Diversity of phytophagous beetles (Coleoptera: Chrysomeloidea,Curculionoidea) in steppe communities in the forest-steppe of the High Trans-Volga region

A total of 551 species from 10 families of phytophagous beetles (superfamilies Chrysomeloidea and Curculionoidea) have been recorded in the steppe communities of the High Trans-Volga forest-steppe zone, 62% of which belong to the steppe landscape-geographic complex. The vast majority of the species belong to three families: Curculionidae (254 species; 46%), Chrysomelidae (186 species; 34%), and Apionidae (51 species; 9%). The regional steppe fauna has a complex arealogical structure combining the Western Scythian and Sarmatian elements, as well as relict species of the Angarian origin and some Eastern European ones. The highest diversity of phytophagous beetles is observed in the zonal meadow steppe communities (299 species; 54%). The most specific are the petrophilous steppe complexes which also include the greatest number of relict forms. Xerophilous Kazakhstan- Turanian species are mostly concentrated in the saline steppe communities of the southernmost forest-steppe zone. The species diversity is also high (249 species) in the open ruderal communities dominated by species characteristic of the pioneer stages of the steppe successions. Some steppe reservations include over 50% of the entire regional fauna of phytophagous beetles. The species diversity in the steppe localities decreases northward due to a gradual decrease in the number and proportion of the Scythian species: from 55% in the middle of the foreststeppe zone to 36% near its northern boundary. The species diversity of the slope communities in the forest-steppe zone is at least not lower than that in the similar areas of the steppe zone. The ratio of the number of Curculionoidea species to that of plant species is very high, reaching about 3: 4 in the model steppe localities of the High Trans-Volga forest-steppes, as compared to 1: 2 in the zonal steppe communities (according to the published data). The data considered confirm the significance of the forest-steppe zone as an important biodiversity center in the East European Plain and as a reservation of relicts of different origins.     

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.     

Long‐term compositional and functional changes in alien and native weed communities in annual and perennial irrigated crops

Agricultural intensification in Europe during the past 30 years has led to changes in compositional and functional weed structure in agroecosystems as well as increases in the prominence of alien weeds. Irrigation is a major driver of agricultural intensification, particularly in semi‐arid zones of the Mediterranean. In the past few decades, irrigated land has expanded in semi‐arid agricultural lands in northeastern Spain. The goals of this study were to identify long‐term temporal changes in compositional and functional weed communities in annual (i.e. maize crops) and perennial (i.e. orchards) irrigated crops of this area and determine whether these changes differentially affect native and alien plants. Changes in the diversity, composition and functional groups of the weed communities in fruit‐tree orchards and maize crops were assessed using plant surveys in 1989 and 2009. During the studied period, a decrease was recorded in the diversity of native species in the fruit‐tree orchards; this decrease was accompanied by an increase in alien weed diversity and a general homogenisation of species in the weed community. In the maize crops, the diversity values of native and alien plants changed little during 20 years. The identification of functional groups revealed that most of the species whose cover increased in the fruit‐tree orchards were graminoid alien species that perform C4 photosynthesis and disperse seed via water or a combination of vectors. In the maize crops, the identified functional groups did not differ in the proportion of species whose cover changed between 1989 and 2009. Hence, in irrigated orchards the observed changes in the weed community and the prominence of alien species are mediated by the selection of a set of traits that let species to overcome management filters. Similarly, the stability of functional composition of weed communities in maize fields is the result of the selection of species functionally similar to the crop.     

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.     

Plant community changes after the reduction of an invasive rangeland weed, diffuse knapweed, Centaurea diffusa

The expected outcome of weed control in natural systems is that the decline of a dominant weed will result in an increase in diversity of the plant community but this has seldom been tested. Here we evaluate the response of the plant community following the decline of diffuse knapweed (Centaurea diffusa) in six different pastures at White Lake, BC, Canada over five years. This period followed the establishment, spread and high levels of attack by the introduced European weevil, Larinus minutus, as part of a biological control program. Knapweed declined immediately before and during the study period, but, contrary to expectations, the species richness and diversity of the rangeland plant community did not increase. The absolute cover of native and introduced forbs and grasses increased following knapweed decline, but only the introduced grasses showed a consistent increase in cover relative to the other life-forms. However, unlike in other studies, the native plants dominated the study site. We conclude that the changes in plant communities following successful biological control are variable among programs and that the impact of replacement species must be evaluated in assessing the success of ecological restoration programs that use biological control to manage an undesirable weed.     

