Grassland Populations Research Articles

Impacts of climate change and human activity on the potential distribution of Aconitum leucostomum in China

Aconitum leucostomum is a poisonous grass that disturbs grassland populations and livestock development, and its spread is influenced by climate change and human activities. Therefore, exploring its potential distribution area under such conditions is crucial to maintain grassland ecological security and livestock development. The present study initially selected 39 variables that may influence the spatial distribution of A. leucostomum, including bioclimate, soil, topography, solar radiation, and human footprint data; the variables were screened by Spearman's correlation coefficient and the jackknife method. Twenty variables were finally identified, and three types of models based on the maximum entropy (MaxEnt) model were constructed to predict the distribution of A. leucostomum within China under three shared economy pathways (SSP126, SSP245, and SSP585): A: prediction of environmental variables under the current climate model; B: prediction of environmental variables + human footprint under the current climate model; and C: prediction of environmental variables under the future climate model (including the 2030s, 2050s, and 2070s). The effects of human activities and climate change on the potential geographic distribution of A. leucostomum were explored separately. The results show that precipitation seasonality, human footprint, solar radiation and mean diurnal range are the main factors affecting the distribution of A. leucostomum. Human activities inhibit the spread of A. leucostomum, and climate change promotes its growth, with areas of high suitability and area variation mainly in northern Xinjiang and northern Yunnan. With climate change, in the future, the distribution center of A. leucostomum shows a tendency to migrate to the southeast on the horizontal gradient and to move to higher altitudes on the vertical gradient. This study provides a positive reference value for the control of A. leucostomum and the maintenance of grassland ecological security.

Population Fluctuations of the Deer Mouse (Peromyscus maniculatus) in Old-Field and Bunchgrass–Sagebrush Habitats: The Role of Agricultural Setting and Optimum Habitat

In semiarid regions, the deer mouse (Peromyscus maniculatus) is a major small mammal species occupying perennial grassland habitats that include old-fields, native bunchgrass–sagebrush, and some agricultural settings. We investigated population changes in deer mouse populations in perennial grasslands, both natural and old-field, from 1982 to 2003 in southern British Columbia, Canada. Hypotheses (H) predicted that P. maniculatus populations will have (H1) multiannual fluctuations in abundance driven by population increases from extended breeding in summer and winter; (H2) relaxed spring reorganization events in some years leading to higher overall recruitment and survival; and (H3) interspecific competition with montane voles that causes deer mice to be lower in density when voles are higher. P. maniculatus populations in old-field and grass–sagebrush sites had clearly defined periods of high “peak” mean numbers (32–52/ha) and other times of low mean numbers (20–22/ha). Based on mean annual peak density in autumn, deer mouse populations exhibited fluctuations of 3–4 years in both habitats, but this pattern was not always present. The greater numbers of P. maniculatus in high than low years was directly related to population increases from extended breeding seasons and an increased number of lactating females, thereby supporting H1. Spring breeding season declines occurred but were similar or less in high than low years of mean abundance and were relaxed in comparison to forest populations of deer mice in other studies. Thus, H2 was supported for recruitment with high numbers of young-of-the-year breeding and total number of juvenile recruits but for survival was equivocal. Total summer survival was consistently higher in high than low population years but juvenile productivity in all years was poor. Mean abundance of P. maniculatus and M. montanus in old-field sites were highly correlated, and hence H3 was not supported. This latter result is the first, to our knowledge, of P. maniculatus coexisting in a similar pattern of population fluctuations with a Microtus species in a mainland grassland habitat. Higher than average precipitation in the year preceding a peak population of deer mice may have enhanced herbaceous vegetation and contributed to population increases in both habitats. We conclude that the old-field habitat associated with this agricultural setting provides optimum habitat for P. maniculatus and facilitates multiannual population fluctuations in this species.

