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Background: Studying the growth and developmental mechanisms of steppe (Brandt's) voles is important for biological control and protection of steppe ecology. In this paper, preliminary biological experiments' data showed that the mortality of Brandt's vole increased after retinoic acid treatment. Methods: LPH inhibitor, retinoic acid, quercetin and DMSO (Standard treatment concentration 10mg/ml) were given them through oral with the help of Animal oral gavage feeding needles. The hind legs muscles of surviving Brandt's voles were collected for transcriptomic analysis. Result: A total of 4047 and 2251 up- and down-regulated transcripts, respectively, were observed upon retinoic acid treatment compared to the DMSO (control) treatment. Transcriptomic changes were enriched significantly in 31 KEGG pathways, most of which were involved in sugar metabolism, particularly for fructose and mannose (ko00051), protein digestion and absorption (ko04974), phenylalanine metabolism (ko00360), tyrosine metabolism (ko00350) and the PI3K-Akt signaling pathway (ko04151), which is related to growth and development. A total of 114 differentially expressed genes were screened as candidate genes according to the enrichment results, including c-Jun N-terminal kinase and tubulin epsilon chain verified by RT-PCR. Ultimately, we proposed a preliminary regulatory molecular mechanism of retinoic acid relevant to mouse development and death. [ABSTRACT FROM AUTHOR]

The research is aimed at studying the species composition, dynamics of the number and harmfulness of dominant pests, which is extremely important for the development and improvement of elements of the onion protection system. After all, the analysis of literature sources showed insufficient information about the distribution and harmfulness of the main phytophages under modern conditions of growing onions in the Right Bank Forest-Steppe of Ukraine. We conducted the monitoring of the phytosanitary condition of onion crops during 2017-2020 and determined the species composition of dominant phytophages. We studied the complex of soil pests: larvae of Melolontha sp., the population density of which over the years of research was 0.8-2.5 specimens/m2, larvae of Elateridae sp., or click beetles (wireworms) - 0.9-2.2 specimens/m2 and Gryllotalpa gryllotalpa L. - 2.5 specimens/m2. Dominant species of phytophages in onion crops included onion fly (Delia Antigua Mg.), onion thrips (Trips tabaci Lind.), and Ceuthorrhynchus jakovlevi Schultze. The four most vulnerable phases of growth and development of onions before colonization and damage by major phytophages were identified: 1) phase of leaf development (a primary shoot) (BBCH 1-19); 2) phase of the beginning of thickening of leaf base - bulb formation (BBCH 41-43); 3) phase of bulb formation - beginning of leaf splitting (BBCH 45-47); 4) phase of the completion of growth and development (state of physiological rest) (BBCH 48-49). [ABSTRACT FROM AUTHOR]

This article studies the use of livestock dung in the social and ecological context of pastoralism in the Tyva Republic, Inner Asia. In steppe ecologies, livestock dung, depending on its (mis)management, can be a valuable resource or a threat to animals' health and herders' well-being. Its use is embedded in the relationships between herder-livestock communities and landscapes, which are sentient and superordinate. Utilizing dung for household needs is simultaneously a form of care for livestock and a method of balancing the relationship with sentient homelands. [ABSTRACT FROM AUTHOR]

The Siberian mammoth steppe ecosystem changed dramatically with the disappearance of large grazers in the Holocene. The concept of Pleistocene rewilding is based on the idea that large herbivore grazing significantly alters plant communities and can be employed to recreate lost ecosystems. On the other hand, modern rangeland ecology emphasizes the often overriding importance of harsh climates. We visited two rewilding projects and three rangeland regions, sampling a total of 210 vegetation relevés in steppe and surrounding vegetation (grasslands, shrublands and forests) along an extensive climatic gradient across Yakutia, Russia. We analyzed species composition, plant traits, diversity indices and vegetation productivity, using partial canonical correspondence and redundancy analysis. Macroclimate was most important for vegetation composition, and microclimate for the occurrence of extrazonal steppes. Macroclimate and soil conditions mainly determined productivity of vegetation. Bison grazing was responsible for small-scale changes in vegetation through trampling, wallowing and debarking, thus creating more open and disturbed plant communities, soil compaction and xerophytization. However, the magnitude of effects depended on density and type of grazers as well as on interactions with climate and site conditions. Effects of bison grazing were strongest in the continental climate of Central Yakutia, and steppes were generally less affected than meadows. We conclude that contemporary grazing overall has rather limited effects on vegetation in northeastern Siberia. Current rewilding practices are still far from recreating a mammoth steppe, although large herbivores like bison can create more open and drier vegetation and increase nutrient availability in particular in the more continental Central Yakutian Plain. [ABSTRACT FROM AUTHOR]

The ecology of invertebrate steppe species requiring active conservation management has not been explored enough. Stenobothrus eurasius is a characteristic steppe species occurring very frequently in the Siberian and Central Asian grasslands, although on the western edge of its area it is present in small, isolated, endangered relict populations. We examined populations and habitats of St. eurasius in the Pannonian vegetation region to (1) seek predictor variables of its density and (2) explore potentially successful conservation management practices which could be used generally on declining steppe relict species. Our results showed that robust populations of St. eurasius are found in short, edaphic, relict steppe grasslands in which the proportion of coarse sand in the soil is high and which are free of significant disturbance by game (specifically by wild boar). According to our study, the most important approach for the enhancement of declining marginal populations of St. eurasius, existing as an umbrella species of steppe relicts, is to reduce individual numbers of game (mainly wild boar and mouflon) which have increased tenfold regionally in the last few decades (or at least to exclude them from the most vulnerable patches). [ABSTRACT FROM AUTHOR]

