soil microbial community assembly is unclear. Therefore, exploring how changing environmental factors affect microbial community assembly responds to will help us predict microbial-mediated ecosystem processes under climate change. Here, we conducted large-scale field sampling from 30 alpine grassland sites (e.g., alpine meadow (AM), alpine steppe (AS) and alpine desert steppe (ADS)) across arid ecosystems on the Qinghai-Tibetan Plateau (QTP), China. Soil bacterial and fungal community assembly and their relationships with spatial, climatic, and vegetation-soil factors were studied with the Molecular Ecological Network Analysis Pipeline (MENAP), analysis of variance (ANOVA), canonical correspondence analysis (CCA) and structural equation models (SEMs). The results showed that the soil microbial diversity and co-occurrence network complexity increased significantly from ADS to AS and AM, and bacteria were more susceptible to environmental factors than fungi. The relative abundances of the dominant bacterial phyla, including Acidobacteria, Proteobacteria, Actinobacteria and Gemmatimonadetes, showed a statistically significant increase, while the relative abundance of the fungal phyla Basidiomycota and Glomeromycota showed significant differences across arid alpine grasslands. Variation partitioning analysis (VPA) revealed that vegetation-soil factors contributed the most to explaining the bacterial community composition, whereas spatial factors contributed the most to explaining the variation in the fungal community composition. The results obtained from the SEMs suggested that latitude and soil pH had the greatest impact on the diversity of bacteria and fungi, respectively. Taken together, the results of this study provide a comprehensive perspective on how the soil microbial communities respond to changes in environmental factors across arid alpine grasslands on the QTP, China.

Geographical variation in community‐wide herbivory matches patterns of intraspecific variation instead of species turnover

AbstractAimAttempts over the past 30 years to explain geographical variation in the strength of herbivore pressure have given rise to ecological hypotheses like the latitudinal herbivory hypothesis. This hypothesis, however, has rarely been tested using community‐level data. Therefore, the aim of our study was to examine the patterns and potential mechanisms underlying geographical variation in community‐wide herbivory.LocationThe Qinghai‐Tibetan Plateau.Time PeriodJuly 2021.Major Taxa StudiedPlants.MethodsWe selected 43 grassland sites along a 1500‐km latitudinal gradient (c. 27°N to 39°N) and a 2698‐m elevational gradient (1886–4584 m) on the Qinghai‐Tibetan Plateau. We evaluated geographical patterns in invertebrate herbivory pressure at the population and community levels, while also evaluating the importance of geographical variation in mediating the effects of abiotic and biotic factors on intraspecific variation (through changes in herbivory on component species) and species turnover effects (through changes in plant community composition).ResultsCommunity‐wide herbivory decreased with latitude, mirroring intraspecific variation, while species turnover effects did not vary along any tested geographical gradients. Furthermore, we found that geographical variation in community‐wide herbivory was strongly positively correlated with soil nitrogen content. We also found a positive effect of soil nitrogen content on intraspecific variation and a negative effect of plant community biomass on species turnover effects.Main ConclusionsThe latitudinal gradient in community‐wide herbivory was primarily mediated by intraspecific variation, which was in turn associated with a gradient in soil nitrogen content. Our findings highlight the need for community‐wide assessments of geographical variation in plant–herbivore interactions, decomposing community‐wide herbivory into intraspecific variation and species turnover effects.

Nitrogen deficiency accelerates soil organic carbon decomposition in temperate degraded grasslands

The impacts of nitrogen (N) availability on soil organic carbon (SOC) decomposition were often explored based on N enrichment (N+) experiments. However, many natural and anthropogenic processes often reduce soil N availability. There is no direct evidence about how decreased N availability (N−) affects SOC decomposition, and the mechanisms of microbe-driven SOC decomposition in response to N availability remain unclear. Here, we used ion-exchange membranes to simulate N−. Soil samples from four temperate grassland sites, ranging from non-degradation to extreme degradation, were incubated with the N− and N+ treatments. We found that the total cumulative carbon (C) release was promoted by the N− treatment (8.60 to 87.30 mg C/g Cinital) but was inhibited by the N+ treatment (−129.81 to −16.49 mg C/g Cinital), regardless of the degradation status. N− dramatically increased recalcitrant C decomposition by increasing soil pH at all grassland sites; while did not affect or even decreased labile C decomposition by significantly increasing microbial C use efficiency and soil microbial biomass N. Interestingly, the effects of N− and N+ on SOC decomposition was asymmetric; with increased grassland degradation, the SOC decomposition was more sensitive to N− than to N+. Our results provide direct evidence for the different effects and mechanisms of N− on SOC decomposition and should be considered in soil process models to better predict the response of the nutrient cycle to global changes.