Peculiarities of the biotopic distribution of orthoptera in the typical steppe of European Russia

The taxonomic composition, ecological and spatial distribution of orthopterans were studied in different vegetation types of the typical steppe on the left bank of the Volga River basin (Saratov Prov.). Some species showed clear selectivity with respect to specific features of the soil and vegetation, despite significant annual fluctuations in the taxonomic composition and abundance of local populations. Two groups can be distinguished: the polytopic species and those inhabiting intrazonal communities but not typical steppe habitats. The orthopteran complexes of the zonal and halophytic habitats show a relatively high similarity; they differ well from those of mesophytic plant communities, restricted to the lower mesorelief areas. Intrazonal habitats with mesophytic conditions comprise almost 45% of the species diversity of orthopterans in the typical steppe subzone, and reveal the greatest diversity of life forms of these insects. The data obtained are of interest for monitoring the successive changes in steppe ecosystems affected by both climatic and anthropogenic factors.     

Floristic diversity of meadow steppes in the Western Siberian Plain: effects of abiotic site conditions,management and landscape structure

Temperate grasslands have suffered from severe habitat loss and degradation worldwide. In Russia, vast areas of forest-steppe grasslands have been converted to cropland during Soviet times, whilst remaining grasslands were often intensively grazed. Contrastingly, the collapse of the Soviet Union have resulted in a massive reduction in livestock numbers and cessation of management. Albeit relatively large natural grassland areas remained in the Western Siberian Plain, their present condition is poorly studied. We analysed plant species composition, functional structure and richness of grassland communities and tested for the effect of local factors (management, abiotic site conditions) and landscape factors (patch size, proportion of land cover types) on diversity patterns. Abiotic site conditions, mainly soil moisture and salinity, differentiated distinct community types. Overall, species richness was highest in meadow steppe communities with lower soil moisture and salinity. Grazing intensity and litter accumulation due to cessation of management were significant negative related to species richness and shaped the functional structure. At the landscape scale, diversity in meadow steppe grasslands was higher in forest-grassland mosaics and in small remnants isolated in a matrix of cropland. Our findings highlight that meadow steppes suffered massively under the historical habitat loss and high grazing pressure. Small species-rich remnants are evidence of the former extent of meadow steppe habitats in agricultural landscape, but are likely threatened by an extinction debt. Low intense, irregular mowing maintained species-rich meadow steppe in forest- grassland mosaics, but currently such practices are declining.     

Dynamics of the Abundance and Community Structure of Small Mammals in the Saratov Trans-Volga Region

A typical feature of the populations of small mammals in different areas of the Saratov Trans-Volga region is the long-term and constantly increasing abundance of Sylvaemus uralensis and its wide distribution in a variety of habitats. The maximal abundance of S. uralensis is 72.0 individuals per 100 trap-days, and its share in catches is 73.0%. The abundance of Microtus arvalis tends to increase. It was shown that Lagurus lagurus has been found again in the steppe zone, on fallow lands and fields, after a prolonged depression in 2012–2013, the average density of species being 4.0 individuals per 100 trap-days. A high abundance of other typical steppe inhabitants (Allocricetulus eversmanni and Ellobius talpinus) was noted as well. The highest indices of species diversity (H = 1.18) are typical of fallow lands.     

Floristic changes related to grazing intensity in a Patagonian shrub steppe

Sheep grazing in and and semiarid Patagonia have the natural vegetation as their exclusive source of food This paper studies the flonstic changes that occur as a response to grazing in the Stipa speciosa, Stipa humilis, Adesmta campestris, Berberis heterophylla , and Poa lanugmosa community in the SW of Chubut (Argentina) by companson of community characters between areas with different degrees of histoncal grazing Stands located on typical zonal soils with sandy cover were sampled, including pairs of stands from neighbouring fields with different grazing history and two areas where large herbivores had been excluded for 27 and 9 yr, respectively Species cover values were recorded m 37 samples of ca 500 m² each A PCA species ordination with the aid of site biplot graphs and species cluster analysis allowed for the identification of five groups of species with differential response to grazing Relative cover of shrub species was positively correlated with grazing intensity, but total plant cover and flonstic nchness showed a less obvious decreasing tendency Diversity was not correlated with this gradient Some of the decreasing species belong to the group shared with the more mesic grassy steppe, and some of the increasing ones belong to the one shared with the more xenc low shrub steppe These results are in accordance with models which propose that continuous grazing promotes a xerophytization of and and semiarid plant communities     