• Using the largest available trophic network of a large steppe ecosystem, we tested that steppe trophic networks including migratory species are associated with (i) migratory strategy and (ii) phylogenetic relatedness of interacting species. • We found that (1) a substantial number of links were established by migrant taxa; (2) the phylogenetic signal in network structure was moderate for both consumer and prey nodes; (3) both consumer and prex phylogenies affected modularity, which was modulated by migration strategy; and (4) all species-level graph properties significantly differed between networks including and excluding migratory taxa. • Our findigs provide information for conservation planning by identifying key trophic links in migratory taxa. Evidence is mounting that the structures of trophic networks are governed by migratory movements of interacting species and also by their phylogenetic relationships. Using the largest available trophic network of a large steppe ecosystem, we tested that steppe trophic networks including migratory species are associated with (i) migratory strategy and (ii) phylogenetic relatedness of interacting species: (1) whole graph-level metrics, estimated as modularity, and (2) species-level network metrics, measured as node degree (number of interacting partners), and centrality metrics. We found that (1) a substantial number of links were established by migrant taxa; (2) the phylogenetic signal in network structure was moderate for both consumer and prey nodes; (3) both consumer and prex phylogenies affected modularity, which was modulated by migration strategy; and (4) all species-level graph properties significantly differed between networks including and excluding migratory taxa. In sum, here we show that the structure of steppe trophic networks is primarily governed by migratory strategies and to a lesser extent, by phylogenetic relatedness, using the largest available food web representative for steppe ecology and migration biology. [ABSTRACT FROM AUTHOR]

Steppe‐tundra is considered to have been a dominant ecosystem across northern Eurasia during the Last Glacial Maximum. As the fossil record is insufficient for understanding the ecology of this vanished ecosystem, modern analogues have been sought, especially in Beringia. However, Beringian ecosystems are probably not the best analogues for more southern variants of the full‐glacial steppe‐tundra because they lack many plant and animal species of temperate steppes found in the full‐glacial fossil record from various areas of Europe and Siberia. We present new data on flora, land snails and mammals and characterize the ecology of a close modern analogue of the full‐glacial steppe‐tundra ecosystem in the southeastern Russian Altai Mountains, southern Siberia. The Altaian steppe‐tundra is a landscape mosaic of different habitat types including steppe, mesic and wet grasslands, shrubby tundra, riparian scrub, and patches of open woodland at moister sites. Habitat distribution, species diversity, primary productivity and nutrient content in plant biomass reflect precipitation patterns across a broader area and the topography‐dependent distribution of soil moisture across smaller landscape sections. Plant and snail species considered as glacial relicts occur in most habitats of the Altaian steppe‐tundra, but snails avoid the driest types of steppe. A diverse community of mammals, including many species typical of the full‐glacial ecosystems, also occurs there. Insights from the Altaian steppe‐tundra suggest that the full‐glacial steppe‐tundra was a heterogeneous mosaic of different habitats depending on landscape‐scale moisture gradients. Primary productivity of this habitat mosaic combined with shallow snow cover that facilitated winter grazing was sufficient to sustain rich communities of large herbivores. [ABSTRACT FROM AUTHOR]

The multi-layered settlement of Turganik in the Tok River valley (steppe region west of the Urals) has been studied using paleopedological and microbiomorphical methods. Early humans lived in the settlement during the Eneolithic epoch (the fifth millennium BC) and in the Early Bronze Age (the fourth millennium BC). The cultural layers attributable to the Atlantic period of the Holocene developed under conditions of a rather dry climate, with the landscapes being dominated by the grass and herb steppe. The settlement area was above the flood water level and was suitable for habitation. The soils in its vicinity were Kastanozems (Endosalic Protosodic). The final stages of the cultural layer formation bear traces of strong (though short-term) floods, with the deposits of the latter partly concealed traces of the preceding long-term arid phase. Maximum aridity was during the final interval of the Atlantic period. The Subboreal and Subatlantic periods were noted for meadow-chernozem soil formation (Luvic Chernozems [Stagnic]) and an increasing proportion of arboreal species in the pollen assemblages. Some phytoliths of aquatic plants were found in the assemblages dominated by those of meadow grasses. The climate was more humid and cool, although short episodes of aridity were possible. [ABSTRACT FROM AUTHOR]

Ukraine has maintained its position as leading producer of sunflower seeds in the world for the past decade. Concerning diet, higher oleic acids are ideal. Sunflower (Helianthus annuus L.) hybrids have high genetic potential for seed yield above 5 t/ha and oil content in seed greater than 50%. Yet, environmental factors seems to limit current sunflower yields to the production range of 1.5-3.0 t/ha. A three years field experiment was conducted in the Left-Bank Forest-Steppe of Ukraine (Latitude: 49.6; Longitude: 34.9; altitude 113 m) to assess the influence of seven different foliar applications of fertilizers and plant growth regulators (control; Sol Bor + Basfoliar 6-12-6; Basfoliar 6-12-6; Wuxal Bio Aminoplant + Wuxal Boron; Wuxal Boron; Spectrum Askorist + Spectrum B + Mo; Spectrum B + Mo) on productivity and quality of five new high oleic sunflower hybrids (SY Experto, Antratsyt, ES Ballistic, Oplot, PR64H32). Foliar applications positively influenced all parameters studied (plant height, leaf surface area, number of seeds per head, seed yield, oil content and oleic acid content). The highest average seed yields occurred in the hybrids PR64H32 (3.73 t/ha) and SY Experto (3.69 t/ha) with no significant difference (P<0.05). However, PR64H32 generated a significantly (P<0.05) higher average seed yield than the other hybrids. Except for Wuxal Boron (sprayed twice sequentially) with an average seed yield of 3.53 t/ha, sequential spraying of Wuxal Bio Aminoplant + Wuxal Boron thrice on all hybrids, ensured a significantly higher average seed yield (3.58 t/ha) than the other foliar sprays. Based on foliar sprays, the increase in seed yields ranged from 0.19-0.36 t/ha when compared to control. Foliar sprays also caused increases in oil content between 0.6-1.6% compared to the control with average oil content for the various hybrids fluctuating between 48.4-49.3%. Average oleic acid content ranged from 71.5-83.7% for the investigated hybrids and foliar applications increased the average oleic acid content by 1.8-4.1%. The combined factors of hybrid and foliar applications had the greatest influence on seed yield (share of 62.6%) than hybrid - 29.1%; foliar applications - 6.3%; other factors - 2.0%. [ABSTRACT FROM AUTHOR]