Protected habitats support bats in Mediterranean dry grasslands

The replacement of natural habitats by urbanization and agricultural land reclamation is one of the main drivers of biodiversity loss. Among European habitat types, natural grasslands are particularly prone to anthropogenic pressures, being also recognized as conservation priorities within the Habitats Directive. Nonetheless, little is known on the relationship between grasslands, their conservation quality, and most animals' taxa that may rely upon them. Here we focus on the role of Mediterranean dry grasslands protected by the EU legislation in sustaining bat populations, setting our study in the biodiversity hotspot of Mediterranean Italy. By conducting acoustic surveillance at 48 sites within a protected area devoted to conserve natural and semi-natural grasslands, we found that all the bat species found in the area are regular exploiters of such open environments. Grassland conservation quality, in terms of extent of high-diversity protected habitats, was the key factor shaping the use of grasslands by bats of all the considered guilds, together with several terrain and landscape features, which showed more guild-specific effects. Moreover, our results indicate that bat assemblages are functionally shifted along an ecological gradient from highly modified to well-conserved grassland sites, indicating a prevalence of opportunistic taxa in the former, and higher abundance of species of conservation concern in the latter. Overall, we demonstrate that the effects of EU-listed habitats may extend also onto bats in the case of Mediterranean dry grasslands, highlighting the importance of preserving such habitats as a tool for conserving highly mobile species.

Mapping Forage Biomass and Quality of the Inner Mongolia Grasslands by Combining Field Measurements and Sentinel-2 Observations

Grasslands provide essential forage sources for global livestock production. Remote sensing approaches have been widely used to estimate the biomass production of grasslands from regional to global scales, but simultaneously mapping the forage biomass and quality metrics (e.g., crude fiber and crude protein) is still relatively lacking despite an increasing need for better livestock management. We conducted novel gradient grass-cutting experiments and measured hyperspectral reflectance, forage biomass, crude fiber per area (CFarea), and crude protein per area (CParea) across 19 temperate grassland sites in the Xilingol region, Inner Mongolia, China. Based on these measurements, we identified sensitive spectral bands, calculated nine potential spectral indices (Normalized Difference Vegetation Index, Enhanced Vegetation Index, Red Edge Normalized Difference Vegetation Index, Red-Edge Inflection Point, Inverted Red-Edge Chlorophyll Index algorithm, Normalized Difference Red Edge Index, Nitrogen Reflectance Index, Normalized Greenness Index, Land Surface Water Index) and established Random Forest (RF) models that well predicted forage biomass (R2 = 0.67, NRMSE = 12%), CFarea (R2 = 0.59, NRMSE = 14%), and CParea (R2 = 0.77, NRMSE = 10%). Among these nine indices, Land Surface Water Index (LSWI, calculated by R785-900 and R2100-2280) was identified to be the most important predictor and was then used to establish empirical power law models, showing comparable prediction accuracies (forage biomass, R2 = 0.53; NRMSE = 14%; CFarea, R2 = 0.40, NRMSE = 17%; CParea, R2 = 0.72, NRMSE = 11%) in comparison to Random Forest models. Combining the empirical power law models with the LSWI calculated from Sentinel-2 observations, we further mapped the forage biomass and quality and estimated the livestock carrying capacity. The predicted forage biomass, CFarea, and CParea all showed a significant increase with higher mean annual precipitation, but showed no significant correlations with mean annual temperature. Compared with the estimates based on crude protein, the conventional approach solely based on forage biomass consistently overestimated livestock carrying capacity, especially in wetter areas. Our work provides an approach to simultaneously map the forage biomass and quality metrics and recommends a LSWI-based power law model for rapid and low-cost assessment of regional forage status to guide better livestock management.

Land use modification causes slow, but predictable, change in soil microbial community composition and functional potential

BackgroundBacterial communities are critical to ecosystem functioning and sensitive to their surrounding physiochemical environment. However, the impact of land use change on microbial communities remains understudied. We used 16S rRNA gene amplicon sequencing and shotgun metagenomics to assess soil microbial communities' taxonomic and functional responses to land use change. We compared data from long-term grassland, exotic forest and horticulture reference sites to data from sites that transitioned from (i) Grassland to exotic forest or horticulture and from (ii) Exotic forest to grassland.ResultsCommunity taxonomic and functional profiles of the transitional sites significantly differed from those within reference sites representing both their historic and current land uses (P < 0.001). The bacterial communities in sites that transitioned more recently were compositionally more similar to those representing their historic land uses. In contrast, the composition of communities from sites exposed to older conversion events had shifted towards the compositions at reference sites representing their current land use.ConclusionsOur study indicates that microbial communities respond in a somewhat predictable way after a land use conversion event by shifting from communities reflecting their former land use towards those reflecting their current land use. Our findings help us to better understand the legacy effects of land use change on soil microbial communities and implications for their role in soil health and ecosystem functioning. Understanding the responsiveness of microbial communities to environmental disturbances will aid us in incorporating biotic variables into soil health monitoring techniques in the future.