Evaluating strategies for facilitating native plant establishment in northern Nevada crested wheatgrass seedings

Non‐native crested wheatgrasses (Agropyron cristatum and A. desertorum) were used historically within the Great Basin for the purpose of competing with weed species and increasing livestock forage. These species continue to be used in some areas, especially after wildfires occurring in low elevation/precipitation, formerly Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis)/herbaceous communities. Seeding native species in these sites is often unsuccessful, and lack of establishment results in invasion and site dominance by exotic annuals. However, crested wheatgrass often forms dense monocultures that interfere competitively with the establishment of desirable native vegetation and do not provide the plant structure and habitat diversity for wildlife species equivalent to native‐dominated sagebrush plant communities. During a 5‐year study, we conducted trials to evaluate chemical and mechanical methods for reducing crested wheatgrass and the effectiveness of seeding native species into these sites after crested wheatgrass suppression. We determined that discing treatments were ineffective in reducing crested wheatgrass cover and even increased crested wheatgrass density in some cases. Glyphosate treatments initially reduced crested wheatgrass cover, but weeds increased in many treated plots and seeded species diminished over time as crested wheatgrass recovered. We concluded that, although increases in native species could possibly be obtained by repeating crested wheatgrass control treatments, reducing crested wheatgrass opens a window for invasion by exotic weed species.     

Nematode Community Structure in Dogwood,Maple, and Peach Nurseries in Tennessee

Nursery blocks (48 dogwood, 27 maple, 17 peach) in 20 middle Tennessee nurseries were sampled for nematodes in March,July, and October 1981. Dogwoods and maples were grouped in three age classes: 1-2, 3-5, and 10+ years. Nematodes were extracted from soil samples, counted, and assigned to trophic groups as follows: plant parasites, microbivores, fungivores, predators, and omnivores (= Dorylaimida). Total nematode numbers per 200 cm s soil ranged from 52 to 9,166 (mean = 1,785 ± 1,420). Nematodes were more abundant in dogwood and maple than in peach blocks, and their numbers were significantly correlated with percentage of weed ground cover and number of weed species. Nematode numbers in dogwood sites were also correlated with dogwood age. Microbivores were the most abundant trophic group in all sites, followed by plant parasites, fungivores, omnivores, and predators. Nematode communities in nursery sites shared characteristics of both undisturbed and agricultural habitats. Degree and diversity of plant ground cover appeared to be the most important factors determining nematode community structure.     

Dynamics of the range of <Emphasis Type="Italic">Artemisia</Emphasis> genus over the territory of Western Siberia and adjacent regions in holocene in connection with climate change on the basis of pollen data

Reconstruction of the dynamics of the range of Artemisia genus was carried out with the help of palynoareological method on the basis of the data of 97 pollen diagrams from the territory of Western Siberia and the Altai-Sayan mountainous region over the millennial time sections since the Late Glacial time till the present time. It was revealed that the maximal spread of the Artemisia steppe communities (probably of the cryoarid pattern) occurred at the territory under examination at 13–10 ka yr BP. After the time point of 9 ka yr BP a fundamental change in landscapes of Western Siberia occurred which resulted in the disintegration of previously continuous Artemisia steppe cover into separate blocks. Since 8 ka yr BP the Artemisia steppe communities of modern appearance occupied the zones of modern steppe and forest-steppe of Western Siberia and Northern Kazakhstan while over the taiga zone the Artemisia plant communities were spread occasionally under the extra zonal conditions and as the pioneering plant groupings on naturally disturbed soils. Since the time point of 4 ka yr BP till the present time the northern boundary of the steppe zone under-went pulsing shifts to the north and back and also broadening and narrowing of isolated insular steppes in Altai-Sayan mountain region took place. At present time we observe an increase in the role of plants of Artemisia genus in the tundra zone of Western Siberia and in the Altai mountains.     

