Meadow Steppe Research Articles

Application of temperature vegetation dryness index for drought monitoring in Mongolian Plateau.

Taking the Mongolian Plateau as the study area, the MODIS normalized difference vegetation index (NDVI) and the land surface temperature (LST) in the growing season from 2000 to 2019 were used to construct the NDVI-LST feature space, and based on which the temperature vege-tation dryness index (TVDI) of the Mongolian Plateau was calculated. We used Theil-Sen Median trend analysis, Mann-Kendall test, and Hurst index method to analyze the spatial and temporal varia-tions and future trends of TVDI on the Mongolian Plateau. Furthermore, we examined the relationship between meteorological factors and TVDI on the Mongolian Plateau using partial correlation analysis. The results showed that the TVDI of the Mongolian Plateau during 2000-2019 showed an increasing trend with a rate of 0.0001·a-1, indicating that the Mongolian Plateau's drought condition became heavier slightly in the last 20 years. The drought condition in meadow steppe and typical steppe gradually decreased, and that in desert steppe and alpine grassland was increased. The average Hurst index of TVDI in the growing season was 0.45, and the area with TVDI less than 0.5 accounted for 71.5% of the total area, which indicated that the TVDI during 2000-2019 in most areas turned opposite to the past. In the future, the drought condition in the central desert steppe area and the eastern meadow steppe area might increase, and that in most of the typical steppe and the desert steppe in Inner Mongolia tended to decrease. The drought change in the alpine grassland area was uncertain. There was a significant positive correlation between the TVDI and temperature in 33.6% area of the Mongolian Plateau and a significant negative correlation between the TVDI and precipitation in 34.8% of the area. Moreover, the meteorological factors heavily affected the typical steppe.

Phytodiversity and bioproductivity of the Leymus chinensis steppes in eastern Transbaikalia

The research objective is caused by wide spread of leymus communities in the southeastern Transbaikalia and gaps in studying their species composition, structure, and phytomass accumulation; it is to give a phytocenotic characteristics of leymus communities in the steppe zone of eastern Transbaikalia, and to determine the level of their biological productivity using standard geobotanical, agrochemical and soil methods. The paper studies monodominant Leymus chinensis communities growing on various soil types of meadow steppe, steppe floodplain meadows and haloxerophytic steppe of the south-eastern Transbaikalia. The species composition of communities is represented by 21 families, 45 genera, 62 species. Halophytes account for 11.3 % (7 species), halotolerant – 29 % (18 species), glycophytes – 59.7 % (37 species). The species of the families Asteraceae – 30.6 %, Poaceae – 17.7 %, Rosaceae – 8 % form the largest share in the projective cover of communities. The rest families are of 1 – 2 species. The species composition of Leymus is represented mainly by the steppe complex with xerophytes different variants belonging to the Asian type of area. The main part belongs to rhizome species in the biomorph composition, and the share of annuals and biennials is significant as well. The similarity between communities is within the range from low to medium, which is due to the great participation of single-species families and genera. The authors have assessed the contribution to aboveground phytomass of a dominant species, Leymus chinensis, other species and died grass. The greatest contribution of ears to the aboveground phytomass is marked only in Descriptions 4 and 5. The primary production of Leymus chinensis communities is estimated as high, 2105 – 3189 g/m2 a year. Underground phytomass is 84 – 94 % of the total productivity. The underground and aboveground phytomass ratio is 1:5 – 15, that is determined by various soil and environmental conditions of growing the communities.

Vegetation dynamics of Kulikovo Field agrosteppes: the contribution of environmental factors