Henslow’s Sparrow shows positive response to prescribed fire rotation

Abstract We examined Henslow’s Sparrow (Centronyx henslowii) response to prescribed fire at 32 grasslands at Big Oaks National Wildlife Refuge in southeastern Indiana from 1999 to 2009. We burned grasslands in the spring between 1999 and 2007 and monitored Henslow’s Sparrows for up to 4 yr after treatment. We used linear mixed models to analyze our data. Henslow’s Sparrow counts were correlated with time since prescribed fire and grassland size. The estimated changes in mean Henslow’s Sparrow density relative to pre-burn densities were −0.19, 1.15, 0.74, and −0.68 birds ha−1 for 1–4 breeding seasons after a spring burn, respectively. We found that Henslow’s Sparrows preferred larger grasslands both during the first breeding season after prescribed fire, when vegetation was presumed to possess less litter and structural density, and during the fourth breeding season after fire, when vegetation was presumed to be a more ideal composition, but preferred smaller grasslands in the interim. Thus, grassland size shapes the magnitude of Henslow’s Sparrow population response to fire, with populations in smaller grasslands experiencing greater amplitude changes. Larger grasslands might provide more habitat diversity following prescribed fire, attenuating population change. On average, Henslow’s Sparrows responded positively to prescribed fire in a network of grasslands and cumulative net change in densities were highest three breeding seasons after a burn suggesting that maintaining this burn frequency would be beneficial to Henslow’s Sparrow abundance.

Pleistocene megafaunal extinction in the grasslands of Junín‐Peru

AbstractAimTo determine the timing of megafaunal extinction in the high plains of Peru and also to determine if the timing was delayed in grasslands compared with previously published forested settings to dissociate the effects of succession from human or climatic impacts.LocationThe Junín Plateau, Peru.TaxonFlowering plants and Ascomycetes.MethodsThe sediments used in this analysis were collected from the edge of Lake Junín, Peru. Eleven ages derived from 14C accelerator mass spectrometry provide a chronology. We provide a paleoecological reconstruction of past climate and vegetation change, fire history and megafaunal herbivore presence from c. 20,000–7000 years ago based on fossil pollen, charcoal and Sporormiella spores. Data were analysed using multivariate analysis and Bayesian change point analysis.ResultsMegafaunal populations appear to have been positively impacted by dry climatic oscillations until c. 15,200 years ago. A reduction in Sporormiella abundance between 13,000 and 12,300 years before the present coincides with increased charcoal abundance and is identified as the period of megafaunal population collapse leading to extinction. The timing of the extinction does not differ substantially from that observed in wooded Andean settings.Main ConclusionThe timing of the collapse of megafaunal populations in high grasslands was very similar to that of lower, now‐forested settings. Upticks in fire activity, during what is generally seen to be a wet period, formed the backdrop to extinction and are strongly associated with human activity.

Green infrastructure can promote plant functional connectivity in a grassland species around fragmented semi‐natural grasslands in NW‐Europe

Species may benefit from green infrastructure, i.e. the network of natural and anthropogenic habitat remnants in human‐dominated landscapes, if it helps isolated populations in remaining habitat patches to be functionally connected. The importance of green infrastructure is therefore increasingly emphasized in conservation policy to counter biodiversity loss. However, there is limited evidence, particularly in plants, that green infrastructure promotes functional connectivity, i.e. supports the colonization of habitat patches across a landscape. We applied landscape genetics to test whether the green infrastructure supports structural and functional connectivity in the grassland perennial Galium verum, in 35 landscapes in Belgium, Germany and Sweden. We used multivariate genetic clustering techniques, nestedness analyses and conditional inference trees to examine landscape‐scale patterns in genetic diversity and structure of plant populations in the green infrastructure surrounding semi‐natural grasslands. Inferred functional connectivity explained genetic variation better than structural connectivity, yielding positive effects on genetic variation. The road verge network, a major structural component of the green infrastructure and its functional connectivity, most effectively explained genetic diversity and composition in G. verum. Galium verum ramets occupying the surrounding landscape proved to be genetic subsets of focal grassland populations, shaping a nested landscape population genetic structure with focal grasslands, particularly ancient ones, harbouring unique genetic diversity. This nested pattern weakened as road network density increased, suggesting road verge networks enable high landscape occupancy by increased habitat availability and facilitates gene flow into the surrounding landscape. Our study proposes that green infrastructure can promote functional connectivity, providing that a plant species can survive outside of core habitat patches. As this often excludes habitat specialist species, conservation practice and policy should primarily focus on ancient, managed semi‐natural grasslands. These grasslands both harbour unique genetic diversity and act as primary gene and propagule sources for the surrounding landscape, highlighting their conservation value.