In recent years, the continued loss and fragmentation of steppe has caused decreased ecosystem functions and species losses in insect diversity. In the 2000s, the Chinese government developed a series of national projects, such as the construction of enclosures, to conserve natural ecosystems, including steppe. However, the effects of these enclosures on steppe arthropod community are largely unknown. In the present study, we selected enclosed and low‐grazing regions at eight National Grassland Fixed Monitoring Stations to examine the compositional differences in four insect functional groups and their associated ecological functions. The results showed that diversity significantly differed between the enclosed and low‐grazing regions, with the number of insect families being significantly higher in enclosed regions than in regions with low‐grazing pressure. The responses of the insect community to steppe management also varied among the four groups (herbivores, predators, parasitoids, and pollinators). The abundances of herbivores, predators, and parasitoids were higher in enclosed regions than in low‐grazing regions, while there was no significant difference in pollinators. Additionally, there were no significant differences in the predator/prey ratio between enclosed regions and low‐grazing regions in any of the steppe types. The parasitic wasp/prey ratio was higher in enclosed regions than in low‐grazing regions in meadow steppe and typical steppe, while there were no significant differences between the enclosed and low‐grazing regions in desert steppe and steppe desert. Herbivores were observed to benefit much more from enclosures than predators, parasitoids, and pollinators. Therefore, we recommend low‐grazing should be considered in steppe conservation, which could conserve biodiversity and achieve biocontrol functions of arthropod community. The abundances of herbivores, predators, and parasitoids were higher in enclosed regions than in low‐grazing regions, while there was no significant difference in pollinators. The parasitic wasp/prey ratio was higher in enclosed regions than in low‐grazing regions in meadow steppe and typical steppe, while there were no significant differences between the enclosed and low‐grazing regions in desert steppe and steppe desert. Herbivores were observed to benefit more from enclosures than predators, parasitoids, and pollinators. [ABSTRACT FROM AUTHOR]

Few studies have addressed the potential grazing effects on microclimate, such as surface temperature and moisture, and their feedback effects on grassland function. A continuous, approximately three-year long study was conducted in experimental plots of various grazing intensities, and in situ soil temperature and moisture were measured. The results indicated that grazing significantly altered soil temperature and moisture. Soil temperature increased exponentially with increasing grazing intensity in the warm season due to the removal of aboveground biomass (AGB) and decreased linearly with increasing grazing intensity in the cold season due to decreases in both AGB and wind-blown snow accumulation. Heavy grazing increased soil temperature (10 cm depth) by an average of 2.6 °C from April to October (the largest hourly temperature increase was 8.8 °C), representing a soil warming effect 3.7 times that of global warming. Our findings showed that, compared with ungrazed plots, grazed plots had decreased soil water storage due to less winter snow accumulation, especially in the early growing season (EGS) because of the smaller amount of winter snow accumulation than in ungrazed plots. In the EGS, the average water storage in the 0–100 cm layer of the ungrazed plots was 23.3%, which was 1.3–1.8 times that of the grazed plots. Our results showed that grazing also produced warming and drying effects on grassland soil. The long-term feedback effects of grazing-induced soil warming and drying on the ecosystem might be an important mechanism accelerating the degradation and desertification of these grasslands. [ABSTRACT FROM AUTHOR]

Summary: Previous evapotranspiration (ET) partitioning studies have usually neglected competitions and interactions between antagonistic plant functional types. This study investigated whether shrubs and grasses have divergent ET partition dynamics impacted by different water‐use patterns, canopy structures, and physiological properties in a shrub‐encroached steppe ecosystem in Inner Mongolia, China. The soil water‐use patterns of shrubs and grasses have been quantified by an isotopic tracing approach and coupled into an improved multisource energy balance model to partition ET fluxes into soil evaporation, grass transpiration, and shrub transpiration. The mean fractional contributions to total ET were 24 ± 13%, 20 ± 4%, and 56 ± 16% for shrub transpiration, grass transpiration, and soil evaporation respectively during the growing season. Difference in ecohydrological connectivity and leaf development both contributed to divergent transpiration partitioning between shrubs and grasses. Shrub‐encroachment processes result in larger changes in the ET components than in total ET flux, which could be well explained by changes in canopy resistance, an ecosystem function dominated by the interaction of soil water‐use patterns and ecosystem structure. The analyses presented here highlight the crucial effects of vegetation structural changes on the processes of land–atmosphere interaction and climate feedback. [ABSTRACT FROM AUTHOR]

How the presence of biological soil crusts (BSCs) and physical soil crusts (PSCs) regulates surface soil hydrological processes in the high-altitude alpine ecosystems is still a pressing scientific issue owing to a lack of convincing field observation data. This study highlights the interesting phenomenon whereby BSCs and PSCs are jointly distributed in opposite orientations under a canopy of patchy Achnatherum splendens grass on the alpine steppe of the Qinghai Lake watershed (Qinghai-Tibet Plateau, northwestern China). The vegetation characteristics (plant species, cover, and biomass) and soil properties (volumetric soil water content, hydraulic conductivity, temperature, salinity, and macroporosity) were investigated for BSCs zones, PSCs zones, and interpatch zones (IPZs) in the A. splendens patches (ASPs) system. The experimental results show that BSCs increased infiltration during wet periods by increasing significantly greater hydraulic conductivity and macroporosity ( p  < 0.01), and reduced soil evaporation by maintaining a lower soil temperature than PSCs and IPZs during dry periods. BSCs had an important role in improving water retention in ASPs and thereby provided highly favorable conditions for plant recruitment and survival. However, PSCs reduced the infiltration capacity of surface soils and were suspected of generating runoff after intense rainfall events, which might promote connectivity of the horizontal water flux for ASPs. PSCs had a negative effect on the vegetation community by creating a saline environment (e.g. 28-fold higher salinity than for BSC zones and IPZs at 5 cm depth) for other herbaceous plants. The predominant wind direction, canopy effects of A. splendens on local microclimate, and salt accumulation were identified as the main factors determining the opposite distribution of BSCs and PSCs. The results suggest that BSCs and PSCs play contrasting roles in soil hydrology in ASPs, and provide valuable insights for understanding the spatial distribution of soil crusts and vascular plants as well as their interactions in high-altitude alpine steppe ecosystems. [ABSTRACT FROM AUTHOR]

