Patterns of zonal changes in the spatial structure of Orthopteran communities in the European steppe

Patterns of zonal changes in the species composition, diversity, and community structure of Orthoptera were studied along the latitudinal series of steppe types from meadow to desert steppe in European Russia. The maximum abundance of Orthoptera was recorded in the typical steppe, while the maximum species richness shifted to the southern dry steppe. Changes in the ecological preferences of orthopterans due to aridization are shown by the example of zonal communities. A gradual decline of the forest-steppe orthopteran complex and an increase in the number of semidesert and desert species are demonstrated. The changes in the species composition are accompanied by the intra-landscape shifts of areas with high species diversity. Most species in the meadow steppe occupy mesophytic habitats in depressions. In the typical and dry steppe, the species richness and abundance are restricted to habitats with zonal and xerophytic vegetation. In the desert steppe, the species diversity is the highest in dry habitats, including halophytic ones, where xerophilic and desert species predominate. The diversity and evenness indices increase in the northern and southern ecotones of the steppe zone.     

Spatial heterogeneity of a ground beetle (Coleoptera,Carabidae) population along a forest-steppe transect: Local level of consideration

Carabid diversity has been studied in the forest-steppe in southern West Siberia along a continuous 180-m transect from the center of a small birch forest outlier through steppe and mesophytic meadows to a single tree. Carabid communities characteristic of open and forest habitats are different. Communities of open habitats are more differentiated than forest ones. The former can be further subdivided into steppe and meadow variants. Some species are generalists, exhibiting no preferences to particular open habitats.     

Changes in the orthopteran population over plant cover restoration in the fallow lands of the European steppe

A comparative analysis of the Orthopteran population in virgin and fallow lands of the European steppe has allowed finding out the colonization sources of the fallow lands: the inhabitants of the mesophytic intrazonal plant communities, including the formations of steppe bushes and polytopic species living in intact and disturbed steppe habitats have been found there. It has been shown that the structure of the Orthopteran population in the fallow lands in determined more by the composition of their plant cover than by the actual age of fallow lands or their zonal position. Fundamental changes in the structure of Orthopteran population are associated with the replacement of tall weed communities by an herb-grass cover; the faunistic similarity between the old fallow lands and zonal plots therewith increases. The abundance of Orthopteras in the fallow lands increases southward, while in zonal communities a reverse tendency is observed. The Orthopteran populations in the fallow lands of all the subzones are characterized by higher diversity and evenness if compared to zonal biotopes. A wide distribution of fallow lands with weed cover turns out to increase the faunistic and ecological diversity of the Orthopteran populations in the European steppe.     

新疆东部天山蝶类多样性及其垂直分布

2006-2008年研究了新疆东部天山蝶类多样性和垂直分布.结果表明:研究区域内共记录蝴蝶7科43属63种,占新疆已记录蝶类种数的24.80％,区系组成主要是古北种,占73％;其次是广布种,占27％,没有发现东洋种.其中蛱蝶科的物种数最多,为11属19种,蚬蝶科的物种数最少,只有1属1种.按海拔将生境分为5个垂直自然带,包括低山灌木草原带、山地森林草原带、亚高山草甸带、高山草甸带、垫状植被带.蝶类物种数和个体数排序为亚高山草甸带＞山地森林草原带＞低山灌木草原带＞高山草甸带＞垫状植被带.采用Shannon-Wiener指数和G-F指数对蝶类物种和科、属的多样性进行了分析评价,结果显示亚高山草甸带的蝶类多样性最为丰富,其次是山地森林草原带和低山灌木草原带,而高山草甸带和垫状植被带的蝶类多样性相对较低,物种和科、属多样性分析结果均一致.蝶类垂直分布明显,物种数和个体数随海拔变化的趋势类似,均为先增加后下降.蝶类区系成分随着海拔升高发生改变,广布种的比例逐渐降低,高山草甸带和垫状植被带只有古北种分布.研究结果显示,生境改变对蝴蝶群落影响明显,保护生境是保护蝴蝶生存的最主要措施.     