Cattle grazing in CRP grasslands during the nesting season: effects on avian reproduction

AbstractBird populations in grasslands have experienced declines coinciding with loss and fragmentation of prairies. The United States Department of Agriculture (USDA)‐administered Conservation Reserve Program (CRP) is the most extensive grassland restoration program in North America and it has especially benefitted grassland birds. Grazing by domestic cattle has been restricted in CRP during avian nesting seasons despite the potential improvements in structuring habitat for a greater diversity of grassland bird species. Potential negative consequences of grazing in CRP grasslands include trampling of nests by cattle, reductions in nest concealment from predators, and attraction of brood‐parasitic brown‐headed cowbirds (Molothrus ater). We designed an experiment to test for effects of cattle grazing in CRP fields during the nesting season on nest survival and brood parasitism of 5 bird species that commonly nest in CRP grasslands: mourning dove (Zenaida macroura), grasshopper sparrow (Ammodramus savannarum), dickcissel (Spiza americana), and eastern (Sturnella magna) and western (S. neglecta) meadowlarks. Grazing was implemented during summers 2017 and 2018 on 17 of 36 fields followed by a year of rest on all fields in 2019. Of the 879 nests on grazed fields, only 4 were likely trampled by cattle (vs. 54% of all nests estimated as failing because of depredation). Experimental grazing (grazed vs. ungrazed fields) had variable effects on nest survival and cowbird parasitism among the bird species analyzed. Negative effects of grazing on daily nest survival of dickcissel and meadowlarks were apparent, at least in some years. We found no direct effects of grazing on nest survival of mourning dove or grasshopper sparrow. Probability and intensity (cowbird offspring/nest) of cowbird parasitism in dickcissel nests was higher on grazed versus ungrazed sites but only in conservation practice (CP) CP2 (vs. CP25 fields). Parasitism probability of grasshopper sparrow nests by cowbirds was higher on grazed fields in the 2 years after introduction of cattle in 2017. Greater vegetative concealment around nest sites was associated with reduced cowbird parasitism of meadowlark and grasshopper sparrow nests and higher nest survival for grasshopper sparrows. Reductions in vegetative height caused by longer‐term or high‐intensity grazing might therefore have negative consequences for some grassland birds by increasing nest site visibility and exposure to cowbird parasitism. Our results indicate that cattle grazing in CRP fields during the nesting season might have some negative effects on reproductive success of some grassland bird species, at least in the short term; however, the potential improvements of structuring habitat to accommodate more grassland bird species and increasing landowner participation in the CRP are considerable.

Occurrence of an endangered grassland butterfly is mainly driven by habitat heterogeneity, food availability, and microclimate.