Shift in precipitation regime could greatly alter plant and microbial activity, and thus the contemporary and future ecosystem dynamics in grasslands. We investigated how changes in snow depth affect plants, microbes and their relationships after 10 consecutive years of snow treatments in different steppes. We selected 8 snow fences along a mean annual precipitation (MAP) gradient from 225 to 375 mm in Inner Mongolia. For each snow fence, study plots were set up at 7 transects with different levels of snow depth. We found that ecosystem properties, including soil moisture, the biomass and nitrogen (N) pools of microbes and plants, the fungi: bacteria ratio and the grass: forb ratio, increased with increasing snow depth at the drier sites with lower MAP, but not at the wetter sites with higher MAP. At any given site, the sensitivity of these ecosystem properties to changes in snow depth was determined by the slopes of these variables against snow depth. The results showed that the sensitivity of these ecosystem properties to changes in snow depth decreased linearly with increase in MAP levels. In addition, we also found that increased snow depth shifted the relationship between microbial and plant biomass from positive to negative. Our work reveals the importance of snow water in regulating plant and microbial processes in temperate steppes, especially under lower MAP conditions. The greater plant and microbial biomass and the shift of community toward greater fungi: bacteria and grass: forb ratio imply that increased snowmelt input alleviated water limitation in temperate steppes and altered plant and microbial communities. Our study helps to better predict that how changes in winter precipitation could affect the biomass and composition of plants and soil microbes in grasslands. [ABSTRACT FROM AUTHOR]

The methane (CH4) cycle on the Qinghai-Tibet Plateau (QTP), the world's largest high-elevation permafrost region, is sensitive to climate change and subsequent freezing and thawing dynamics. Yet, its magnitudes, patterns, and environmental controls are still poorly understood. Here, we report results from five continuous year-round CH4 observations from a typical alpine steppe ecosystem in the QTP permafrost region. Our results suggest that the QTP permafrost region was a CH4 sink of -0.86±0.23 g CH4- Cm-2 yr-1 over 2012-2016, a rate higher than that of many other permafrost areas, such as the Arctic tundra in northern Greenland, Alaska, and western Siberia. Soil temperature and soil water content were dominant factors controlling CH4 fluxes; however, their correlations changed with soil depths due to freezing and thawing dynamics. This region was a net CH4 sink in autumn, but a net source in spring, despite both seasons experiencing similar top soil thawing and freezing dynamics. The opposite CH4 source-sink function in spring versus in autumn was likely caused by the respective seasons' specialized freezing and thawing processes, which modified the vertical distribution of soil layers that are highly mixed in autumn, but not in spring. Furthermore, the traditional definition of four seasons failed to capture the pattern of the annual CH4 cycle. We developed a new seasonal division method based on soil temperature, bacterial activity, and permafrost active layer thickness, which significantly improved the modeling of the annual CH4 cycle. Collectively, our findings highlight the critical role of fine-scale climate freezing and thawing dynamics in driving permafrost CH4 dynamics, which needs to be better monitored and modeled in Earth system models. [ABSTRACT FROM AUTHOR]

Abstract: Root‐hemiparasitic interaction between the dominant grass Calamagrostis epigejos and the hemiparasite Thesium linophyllon was studied to assess the potential of the parasite to regulate dominance of the grass, which is expanding into species‐rich steppe grasslands. First, we aimed to identify physiological links between the two species as a principal indicator of the parasitic relationship. Second, we analysed the dynamics of the two species in the vegetation of a steppe grassland at the foot of the Bükk Mountains, Hungary, where their joint presence is recorded in a long‐term permanent plot monitoring dataset to detect patterns associated with the parasitic ecological interaction. Numerous well‐developed functional haustoria of Th. linophyllon were identified on the root systems of C. epigejos. The joint dynamics of C. epigejos and Th. linophyllon displayed clear signs of the parasitic interaction: (1) the dynamics of Th. linophyllon frequency was positively associated with the initial cover of C. epigejos; (2) maximum recorded cover values of the two species were strongly positively correlated; and (3) the extent of C. epigejos decrease in the vegetation was significantly positively associated with maximum Th. linophyllon cover recorded throughout the monitoring period. We demonstrate that C. epigejos can be parasitized by Th. linophyllon, which restricts abundance of the grass. Th. linophyllon thus has potential to act as a native biological control of C. epigejos in steppe grasslands. [ABSTRACT FROM AUTHOR]

An algorithm of regional assessment of the size and structure of the actual (corresponding to the modern state of ecosystems and land use patterns) and potential (for hypothetic natural ecosystems analogous to modern native ecosystems) pools of carbon has been developed and tested. A comparison between actual and potential values of carbon pools makes it possible to assess the integral result of land use in the studied region with multiple changes in the types of land use during the historical period. The calculations are made using a unified cartographic base and take into account the taxonomic position and texture of soil units, the types of modern land use, and the type and age structure of the reconstructed and actual vegetation. The results obtained for the southern taiga and forest-steppe zones of European Russian indicate that the modern actual carbon pool is 24% less than the potential carbon pool in Kostroma oblast (southern taiga zone) and 32% less than the potential carbon pool in Kursk oblast (forest-steppe zone). The actual phytomass reserves in these two regions have decreased by 40 and 75%, respectively, relative the potential phytomass reserves, so the portion of the soil carbon pool in the total carbon pool has increased. It is argues that the use of the territory for forestry and agriculture increases the role of the soil cover in sustaining the carbon budget of the region. [ABSTRACT FROM AUTHOR]

The GaoFen-3 (GF-3) satellite is the first fully polarimetric synthetic aperture radar (PolSAR) satellite in China. It has three fully polarimetric imaging modes and is available for many applications. The system has been taken on several calibration experiments after the launch in Inner Mongolia by the Institute of Electronics, Chinese Academy of Sciences (IECAS), and the polarimetric calibration (PolCAL) strategy of GF-3 are also improved. Therefore, it is necessary to assess the image quality before any further applications. In this paper, we evaluated the polarimetric residual errors of GF-3 images that acquired in July 2017 in a steppe site. The results shows that the crosstalk of these images varies from -36dB to -46dB, and the channel imbalance varies from -0.43dB to 0.55dB with angle varying from -1.6 to 3.6 degree. We also made a PolCAL experiment to restrain the polarimetric distortion afterwards, and the polarimetric quality of the image got better after the PolCAL processing. [ABSTRACT FROM AUTHOR]

Abstract: Rodent damage is a serious threat to sustainable management of grassland. The effects of nitrogen (N) deposition and grassland management on rodent damage have been scarcely studied. Here, we reported the effects of 2 years of N addition and mowing on burrow density and damage area of Citellus dauricus in a semiarid steppe in Inner Mongolia. N addition significantly aggravated, while mowing alleviated rodent damage in the grassland under study. Burrow density and damage area increased 2.8‐fold and 4.7‐fold, in N addition plots compared to the ambient N addition treatment, respectively. Conversely, mowing decreased burrow density and damage area by 75.9% and 14.5%, respectively, compared to no mowing plots. Observed changes in rodent damage were mainly due to variations in plant community cover, height, and aboveground net primary productivity. Our findings demonstrate that N addition and mowing can affect the rodent density and activity in grassland, suggesting that the effects of a changing atmospheric composition and land use on rodent damage must be considered in order to achieve better grassland management. [ABSTRACT FROM AUTHOR]

