Grasshopper Assemblages Research Articles

Grasshopper (Orthoptera: Acridomorpha) diversity in response to fallow-land use in southern Cameroon with recommendations for land management.

The sensitivity of grasshoppers to disturbance makes them useful bioindicators for land management. The current study compared the grasshopper communities of three fallow-lands at different levels of human pressure: heavily used land (Ongot), moderately used land (Zamakoe), and least-used land (Ngutadjap). Grasshoppers were sampled by nets, pitfall traps, and box quadrats. Their species composition was analyzed using species-richness, abundance, abundance distribution-model, occurrence, and diversity indexes. Species number was not very different between localities. However, the opening up of forests by human activities offers suitable environment for the development or proliferation of the pest grasshopper populations such as Zonocerus variegatus (Linnaeus, 1758), Eyprepocnemis plorans (Charpentier, 1825), and Catantops sylvestrisJago, 1984, which are adapted to the very common Asteraceae found in fallow lands. Native forest species [such as Mazaea granulosa Stål, 1876, Holopercna gerstaeckeri (Bolívar, 1890), Digentia fasciataRamme, 1929] were, generally absent or rare and were collected in only forest/fallow-land ecotones. Low abundance and low occurrence of ecotone species fitted the log-normal abundance distribution model. The grasshopper communities of the less degraded localities were quite similar, but different from the Ongot community. Forest management by reforestation, reduction of slash-and-burn agriculture, and wood cutting, would restore the original grasshopper assemblages and general environmental health.

Assessing grasshopper communities in mountainous meadows – a comparison of a visual‐acoustic and a novel, purely acoustic soundscape method

AbstractGrasshoppers (Orthoptera, suborders Ensifera and Caelifera) are often used as bioindicators to assess the effects of human‐induced land‐use changes. However, such assessment is largely depending on the methods that provide an accurate estimation. In the present study, we compared grasshopper species richness and assemblages on mountainous meadows in the Austrian Alps by applying a commonly used visual‐acoustic method and a novel soundscape method. For the visual‐acoustic method, we walked through the meadows for 1 h at a slow pace and recorded any visually and acoustically noticeable species. For the soundscape method, sound recorders combined with bat detectors were installed at fixed positions. Comparing both methods, there was no significant difference in species richness; however, we found significantly higher numbers of Caelifera species with the visual‐acoustic method and marginally higher numbers of Ensifera species with the soundscape method. Grasshopper assemblages differed marginally significantly between the two methods. With the soundscape method significantly more species were found between 12:00 and 17:00 hours compared to the samples taken between 10:00 and 12:00 hours. The soundscape method represents a reliable and by the observer unbiased technique to investigate grasshoppers within their environment. The visual‐acoustic method is especially preferable for the detection of non‐stridulating species which cannot be assessed with the soundscape method. Thus, researchers might consider using a sampling plan that mixes different sampling methods in order to offset potential limitations in sampling grasshopper species.

Effects of land-use and climate change on grasshopper assemblages differ between protected and unprotected grasslands

Land-use and climate change are considered the major drivers of recent insect loss. Orthoptera (hereinafter termed ‘grasshoppers’) are the main arthropod consumers in grasslands and, hence, are important elements for supporting ecosystem services. However, for intensively-used agricultural landscapes, it is largely unknown to what extent both factors have affected grasshopper assemblages in protected (nature reserves) and unprotected grasslands.Here, we analysed species richness of grasshopper assemblages in protected (n = 14) and unprotected grasslands (n = 49) by comparing two surveys—one in 1995 and one in 2012—of a landscape with intensive agriculture in the NW-German Lowland. The observed changes were associated with the Community Farmland Index (CFI) and the Community Temperature Index (CTI) in order to disentangle possible effects of land-use and climate change on assemblage shifts.Between the two surveys, environmental conditions substantially changed. Summer temperatures increased by 1.1°C, and grasslands suffered from a severe loss of patches. However, the latter only occurred in unprotected grasslands. Here, 35% of the patches were converted to other biotope types, in particular maize fields as a result of the expansion of bioenergy-crop cultivation. In the grasslands still existing in 2012, irrespective of its protection status, species richness usually increased, except for species with low dispersal ability in unprotected grasslands. By contrast, the development of the CFI and CTI clearly varied between the two grassland types. In protected grasslands, neither the CFI nor the CTI changed. However, in unprotected grasslands, the CFI decreased but the CTI increased.Land-use change has led to a biotic homogenisation at the landscape level and within unprotected grassland patches. Additionally, our study highlights that the legal designation of grasslands as a nature reserve successfully prevents the conversion of grasslands. Overall, well-managed grasslands in nature reserves play a vital role for the conservation of grasshopper biodiversity.