Bacterial Communities in the Rhizosphere of Biofuel Crops Grown on Marginal Lands as Evaluated by 16S rRNA Gene Pyrosequences

Microbes are key components of the soil environment and are important contributors to the sustainability of agricultural systems, which is especially significant for biofuel crops growing on marginal lands. We studied bacterial communities in the rhizosphere of five biofuel crops cultivated in four locations in Michigan to determine which factors were correlated to changes in the structure of those communities. Three of these sites were marginal lands in that two were not suitable for conventional agriculture and one was regulated as a brownfield due to prior industrial pollution. Bacterial community composition and structure were assessed by 454 sequencing of the 16S rRNA gene. A total of 387,111 sequences were used for multivariate statistical analysis and to test for correlation between community structure and environmental variables such as plant species, soil attributes, and location. The most abundant bacterial phyla found in the rhizosphere of all crops were Acidobacteria, Proteobacteria, Actinobacteria, and Verrucomicrobia. Bacterial communities grouped by location rather than by crop and their structures were correlated to soil attributes, principally pH, organic matter, and nutrients. The effect of plant species was low but significant, and interactions between locations, plant species, and soil attributes account for most of the explained variation in the structure of bacterial communities, showing a complex relationship between bacterial populations and their environment. Bacterial diversity was higher in the agricultural sites compared to adjacent forest sites, indicating that the cultivation of those biofuel crops increased the rRNA diversity.     

太子参不同休耕年限土壤理化特征和微生物群落变化

太子参为福建道地中药材,连作效应严重限制其产业发展。休耕可以在一定程度上缓解连作效应,然而休耕对于缓解连作效应的机制尚不清楚。本文通过高通量测序分析不同休耕年限对太子参土壤微生物丰度及群落多样性的影响,并探索土壤理化性质、酚酸类物质与土壤微生物群落之间的关联性。结果表明:与对照太子参土壤相比,休耕土壤真菌多样性降低,细菌多样性增多。在细菌优势菌门中,酸杆菌门相对丰度显著增加,变形菌门与放线菌门相对丰度显著降低;真菌优势菌门相对丰度无显著变化。土壤酸性减弱,有机质含量随休耕年限增加呈现递减模式,酚酸类物质中苯甲酸和水杨酸含量显著降低,而对香豆酸等逐渐积累。综上,太子参土壤休耕改善了土壤微生物的菌群结构、土壤性质,从而缓解了连作效应。     

The Recent Trend of the Biodiversity Dynamic of Biotic Communities in Forest-Steppe Oak Forests

Comparative studies of the structure and diversity of model biotic communities (grass cover, soil macrofauna, xylotrophic fungi and xylophilous coleopterans) were carried out in oak forests of the core and buffer zones of the Voronezh biosphere reserve. The functional structure of the communities in the buffer zone had clearly expressed nemorose features characteristic of the broad-leaved zonal forests, while that in the core zone demonstrated more xerophilous patterns with a wide participation of meadow-steppe elements. The restricted anthropogenic activity in the buffer zone enhances the mesophytization of the oak forest habitats. The complete elimination of anthropogenic pressure in the core zone for two last decades results in the formation of a peculiar, dynamic pattern of forest ecosystems, which corresponds to the zonal climatic conditions.     

Comparison of Soil Bacterial Communities Under Diverse Agricultural Land Management and Crop Production Practices

The composition and structure of bacterial communities were examined in soil subjected to a range of diverse agricultural land management and crop production practices. Length heterogeneity polymerase chain reaction (LH-PCR) of bacterial DNA extracted from soil was used to generate amplicon profiles that were analyzed with univariate and multivariate statistical methods. Five land management programs were initiated in July 2000: conventional, organic, continuous removal of vegetation (disk fallow), undisturbed (weed fallow), and bahiagrass pasture (Paspalum notatum var Argentine). Similar levels in the diversity of bacterial 16S rDNA amplicons were detected in soil samples collected from organically and conventionally managed plots 3 and 4 years after initiation of land management programs, whereas significantly lower levels of diversity were observed in samples collected from bahiagrass pasture. Differences in diversity were attributed to effects on how the relative abundance of individual amplicons were distributed (evenness) and not on the total numbers of bacterial 16S rDNA amplicons detected (richness). Similar levels of diversity were detected among all land management programs in soil samples collected after successive years of tomato (Lycopersicon esculentum) cultivation. A different trend was observed after a multivariate examination of the similarities in genetic composition among soil bacterial communities. After 3 years of land management, similarities in genetic composition of soil bacterial communities were observed in plots where disturbance was minimized (bahiagrass and weed fallow). The genetic compositions in plots managed organically were similar to each other and distinct from bacterial communities in other land management programs. After successive years of tomato cultivation and damage from two major hurricanes, only the composition of soil bacterial communities within organically managed plots continued to maintain a high degree of similarity to each other and remain distinct from other bacterial communities. This study reveals the effects of agricultural land management practices on soil bacterial community composition and diversity in a large-scale, long-term replicated study where the effect of soil type on community attributes was removed.     