Soil-borne seed pathogens are omnipresent but are often overlooked components of a community’s biotic resistance to plant naturalization and invasion. Using multi-year greenhouse experiments, we compared the seed mortality of single invasive, naturalized, and native grass species in sterilized and unsterilized soils collected from Pacific Northwest (USA) steppe and forest communities. Native Pseudoroegneria spicata displayed the greatest seed mortality, naturalized Secale cereale displayed intermediate seed mortality, and invasive Bromus tectorum was least affected by soil pathogens. Seed mortality across all three species was consistently greater in soils collected from steppe than soils collected from forest; seeds sown into sterilized steppe soil experienced half the overall seed mortality compared to seeds sown into unsterilized steppe soil. Soil sterilization did not affect grass seed mortality in forest soils. We conclude that (1) removing soil-borne pathogens with sterilization does increase native and non-native grass seed survival, and (2) soil-borne pathogens may influence whether an introduced species becomes invasive or naturalized within these Pacific Northwest communities as a result of differential seed survival. Soil-borne pathogens in these communities, however, have the greatest negative effect on the survival of native grass seeds, suggesting that the native microbial soil flora more effectively attack seeds of native plants than seeds of non-native species. [ABSTRACT FROM AUTHOR]

Water use efficiency (WUE) is an important indicator of ecosystem functioning but how ecosystem WUE responds to climate change including precipitation and nitrogen (N) deposition increases is still unknown. To investigate such responses, an experiment with a randomized block design with water (spring snowfall or summer water addition) and nitrogen addition was conducted in a temperate steppe of northern China. We investigated net ecosystem CO2 production (NEP), gross ecosystem production (GEP) and evapotranspiration (ET) to calculate ecosystem WUE (WUEnep = NEP/ET or WUEgep = GEP/ET) under spring snow and summer water addition with or without N addition from 2011 to 2013. The results showed that spring snow addition only had significant effect on ecosystem WUE in 2013 and summer water addition showed positive effect on ecosystem WUE in 2011 and 2013, as their effects on NEP and GEP is stronger than ET. N addition increased ecosystem WUE in 2012 and 2013 both in spring snow addition and summer water addition for its increasing effects on NEP and GEP but no effect on ET. Summer water addition had less but N addition had greater increasing effects on ecosystem WUE as natural precipitation increase indicating that natural precipitation regulates ecosystem WUE responses to water and N addition. Moreover, WUE was tightly related with atmospheric vapor-pressure deficit (VPD), photosynthetic active radiation (PAR), precipitation and soil moisture indicating the regulation of climate drivers on ecosystem WUE. In addition, it also was affected by aboveground net primary production (ANPP). The study suggests that ecosystem WUE responses to water and N addition is determined by the change in carbon process rather than that in water process, which are regulated by climate change in the temperate steppe of northern China. [ABSTRACT FROM AUTHOR]

High disturbance frequency, low water availability, and advantageous growth mechanisms of invasive annual compared to native perennial grasses reduce native grass establishment throughout arid rangelands. Modifying seeding dispersal processes, including seeding rate and time, may increase native grass recruitment by influencing safe site occupation. A better understanding of seedling development through life history stages and the ecological processes occurring during these stages may be necessary to comprehend modified dispersal dynamics on plant community assembly. We tested the effects of spring vs. fall annual grass seeding times, adding water, and varying annual and perennial grass propagule pressure on perennial and annual grass recruitment in an eastern Oregon shrub-steppe ecosystem. Across species, survival rates were lowest between germination and emergence stages. However, perennial grass germination rates were highest when perennials were seeded with annual grasses in autumn. Perennial grass recruitment was generally low, especially when annual grass propagule pressure was higher than 150 seeds m −2 . Although, by the second growing season, perennial grasses had the highest density when perennials were seeded with annuals in autumn and water was added. Consequently, modifying native perennial grass dispersal, like priority autumn seeding and increasing propagule pressure, should produce higher perennial grass recruitment across arid lands. [ABSTRACT FROM AUTHOR]

Many biodiversity experiments have demonstrated that plant diversity can stabilize productivity in experimental grasslands. However, less is known about how diversity-stability relationships are mediated by grazing. Grazing is known for causing species losses, but its effects on plant functional groups ( PFGs) composition and species asynchrony, which are closely correlated with ecosystem stability, remain unclear. We conducted a six-year grazing experiment in a semi-arid steppe, using seven levels of grazing intensity (0, 1.5, 3.0, 4.5, 6.0, 7.5, and 9.0 sheep per hectare) and two grazing systems (i.e., a traditional, continuous grazing system during the growing period ( TGS), and a mixed one rotating grazing and mowing annually ( MGS)), to examine the effects of grazing system and grazing intensity on the abundance and composition of PFGs and diversity-stability relationships. Ecosystem stability was similar between mixed and continuous grazing treatments. However, within the two grazing systems, stability was maintained through different pathways, that is, along with grazing intensity, persistence biomass variations in MGS, and compensatory interactions of PFGs in their biomass variations in TGS. Ecosystem temporal stability was not decreased by species loss but rather remain unchanged by the strong compensatory effects between PFGs, or a higher grazing-induced decrease in species asynchrony at higher diversity, and a higher grazing-induced increase in the temporal variation of productivity in diverse communities. Ecosystem stability of aboveground net primary production was not related to species richness in both grazing systems. High grazing intensity weakened the temporal stabilizing effects of diversity in this semi-arid grassland. Our results demonstrate that the productivity of dominant PFGs is more important than species richness for maximizing stability in this system. This study distinguishes grazing intensity and grazing system from diversity effects on the temporal stability, highlighting the need to better understand how grazing regulates ecosystem stability, plant diversity, and their synergic relationships. [ABSTRACT FROM AUTHOR]