Traditional grazing management creates heterogeneous swards and fosters grasshopper densities

Common pastures were once the dominant type of land use in many European regions. However, during the past 150 years, they have declined dramatically. Recent studies have shown that they are hotspots for rare plant, butterfly, and bird species in the study area, the Bavarian pre-Alps (southern Germany). However, studies on the value of these pastures for Orthoptera (hereinafter termed "grasshoppers") have been scarce. Here, we studied the effects of traditional summer grazing in common pastures on grasshopper assemblages. Our study revealed that grasshopper species richness did not differ between common pastures (n=57) and controls (n=57). By contrast, density of all and of threatened species varied between common pastures and controls in all plots and within the two vegetation types with the highest grasshopper abundance, grasslands on mineral soil and fens. Two threatened species, Pseudochorthippus montanus and Stethophyma grossum, were identified as indicators for common pastures; controls had no indicative species. Traditional low-intensity grazing in common pastures has resulted in open and heterogeneous swards with some bare ground, a low cover of litter and an intermediate vegetation height favouring high densities of grasshopper species in general and threatened species in particular. This is especially true for the two most productive vegetation types, grasslands on mineral soil and fens. To promote biodiversity in general and grasshopper densities in particular, we recommend maintaining traditional cattle grazing (stocking capacities: 0.5-2.0 livestock units/ha) in common pastures. Where possible, this grazing regime should also be introduced in the surrounding landscape.

Identifying managerial legacies within conservation corridors using remote sensing and grasshoppers as bioindicators.

Biodiversity conservation under global change requires effective management of key biodiversity areas, even areas not under formal protection. Natural grassland conservation corridors between plantation forests are such areas, as they improve landscape connectivity, mitigate the impact of landscape fragmentation, and conserve biodiversity. However, empirical evidence is required to identify the extent to which past management actions promote effectiveness of conservation corridors into the future. We address this issue using grasshoppers, which are well-established indicators of habitat quality. In particular, we assess grasshopper response within corridors to historic grassland photosynthetic activity using a 25-yr normalized difference vegetation index (NDVI) time series. We then use vegetation characteristics measured in the field to understand the potential mechanisms driving grasshopper response. Furthermore, we explore the efficacy of satellite remote sensing for monitoring grasshopper habitat using additive models. We found that grasshopper evenness responded positively to deviation in NDVI within a 3-yr period, whereas assemblage composition responded positively over a shorter time of two years. Grasshopper richness and evenness responded strongly to the local vegetation height and bare ground, whereas grasshopper assemblage composition also responded to plant species richness. We found a major negative impact of the invasive alien bramble (Rubus cuneifolius) on large-sized grasshoppers and species of conservation concern. Overall, the results illustrate the importance of maintaining primary high-quality habitat for maintaining grasshopper diversity, alongside removal of invasive bramble. We recommend prescribed burning to maintain high-quality habitat heterogeneity, with sites burned within three years. Furthermore, high-resolution satellite imagery is effective for monitoring grasshopper richness and assemblage composition response to changes in vegetation within the corridors. Grassland conservation corridors do conserve biodiversity, although effective management and monitoring needs to be in place to ensure biodiversity resembles that of neighbouring protected areas.

Habitat availability and climate warming drive changes in the distribution of grassland grasshoppers