The Marsh Fritillary (Euphydryas aurinia) was once widespread in large parts of Central Europe. However, in the course of the last century, populations of the butterfly largely collapsed. Here, we surveyed patch and microhabitat occupancy and its drivers in one of the last vital populations in calcareous grasslands. Our study revealed that environmental conditions at the landscape and habitat level determined the occurrence of E.aurinia in a montane agricultural landscape with low land-use intensity. Patch occupancy increased with the cover of Devil's-bit Scabious (Succisa pratensis) grasslands in the surroundings of the patches, habitat heterogeneity and host-plant cover. Microhabitat occupancy was driven by a warm microclimate and high availability of host plants. In the well-connected landscape of nutrient-poor grasslands, patch occupancy of E. aurinia was driven by parameters defining a high habitat quality. Habitat heterogeneity very likely buffers E. aurinia populations against environmental stochasticity and, hence, enhances long-term viability. For the gregariously feeding caterpillars of E. aurinia, host-plant biomass is essential. Due to their more luxuriant growth, S. pratensis plants were clearly preferred, although the Glossy Scabious (Scabiosa lucida) was also widespread. Additionally, the growth of large Succisa plants was favored by soil humidity and grassland abandonment. To cope with the adverse macro- and mesoclimatic conditions of the study area, females of the butterfly selected host plants growing in extraordinarily warm microhabitats for oviposition. To secure long-term viability of E. aurinia populations, we recommend creating mosaics of traditionally managed grasslands and early stages of abandonment within the patches.

Impacts of sheep versus cattle livestock systems on birds of Mediterranean grasslands

Mediterranean pastures are experiencing strong changes in management, involving shifts from sheep to cattle-based livestock systems. The impacts of such shifts on biodiversity are still poorly understood. Here, we sought to contrast the grazing regime, vegetation structure, bird species richness and abundance, between sheep and cattle grazed parcels, to understand the mechanisms through which management decisions impact farmland birds. During spring 2019, we characterized livestock management, bird populations and sward structure in 23 cattle and 27 sheep grazed parcels. We used a Structural Equation Model to infer the direct and indirect effects of sheep and cattle grazing on birds. Although no effects were found on overall species richness, there were species-specific responses to sheep and cattle grazed systems. Grazing pressure (variable integrating stocking rate and the number of days in the parcel) had negative impacts on the prevalence/abundance of Zitting Cisticola, Corn Bunting and Little Bustard, either directly or indirectly, through the effects of grazing pressure on vegetation height. Animal density and vegetation cover had direct positive effects in Galerida spp. and Common Quail, respectively. Zitting Cisticola and Little Bustard also showed a direct response to livestock type. Our study emphasizes the importance of grazing pressure as a driver of negative impacts for bird populations in Mediterranean grasslands. Since the ongoing transition from sheep to cattle-based systems involves increases in stocking rate, and therefore potentially higher grazing pressure, we propose a policy change to cap the maximum allowed grazing pressure. At the landscape scale, a mix of sheep and cattle grazed fields would be beneficial for maintaining bird diversity.

Surrounding landscape structures, rather than habitat age, drive genetic variation of typical calcareous grassland plant species

ContextLand use change reduced calcareous grasslands throughout Europe during the last decades. Subsequent fragmentation and habitat deterioration led, moreover, to a massive biodiversity decline. To counteract this alarming development, a clear understanding of genetic variation patterns, as fundamental level of biodiversity, becomes inevitable.ObjectivesThe aim of our study was to identify the drivers of genetic variation in common calcareous grassland plant species. More specifically, we tested whether genetic diversity or differentiation of Asperula cynanchica, Campanula rotundifolia, and Linum catharticum depend on habitat age, landscape structure, habitat quality, and/or population size.MethodsWe investigated 912 individuals, 304 per study species, from 19 calcareous grasslands across the Swabian Alb in Baden-Württemberg (Germany) using AFLP analyses.ResultsWe observed no significant influence of habitat age on genetic diversity and differentiation. Habitat quality also had no impact on genetic diversity and population size only showed weak effects. However, genetic diversity strongly depended on landscape structure represented by distance to the nearest settlement, total area of surrounding calcareous grasslands, and their connectivity.ConclusionsMigratory sheep herding is considered as main land use in calcareous grasslands on the Swabian Alb and thus, landscape structures in the study region may describe movement patterns of grazing livestock. In this study, genetic variation in calcareous grassland populations was strongly affected by surrounding landscape structures and subsequent grazing patterns. Therefore, we assume that moderate grazing intensities over the long term may increase levels of genetic diversity, whereas periods of overgrazing or abandonment could lower genetic diversity.