Landscape dynamics is the result of interactions between social systems and the environment, these systems evolving significantly over time. climatic conditions and biophysical phenomena are the main factors of landscape dynamics. Also, currently man is responsible for most changes affecting natural ecosystems. The objective of this work is to study the dynamics of a typical landscape of western Algeria in time and space, and to map the distribution of vegetation groups constitute the vegetation cover of this ecosystem. as well as using a method of monitoring the state of a fragile ecosystem by remote sensing to understand the processes of changes in this area. The steppe constitutes a large arid area, with little relief, covered with low and sparse vegetation. it lies between the annual isohyets of 100 to 400 mm, subjected to a very old human exploitation with an activity of extensive breeding of sheep, goats, and camels. Landsat satellite data were used to mapping vegetation groups in the Mecheria Steppe at a scale of 1: 300,000. Then, a comparison was made between the two maps obtained by a classification of Landsat-8 sensor Operational Land Imager (OLI) acquired on March 18, 2014, and Landsat-5 sensor Thematic Mapper (TM) acquired on April 25, 1987. The results obtained show the main changes affecting the natural distribution of steppe species, a strong change in land occupied by the Stipa tenacissima steppe with 65% of change, this steppe is replaced by Thymelaea microphylla, Salsola vermiculata, lygeum spartum and Peganum harmala steppe. an absence from the steppe Artemisia herba-alba that has also been replaced by the same previous steppes species. The groups with Quercus ilex and Juniperus phoenicea are characterized by a strong regression that was lost 60% of its global surface and transformed by steppe to stipa tenacissima and bare soil. [ABSTRACT FROM AUTHOR]

The effect of fire on vegetation of semi-arid steppe has not been studied extensively. Wildfires are rare in some steppe rangelands because of high levels of large herbivore grazing. However, grazing is sometimes restricted or excluded in areas such as national parks or the areas where afforestation projects are conducted. Therefore, sometimes, wildfires occur during the dormant season when litter (the uppermost layer of organic debris on the soil surface; essentially the freshly fallen or slightly decomposed vegetal material) mass has resulted in peak levels. Our study assessed the effects of a single fire on litter mass, forage production, and forage crude protein, Neutral Detergent Fiber (NDF), and Acid Detergent Fiber (ADF) in high altitude rangelands of Eastern Anatolia. We found significant effects of treatment (fire and no fire), years, and sampling date on all variables. Following the prescribed fire in 2011, litter mass and forage production was less in treated plots compared to untreated control plots during both years. The effect of the fire on litter and forage production was more pronounced in 2012 compared to 2013. The effects of the fire on forage quality variables were also greater in 2012 than in 2013. Forage crude protein levels were consistently higher in treated plots during all 2012 sampling periods. Similarly, NDF and ADF tended to be lower in treated plots relative to the control plots during 2012. All effects we found were more pronounced in the first growing season following the fire compared to the second growing season, suggesting a relatively transient nature of fire effects in the steppe vegetation we studied. [ABSTRACT FROM AUTHOR]

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Climate change and land use change are two major elements of human-induced global environmental change. In temperate grasslands and woodlands, increasing frequency of extreme weather events like droughts and increasing severity of wildfires has altered the structure and dynamics of vegetation. In this paper, we studied the impact of wildfires and the year-to-year differences in precipitation on species composition changes in semi-arid grasslands of a forest-steppe complex ecosystem which has been partially disturbed by wildfires. Particularly, we investigated both how long-term compositional dissimilarity changes and species richness are affected by year-to-year precipitation differences on burnt and unburnt areas. Study sites were located in central Hungary, in protected areas characterized by partially-burnt, juniper-poplar forest-steppe complexes of high biodiversity. Data were used from two long-term monitoring sites in the Kiskunság National Park, both characterized by the same habitat complex. We investigated the variation in species composition as a function of time using distance decay methodology. In each sampling area, compositional dissimilarity increased with the time elapsed between the sampling events, and species richness differences increased with increasing precipitation differences between consecutive years. We found that both the long-term compositional dissimilarity, and the year-to-year changes in species richness were higher in the burnt areas than in the unburnt ones. The long-term compositional dissimilarities were mostly caused by perennial species, while the year-to-year changes of species richness were driven by annual and biennial species. As the effect of the year-to-year variation in precipitation was more pronounced in the burnt areas, we conclude that canopy removal by wildfires and extreme inter-annual variability of precipitation, two components of global environmental change, act in a synergistic way. They enhance the effect of one another, resulting in greater long-term and year-to-year changes in the composition of grasslands. [ABSTRACT FROM AUTHOR]

To understand the effects of different disturbance regimes on the bud bank demography in perennial grasslands, we conducted a demographic field investigation of the bud bank in a typical steppe on the Loess Plateau. Grazing significantly decreased and fire significantly increased bud bank density compared to fenced grasslands. For different bud bank types, grazing significantly decreased tiller bud bank density, and fire significantly increased the density of root crown buds and rhizomatous buds in relation to fenced grasslands. Tiller buds accounted for the majority of the total bud banks independently of the disturbance regimes. Our study suggests that the grasslands with a large reserve bud bank may be the most resistant to disturbance, and fencing is an effective grassland management measure to keep a large bud bank in typical steppe on the Loess Plateau. [ABSTRACT FROM AUTHOR]

Pollen productivity estimates (PPEs) and the relevant source area of pollen (RSAP) are critical to the reconstruction of past plant abundances. Extended R-value (ERV) models are commonly used for developing PPEs and estimating the RSAP. In this study, in the forest-steppe ecotone of northern China that is sensitive to climate change and significant in vegetation openness reconstruction, pollen data from surface sediment samples of 24 lakes and high-resolution data of vegetation within the lake basins were applied to ERV models to calculate the PPEs of Pinus, Quercus, Betula, Ulmus, Poaceae, Artemisia, Chenopodiaceae, Compositae, and Cyperaceae and the RSAP of different lake sizes. The PPEs of arboreal pollen were higher than herbaceous pollen, and Chenopodiaceae had the highest productivity of herbaceous pollen taxa. The RSAP of lakes with an average lake radius of 400 m was estimated to be 1600 m. Our results suggested that PPEs and RSAP are region specific and that RSAP is also lake size specific even within the same region. Although environmental factors and imperfections in the ERV models may affect the accuracy of results, our study emphasized that a systematic vegetation survey considering zonal and azonal vegetation, the forest and steppe mosaic, and the vertical vegetation belt can help improve the PPEs and RSAP in areas with complicated vegetation distribution, such as the forest-steppe ecotone. [ABSTRACT FROM AUTHOR]