On the territory of the Kulikovo Field Museum-Reserve (Tula region) the restoration of meadow-steppe communities is carried out by different methods: the sowing grass mixtures, seed material and using a combined approach. The aim of the work is to assess of structure phytodiversity of plant communities on the gradient of reconstruction succession. The using DCA-ordination analysis of geobotanical descriptions is allowed us to select 4 groups of communities that differ by age of sowing. In phytosociological spectrum of youngest communities the activity of species of the classes of natural and synanthropic vegetation is approximately the same. With an increase in the age of experiments the activity of apophyte species from natural vegetation classes increases and the activity of synanthropic species decreases. The revealed trend is confirmed by the analysis of the activity of species of different life forms: with an increase in the age of communities, there is a decrease in the activity of monocarpic one- and two-year-old weed species, which have high activity at the initial stages of succession. In the middle stages of succession, dense-sod species are more active in communities, and in the latter stages, the activity of loose-sode and rod-root species increases. During the succession of agrosteps, there is an increase in the activity of meadow-steppe and steppe species from the classes Festuco-Brometea, Molinio-Arrhenatheretea, Trifolio-Geranietea and a decrease in the activity of synanthropic vegetation species (Papaveretea rhoeadis, Sisymbrietea, Artemisietea, Epilobietea angustifolii). The results obtained indicate a succession in the direction of formation of steppe meadows.

Effects of grazing on plant species and phylogenetic diversity in alpine grasslands, Northern Tibet

Plant diversity plays an important role in maintaining and upgrading ecosystem structure and functions, and there remain uncertainties on plant species and especially phylogenetic diversity to grazing in alpine grasslands. Therefore, this study compared the differences of plant species and phylogenetic α- and β-diversity between grazing and fencing conditions at three alpine grasslands (ASMWG: alpine steppe meadow for winter grazing; ASMSG: alpine steppe meadow for summer grazing; AMSG: alpine meadow for summer grazing), Northern Tibet. At the ASMSG site, grazing significantly decreased mean nearest taxon distance (MNTD) by 19.33%, and increased Pielou by 7.06%. Plant community compositions between fencing and grazing conditions were different (p = 0.021) at the ASMSG site. However, the Pielou, MNTD and plant community composition were not significantly different between the fencing and grazing conditions at the ASMWG and AMSG site. Grazing significantly increased the niche overlap at the ASMWG (levins: 51.36%, schooner: 28.97%, pianka: 28.11%, Czech: 28.97%; morisita: 28.75%) and ASMSG site (schooner: 35.19%, petraitis: 4.63%, pianka: 26.45%, czech: 35.19%; morisita: 30.86%), indicating that grazing may increase plant species competition and competitive exclusion at the ASMWG and ASMSG site. In contrast, grazing did not significantly affect niche overlap at the AMSG site. Therefore, the response of plant diversity to grazing can be different between species and phylogenetic diversity, and among alpine grasslands.

Niche overlap and species co-occurrence patterns in carabid communities of the northern Chinese steppes.

Understanding how species sort themselves into communities is essential to explain the mechanisms that maintain biodiversity. Important insights into potential mechanisms of coexistence may be obtained from observation of non-random patterns in community assembly. The spatial niche overlap (Pianka index) and co-occurrence (c-score) patterns in carabid species in three types of steppes (desert steppe, typical steppe, and meadow steppe) in China was investigated. Non randomness was tested using null models. Niche overlap values were significantly higher than expected by chance in the desert steppe, where vegetation cover is less abundant and less uniformly distributed, which possibly forces species to concentrate in certain places. In the typical and meadow steppes, results were influenced by the scale of the analysis. At a broad scale, niche separation was found as a result of species segregation among different sectors (habitats) within these steppes, but when the analysis was conducted at a finer scale, species appeared to be no more segregated than expected by chance. The high co-occurrence averages found in the meadow and typical steppes indicate that the distributions of the species found in a site may be negatively affected by the presence of other species, which suggests that some species tend to exclude (or reduce the abundance of) others. The very low c-score average observed in the desert steppe suggests that competition is not involved there. Thus, in more homogeneous landscapes (such as the typical and meadow steppes), competition might play some role in community structure, whereas spatial variation in the abundances of species is more driven by the uneven spatial distribution of vegetation in the landscape where productivity is lower and less uniformly distributed.