鄂尔多斯高原植物群落多样性时空变化特点

作者利用1999年和2000年野外植物群落调查资料,结合李博(1990)的植物群落调查结果,分析了鄂尔多斯高原植物群落多样性的时空变化特点。鄂尔多斯高原主要植物群落类型有23类,不同植被类型的群落多样性表现出一定的差异性,其中丰富度指数的差异不显著,而Simpson指数和Shannon-Wiener指数及群落盖度的差异明显。中东部典型草原表现为高多样性高盖度;西鄂尔多斯荒漠草原和草原化荒漠物种多样性较高,但盖度较低;毛乌素沙地植物群落物种多样性低,但盖度较高。从1986年到2000年,该地区典型草原群落、荒漠草原和沙地植被的群落多样性指数都有下降趋势;典型草原和草原化荒漠的群落盖度有所增加,荒漠草原有所下降。以上结果表明,沙地植被和草原化荒漠生物多样性已经得到了一定的保护,但还有待加强,而荒漠草原的保护亟待引起重视。     

Disentangling the role of management,vegetation structure,and plant quality for Orthoptera in lowland meadows

Seminatural grasslands provide habitats for various species and are important for biodiversity conservation. The understanding of the diverse responses of species and traits to different grassland managenient methods is therefore urgently needed. We disentangled the role of grassland management (fertilization and irrigation), vegetation structure (biomass, sward height) and plant quality (protein and fiber content) for Orthoptera communities in lowland hay meadows in Germany. We found vegetation structure to be the most important environmental category in explaining community structure of Orthoptera (species richness, total individuals, fiinctional diversity and species composition). Intensively used meadows (fertilized, irrigated, high plant biomass) were characterized by assemblages with few species, low functional diversity, and low conservation value. Thereby, the relatively moderate fertilizer inputs in our study system of up to -75 kg N/ha/year reduced functional diversity of Orthoptera, while this negative effect of fertilization was not detectable when solely considering taxonomic aspects. We found strong support for a prominent role of plant quality in shaping Orthoptera communities and especially the trait composition. Our findings demonstrate the usefulness of considering both taxonomic and functional comp on ents (functio nal diversity) in biodiversity research and we suggest a stronger involvement of plant quality measures in Orthoptera studies.     

Plant cover associated with aboveground net primary productivity (ANPP) mediates insect community composition in steppes of Northwest China

Temperate steppe is one of the most important natural habitats for the conservation of arthropod and bird biodiversity across the Eurasian Tectonic Plate. Since 1950, fragmentation of the steppe habitat has caused a loss of biodiversity and degradation of the species communities found in natural steppe. Therefore, in this study, both plants and insects were sampled at 56 sites in the steppe biome of northwestern China to explore the effects of plant community on insect community composition and diversity. The insect community structure varied in the four different steppe types (meadow steppe, typical steppe, desert steppe, and steppe desert). Plant cover (diversity) was an important driving force, which could enhance number of families and abundance of an insect community. Aboveground net primary productivity and water content of plants had no significant effects on insect community, although the plant community as a whole did mediate insect composition and community structure. Future research should explore the ecological role of particular functional groups in plant and insect communities. Supplemental sowing to improve plant diversity in steppe habitat may be another strategy to enhance biodiversity and achieve sustainable management.     

Cross-spatial-scale patterns in the facilitative effect of shrubs and potential for restoration of desert steppe

Facilitation (positive plant–plant interactions) is a potential means to accelerate vegetation restoration in arid areas. Shrubs can accelerate vegetation recovery by means of soil amelioration, but this effect has not been evaluated at large spatial scales or across scales. Here, we examined the facilitative function of shrub change across spatial scales at a desert steppe in Mongolia. Using a high-resolution satellite image, we established five 2500 m² plots in each of three shrub density classes (low, moderate, high) in a desert steppe in Mongolia. To evaluate the facilitative functions of shrubs at multiple spatial scales, we recorded the total number of plant species at three nested spatial scales in each plot: 25, 400, and 2500 m². The facilitative effect of shrubs on plant species richness was more pronounced at larger scales. Denser shrub communities increased plant species diversity at a larger scale. However, the increased taxonomic diversity was not clearly related to increased functional diversity in this system. This scale dependency in species diversity can be explained by the degree to which spatial heterogeneity of habitats within the plots increased as plot size increased. These results support the hypothesis of scale-dependent changes in the balance between facilitation and competition. Therefore, transplanting shrub saplings at high-density and a larger scale could potentially improve the success of vegetation restoration in arid regions.     

Local and regional-scale responses of ant diversity to a semiarid biome transition

The locations of biome transitions and ecotones are frequently defined by the rapid shift from one form of dominant vegetation to another. The composition of animal taxa is predicted to shift in parallel with that of dominant plants and species diversity is predicted to he greater in transitional zones than in adjacent areas. We asked whether ant species diversity and composition supported these predictions across a biome transition between shortgrass steppe and Chihuahuan desert vegetation. Neither species richness nor diversity was highest at the biome transition region as a whole, or within habitats in the biome transition. The biome transition region was not intermediate in ant species composition or in the representation of different faunal complexes. The community similarity between matched habitats shared between the biome transition zone and adjacent regions was less than that between distinct habitats occurring within regions. A zoogeographic transition for ants may occur to the north of the phytogeographic transition and may be coincident with the northern limits of monsoonal precipitation patterns. In contrast, the phytogeographic transition may be related to less extreme climatic variation within the monsoonal region occurring further south.     