Land use and climate change are considered the major drivers of current insect declines. However, in intensively used agricultural landscapes the impacts of both on Orthoptera (hereinafter termed ‘grasshoppers’) are still poorly understood. We analysed grasshopper assemblages in two grassland types (patches, N = 63 and verges, N = 118) by comparing two surveys – one in 1995 and one in 2012 – in an agricultural landscape of the NW-German Lowland. Despite the short time period between the two surveys, we detected strong changes in environmental conditions and grasshopper assemblages. In contrast to grassland verges, grassland patches suffered from severe habitat loss. More than a quarter of all grassland patches were converted to other biotope types, in particular, arable fields cropped with maize. Additionally, summer temperatures rose by 1.1 °C. Species richness and the Community Temperature Index also increased in grassland patches and verges. By contrast, the Community Farmland Index decreased. The ongoing cultivation of maize as a bioenergy crop was responsible for a severe loss of grassland patches leading to a homogenization at the landscape level. However, due to the high connectivity of grasslands, thermophilous and generalistic grasshopper species with both low and high dispersal ability were able to track global warming. Based on our study, (i) the availability of suitable habitats and (ii) climate warming were the major drivers of grasshopper assemblage shifts. With the ongoing loss of grassland patches, grassland verges become increasingly important not only as dispersal corridors, but also as refuges for biodiversity.

Elevational partitioning in species distribution, abundance and body size of Australian alpine grasshoppers (Kosciuscola)

AbstractChanges in the physical environment with elevation can influence species distributions and their morphological traits. In mountainous regions, steep temperature gradients can result in patterns of ecological partitioning among species that potentially increases their vulnerability to climate change. We collected data on species distributions, relative abundance and body size for three grasshopper species of the genus Kosciuscola (K. usitatus, K. tristis and K. cognatus) at three locations within the mountainous Kosciuszko National Park in Australia (Thredbo, Guthega and Jagungal). All three species showed differences in their distributions according to elevation, with K. usitatus ranging from 1400 to 2000 m asl, K. tristis from 1600 to 2000 m asl and K. cognatus from 1550 to 1900 m asl. Decreasing relative abundance with increasing elevation was found for K. usitatus, but the opposite pattern was found for K. tristis. The relative abundance of K. cognatus did not change with elevation but was negatively correlated with foliage cover. Body size decreased with elevation in both male and female K. usitatus, which was similarly observed in female K. tristis and male K. cognatus. Our results demonstrate spatial partitioning of species distributions and clines in body size in relation to elevational gradients. Species‐specific sensitivities to climatic gradients may help to predict the persistence of this grasshopper assemblage under climate change.

Yaks and sheep trigger different changes in the grasshopper assemblages of the Qilian Mountains via differentially altering plant assemblages

1. The Qilian Mountains represent one of the key livestock‐raising grasslands in China. The two main herbivore species raised in this area – yaks and sheep – are of critical economical value. Grasshoppers compete with these animals for available nutrients, creating multifaceted relationships between livestock, grasshoppers and plants. A clear understanding of such relationships is lacking and is urgently needed to guide conservation efforts.2. This study aims to document the effects of yak and sheep grazing on grasshopper assemblages and to elucidate the underlying mechanisms of such effects.3. It is shown here that yaks and sheep impact grasshopper assemblages differently. Grasshopper assemblages exhibited lower density, biodiversity, richness, and evenness of distribution in yak‐grazed pastures than in grazing‐free grasslands. Sheep‐grazed pastures exhibited a dramatically divergent picture, with elevated density, biodiversity and richness, and a slightly decreased evenness of distribution. Grasshoppers were generally larger in grazed pastures than in grazing‐free grasslands, especially in yak‐grazed plots.4. The present study suggests that differences between yak and sheep pastures in plant assemblage structure and plant traits are probably the underlying forces driving the differences in grasshopper assemblage structure and grasshopper traits, respectively.5. The study shows that the grasshopper habitat indicator species differ between yak and sheep pastures, raising the possibility that such indicators can be used to monitor grassland usage and degradation in the Qilian Mountains.6. These results provide novel insights into the dynamic interactions of common domesticated herbivore species, grasshoppers and plants in Qilian Mountains, which augment current knowledge and may ultimately lead to better conservation practices.

Feeding and Mobility Traits Influence Grasshopper Vulnerability to Agricultural Production in the Cape Floristic Region Biodiversity Hotspot.