To counter species loss living ex situ collections in botanic gardens became important elements of robust conservation programs. Several limitations, problems, and risks associated with living ex situ collections have been reported such as appropriate cultivation management to maintain genetic diversity and stochastic effects in small isolated populations in artificial habitats. However, not all small and isolated populations exhibit these predicted genetic changes. In a multi-species in situ/ex situ comparison of sand dune steppe- and grassland vegetation >30 years after the ex situ population establishment, we compared four different species' population genetic diversities ( Alyssum montanum ssp. gmelinii, Gypsophila fastigiata, Helianthemum nummularium ssp. obscurum, Onosma arenaria) by means of ISSR. We observed different species-specific genetic responses to quite similar abiotic selective forces concerning different neutral genetic diversities of wild versus botanic garden populations. The genetic divergence was kept relatively low in two of the four investigated species between the model steppe plant community within the botanic garden where human interference was kept at a minimum and the wild population. However, the moderate genetic divergence of the two other species kept under the same conditions highlights the importance of species-specific intrinsic responses and stochastic effects to ecosystem changes and provides data on population genetic dynamics in small and isolated populations. This contributes to further improve recommendations on how to best conserve endangered plant species in ex situ environments (cultivation in near nature-like replicas of the original site with as little human inference as possible over only certain periods of time, >30 years). [ABSTRACT FROM AUTHOR]

The Ukrainian feather-grass steppe ecosystems are highly vulnerable to climate changes. To study the impact of climatic factors on steppe ecosystems' productivity, the correlation and stepwise regression analysis between ANPP and other variables were provided. The correlation of bioclimatic variables (month precipitation, relative humidity and air and soil temperatures) and aboveground net primary production (ANPP) were investigated for three study plots that represent major steppe microrelief: plain, slope and lowland. The results of multiple regression analysis showed the major components that influenced the ANPP at each of the study plots 'Plain', 'Slope' and 'Lowland'. The precipitation and relative humidity in the months before the vegetation peak were most important for ANPP accumulation. Results of this study are important for the prediction of ecosystem changes under the climate changes and also for the development of nature conservation programmes. [ABSTRACT FROM AUTHOR]

Land-cover change has long been recognized as having marked effect on the amount of soil organic carbon ( SOC). However, the microbially mediated processes and mechanisms on SOC are still unclear. In this study, the soil samples in a degenerative succession from alpine meadow to alpine steppe meadow in the Qinghai-Tibetan Plateau were analysed using high-throughput technologies, including Illumina sequencing and geochip functional gene arrays. The soil microbial community structure and diversity were significantly ( p < .05) different between alpine meadow and alpine steppe meadow; the microbial ɑ-diversity in alpine steppe meadow was significantly ( p < .01) higher than in alpine meadow. Molecular ecological network analysis indicated that the microbial community structure in alpine steppe meadow was more complex and tighter than in the alpine meadow. The relative abundance of soil microbial labile carbon degradation genes (e.g., pectin and hemicellulose) was significantly higher in alpine steppe meadow than in alpine meadow, but the relative abundance of soil recalcitrant carbon degradation genes (e.g., chitin and lignin) showed the opposite tendency. The Biolog Ecoplate experiment showed that microbially mediated soil carbon utilization was more active in alpine steppe meadow than in alpine meadow. Consequently, more soil labile carbon might be decomposed in alpine steppe meadow than in alpine meadow. Therefore, the degenerative succession of alpine meadow because of climate change or anthropogenic activities would most likely decrease SOC and nutrients medicated by changing soil microbial community structure and their functional potentials for carbon decomposition. [ABSTRACT FROM AUTHOR]

There are few continuous palaeoenvironmental records spanning the Holocene in Andean Southern Patagonia near the Northern Patagonian Ice Field (~47°S). Insights into the environmental context for human-landscape interactions have relied mostly on data extrapolated from distant extra-Andean locations that suggest limited environmental change during the Holocene. La Frontera (46°S2'S), a high altitude site on the southern beech forest-steppe ecotone boundary in the Río Zeballos valley, provides lithostratigraphical and palaeoecological evidence, constrained by 14C dating and tephrochronology, for dynamic environmental change during the last ~8000 years. An initial amelioration in environmental conditions after c. 8210 cal. BP was followed by a reversal to colder conditions between c. 7420 and 6480 cal. BP, coincident with initial human occupation within the Paso Roballos and Lago Pueyrredón basin. Between c. 6480 and 3700 cal. BP, the woodland/steppe composition continued to fluctuate in response to climatic change. After c. 3700 cal. BP, a gradual shift to more stable and temperate conditions, punctuated by increased fire activity, is contemporary with the later phases of human occupation extending up into the Paso Roballos-Río Zeballos corridor. [ABSTRACT FROM AUTHOR]

Global climate change is projected to increase both the intensity and frequency of extreme precipitation events (EPEs), which are considered to have stronger impacts on ecosystem functions than gradual changes in mean precipitation conditions. In this study, a consecutive 20-day extreme precipitation event (282 mm) was applied during the mid- and late-growing season periods in a semiarid steppe for three years to investigate the effects of extreme large precipitation events on aboveground net primary productivity (ANPP) and ecosystem carbon dioxide (CO 2 ) fluxes, including net ecosystem carbon absorption (NEE), gross primary productivity (GPP) and ecosystem respiration (Re). Although soil moisture was significantly increased by extreme precipitation, and even exceeded field capacity during the treatment periods, ANPP remained stable across all the treatments. There was also little change in mean growing season ecosystem CO 2 fluxes under the two precipitation treatments, despite GPP rates decreased by 34.4 and 26.3%, and NEE rates were suppressed by 77 and 68% during the mid- and late-season treatment periods, respectively. The stable CO 2 fluxes could be attributed to the recovery of GPP and NEE in 7 and 12 days after the end of EPEs. Our study demonstrated that both ANPP and CO 2 fluxes in this semiarid steppe were very stable in the face of extreme large precipitation events, regardless of the timing of events occur. Nevertheless, future, long-term studies need to investigate the potential tipping points or thresholds for ecosystem function shifts, as an increasing occurrence of EPEs has been forecasted in future climate change scenarios. [ABSTRACT FROM AUTHOR]