Vegetation change in acidic dry grasslands in Moravia (Czech Republic) over three decades: Slow decrease in habitat quality after grazing cessation

AbstractAimsShallow soils on acidic bedrock in dry areas of Central Europe support dry grasslands and heathlands that were formerly used as extensive pastures. These habitats are of high conservation value, but their abandonment in the 20th century triggered slow natural succession that poses a threat to specialized plant species. We asked how this vegetation and its plant diversity have changed over the past three decades and whether protected areas have positively affected habitat quality.LocationSouthwestern and central Moravia, Czech Republic.MethodsIn 2018–2019, we resurveyed 94 vegetation plots first sampled in 1986–1991 at 47 acidic dry grassland and heathland sites. We compared the number of all vascular plant species, Red List species and alien species per plot using parametric and non‐parametric tests, life‐form spectra using the chi‐square test, species composition using detrended correspondence analysis, and indicator values using a permutation test. We also compared these changes between sites within and outside protected areas.ResultsVegetation changes over the past three decades have been relatively small. However, we detected a decrease in total species richness, the number of Red List species and the number of characteristic species of dry grasslands. Neophytes were infrequent, while archaeophytes increased slightly. The competitive tall grass Arrhenatherum elatius, annual species and young woody plants increased in abundance or newly established at many sites. Indicator values did not change except for a slight increase in nutrient values. These negative trends occurred both within and outside protected areas but were more pronounced outside.ConclusionsFormerly grazed acidic dry grasslands and heathlands in Moravia are slowly losing habitat specialists, including threatened plant species, and are increasingly dominated by Arrhenatherum elatius. Conservation management, especially cutting in protected areas, slows down the negative trends of decline in plant diversity and habitat quality but is insufficient to halt these processes completely.

Effects of habitat management on rodent diversity, abundance, and virus infection dynamics.

As anthropogenic factors continue to degrade natural areas, habitat management is needed to restore and maintain biodiversity. However, the impacts of different habitat management regimes on ecosystems have largely focused on vegetation analyses, with limited evaluation of downstream effects on wildlife. We compared the effects of grassland management regimes (prescribed burning, cutting/haying, or no active management) on rodent communities and the viruses they hosted. Rodents were trapped in 13 existing grassland sites in Northwest Arkansas, USA during 2020 and 2021. Rodent blood samples were screened for antibodies against three common rodent-borne virus groups: orthohantaviruses, arenaviruses, and orthopoxviruses. We captured 616 rodents across 5953 trap nights. Burned and unmanaged sites had similarly high abundance and diversity, but burned sites had a higher proportion of grassland species than unmanaged sites; cut sites had the highest proportion of grassland species but the lowest rodent abundance and diversity. A total of 38 rodents were seropositive for one of the three virus groups (34 orthohantavirus, three arenavirus, and one orthopoxvirus). Thirty-six seropositive individuals were found in burned sites, and two orthohantavirus-seropositive individuals were found in cut sites. Cotton rats and prairie voles, two grassland species, accounted for 97% of the rodents seropositive for orthohantavirus. Our study indicates that prescribed burns lead to a diverse and abundant community of grassland rodent species compared with other management regimes; as keystone taxa, these results also have important implications for many other species in food webs. Higher prevalence of antibodies against rodent-borne viruses in burned prairies shows an unexpected consequence likely resulting from robust host population densities supported by the increased habitat quality of these sites. Ultimately, these results provide empirical evidence that can inform grassland restoration and ongoing management strategies.

Detecting ecological traps in human-altered landscapes: A case study of the thick-billed longspur nesting in croplands.