To be able to foretell which species will be at risk of extinction from possible expansion of agriculture into natural areas, we need to determine how land use affects animal groups especially insects with different life history traits. Intuitively, we can predict that the proportion of specialist versus generalist grasshoppers and widespread versus localised species can be an indicator of change in vegetation patterns in a landscape. As a result, the study examined the relationship between the extent of range distribution and mobility of grasshoppers and land-use type in the Cape Floristic Region (CFR) biodiversity hotspot. It aimed at examining grasshopper assemblage composition in association with different land uses. We specifically related the number and type of sites occupied by grasshopper species to their mobility and distribution type to find out which characters improve species survival under highly modified habitats. Grasshopper assemblages were dominated by highly mobile generalists that tolerated transformed landscapes, and mostly geographically widespread. This contrasts with the low- to medium-mobile, range-restricted specialists, which make up close to 30% of the total collection, with a lower tolerance for anthropogenically modified landscapes in the CFR. This study also reveal that the fynbos biome is an important habitat for low-mobility and range-restricted species, and hence require conscious conservation efforts to conserve such species to prevent possible future biotic erosion and homogenisation in this hotspot. This result can be used to assess the possible extent of biotic erosion or otherwise in order to recommend better conservation efforts in the CFR.

Is cattle grazing more important than landscape heterogeneity for grasshoppers in Afromontane grassland?

Overgrazing is a major driver of habitat degradation, especially in southern Africa. Although grasshoppers are adapted to and benefit from natural disturbances, such as grazing by indigenous game and burning, we do not know how they respond to heavy cattle grazing, and how this response interacts with different fire regimes. We also do not know whether grasshoppers respond principally to these disturbances, to changes in the vegetation layer, or to larger landscape attributes (e.g. elevation). We addressed these questions in the topographically heterogeneous Central Midlands of KwaZulu-Natal Province, South Africa. We compared grasshopper assemblages among sites differing in grazing intensity (light, moderate and heavy), fire regime, rocky outcrops and vegetation structure, and attributes of landscape heterogeneity. The local environment (rocky outcrops, bare ground cover, grass height and total vegetation cover) was more important than landscape attributes for all measures of diversity. Grasshopper species richness was best explained by grazing intensity, with the specific response determined by fire regime. Greatest species richness was consistently recorded in heavily-grazed grassland. Thus, we found no evidence in support of the Intermediate Disturbance Hypothesis. Grasshopper assemblage composition of areas with light grazing was different from those with heavy grazing, but areas with light grazing were similar to those with moderate grazing under all fire regimes. Different suites of grasshopper species were adapted to changes in the local environment, with greatest diversity (Shannon H’) associated with elevated levels of bare ground and sparse vegetation cover. The greatest proportion of rare, endemic and sensitive grasshoppers (incl. Lentula minuta, Machaeridia conspersa and Qachasia fastigiata) was associated with a greater proportion of vegetation cover. The sensitivity of grasshopper assemblages to fire-grazing interactions, and the habitat requirements of different suites of species necessitates consideration of different types (fire and grazing) as well as levels of disturbances when adjusting management practices. We recommend that conservation of rare, endemic and sensitive grasshoppers should be prioritized, as these are most vulnerable to local extirpation.

Impacts of grazing intensity and increased precipitation on a grasshopper assemblage (Orthoptera: Acrididae) in a meadow steppe

1. Grasshoppers are dominant herbivores in grassland ecosystems, and many studies have examined how grazing by large herbivores and precipitation patterns individually influence the dynamics of grassland grasshopper assemblages, but their combined effects are largely unknown.2. In this study, grazing intensities (ungrazed, moderate, and heavy) were manipulated and precipitation (ambient and increased amount of rainfall) altered in a field experiment to test the effects of grazing and altered precipitation on a grasshopper community in a meadow steppe in northeastern China.3. It was found that grasshopper species richness did not change according to different grazing intensities under ambient precipitation, but was significantly higher (by 38.1%) in moderate grazing intensities under increased precipitation. Grasshopper abundance increased considerably with increasing grazing intensities in ambient precipitation treatments; however, grasshopper abundance in heavy grazing intensities was significantly lower (by 32.9%) than in the other two grazing intensities under increased precipitation. Moreover, the responses of grasshopper abundance to grazing under altered precipitation were species‐specific.4. Grazing effects on grasshopper species diversity were mediated through the species richness and biomass of grasses (food resources), but the effects on grasshopper abundance were mediated through plant height (vegetation structure) under altered precipitation.5. These results suggest that appropriate grazing by large herbivores would be considered as beneficial management practices for maintaining grasshopper diversity and abundance under conditions of increased precipitation in grassland ecosystems. Additionally, greater attention should be paid to the population dynamics of different grasshopper species to better understand the responses of grasslands to grazing and altered precipitation.