Rodents' responses to manipulated plant litter and seed densities: implications for restoration.

Rodent populations in arid grasslands do not always track seed production, possibly due to high levels of plant litter. When natural disturbances are suppressed, litter accumulates becoming physically complex, causing rodents to harvest fewer seeds per equivalent time foraging. It also alters security from predation. Restoring natural disturbances may be an important element in conserving rodent communities. The aim of this study was to assess the influence of two levels of plant litter cover and seed densities on nocturnal rodent population characteristics in a semiarid grassland. Specifically, I hypothesized that kangaroo rats, pocket mice, grasshopper mice, and total rodents would be higher in the sparse plant litter treatment than dense litter, whereas deer mice would be lower in sparse plots. I further hypothesized that kangaroo rats and deer mice would be higher in the seed augmented treatment compared to the unseeded treatment. A prescribed fire removed litter in four of eight plots prior to sowing native seeds 1 year postfire into two burned and two unburned plots. Rodents were live-trapped during spring and fall 1 year. Sparse litter treatment had higher total rodent abundance, biomass, and frequency of offspring compared to dense plots indicating use of stored seeds. Banner-tailed kangaroo rats had higher abundance, implying reduced predation risk. Pocket mice body mass was greater in dense plots. After winter, seeded plots had higher kangaroo rat body mass and grasshopper mice abundance than unseeded, reflecting the use of stored seeds. These short term results demonstrate litter’s physical complexity may be equivalent to seed pulses on the responses of nocturnal rodents. Managers might positively influence grassland rodents by providing a mosaic of varying levels of plant litter.

No Net Loss of Species Diversity After Prescribed Fires in the Brazilian Savanna

Although savannas are fire-adapted ecosystems, prescribing fire for biodiversity conservation remains controversial at least in some regions where savannas occur. Faced with uncertainty, many decision makers and even scientists are still reluctant to prescribe fire for conservation purposes in fire-prone ecosystems, invoking the precautionary principle. Knowledge gaps on the ideal fire regime, such as how and when to burn, and especially the fear of biodiversity losses, are among the main arguments against fire management applied to remnants of native savanna vegetation. To inform this debate, we assessed the impact of prescribed fires on diversity of plants (different growth forms), ants, frogs, lizards, birds, and small mammals, in savannas and grasslands of the Brazilian Cerrado. We assessed the existing species richness, composition, and abundance in areas subjected to long periods of fire suppression and compared to that observed over a short period after prescribed dry-season fires, within each group of plants and animals. Whenever possible, we carried out separate analyses for grassland and savanna. Burning did not significantly reduce species richness of any of the groups analyzed, but had a positive effect on richness of graminoids in grassland. When analyzed at the species level, abundance of most animal groups did not show consistent responses to fire, except for a decrease in some frog populations in grasslands. Forbs, graminoids and subshrubs increased in abundance after fire in grassland areas, though in savanna areas, abundance of forbs and subshrubs tended to decline after fire. Species composition changed little in response to fire as indicated by low levels of dissimilarity between burned and unburned areas. These results confirm the high resilience of Cerrado biota to fire, as expected for savanna ecosystems in general. Besides, we demonstrate here that the risk of biodiversity losses cannot justify the objections to the use of prescribed fire for conservation purposes in the Cerrado.