Response of alpine meadow communities to burrow density changes of plateau pika (Ochotona curzoniae) in the Qinghai-Tibet Plateau

Plateau pika (Ochotona curzoniae) is a key component of alpine meadow ecosystem in the Qinghai- Tibetan Plateau, and the increase of its number leads plant components of alpine meadow ecosystem to adaptively response. A field survey was carried out to determine the response of alpine meadow community to population densities of plateau pika by using available burrow density to replace the population density of plateau pika. This study showed that the height of alpine meadow communities gradually increased, and the cover of alpine meadow communities firstly decreased, and then increased as the available burrow density increased. With the increase of available burrow density, the richness index of alpine meadow communities firstly decreased and then increased, and the evenness index of alpine meadow communities firstly increased and then decreased, however, the diversity index of alpine meadow communities firstly increased, and then decreased, finally increased. In the increasing process of available burrow density, the total plant biomass and the unpalatable plant biomass firstly decreased and then increased, and the palatable plant biomass firstly increased and then decreased, indicating that the palatable plant biomass was the highest and the unpalatable plant biomass was the lowest at 14 available burrow per 625 m². In the economic groups of plant biomass, the weed biomass was the highest and the legume biomass was the lowest at any available burrow densities, and the grass biomass and the sedge biomass were related to available burrow densities, indicating that the sedge biomass were bigger than the grass biomass at 3 available burrow per 625 m², inverse at 54 available burrow per 625 m², similar between 3 and 34 available burrow per 625 m². Accompanying by the increase of available burrow densities, the legume biomass and the sedge biomass significantly decreased (P < 0.05) and the legume became disappearance at 54 available burrow per 625 m²; the grass biomass firstly increased and then decreased, peaking at 14 available burrow per 625 m². The weed biomass firstly decreased and then increased, and was the lowest at 14 available burrow per 625 m². This study suggested that the responses of alpine meadow communities to population density of plateau pika at 14 available burrows per 625 m² were more sensitive than that at other available burrow per 625 m² from plant species diversity, biomass, height, cover and economic group.     

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.     

内蒙古白音锡勒典型草原区鼠类群落多样性的研究

在草原生态系统中,鼠类既是消费者又是次级生产者,因此这个类群在草原生态系统中占有重要的地位。 鼠类群落结构是生态系统结构的一部分,它的存在是地理的、生态的和进化的诸因素共同作用的结果。鼠类群落的多样性,反映了同一地区各群落之间的相似程度,也反映了群落与其外界条件的关系,它作为群落的结构参数,是群落特征的重要方面,日益受到生态学工作者的重视。 1979年7-9月,我们曾对内蒙古白音锡勒典型草原区的鼠类群落空间配置及其结构进行研究(钟文勤等,1981)。本文将通过分析这些群落的多样性,进一步探讨鼠类群落与植被、土壤等条件的关系。     

Dynamic effects of ground-layer plant communities on beetles in a fragmented farming landscape

Vegetation effects on arthropods are well recognized, but it is unclear how different vegetation attributes might influence arthropod assemblages across mixed-agricultural landscapes. Understanding how plant communities influence arthropods under different habitat and seasonal contexts can identify vegetation management options for arthropod biodiversity. We examined relationships between vegetation structure, plant species richness and plant species composition, and the diversity and composition of beetles in different habitats and time periods. We asked: (1) What is the relative importance of plant species richness, vegetation structure and plant composition in explaining beetle species richness, activity-density and composition? (2) How do plant-beetle relationships vary between different habitats over time? We sampled beetles using pitfall traps and surveyed vegetation in three habitats (woodland, farmland, their edges) during peak crop growth in spring and post-harvest in summer. Plant composition better predicted beetle composition than vegetation structure. Both plant richness and vegetation structure significantly and positively affected beetle activity-density. The influence of all vegetation attributes often varied in strength and direction between habitats and seasons for all trophic groups. The variable nature of plant-beetle relationships suggests that vegetation management could be targeted at specific habitats and time periods to maximize positive outcomes for beetle diversity. In particular, management that promotes plant richness at edges, and promotes herbaceous cover during summer, can support beetle diversity. Conserving ground cover in all habitats may improve activity-density of all beetle trophic groups. The impacts of existing weed control strategies in Australian crop margins on arthropod biodiversity require further study.