Market basket analysis of grasshopper (Orthoptera: Acrididae) assemblages in eastern Wyoming: a 17‐year case study using associative analysis for ecological insights into grasshopper outbreaks

1. This study utilised an associative analysis (AA) technique named market basket analysis (MBA) to investigate whether particular grasshopper (Orthoptera: Acrididae) species associations are common during outbreaks (>9.6 grasshoppers m−2) that last >3 years. This study is the first of its kind to use MBA on animal communities.2. A subset of the 17 years of grasshopper density data from the Wyoming Grasshopper Survey Dataset was used to explore associations among grasshopper species.3. Associations of certain species were found with over 80% confidence. Life‐history traits of those species commonly found together were examined and compared (a posteriori), creating opportunities to hypothesise certain ecological relationships (e.g. interspecific competition, indirect mutualism) for future studies.4. This case study shows that further MBA analysis of grasshopper assemblages should prove useful in discovering ecological relationships of grasshopper species during outbreaks. Preliminary examples are demonstrated.

Range restricted grasshoppers better conserved in a terrestrial zone than in a riparian zone

Riparian zones (RZs) functionally connect aquatic and terrestrial ecosystems, and have azonal and geographically widespread plant communities that differ from those of the neighboring terrestrial zone (TZ). Although well studied botanically, RZs are not well understood in terms of their terrestrial insect diversity, including grasshoppers. The Cape Floristic Region (CFR) is a global biodiversity hotspot with small rocky rivers running through highly diverse sclerophyllous vegetation. It has high levels of endemism among many taxa, including grasshoppers, making it ideal for testing the effect of azonal vegetation on grasshopper assemblages of the RZ, and determining whether conservation efforts should be focused on the RZ as well as the TZ. We determine grasshopper dispersion patterns along the RZ of an important CFR river, and compare these patterns with those of the TZ to understand the habitat occupancy relative to 27 environmental variables of the zones and geographical distribution of the grasshoppers. Forty percent of individuals we collected were CFR endemics. We found only weak differences in the grasshopper assemblages between the RZ and TZ, apparently driven by deep history, complex geomorphology, stressful environmental conditions, a diverse vegetation and land mosaic, and probable high predator pressure. There were two groups: large-sized, well-flighted, geographically widespread generalists that were overall more abundant in the RZ than TZ, and small, flightless or poorly-flighted, vegetation-specialists which are narrow-range endemics adapted to both RZ and TZ, but still more abundant in the TZ. We conclude that although the vegetation of this riparian zone may require some special conservation attention, this is not so for the grasshoppers which overall are best conserved in the TZ.

Extent to which an agricultural mosaic supports endemic species-rich grasshopper assemblages in the Cape Floristic Region biodiversity hotspot

The impact of expansion and intensification of agriculture on biodiversity requires quantification, especially in areas of exceptionally high biodiversity like the Cape Floristic Region (CFR). In the CFR, landscape mosaics consist of agriculture alongside Mediterranean-type fynbos scrubland natural vegetation rich in endemic insect species. However, little is known about how ground-dwelling insect herbivores utilize the various elements of the mosaic. We compared species richness, abundance, species composition, diversity and evenness of grasshoppers among 46 sites in four geographical areas in the CFR. We investigated three land-use types: fynbos (the historic condition as reference), vineyards and deciduous fruit orchards, the main production types in the region. Grasshopper abundance was significantly higher in vineyards than in fynbos or orchards. Species richness, diversity, and evenness were highest in fynbos followed by vineyards and then orchards. Orchards had no unique species, vineyards two, and fynbos 14 unique species. Nevertheless, there was overall high species similarity among all three land-use types, with high species assemblage similarities between vineyards and orchards. Species that preferred fynbos were mostly flightless and endemic to the CFR. We show that agricultural areas do not support the entire species assemblage of natural vegetation, although vineyards are more diverse than orchards, probably because of the presence of often grassy ground cover and an open canopy. Vineyards provide the greatest opportunity for improved harmony between production and biodiversity conservation through continuing to improve the ground cover quality and other farming practices. Fewer opportunities are provided by orchards in view of their closed canopy and absence of grassy ground cover (for generalist species) and fynbos plants (for endemic species). However, protected areas still remain vital for maintaining the full complement of species, especially flightless endemics.