This study complements earlier research on wild bees (Apiformes) in the “Góra Gipsowa” steppe reserve and other habitats near the town of Kietrz (SW Poland), close to the Czech border. It also attempts to reassess the opinion of some researchers about the Moravian Gate as a migration route of southern species to Poland. 109 bee species were recorded at the study sites, including 10 red-listed ones; southern species accounted for 16.5% of this number. The hypothetical route of migration of thermophilous bees through the Moravian Gate to Poland was analysed and the species composition of southern species at either side of the Moravian Gate compared. The results of this study indicate that at present the Moravian Gate plays no part in the migration of southern bee species to Poland. [ABSTRACT FROM AUTHOR]

Grassland and shrub-steppe ecosystems are increasingly threatened by anthropogenic activities. Loss of native habitats may negatively impact important small mammal prey species. Little information, however, is available on the impact of habitat variability on density of small mammal prey species at broad spatial scales. We examined the relationship between small mammal density and remotely-sensed environmental covariates in shrub-steppe and grassland ecosystems in Wyoming, USA. We sampled four sciurid and leporid species groups using line transect methods, and used hierarchical distance-sampling to model density in response to variation in vegetation, climate, topographic, and anthropogenic variables, while accounting for variation in detection probability. We created spatial predictions of each species’ density and distribution. Sciurid and leporid species exhibited mixed responses to vegetation, such that changes to native habitat will likely affect prey species differently. Density of white-tailed prairie dogs (Cynomys leucurus), Wyoming ground squirrels (Urocitellus elegans), and leporids correlated negatively with proportion of shrub or sagebrush cover and positively with herbaceous cover or bare ground, whereas least chipmunks showed a positive correlation with shrub cover and a negative correlation with herbaceous cover. Spatial predictions from our models provide a landscape-scale metric of above-ground prey density, which will facilitate the development of conservation plans for these taxa and their predators at spatial scales relevant to management. [ABSTRACT FROM AUTHOR]

Understanding the differentiation of soil bacterial communities under precipitation and temperature gradients is crucial for assessing the impacts of environmental filters on ecosystem structure and function. Here we investigated spatial variations of bacterial communities along a precipitation and temperature transect in the eastern Inner Mongolia steppe, China. The aims are to understand the biogeographic pattern and key drivers shaping soil bacterial communities along the transect. Our results showed that the soil bacterial community along the 451-km transect exhibited the distance-decay relationship, decreasing in community similarity with geographic distance. Obvious changes in the bacterial community structure occurred at an annual precipitation from 215 to 261 mm, which was close to the boundary between arid and semi-arid systems. The relative abundances of Proteobacteria, Bacteroidetes, and Acidobacteria increased with precipitation, while those of Actinobacteria, Chloroflexi, and Gemmatimonadetes decreased. Environmental filtering was observed to be the key in shaping bacterial biogeographic patterns, and climate conditions exert indirect effects on soil bacterial communities mainly through direct effects on soil properties. Soil pH and plant coverage were important to soil bacterial communities in both arid and semi-arid steppes. Our findings provided insights for understanding the linkages among geographic distance, environmental filters, and soil bacterial communities in Eurasian steppe ecosystems. [ABSTRACT FROM AUTHOR]

The rhizosphere is a dynamic root-soil interface characterized by interactions between soil microorganisms and roots. These interactions can be potential drivers of the structure of the plant and bacterial communities in desertic shrub and grassy steppe highlands. We analyzed the relationships of rhizospheric bacterial density and occurrence (presence/absence) with dominance degree of grasses and soil properties in Argentina’s Puna ecosystem. Rhizospheric bacterial density was low and showed a strong relationship with the dominance degree of grasses without any significant influence from the soil or other vegetation variables. In addition, we determined rhizospheric bacterial occurrence with PCR-DGGE analysis of the 16S rRNA genes. Actinobacteria, Firmicutes and Proteobacteria were the predominant bacterial groups associated to the rhizosphere of grasses. In Puna highlands, the rhizospheric bacterial community appear driven by the dominance degree of grasses with little influence from other biotic or abiotic factors. We suggest that tight plant-bacterial interactions have evolved in these harsh environments that promote some level of grass dominance and maintain the diversity of the rhizospheric bacterial communities. [ABSTRACT FROM AUTHOR]

Plant nutrient concentrations and stoichiometry drive fundamental ecosystem processes, with important implications for primary production, diversity, and ecosystem sustainability. While a range of evidence exists regarding how plant nutrients vary across spatial scales, our understanding of their temporal variation remains less well understood. Nevertheless, we know nutrients regulate plant function across time, and that important temporal controls could strongly interact with environmental change. Here, we report results from a 3-year assessment of inter-annual changes of foliar nitrogen (N) and phosphorus (P) concentrations and stoichiometry in three dominant grasses in response to N deposition and prescribed fire in a temperate steppe of northern China. Foliar N and P concentrations and their ratios varied greatly among years, with this temporal variation strongly related to inter-annual variation in precipitation. Nitrogen deposition significantly increased foliar N concentrations and N:P ratios in all species, while fire significantly altered foliar N and P concentrations but had no significant impacts on N:P ratios. Generally, N addition enhanced the temporal stability of foliar N and decreased that of foliar P and of N:P ratios. Our results indicate that plant nutrient status and response to environmental change are temporally dynamic and that there are differential effects on the interactions between environmental change drivers and timing for different nutrients. These responses have important implications for consideration of global change effects on plant community structure and function, management strategies, and the modeling of biogeochemical cycles under global change scenarios. [ABSTRACT FROM AUTHOR]

The linear increment of Sphagnum fuscum and S. magellanicum in ombrotrophic mires of Western Siberia has been measured during two years over a transect about 2500 km long extending from forest-steppe to forest-tundra. Along the latitudinal gradient, the increment of both species has proved to be correlated with annual average air temperature and, in S. magellanicum, also with annual precipitation. The determinants of their growth differ between the southern, central, and northern parts of the study region. At the regional level, the annual and summer precipitation plays a more important role than the average air temperature. The increment of S. fuscum in the southern part is positively correlated with the amount of precipitation and negatively correlated with summer temperature, whereas the situation in the central part is inverse. In S. magellanicum, the linear increment is directly dependent on the annual average temperature and annual and summer precipitation in the south and on the annual and summer precipitation in the north of Western Siberia. The dynamics of linear growth of both species in bog pine forests during the growing season are similar: its rate is the highest in June, when the linear increment of S. fuscum and S. magellanicum amounts to 60 and 85% of the annual total, respectively. [ABSTRACT FROM AUTHOR]