Genetic variability of Anthoxanthum aristatum Boiss. (Poaceae) at the non-native range limit

Anthoxanthum aristatum Boiss. is native to southern and western Europe and North Africa. In Central Europe this species is recognized as invasive. Its ability to colonize various habitats may result from a high level of polymorphic isozyme loci and high morphological variability. The aim of this study was to recognize the degree of genetic diversity of the studied invasive species at its non-native range limit using molecular markers. The examined plant material consisted of 70 samples collected from 7 populations originating from various habitats: arable fields, recently abandoned field and sandy grassland. Ninety-six the Directed Amplification of Minisatellite-region DNA loci and 82 Sequence-Related Amplified Polymorphism loci were detected. The genetic diversity at the species level was high. The majority of genetic variation was present within populations (68% and 66%), while the remaining molecular variation was distributed among populations within and among habitat types. Specimens originating from sandy grassland populations were grouped together in one cluster that was genetically distinct from the arable field and fallow populations. The high genetic diversity populations at the A. aristatum non-native range limit in Central Europe and their marked diversity in arable field and sandy grassland habitats suggest that this species may systematically cross both geographical and ecological barriers.

The impact of individual inaccuracy of reciprocal herkogamy on legitimate pollen deposition and seed set in a distylous self‐incompatible herb

Abstract Heterostyly is a floral polymorphism that has been observed in at least 28 different plant families across the globe. Heterostyly is characterized by reciprocal arrangement of the anthers and stigmas and the presence of a heteromorphic self‐incompatibility system, which together have been hypothesized to promote cross pollination and to avoid interference of self‐pollen and the deleterious effects of inbreeding. Recent analyses have shown that the reciprocal positioning of the sexual organs in heterostylous plant species is not always perfect. Inaccuracies in the positioning of styles and anthers within populations are expected to affect both male and female fitness of plants by disturbing pollen uptake and stigmatic deposition by insects. However, at present, little is known about how inaccuracies in the reciprocal positioning of the sexual organs affect stigmatic pollen deposition and subsequent seed set in heterostylous plant species. In this study, we quantified the level of reciprocity in a grassland and forest population of the distylous herb Primula veris and tested the hypothesis that inaccuracies in the positioning of the sexual organs were related to stigmatic deposition of pollen by insects and ultimately seed set in the field. Total inaccuracy in reciprocal positioning of the sexual organs was about four times larger in the forest population than in the grassland population (20.67 and 5.47 respectively). Individual inaccuracies in stigma positioning varied between 0.02 and 67.93 (L‐morph) and 0.03 and 45.34 (S‐morph) in the forest population, and between 0.00 and 13.19 (L‐morph) and 0.00 and 26.15 (S‐morph) in the grassland population. Legitimate pollen deposition decreased significantly with increasing inaccuracy, both in the grassland and forest population, but effects were most pronounced in the forest population. In both populations, short‐styled individuals suffered larger reductions in legitimate pollen deposition with increasing inaccuracies than long‐styled individuals. Seed set was significantly and positively affected by the number of legitimate pollen and decreased significantly with increasing inaccuracy, especially in the forest population where inaccuracies were most pronounced. Synthesis. Overall, these results indicate that deviations from perfect reciprocity significantly affect the reproductive success of heterostylous plants by diminishing legitimate stigmatic pollen deposition and concurrently reducing seed set. As a result of their lower fitness, maladaptive genotypes should be selected against in natural populations, leading to the maintenance of floral polymorphisms in general and the heterostylous syndrome in particular.

Distinct seeds in contrasting habitats: Morphological and reproductive responses in Butia eriospatha to new environmental conditions

Distinct environments drive particular responses in the reproduction pattern of plants and may have ecological and evolutionary consequences for local populations. Currently, populations of the palm Butia eriospatha are found in forests and open grasslands in southern Brazil, providing opportunities to investigate how this species responds to recent habitat transformations. We assessed phenology and fruit morphology in two geographically close populations of B. eriospatha under contrasting environmental conditions – forest and open grassland – to address the following questions: 1) Are there phenotypic differences between populations of B. eriospatha occurring in contrasting habitats? 2) What ecological and evolutionary consequences could those differences impose on local populations? Greater variation was observed within the forest population. The grassland population showed lighter endocarps on average, reflecting a greater proportion of pulp per fruit, but smaller seeds, which may suggest plasticity, local adaptation, or both after the habitat transformation. Reproductive status is dependent on individuals' sizes in the forest environment but not for the open grassland population. Additionally, the average production of infructescences per individual is lower in the forest environment. Our findings indicate that the transformation of B. eriospatha's habitat has promoted important phenotypic changes. We emphasize the importance of forest environments in promoting dispersal selectivity, which may increase population fitness through time.