The Ecosystems of the Danube Delta Biosphere Reserve state-of the-art

Taking into account the morphologic-hydrographic configuration of natural ecosystems or ecosystems partly modified by man the area, its flora and fauna communities and the long-term human impact, the two main categories of Danube Delta ecosystems associated with Razim-Sinoie lake complex, coastal marine waters and the Danube flood plain between Isaccea and Tulcea, as part of Danube Delta Biosphere Reserve, have been delimited: natural ecosystems or ecosystems partly modified by man; anthropic ecosystems. To identify and characterize ecosystems, there have been analysed the data on hydrography, morphology, biodiversity, human settlements, types of land use, spatial changes through the construction of agricultural, fisheries, forestry polders, modification of the network of channels and canals with consequences on the water circulation system inside the delta. The first category, of natural and partly modified by man ecosystems comprises 23 types (water bodies: running waters-Danube and its main branches, channels and canals; standing freshwater-lakes; standing brackish and salt waters-coastal lagoons, coastal, marine zones; wetlands: water fringe vegetation-flooded reed beds, floating reed beds , riparian willow formations, frequently flooded river levees; forests, shrubs and herbaceous vegetation: temperate riverine forests-mixed oak woods, shrubs and herbaceous vegetation, steppe meadows, meadows on low marine levees; dunes, beaches).The second category, of anthropic ecosystems includes 7 types (agricultural lands, forest areas-plantation on the river banks, fish farms, settlements-villages, towns). With the establishment of the Danube Delta Biosphere Reserve in 1990, with the statutory provisions on the protection and conservation of biodiversity, the deltaic landscape, some of the previous pressures were reduced, but the pollution of the Danube waters less consolidated beaches (Sulina, Sfântu Gheorghe, Chituc) and related with touristic activities, on ecosystems as a whole. The tourism activities also must represent not only a positive and dynamic development factor but also a practical solution to keeping the environment unaltered. These aspects were mentioned in the characterization of the ecosystems presented in this article.

Cattle grazing mitigates the negative impacts of nitrogen addition on soil nematode communities

Livestock grazing and atmospheric nitrogen (N) deposition have been reported as important factors affecting soil communities. However, how different large herbivore grazing and N addition may interact to affect soil biota in grassland ecosystems is unclear. Nematodes are the most abundant metazoan in soil ecosystems, play critical roles in regulating carbon and nutrient dynamics, and are valuable bioindicators. We examined the independent and interactive effects of grazing regimes (no grazing; sheep grazing; cattle grazing; mixed grazing of sheep and cattle) and N addition (ambient N; N addition) on soil nematodes in a meadow steppe. We found that grazing and N addition interacted to influence total nematode abundance, trophic group abundance, generic richness, diversity and several nematode-based indices (maturity index, channel ratio, enrichment index). In cattle grazing treatment, N addition significantly increased total nematode abundance, and the abundance of bacterial feeders, plant feeders, and omnivore-predators, and generic richness. By contrast, in the sheep and mixed grazing treatments, N addition had a negative effect on the same variables. Moreover, N addition reduced nematode maturity, enrichment and structure indices, and enhanced nematode channel ratio, in most grazing treatments, except mixed grazing where N addition had no effect on these variables. Structural equation modeling (SEM) revealed that N addition indirectly reduced nematode abundance and richness through increased soil NO3−-N content, whereas the effects of grazing were associated with increased relative biomass of grasses. Our results suggested that the response of soil nematodes to N addition strongly depended on herbivore assemblages. Nitrogen addition enhanced soil nematode diversity and maintained a relatively complex and mature soil food web in the presence of cattle rather than sheep grazing. Furthermore, our study highlighted that under N deposition, cattle grazing could benefit the soil nematode community.

Effects of Grazing on the Grassland Vegetation Community Characteristics in Inner Mongolia

The continuous increase of livestock production in Inner Mongolia has caused severe degradation of the grassland ecosystems in recent years. Previous grazing experiments have shown a wide range of vegetation responses between the biome types on a global scale, but there is still a lack of sufficient studies to discern the relative responses of a given biome type. We conducted a meta-analysis of vegetation coverage (VC), plant density (PD), total biomass (TB), above-ground biomass (AGB), under-ground biomass (UGB) and Shannon–Weaver Index (SI) in different grassland types in Inner Mongolia obtained under conditions of different grazing intensities and durations. The results showed that grazing decreased VC, TB, AGB, UGB, and PD significantly. Compared to the global and national average values, the negative effects of grazing to steppe biomass in Inner Mongolia were higher than that on the global scale, while less pronounced than that in China. TB of the meadow steppe in Inner Mongolia increased by 40% under moderate grazing intensity and duration because of compensatory growth. SI of the desert and meadow steppe showed negative linear relationships with the grazing intensity in Inner Mongolia. The percentage changes in AGB, PD, and SI to grazing showed quadratic relationships with the mean annual temperature of the experimental year. With increasing mean annual precipitation, the negative effects of grazing on UGB and SI first decreased and then increased, with that of VC and grazing showing a cubic relationship.