Patterns of ecological diversity in fossil and modern mammalian faunas

Ecological diversity provides a means of analysing the community structure of fossil mammalian faunas in order to obtain information on the habitat of the fauna. As a basis for the analysis, 23 modern mammalian communities from distinct habitats have been used to establish patterns of community structure for tropical African habitats according to their species diversity by taxonomic group, size, locomotor zonal adaptation, and feeding adaptation. All the communities tested were in tropical Africa, but additional analyses on tropical forest communities in Australia, Malaya, and Panama have shown that these communities, which all have completely different species composition, nevertheless have community structures very similar to each other and to those of the African forest communities.     

Soil-moisture conditions indicated by field-layer plants help identify vulnerable forests in the forest-steppe of semi-arid Southern Siberia

High variability in soil-moisture conditions is typical for semi-arid forest-steppe ecosystems where precipitation varies greatly over time. Plant species that inhabit these environments integrate responses to broadly fluctuating wetness conditions. Indirect assessment of contrasting habitat wetness based on plant indicator values, species frequency, and species coverage was carried out in two sites representing the larch (Larix sibirica) and pine (Pinus sylvestris) forest-steppe communities. For the larch forest-steppe, we found that plant community composition and spatial structure depended strongly on wetness. In addition, we found that the vegetation was clearly differentiated into forest stands and steppe communities, depending on the slope aspect. There was also a strong correlation between dissimilarities of species composition and differences in habitat wetness revealed in the larch forest-steppe. In contrast, soil properties, such as gravel and stone content were found to be a key factor in the spatial distribution of plant species composition in the pine-forest-steppe communities. Indirect assessment of moisture conditions in the forest-steppe habitats, based on the field-layer plant species, was found to be preferable for indicating soil water deficits in the forest. Furthermore, as long-term observational data is often lacking, indirect assessment of the forest-steppe vegetation provides an opportunity to identify vulnerable forests at the marginal distribution. Based on indirect assessments of soil-moisture conditions, and taking into account differences in potential drought resistance between larch and pine forests, we concluded that increasing aridity will cause the replacement of Siberian larch by Scots pine in the South Siberian forest-steppe landscape. Consequently, in the future it is likely that forest-steppe typological diversity will decrease, and the semi-arid landscape may become more monotonous.     

Relationship of different feeding groups of true bugs (Hemiptera: Heteroptera) with habitat and landscape features in Pannonic salt grasslands

Eastern European grasslands are still inhabited by a rich arthropod fauna, but the drivers and mechanisms influencing their communities have to be understood to ensure their future survival. Heteroptera communities were studied in 20 plot-pairs in Pannonic salt steppe–salt marsh mosaics in Hungary. The effects of vegetation characteristics, landscape diversity and the proportion of surrounding grasslands on the composition, species richness and abundance of different feeding groups of true bugs (carnivores, specialist and generalist herbivores) were examined using ordinations and mixed-effect models. We found distinct herbivorous assemblages corresponding to microtopography-driven differences in water regime and vegetation between steppe and marsh plots, but this pattern was less pronounced in carnivorous assemblages. A higher species richness of true bugs was found in the more diverse steppe vegetation than in the salt marsh vegetation, while the abundance pattern of true bugs was opposite. Landscape diversity had a positive effect on the species richness and abundance of generalist herbivores and carnivores. Our results suggested that generalist herbivores and carnivores appear to drive diversity patterns in the local landscape due to their high dispersal abilities and the broader range of resources they can utilize. Specialist herbivores strongly influence the local insect biomass in relation to the distribution and density of their host plants. The present study highlights the importance of both habitat and landscape diversity for local insect diversity in Pannonic salt grasslands and suggests that the main threats for arthropod diversity are those processes and activities that homogenize these areas.     