Conversion of the North American prairies to cropland remains a prominent threat to grassland bird populations. Yet, a few species nest in these vastly modified systems. Thick-billed longspurs historically nested in recently disturbed or sparsely vegetated patches within native mixed-grass prairie, but observations of longspurs in spring cereal and pulse crop fields during the breeding season in northeastern Montana, USA, suggest such fields also provide cues for habitat selection. Maladaptive selection for poor-quality habitat may contribute to ongoing declines in longspur populations, but information on thick-billed longspur breeding ecology in crop fields is lacking. We hypothesized that crop fields may function as ecological traps; specifically, we expected that crop fields may provide cues for territory selection, but frequent human disturbance would result in reduced reproduction. To address this hypothesis, we compared measures of habitat selection (settlement patterns and trends in abundance) and productivity (nest density, nest survival, and number of young fledged) between crop fields and native grassland sites during 2020-2021. Across both years, settlement patterns were similar between site types and occupancy ranged from 0.52 ± 0.17 SE to 0.99 ± 0.01 on April 7 and 30, respectively. Early season abundance differed by year, and changes in abundance during the breeding season appeared to be associated with precipitation-driven vegetation conditions rather than habitat type. While an index of nest density was lower in crop than native sites, the number of young fledged per successful nest (2.9 ± 0.18 SE) and nest survival (0.24 ± 0.03 SE; n = 222 nests) were similar for crop and native sites. Collectively, the data did not support our ecological trap hypothesis: longspurs did not exhibit a clear preference for crop sites and reproductive output was not significantly reduced. Our results indicate that croplands may provide alternative breeding habitat within a human-dominated landscape.

Intensity‐dependent effects of cattle and sheep grazing in sand grasslands — Does livestock type really matter?

AbstractAimsBy analysing cattle‐ and sheep‐grazed sand grasslands, we tested the following hypotheses: (i) livestock type has a stronger effect on the vegetation characteristics than grazing intensity; (ii) sheep grazing results in lower biomass and species and functional diversity than cattle grazing, regardless of intensity; and (iii) increased grazing intensity causes a shift of the trait composition in grasslands.LocationSand grasslands in the Nyírség region, East Hungary.MethodsWe selected 26 sand grassland sites grazed by cattle or sheep and classified them into four intensity levels. Vegetation composition was surveyed in 2 m × 2 m plots. We harvested the above‐ground biomass from 20 cm × 20 cm plots; then dried and sorted it to live biomass, litter, moss, and lichen. We compared Rao dissimilarity index, species richness, Shannon diversity, evenness, and the community‐weighted means of nine vegetative and generative traits along a grazing intensity gradient. We calculated functional richness, evenness, and divergence for comparison.ResultsWe found that some diversity metrics and community‐weighted means of most studied traits were significantly affected by grazing intensity. Several characteristics were also affected by the interaction of grazing intensity and livestock type, but none of the studied characteristics was affected by livestock type in itself. Increasing Rao dissimilarity index peaking at the fourth grazing intensity level was detected, but for other multitrait indices, no such changes were proven, except for functional divergence, which was the lowest at the first intensity level. Graminoid, forb, and litter biomass were significantly affected by intensity, but none of the biomass fractions was affected by livestock type.ConclusionsWe suggest that for the management of sand grasslands, grazing intensity should be carefully adjusted, considering not only livestock units per hectare. For practical recommendations, well‐defined, long‐term experiments studying different livestock and habitat types along an intensity gradient would be essential.

Grassland species colonization of a restored grassland on a former forest varies in short‐term success but is facilitated by greater functional connectivity

In recent years, restoration on former grassland sites has been widely encouraged globally, aiming to address the historical loss of 90% of ancient species‐rich grasslands, and to mitigate the associated threat to grassland biodiversity. The objective of our study was to investigate on a small‐scale how plant species spontaneously colonize restored grasslands. We inventoried 275 permanent plots twice (in 2019 and 2021) in a restored grassland, following the removal of a conifer plantation. Species richness and vegetation cover in surveyed plots were dependent on grazing activity and distance to adjacent grassland. Plant species associated with forest habitats declined, while the occurrence of generalist species together with a few grassland specialists generally increased. However, not all grassland specialists gained occurrence and the colonization pattern was not consistent over time, possibly due to the lack of continuous seed arrival and low livestock activity and hence lack of disturbance. These results suggest that successful colonization of plant species benefits from links to species‐rich sites adjacent to the restoration target, with spatial dispersal and improved conditions for species establishment being key to species occurrence. Both dispersal and establishment potential are likely facilitated through the presence of grazing livestock with access to both species‐rich grasslands and restoration targets. However, the shift towards a more typical grassland community takes place gradually, with vulnerable populations of early colonizing grassland species prone to local extinction in short‐term. As a result, continued functional connectivity provided by grazing animals is necessary to improve the diversity of the restored site and ensure the establishment of grassland specialists and to maintain the plant community composition.