Conservation possibilities of Isophya costata (Orthoptera: Tettigoniidae: Phaneropterinae) based on frequency, population size, and habitats

Isophya costata Brunner von Wattenwyl, 1878, commonly called the Keeled Plump Bush-cricket, is an endemic Natura 2000 species in the Carpathian Basin and is included in the IUCN Red List of Threatened species. We used extensive data collection from Hungary retrieved between 2004 and 2019 from 700 sampling sites spread over an area of 12,700 km2 to examine the occurrence of the species in different regions in grasslands of similar structure but different origin, naturalness, and character. The results confirmed that I. costata currently occurs with the highest number of populations and highest density in regularly mowed, mesophilic hayfields rich in dicotyledonous plants (Arrhenatheretalia). The species also appears in smaller numbers in grasslands adjacent to hayfields, such as wetland meadows (Molinion coeruleae), marsh meadows (Deschampsion caespitosae, Alopecurenion pratensis), and edge habitats dominated by herbaceous plants. However, the results show that the extension of these habitats has a negatively significant correlation with both the occurrence of the species and its density. Isophya costata occurs in steppe meadows much less frequently than in mesophilic hayfields. The species is endemic to the Pannonian Steppe, and the key to their conservation is by maintaining stocks of hayfields in the species’ area of distribution. According to this study, overseeding of mowed grasslands leads to the decline of the species. To preserve I. costata, it is necessary to eliminate trampling in its areas of occurrence (prohibition of grazing) and encourage late-season mowing adapted to the phenology of the species (not as early as mid-July) or, if this is not feasible, mosaic-type treatment leaving unmown patches (e.g., 1/3 of the plot).

Emergent Rarity Properties in Carabid Communities From Chinese Steppes With Different Climatic Conditions

Species abundance distributions (SADs) are increasingly used to investigate how species community structure changes in response to environmental variations. SAD models depict the relative abundance of species recorded in a community and express fundamental aspects of the community structure, namely patterns of commonness and rarity. However, the influence of differences in environmental conditions on SAD characteristics is still poorly understood. In this study we used SAD models of carabid beetles (Coleoptera: Carabidae) in three grassland ecosystems (desert, typical, and meadow steppes) in China. These ecosystems are characterized by different aridity conditions, thus offering an opportunity to investigate how SADs are influenced by differences in environmental conditions (mainly aridity and vegetation cover, and hence productivity). We used various SAD models, including the meta-community zero sum multinomial (mZSM), the lognormal (PLN) and Fisher’s logseries (LS), and uni- and multimodal gambin models. Analyses were done at the level of steppe type (coarse scale) and for different sectors within the same steppe (fine scale). We found that the mZSM model provided, in general, the best fit at both analysis scales. Model parameters were influenced by the scale of analysis. Moreover, the LS was the best fit in desert steppe SAD. If abundances are rarefied to the smallest sample, results are similar to those without rarefaction, but differences in models estimates become more evident. Gambin unimodal provided the best fit with the lowest α-value observed in desert steppe and higher values in typical and meadow steppes, with results which were strongly affected by the scale of analysis and the use of rarefaction. Our results indicate that all investigated communities are adequately modeled by two similar distributions, the mZSM and the LS, at both scales of analyses. This indicates (1) that all communities are characterized by a relatively small number of species, most of which are rare, and (2) that the meta-communities at the large scale maintain the basic SAD shape of the local communities. The gambin multimodal models produced exaggerated α-values, which indicates that they overfit simple communities. Overall, Fisher’s α, mZSM θ, and gambin α-values were substantially lower in the desert steppe and higher in the typical and meadow steppes, which implies a decreasing influence of environmental harshness (aridity) from the desert steppe to the typical and meadow steppes.