Impacts of Myriophyllum aquaticum invasion in a Mediterranean wetland on plant and macro-arthropod communities

The invasion by alien macrophytes in aquatic ecosystems may produce a strong alteration of the native aquatic vegetation leading to heavy impacts for both plant and faunal native diversity. Myriophyllum aquaticum is an aquatic plant native of Southern America, invasive in several part of the world. We studied the effects of M. aquaticum invasion on plant and macro-arthropod communities in the canals around a protected wetland in the Mediterranean basin. We sampled plant and macro-arthropod communities in 10 transects in invaded and non-invaded tracts of the canals. We assessed the differences in plant and macro-arthropod species richness, diversity, taxonomic diversity and species composition between invaded and non-invaded habitats by means of univariate and multivariate analyses. Our study shows a significant loss of plant diversity between non-invaded to invaded sites, leading to communities numerically and taxonomically impoverished and highly divergent in the species composition. We also detected significant differences in arthropod species composition between invaded and non-invaded transects. Some taxa such as mosquitoes and malacostraca were more frequent in the M. aquaticum-dominated stands. Furthermore, the study shows a positive relation between invaded habitats and juvenile individuals of the invasive alien crayfish Procambarus clarkii.     

Habitats of Pleistocene megaherbivores reconstructed from the frozen fauna remains

The Late Pleistocene landscape in northern Eurasia and North America was inhabited by a specific megafaunal complex, which largely disappeared during the Pleistocene/Holocene transition. Vegetation changes are considered as one of the factors responsible for these extinctions, but the structure and composition of the Pleistocene vegetation are still poorly known. Here we complement previous studies by comparing the taxonomic composition of the plant remains found in the gastrointestinal tracts of the frozen carcasses of Pleistocene megaherbivores with the species composition of the current Siberian vegetation. We compiled a dataset of palaeobotanical records from frozen individuals of Pleistocene megaherbivores found in northern Siberia and Beringia and dated to the period from more than 50 kyr BP to 9 kyr BP. We also compiled a dataset of vegetation plots from several regions in Siberia. We analysed the similarity in taxonomic composition of plants between these two datasets using a novel method that accounts for variable taxonomic resolution in palaeobotanical data. For most megaherbivore individuals, plant remains in their gastrointestinal tracts corresponded to tundra, forest and mire vegetation, while they showed low similarity to steppe. This pattern was relatively constant over time, showing no remarkable differences between the Last Glacial Maximum and the periods before and afterwards. This suggests that during the Upper Pleistocene, a mosaic of mesic and wet vegetation types such as tundra with patches of forests and mires was common in northern Siberia and Beringia. In contrast, the steppe was rare to absent in the landscape or underused by the megaherbivores as a pasture since they found enough food in the widespread mesic and wet habitats with more productive vegetation.     

Leaving uncut refuges during meadow harvesting increases the functional diversity of Orthoptera

In the past, insect species richness was high in Central European seminatural grasslands, which were characterized by low‐intensity land use. Currently, however, the hay in most of these grasslands is mechanically harvested, which negatively impacts insect biodiversity. One way to reduce this negative effect is to leave unmown patches as refuges. In the current research we evaluated the short‐term effects of leaving an unmown patch on the taxonomic and functional diversity of the Orthoptera assemblage in a meadow. We found that orthopteran species richness and abundance were significantly reduced by mowing, whether or not a patch was left uncut. In contrast, functional evenness, indicating distribution of species abundances in a niche space, was reduced by mowing only if the plot lacked an uncut refuge. Functional richness, indicating the amount of niche space occupied by species, was elevated if the plot had an uncut refuge. Larger species were negatively affected by mowing, while habitat specialists, mobile species and soil‐ovipositing species benefitted from it. We infer that the presence of an uncut patch increased the diversity of habitats available to orthopterans and maintained even distribution of species among niche space. In summary, leaving an unmown refuge in grasslands could increase the functional diversity of orthopterans, even if it does not preserve taxonomic diversity.     

The ground beetle fauna (Coleoptera,Carabidae) of Southeastern Altai

Long-term studies of the ground beetle fauna of Southeastern Altai (SEA) revealed 33 genera and 185 species; 3 and 15 species are reported for the first time from Russia and SEA, respectively. The following genera are the most diverse: Bembidion (47 species), Amara and Harpalus (21 each), Pterostichus (14), and Nebria (13). The subarid (35%) and boreal (32%) species prevail in the arealogical spectrum, while the mountain endemics comprise 13% of the fauna. The carabid fauna of SEA is heterogeneous in composition and differs significantly from that of the Western and Central Altai. The boreal mountain component mostly comprises tundra species with circum-boreal or circum-arctic ranges, while the subarid component (typical Mongolian together with Ancient Mediterranean species) forms more than one-half of the species diversity in the mountain basins. The species diversity increases from the nival mountain belt (15 species, predominantly Altai-Sayan endemics) to moss-lichen tundras (40, mostly boreal, species). The variety of habitats and constant hydrothermal regimes in the intrazonal valley communities determine high taxonomic diversity of Carabidae, including both tundra or meadow-steppe species typical of the region and some forest ones. Under the condition of moisture deficiency, many steppe species also concentrate in river floodplains.     