Positive effects of burning and cattle grazing on grasshopper diversity

Abstract Grasshoppers constitute a significant proportion of invertebrate diversity in grasslands, but little is known about how fire and grazing, two of the main drivers of grassland dynamics, influence them. Here, we determine how these disturbances influence grasshopper diversity in remnant grassland ecological networks (ENs) among commercial forestry compartments in Afromontane grassland, South Africa. Sites differed in fire frequency (annual vs. longer rotation burning), time since last fire (<12 months vs. >12 months ago), and presence or absence of domestic cattle grazing. Reference sites were in an adjacent protected area (PA). We also recorded bare ground, vegetation cover, and vegetation height. Grasshopper abundance significantly benefitted from annual burning, cattle grazing, short grass, and when the last fire was <12 months prior to sampling. Fire frequency was the only disturbance with a significant effect on grasshopper species composition, but without significantly affecting species richness. In the PA, heterogeneity of dispersion was smaller in annually burned firebreaks than in sites with longer fire‐return intervals, which points to homogenisation of resident grasshopper assemblages. Although most grasshopper species favoured recently burned or grazed grassland, some preferred low or no disturbance. This illustrates a considerable range of habitat preferences in the grasshopper assemblage. Management recommendation: Burning and grazing at moderate levels should be integral to local landscape management, as these impacts benefit grasshoppers in grassland ENs. Some areas should be left undisturbed to create a mosaic of different successional stages at the landscape spatial scale, providing diverse habitat for a wide range of species.

Effects of traditional pastoralism on grasshopper (Caelifera) assemblages in East Africa

AbstractIn East Africa, traditional pastoralists increase landscape heterogeneity by creating traditional livestock corrals (bomas). When these bomas are abandoned, they serve as long‐term hot spots of increased nutrients and unique vegetation. However, the effect of bomas on insect populations is unclear. Grasshopper (Suborder Caelifera) assemblages are thought to reflect vegetation, and within Caelifera, the subfamily Oedipodinae is known to be associated with degraded areas. We sampled vegetation and collected grasshoppers inside of abandoned bomas, 50 m from abandoned bomas and 250 m from abandoned bomas. Bomas had significantly lower grass abundance than background vegetation. Total grasshopper abundance was positively correlated with grass and forb abundance, while the proportion of grasshoppers in the subfamily Oedipodinae was negatively correlated with grass abundance. Grasshopper abundance was significantly lower inside of bomas than outside of them, but the proportion of grasshoppers in the subfamily Oedipodinae was significantly higher inside of bomas than outside of them. This suggests that the decreased vegetation in abandoned bomas supports fewer grasshoppers, but a higher fraction of the grasshopper assemblage in abandoned bomas is composed of Oedipodinae. Thus, traditional pastoralists can have long‐term effects on the size and composition of grasshopper assemblages through the use of bomas.

Taxonomic and Functional Resilience of Grasshoppers (Orthoptera, Caelifera) to Fire in South Brazilian Grasslands.

Fire is a frequent disturbance in grassland ecosystems enabling variability in habitat characteristics and creating important environmental filters for community assembly. Changes in vegetation have a large influence on herbivore insect assemblages. Here, we explored the responses of grasshoppers to disturbance by fire in grasslands of southern Brazil through a small-scale experiment based in paired control and burned plots. The resilience of grasshoppers was assessed by monitoring changes to their abundance, taxonomic, and functional parameters along time. Burned patches have been already recolonized by grasshoppers 1month after fire and did not differ in terms of abundance and richness from control areas in any evaluated time within 1year. Simpson diversity decreased 1month after fire due to the increased dominance of Dichroplus misionensis (Carbonell) and Orphulella punctata (De Geer). In this period, grasshoppers presented in average a smaller body and a larger relative head size; these are typically nymph characteristics, which are possibly indicating a preference of juveniles for the young high-quality vegetation, or a diminished vulnerability to predation in open areas. Further, at 6months after fire grasshoppers with smaller relative hind femur and thus lower dispersal ability seemed to be benefitted in burned patches. Finally, 1year after fire grasshoppers became more similar to each other in relation to their set of traits. This study demonstrates how taxonomic and functional aspects of grasshopper assemblages can be complementary tools to understand their responses to environmental change.