Natural abundance of 13C and 15N provides evidence for plant–soil carbon and nitrogen dynamics in a N‐fertilized meadow

Natural abundance of carbon (C) and nitrogen (N) stable isotope ratios (δ13 C and δ15 N) has been used to indicate ecosystem C and N status and cycling; however, use of this approach to infer plant and microbial N preference under projected ecosystem N enrichment is limited. Here, we investigated natural abundance δ13 C and δ15 N of five dominant plant species, and soil δ15 N of microbial biomass and available N forms under N addition in a meadow steppe. Additional N, applied as urea, led to decreases in δ15 N of soil NO3 - (δ15 Nnitrate , from 3.0 to 0.4‰) and increases in δ15 N of soil NH4 + (δ15 Nammonium , from -1.3 to 11‰) and dissolved organic N (δ15 NDON , from 8.5 to 15‰) that reflected increased net nitrification rates, a possible increase in NH3 volatilization, and greater availability of the three N forms. An overall increase in δ15 N of soil total N (δ15 NTN ) from 7.1 to 7.9‰ indicated accelerated and greater openness of soil N cycling that was also partially revealed by enhanced net N mineralization rates. Plant δ15 N, which ranged from -1.8 to 2.1‰, generally decreased with N addition, indicating a greater reliance on soil NO3 - under N-enrichment conditions. Nitrogen addition decreased δ15 N of microbial biomass N (from 14 to 2.8‰), possibly due to a shift in preferential N form (DON to NO3 - ), that indicated a convergence of plant and microbial preferential N forms and an increase in plant-microbial N competition. Microbes were thus more flexible than plants in the use of different forms of N. Addition of N decreased plant litter δ13 C, while plant species δ13 C remained unaffected, likely due to a shift in the abundance of dominant species with a greater proportion of biomass coming from δ13 C-depleted species. Enrichment factor (the difference in plant δ15 N relative to δ15 NTN ) of four non-legume species was negatively related to soil inorganic N availability, net nitrification rate, and net N mineralization rate, and was proven to be a good indicator of ecosystem N status. Our study highlights the importance of natural abundance of 15 N as an indicator of plant-microbial N competition and ecosystem N cycling in meadow steppe grasslands under projected ecosystem N enrichment.

INFLUENCE OF SINGLE TREES ON FLORISTIC DIVERSITY OF STEPPE MEADOWS AND POPULATION STRUCTURE OF SOME RARE PLANT SPECIES

In the zone of broad-leaved forests of the European Russia, steppe meadows have been preserved showing rich floristic composition and making a significant contribution to the biological diversity of the territories. Bryansk oblast is one of the forest regions in Russia where such meadows are found. Here, steppe meadows with high floristic diversity and a large number of rare plant species have survived. Trees from surrounding forest areas are constantly encroaching on these meadows. Most of the young trees die from regular grass fires and economic activity. However, some individuals survive and reach a generative state, becoming relatively resistant to ground fires. The influence of single trees on the floristic diversity of steppe meadows was studied at two levels of living system organization – coenotic and population levels. Polydominant steppe meadows and polydominant steppe meadows with single generative trees were studied at the coenotic level; and coenopopulations of Iris aphylla, Anemone sylvestris, and Anthericum ramosum were studied at the population level. Collecting the material, we used different methods: geobotanical, demographic, and measurements of environmental factors (illumination, slope steepness, and the frequency of grass fires). Polydominant steppe meadows were found to be were preserved in the middle part of steep slopes unsuitable for haymaking and grazing and subjected to infrequent grass fires. These communities have high floristic diversity and stable coenopopulations of model species. Ontogenetic spectra of Anemone sylvestris, Anthericum ramosum, and Iris aphylla are of the complete left-hand type with the maximum number of individuals. Single trees (Quercus robur, Tilia cordata) have controversial influence on the vegetation of polydominant steppe meadows. On the one hand, with the introduction of trees, species diversity of communities increases. This is due to the fact that trees offer resting places and shelter for birds that spread plant diaspores. On the other hand, mature trees shade the herb cover. This leads to cover reduction and occurrence of steppe and dry meadow species, as well as affects their population structure. The ontogenetic spectrum of Anemone sylvestris is still complete, whereas that of Iris aphylla becomes incomplete, and the spectrum of Anthericum ramosum becomes unfinished.