The effects of micro-habitats and grazing intensity on the vegetation of burial mounds in the Kazakh steppes

Background: Burial mounds (kurgans) of Eurasian steppes are man-made habitat islands that have the potential to harbour rich plant diversity due to micro-habitats associated with their topography.

Aims: We assessed whether kurgan micro-habitats harboured different species pools and functional groups from those found on the surrounding steppes. In addition, we asked if these mounds were affected by different grazing intensities from those on the surrounding vegetation.

Methods: We surveyed kurgan micro-habitats (northern and southern slopes, surrounding ditch) and adjacent steppe plains in non-grazed, moderately grazed and heavily grazed sites in northern Kazakhstan. We analysed differences in species composition of four habitats under three grazing regimes using Generalised Linear Mixed Models, PCA ordination and indicator species analysis.

Results: Kurgan micro-habitats had diverse vegetation and supported the co-existence of plant species with different environmental needs. We identified 16 steppe specialists confined to kurgan micro-habitats. Steppe vegetation was well-adapted to extensive grazing, although heavy grazing supported ruderals and a decline in steppe specialists. There was a significant interaction between grazing intensity and habitat type: heavy grazing supported ruderals and suppressed steppe specialists especially on the slopes.

Conclusions: We highlighted that kurgans play an important role as maintaining high plant diversity locally in extensive steppe plains in Central-Asia by increasing environmental heterogeneity and supporting specialist species confined to these micro-habitats.     

The effects of fire on ant communities in north-western Patagonia: the importance of habitat structure and regional context

Abstract. We investigated the effects of recent fires on the native ant communities in two habitats of north-west Patagonia that differ in vegetation structural complexity. Using bait traps, we sampled ants in replicated scrub and steppe areas including paired burned and unburned sites. Fires significantly reduced plant cover and ant diversity only in scrub sites. The drop in diversity was due to (a) a reduction in the abundance of rare species associated with woody vegetation, and (b) an increase in the abundance of the dominant species, which thrive in more xeric microclimatic conditions. Consequently, ant assemblage structure of burned scrub approaches that of steppe sites. Our findings suggest that the effects of disturbances on ant assemblages depends both on habitat characteristics, which in turn determine the extent of the changes induced by the disturbance, and on the regional context of the ant fauna, which in turn determines the ability of the ants to deal with the post-disturbance conditions.     

青海省芨芨草草原的群落特征及其分布规律

芨芨草(Achnatherum splendens)是一种旱生植物,广泛分布于欧亚草原和荒漠地区。它是一种生态可塑性很强的植物,可分布于草原、荒漠草原等植被带内。以其为优势种可以形成盐生草甸、草原、荒漠草原等多种植被类型。青海省共和盆地、青海湖盆地和柴达木盆地东部等地大面积分布有芨芨草群落,并和本区分布的其他草原类型形成基带植被。无论是其生境条件、生物生态学特性、群落的组成及分布规律均具有草原性质,应划归草原植被类型较为合适。     

Taxonomical vs. functional responses of bee communities to fire in two contrasting climatic regions

1. Valuable insights into mechanisms of community responses to environmental change can be gained by analysing in tandem the variation in functional and taxonomic composition along environmental gradients. 2. We assess the changes in species and functional trait composition (i.e. dominant traits and functional diversity) of diverse bee communities in contrasting fire-driven systems in two climatic regions: Mediterranean (scrub habitats in Israel) and temperate (chestnut forests in southern Switzerland). 3. In both climatic regions, there were shifts in species diversity and composition related to post-fire age. In the temperate region, functional composition responded markedly to fire; however, in the Mediterranean, the taxonomic response to fire was not matched by functional replacement. 4. These results suggest that greater functional stability to fire in the Mediterranean is achieved by replacement of functionally similar species (i.e. functional redundancy) which dominate under different environmental conditions in the heterogeneous landscapes of the region. In contrast, the greater functional response in the temperate region was attributed to a more rapid post-fire vegetation recovery and shorter time-window when favourable habitat was available relative to the Mediterranean. 5. Bee traits can be used to predict the functional responses of bee communities to environmental changes in habitats of conservation importance in different regions with distinct disturbance regimes. However, predictions cannot be generalized from one climatic region to another where distinct habitat configurations occur.