Land-use history influence the vegetation in coniferous production forests in southern Sweden

During the last centuries, land use in Europe intensified, which has led to a drastic decrease in the cover of semi-natural grasslands. In Sweden, much of the lost grasslands was turned into forest. This study investigated if species typical of managed grasslands could be found in coniferous production forests more than 80 years after grassland management ceased. Species and trait composition for plants was investigated in two types of forest differing in land use history (meadow in the 1870s or continuous coniferous forest), and in reference grasslands. The average plant species richness as well as the richness of grassland indicator species were 30% higher in forests with a history as meadow compared to in forests with a history as forest, hence clear signs of historical grassland management in today’s forests. Compared with forests with continuous coniferous history, vegetation in forests with a meadow history tended to be more similar to reference grassland regarding both plant species and especially plant trait composition. The study provides proof of remnant grassland populations in coniferous production as the source for the biodiversity of clearcuts, rather than seed dispersal or seed bank survival. The result highlights the importance of land use for biodiversity of clearcuts, and points to the potential value of forests with a history of meadow in grassland conservation and restoration.

Anxiety and exploratory behavior in the African striped mouse, Rhabdomys, taxa are partially modified by the physical rearing environment.

The environment may modulate genetic influences on behavioral expression. We investigated whether the physical rearing environment modulates anxiety and exploratory behavior in four populations, representing three species, of the striped mouse Rhabdomys. One population originated from an arid, open habitat and the others from grassy, covered habitats, and two species occurred in sympatry. We raised captive individuals of all populations in treatments that simulated cover or no cover for two generations and investigated the behavior of resulting adults in an open-field, light-dark and startle response tests. We expected that, when raised without cover, the arid population would be less anxious and more exploratory than grassland populations, but found the opposite in the open-field test only. We also expected that all individuals would be anxious and less exploratory when raised under cover, which was the case for anxiety in a light-dark test, but individuals from the no cover treatment were more anxious in the open-field test. Only one population × treatment interaction was detected in which the arid population was least exploratory. Therefore, the physical rearing environment had less of an influence than phylogeny on the development of anxiety and exploration in Rhabdomys.

Get larger or grow longer wings? Impacts of habitat area and habitat amount on orthopteran assemblages and populations in semi-natural grasslands

Habitat loss and fragmentation are major threats to biodiversity and can change community composition, species traits and intraspecific morphology. Calcareous grasslands are hotspots of diversity for plants and invertebrates in Europe, but habitat area and habitat amount declined strongly over the last century. It is controversially discussed how habitat area and habitat amount independently affect species assemblages, traits and morphology. With variable transects we recorded orthopteran assemblages on 22 calcareous grasslands along independent gradients of habitat area and habitat amount in a 1 km matrix. We measured male body size and wing length of two abundant grasshopper species. Orthopteran assemblages showed positive species–area and abundance–area relationships with habitat area and (extenuated) with habitat amount. We found a stronger effect of habitat area reduction on specialists and endangered species, compared to generalists and non-threatened species. The species Chorthippus biguttulus and Gomphocerippus rufus had a larger body size (fitness-related trait) in landscapes with high habitat area and habitat amount. Grasshoppers had longer wings in relation to body size (dispersal-related trait) in landscapes with a low amount of habitat. Our findings emphasize the value of large patches and landscapes with high habitat amount to (i) enhance species richness and abundances, (ii) protect threatened species, (iii) ensure long term survival of habitat-specialists and (iv) preserve individuals with high fitness traits (large body size). Conservation strategies for Orthoptera should focus on large habitats and areas with a high habitat amount.