Effects of stocking rate on the interannual patterns of ecosystem biomass and soil nitrogen mineralization in a meadow steppe of northeast China

Understanding the effects of livestock grazing on the ecosystem biomass and soil nitrogen processes of grassland ecosystems is critical to improving knowledge on the mechanisms underlying grassland degradation and accurately assessing the influence of grazing management on grassland functions. We examined the interannual patterns of ecosystem biomass and soil nitrogen mineralization in response to cattle grazing in a Chinese meadow steppe. The soil core incubation method was employed for soil N transfer estimation, whilst the fumigation extraction method, a modified Baermann funnel method and harvest method were used for various measurements of ecosystem biomass parameters. We found that cattle grazing caused consistent significant increases in soil temperature, irrespective of the stocking rate and year, whereas significant effects on soil moisture and edaphic properties were observed only in individual years and/or at specific stocking rates. Consistent positive effects at moderate stocking rates were observed for aboveground net primary production and soil nematode biomass in all study years. The across stocking rate pattern of N mineralization in response to cattle stocking appeared to be year-specific, although negative effects were found in most cases. In contrast, the interannual pattern of N mineralization was determined principally by the interannual patterns in precipitation and soil moisture and was much less affected by cattle grazing. Soil N mineralization in this meadow steppe was affected by cattle grazing via two major mechanisms, i.e., its effects on the aboveground net primary production (ANPP) and thus the quantity of plant litter input into the soil and its effects on soil temperature and moisture. Overall, our study spanned the longest consecutive years with the broadest range of stocking rates thus far of its kind, which revealed for the first time that the soil nitrogen mineralization pattern with respect to stocking rate was year-specific. Our findings have important implications for adaptive management and sustainable utilization of Chinese grasslands.

Characteristics and composition of vegetation carbon storage in natural grassland in Ning-xia, China.

We measured the total vegetation carbon stock in the widely distributed natural grassland of meadow steppe (MS), warm steppe (WS), steppe desert (SD) and desert steppe (DS)] in Ningxia, using survey and sampling method. The results showed that the average carbon rate of vege-tation, shrubs and root were 0.40, and that of litter was 0.39. The total vegetation carbon density of meadow steppe, warm steppe, steppe desert and desert steppe (including aboveground vegetation, litter and roots) was 470.26, 192.23, 117.17 and 83.36 g·m-2, while that of aboveground vegetation was 87.35, 68.50, 59.32 and 40.05 g·m-2, and that of roots was 344.29, 108.83, 50.65 and 30.29 g·m-2, litter carbon storage was 38.62,14.91, 7.19 and 13.03 g·m-2, respectively. The order of those grassland types ranked as MS＞WS＞SD＞DS. Root carbon storage contributed the most to carbon storage in meadow steppe and warm steppe, and aboveground vegetation carbon storage contributed the most to steppe desert and desert steppe. Root carbon storage showed a decreasing trend with the increases of soil depth within 40 cm soil layer. For the spatial distribution of total carbon stock, the southern part of meadow steppe and temperate steppe had obviously higher carbon stock than the middle and north part of desert steppe and steppe desert.

Soil moisture, temperature and nitrogen availability interactively regulate carbon exchange in a meadow steppe ecosystem