Land-use history alters contemporary insect herbivore community composition and decouples plant-herbivore relationships.

Past land use can create altered soil conditions and plant communities that persist for decades, although the effects of these altered conditions on consumers are rarely investigated. Using a large-scale field study at 36 sites in longleaf pine (Pinus palustris) woodlands, we examined whether historic agricultural land use leads to differences in the abundance and community composition of insect herbivores (grasshoppers, families Acrididae and Tettigoniidae). We measured the cover of six plant functional groups and several environmental variables to determine whether historic agricultural land use affects the relationships between plant cover or environmental conditions and grasshopper assemblages. Land-use history had taxa-specific effects and interacted with herbaceous plant cover to alter grasshopper abundances, leading to significant changes in community composition. Abundance of most grasshopper taxa increased with herbaceous cover in woodlands with no history of agriculture, but there was no relationship in post-agricultural woodlands. We also found that grasshopper abundance was negatively correlated with leaf litter cover. Soil hardness was greater in post-agricultural sites (i.e. more compacted) and was associated with grasshopper community composition. Both herbaceous cover and leaf litter cover are influenced by fire frequency, suggesting a potential indirect role of fire on grasshopper assemblages. Our results demonstrate that historic land use may create persistent differences in the composition of grasshopper assemblages, while contemporary disturbances (e.g. prescribed fire) may be important for determining the abundance of grasshoppers, largely through the effect of fire on plants and leaf litter. Therefore, our results suggest that changes in the contemporary management regimes (e.g. increasing prescribed fire) may not be sufficient to shift the structure of grasshopper communities in post-agricultural sites towards communities in non-agricultural habitats. Rather, repairing degraded soil conditions and restoring plant communities are likely necessary for restoring grasshopper assemblages in post-agricultural woodlands.

Effects of Climate Change and Various Grassland Management Practices on Grasshopper (Orthoptera) Assemblages

Influence of different grassland management practices on Orthoptera assemblages inhabiting humid grassland areas was studied since 2003 to 2011. The examined sites were within the protected area of Balaton Uplands National Park. The physiognomy and climatic conditions of the studied habitats were similar but their land use types were significantly different. After the preliminary analyses of Nonmetric multidimensional scaling, neighbour joining clustering, and Spearman rank correlation, we examined the possible effects of such independent variables as land use (nonmanagement, mowing, grazing), microclimate (humidity and temperature), regional macroclimate (annual and monthly mean temperatures and rainfall), using General Linear Mixed Models, and canonical correlation analysis. Our results showed that the effect of grassland management practices on the organization of Orthoptera assemblages was at least as important as that of macro- and microclimate. Furthermore, grassland management could intensify the influence of several local and regional parameters. These results can help finding the most suitable type of grassland management to conserve the grasshopper assemblages.

Grasshopper assemblage response to surface rockiness in Afro‐montane grasslands

Abstract Grasshoppers are often an important functional component of ecosystems, and many species show high levels of endemism. Evidence exists that percentage surface rock cover within a landscape can predict diversity of grasshopper species. Nevertheless, the reason why grasshopper species are responding to rocky landscapes has not been established. Here, we explore whether grasshoppers are responding to physical rockiness per se, or rather to specific correlates of higher surface rock exposure within a landscape. We also determine if this response varies between grasshopper taxonomic groups. We sampled grasshoppers in Afro‐montane grasslands in KwaZulu‐Natal, South Africa, and recorded 10 environmental variables. We explored the influence of these variables on grasshopper community composition and grasshopper family composition. We also determined the vegetation characteristics, which significantly correlate with percentage surface rock cover in this landscape (geophyte richness, perennial grass richness and vegetation density), and then measured the similarity of species composition across these correlates. Overall, grasshopper assemblage composition, as well as familial composition, responded strongly to an elevation gradient, and not to the correlates of surface rock cover. In turn, the higher species richness in such areas is more likely a function of the significant vegetation correlates of higher surface rock cover. Across taxonomic groups, there are specialist species within each group which are associated with environmental conditions related to surface rockiness through its underlying correlates. Rock exposure across this grassland landscape is therefore an important contributor to grasshopper dispersion patterns, and has important implications for conservation planning for this taxon.