Context dependency of insect and mammalian herbivore effects on tall thistle (Cirsium altissimum) populations

Abstract Aims Identifying factors that drive variation in herbivore effects on plant populations can provide insight for explaining plant distributions and for limiting weeds. Abiotic resource availability to plants is a key explanation for variation in herbivore effects on individual plants, but the role of resources in determining herbivore effects on plant populations is largely unexplored. We tested the hypothesis that soil nutrient availability drives variation in insect and mammal herbivore effects on tall thistle (Cirsium altissimum) population growth. Methods In a Kansas USA restored tallgrass grassland that experienced prescribed fires, we manipulated soil nutrients, through fertilizer addition, and presence of insect and mammal herbivores, using combinations of insecticide and fencing, in experimental plots. Over 7 years, we quantified herbivore damage to reproductive tall thistles, tall thistle seed production and population growth rates. Important Findings Seed production was reduced by insect herbivores and increased by fertilizer addition, but treatment effects were independent. Herbivore effects on tall thistle population growth depended upon soil nutrients in only one of seven annual transitions. Herbivores reduced thistle population growth in two of three annual transitions that included prescribed fire, whereas they reduced population growth in only one of four transitions without fire. Soil nutrient availability does not provide a general explanation for variation in herbivore effects on tall thistle population growth rates. Disturbance regime may be a more important aspect of ecological context for influencing herbivore effects on tall thistle populations in mesic grasslands.

Structure, stability and ecological significance of natural epigenetic variation: a large-scale survey in Plantago lanceolata.

Within-species diversity is an important driver of ecological and evolutionary processes. Recent research has found that plants can harbour significant epigenetic diversity, but its extent, stability and ecological significance in natural populations is largely unexplored. We analysed genetic, epigenetic and phenotypic variation in a large number of natural grassland populations of Plantago lanceolata, covering a broad geographical and environmental range. Within-population diversity and among-population differentiation were calculated from genetic and epigenetic marker data and from measurements of phenotypic traits, both for plants in the field and for the F1 generation grown in a common environment. We found weak but significant epigenetic population structure. A large part of the epigenetic population differences observed in the field was maintained in a common environment. Epigenetic differences were consistently related to genetic and environmental variation, and to a lesser degree to phenotypic variation and land use, with more grazed populations harbouring greater epigenetic diversity. Our study demonstrates that epigenetic diversity exists in natural populations of a common grassland species, and that at least part of this epigenetic diversity is stable, nonrandom and related to environmental variation. Experimental and more detailed molecular studies are needed to elucidate the mechanistic basis of these observed patterns.

Evaluating forest clear-cuts as alternative grassland habitats for plants and butterflies

Temperate semi-natural grasslands in Europe and East Asia have been rapidly declining and their conservation is urgently required. Although recent studies have indicated the importance of clear-cuts as alternative habitats for grassland butterflies, there is paucity of studies that directly compare biodiversity and habitat quality between grasslands and clear-cuts using multiple taxa. In this study, we compared the plant and butterfly richness between grasslands and clear-cuts, with a focus on the distribution of butterfly resources (nectaring flowers and host plants) and endangered plant and butterfly species, in a cool temperate area of central Japan. We established three or six transects in five grassland and five clear-cut sites, and measured the richness of plants and butterflies and environmental variables such as vegetation height and coverage at both transect and site levels. At the site level, there were no differences in the richness of all plants, butterflies, and butterfly host plants, but there were significant or marginal differences in the richness of endangered plants, butterflies, and butterfly host plants. Almost all endangered plants and butterflies were found in the overall grasslands, but only half of the endangered butterfly species were observed in the overall clear-cuts. At the transect level, species richness of endangered plants and butterflies peaked at an intermediate vegetation height. Our results indicate the primary importance of existing semi-natural grasslands and the necessity of management when the vegetation becomes too high. We recommend active creation of clear-cuts near or between the existing grasslands, so that clear-cuts can provide source or backup populations and act as stepping stones to connect the isolated grassland populations.