Primary productivity in terrestrial ecosystems can be significantly altered by the predicted increases in nitrogen (N) deposition, but it is still unclear how N deposition influences the carbon (C) exchange processes especially in dryland ecosystems. In this study, a 3-year experiment with two types of fertilizers and five N addition levels was conducted in a semiarid steppe of Erguna, Inner Mongolia to assess the effects of exogenous N input on net ecosystem productivity (NEP), gross ecosystem productivity (GEP) and ecosystem respiration (ER). Our results showed that enhanced N input significantly increased NEP and GEP when the volumetric soil water content (VWC) was greater than 15% (v/v%), but had trivial and inconsistent effects when VWC was less than that threshold. Moreover, the NEP and GEP increased significantly with increasing N addition but leveled off when the N input reached 10 g N m–2 year–1 and the VWC was above 15%. However, the ER showed a significant increase with N addition rates, regardless of soil water content. Our main findings are as follows. First, the ecosystem C exchange can be significantly enhanced by addition of N only when soil moisture exceeds certain threshold, suggesting co-limitation of water and N in the grassland ecosystem that we studied. Second, in addition to concurrent consideration of water, temperature and N as well as their interactions also need to be accounted for. Third, the frequency of days with the VWC being higher than 15% accounted only around one third of days during the three growing seasons. Taken together, our findings imply that the expected increases of carbon sequestration should be minimal under N deposition in the Inner Mongolia grassland ecosystems.

Vegetation Dynamic Assessment by NDVI and Field Observations for Sustainability of China's Wulagai River Basin.

Accurate monitoring of grassland vegetation dynamics is essential for ecosystem restoration and the implementation of integrated management policies. A lack of information on vegetation changes in the Wulagai River Basin restricts regional development. Therefore, in this study, we integrated remote sensing, meteorological, and field plant community survey data in order to characterize vegetation and ecosystem changes from 1997 to 2018. The residual trend (RESTREND) method was utilized to detect vegetation changes caused by human factors, as well as to evaluate the impact of the management of pastures. Our results reveal that the normalized difference vegetation index (NDVI) of each examined ecosystem type showed an increasing trend, in which anthropogenic impact was the primary driving force of vegetation change. Our field survey confirmed that the meadow steppe ecosystem increased in species diversity and aboveground biomass; however, the typical steppe and riparian wet meadow ecosystems experienced species diversity and biomass degradation, therefore suggesting that an increase in NDVI may not directly reflect ecosystem improvement. Selecting an optimal indicator or indicator system is necessary in order to formulate reasonable grassland management policies for increasing the sustainability of grassland ecosystems.

Different response of alpine meadow and alpine steppe to climatic and anthropogenic disturbance on the Qinghai-Tibetan Plateau

Climate change and anthropogenic disturbance are two main drivers for vegetation dynamics on the Qinghai-Tibetan Plateau (QTP). Alpine meadow and alpine steppe are the primary rangeland ecosystem types on the QTP. However, the vegetation trends of the two land cover types and the underlying mechanisms behind their variation remain under debate. In this study, we used Global Inventory Modeling and Mapping Studies (GIMMS) 3g Normalized Difference Vegetation Index (NDVI) (i.e., GIMMS NDVI3g) by coupling the Breaks for Additive Season and Trend (BFAST) model and the Boosted Regression Tree (BRT) model to analyze alpine meadow and alpine steppe vegetation trends on the QTP between 1982 and 2015. We also assessed vegetation variation response to climatic and anthropogenic indicators in conjunction with climatic and human footprint datasets. Results show that growing season NDVI (GSNDVI) values increased overall for both alpine meadow (0.0001 year−1, p = 0.33) and alpine steppe (0.0002 year−1, p < 0.05) throughout 1982–2015. Significant greening trends in both alpine meadow (0.0007 year−1; p < 0.05) and alpine steppe (0.0005 year−1; p < 0.05) ecosystems were obtained before 1998 and 2001, respectively. However, browning trends ascertained by GSNDVI (−0.0006 year−1; p = 0.12) in alpine meadows were observed throughout 1998–2015, while greening trends ascertained by GSNDVI (0.0002 year−1; p = 0.12) in alpine steppes were observed throughout during 2001–2015. Opposing trends in precipitation, solar radiation, and the Standardized Precipitation Evapotranspiration Index (SPEI) occurred before and after breakpoints in both ecosystems. For the alpine meadow ecosystem, adverse precipitation trends caused browning before 1998 followed by greening after 1998 in the Three-River-Source National Park (TNP). Conversely, opposing changes in precipitation, solar radiation, and SPEI resulted in greening before 1998 followed by browning after 1998 in southern Tibet and the southeastern QTP. Alpine meadow vegetation trends were generally dominated by solar radiation before 1998 and jointly by precipitation and solar radiation after 1998. Prior to 2001 variation in alpine steppe greenness was controlled by precipitation, while after 2001 solar radiation dominated. Along with an increase in human footprint pressure (HFP) gradients, greenness trends gradually increased before 1998 but reversed after 1998 in the alpine meadow ecosystem. Additionally, greenness trends gradually decreased before 2001 but remained unchanged after 2001 for the alpine steppe ecosystem. These results highlight the different effects that climate change and anthropogenic disturbances have had on alpine meadow and alpine steppe ecosystems on the QTP over different time frames.

Simulating the spatiotemporal variations in aboveground biomass in Inner Mongolian grasslands under environmental changes

Abstract. Grassland aboveground biomass (AGB) is a critical component of the global carbon cycle and reflects ecosystem productivity. Although it is widely acknowledged that dynamics of grassland biomass is significantly regulated by climate change, in situ evidence at meaningfully large spatiotemporal scales is limited. Here, we combine biomass measurements from six long-term (&gt; 30 years) experiments and data in existing literatures to explore the spatiotemporal changes in AGB in Inner Mongolian temperate grasslands. We show that, on average, annual AGB over the past 4 decades is 2561, 1496 and 835 kg ha−1, respectively, in meadow steppe, typical steppe and desert steppe in Inner Mongolia. The spatiotemporal changes of AGB are regulated by interactions of climatic attributes, edaphic properties, grassland type and livestock. Using a machine-learning-based approach, we map annual AGB (from 1981 to 2100) across the Inner Mongolian grasslands at the spatial resolution of 1 km. We find that on the regional scale, meadow steppe has the highest annual AGB, followed by typical and desert steppe. Future climate change characterized mainly by warming could lead to a general decrease in grassland AGB. Under climate change, on average, compared with the historical AGB (i.e. average of 1981–2019), the AGB at the end of this century (i.e. average of 2080–2100) would decrease by 14 % under Representative Concentration Pathway (RCP) 4.5 and 28 % under RCP8.5. If the carbon dioxide (CO2) enrichment effect on AGB is considered, however, the estimated decreases in future AGB can be reversed due to the growing atmospheric CO2 concentrations under both RCP4.5 and RCP8.5. The projected changes in AGB show large spatial and temporal disparities across different grassland types and RCP scenarios. Our study demonstrates the accuracy of predictions in AGB using a modelling approach driven by several readily obtainable environmental variables and provides new data at a large scale and fine resolution extrapolated from field measurements.

Comparative assessment of Western Podolia meadow steppes (Ukraine) based on the synphytoindication method

Abstract The aim of our study is to establish the determinant ecological factors that have the greatest differential impact on the distribution of meadow steppe plant communities of Western Podolia (Ukraine) on the base of a synphytoindication analysis. There were 8 study sites within the study area in the L’viv and Ivano-Frankivsk regions. To determine the coenotic affinity of the studied species, 48 relevés were analyzed. Numerical classification based on the Modified TWINSPAN algorithm divided the dataset into five clusters, which have been identified as the associations Pastinaco sativae-Arrhenatheretum elatioris, Geranio sanguinei-Trifolietum alpestris, Inuletum ensifoliae, Jurineo calcareae-Stipetum capillatae and Lembotropio nigricans-Potentilletum arenariae. The results of gradient analyses indicate that the distribution of meadow steppe communities in the Podolia Upland closely correlates with a number of climatic (thermoregime and continentality of climate) and especially edaphic (soil humidity, soil acidity and carbonate content) ecological factors.

Conservation, restoration and biodiversity of Palaearctic grasslands – Editorial to the 6th EDGG special issue in Hacquetia

Abstract This special issue is a collection of articles about the conservation, restoration and biodiversity of Palaearctic grasslands and was initiated by the Eurasian Dry Grassland Group at the 15th Eurasian Dry Grassland Conference (EDGC), held at Graz, Austria in 2019. The papers in this special issue cover a range of grassland habitats from montane dry grasslands to lowland sandy grasslands, feathergrass steppes and meadow steppes, and focus on the biodiversity values, conservation issues and restoration prospects of Palaearctic grasslands. We hope that the articles in this special issue will contribute to a better understanding of the ecology of grasslands and support their more effective conservation.