Grassland Succession Research Articles

Mixed grass species differ in rhizosphere microbial community structure and function response to drought compared to monocultures

Natural grassland succession is the interactions among different grass species and various environmental factors. The dynamics of soil microbial communities along succession stages has received tremendous attention. The effects of the coexistence of different grass species on the structure and function of rhizosphere soil microbial communities, however, are poorly understood, especially under drought stress conditions. Here, we investigated how different grass planting patterns and soil water content affect rhizosphere microbial community structure and function. Two typical grass species (Bothriochloa ischaemum and Stipa bungeana) on the Loess Plateau were planted in three planting systems: B. ischaemum monoculture, S. bungeana monoculture, and a mixed culture of the two species under two water regimes (optimal water: 80% field capacity [FC]; drought stress: 60% FC). Rhizosphere soil samples were collected to evaluate the rhizosphere microbial community structure (via phospholipid fatty acid [PLFA] biomarkers) and function (via six enzyme activities). The mixed culture of grass species noticeably shifted the rhizosphere microbial community structure. It caused the rhizosphere gram-positive:gram-negative PLFA ratio and fungal:bacterial PLFA ratio to increase under optimum water conditions. In comparison, drought stress caused total PLFA, bacterial PLFA, and gram-positive PLFA biomass to increase. Drought stress caused rhizosphere-specific enzyme activity to increase under monoculture treatment and rhizosphere-specific enzyme activity to decrease under mixed culture treatment. Soil water-soluble organic carbon, pH, and water-soluble organic phosphorus were the most important factors driving changes to rhizosphere microbial community composition. In comparison, pH was the predominant factor driving variation in rhizosphere specific enzyme activities. Thus, the coexistence of grass species altered the structure and function of the rhizosphere microbial community through changes in rhizosphere pH and water-soluble nutrients. In conclusion, changes to rhizodeposits under a mixed culture of grass species likely affect the structure and function of the rhizosphere microbial community. The results of the present study improve our understanding of the impacts of grass species interaction on soil biogeochemical processes under future global drought stress scenarios.

Extracellular enzyme stoichiometry reflects the metabolic C-and P-limitations along a grassland succession on the Loess Plateau in China

Soil extracellular enzyme stoichiometry (EES) reflects the biogeochemical balance between microbial metabolic requirements and environmental nutrient availability. Recent research suggests that EES well effect on soil microbial metabolic limitations (SMMLs), however, few field studies have explicitly tested this based on a herbaceous successional chronosequence. We used the EES models to identify the response of SMMLs, and investigated the potential implications of microbial nutritional limitations across the time series (herbaceous succession) and space (transformation interface soil [TIS] and underlying topsoil [UTS] layer) in the grassland restoration series. We show that soil microorganisms were generally limited by C, both in the TIS and UTS. Microbial C-limitation exhibited a unimodal direction, peaking in intermediate successional stages, however, P-limitation presented the opposite trend. During herbaceous succession, microbial P-limitation was more substantial than that in N-limitation. SMMLs gradually transferred from P- to N- and back to P-limitation at later successional stages in the TIS layer. Furthermore, we demonstrate that biotic factors, soil basic index, and soil nutrients explained 92.2 % of the variations in microbial C-limitation and 84.4 % of the variations in microbial P-limitation. Multi–interaction factors exhibited the most significant relative influences of 65.11 % (TIS) and 43 % (UTS) on the SMMLs. Microbial C-limitation was induced by the imbalance between C supply and microbial C demand, whereas the changes in microbial P-limitation were due to the changes in the competition for P between plants and microorganisms. Overall, our findings provide support for microbial C- and P-limitation in the process of herbaceous succession during the restoration. We also highlight the possibility of additive effects on soil SMMLs via interactions of vegetation composition, soil properties, and microbial nutritional demands, which might constrain soil microbial metabolism requirements despite greater living root and litter resource inputs.

Seeds harvested during mowing from semi-natural grasslands as an ad hoc but effective solution for grassland restoration.

Species-rich grasslands formed by local ecotypes of native species provide numerous ecosystem services both in rural areas as well as urban grasslands. Nonetheless, their area is still too small, making grasslands one of the most frequently restored habitats. Successful restoration requires high-quality seed material, which is expensive and often not easy to acquire. In this study, we tested the potential of seeds accidentally collected during the mowing of a semi-natural grassland for grassland restoration. We tested seed purity, species composition, and germination capability in both laboratory and field conditions. Ninety percent of the collected material consisted of pure seeds of numerous species. Their germination capability was relatively low but still sufficient for successful grassland restoration under a typical seed density/mass per unit area seeding ratio. The germination capacity was the highest in the first two weeks after sowing and increased with overwintering seed storage. The results suggested that the seeds could be successfully used for species-rich grassland restoration. In terms of advantages, the seed mixture had a low cost and contained native species seeds representing local ecotypes. In terms of disadvantages, there was a relatively low amount of seed material and an inability to plan the time of seed harvesting. Thus, the use of the accidentally collected seeds can be considered an effective but rather ad hoc solution.

Plant succession of natural grasslands under radical improvement in the southern forest-steppe of the Western Siberia

The low fodder productivity of vast areas of natural forage lands in Siberia necessitates their radical improvement. High fodder productivity will strengthen the fodder base of the region, which is important for the developing cattle breeding. The authors carried out an experiment of radical improvement of natural grasslands in order to clarify and develop methods of increasing the productivity of natural grasslands in the southern forest-steppe of Western Siberia. The authors studied the effect of two factors: The first factor - tillage followed by sowing of perennial grasses; The second factor - the effect of organic fertilizers (20 t/ha). By the second year of observations in the variant where soil disking was carried out, only motley grasses were noted. Disking followed by seeding of perennial grasses promoted the development of seeded grasses (80% of the composition of the herbage). The remaining niche of grass stand was occupied by motley grasses. The influence of organic fertilizers in the second year of observations almost does not affect the structure of herbage, only in the variant with the sowing of grasses the distribution of different botanical groups is more uniform. The composition of grass stand changes significantly between the second and sixth years of observations under the influence of tillage and organic fertilizers. The development of cereals and legumes in the herbage in the variant without tillage in the third and subsequent years is noted. By the sixth year of observations in the herbage remain only cereal grass (60%) and mixed grass (40%). Dynamics of herbage structure by years of development on the background of organic fertilizers differs little from the herbage without fertilizers. By the second year of observations, there is no significant influence of fertilizers and tillage on the yield of grasses. In the sixth year of observations (2016) there was a significant influence of organic fertilizers. Even without soil treatment, the yield almost doubled from 0.6 t/ha in the version without fertilizers to 1.1 t/ha of absolutely dry matter in fertilized variants. The greatest increase in yield was noted in the variant with discing, 2.7 times (from 0.6 to 1.6 t/ha); in the variant with grass seeding and discing 1.4 times (from 1.1 to 1.6 t/ha) (absolute dry matter). The effect of tillage on the yield without fertilizer was much less. Consequently, tillage and fertilization contribute to a more uniform distribution of representatives of different botanical groups of grasses in the herbage. The productivity of the natural meadow increases significantly by the sixth year of observations after the improvement.

Free particulate organic carbon plays critical roles in carbon accumulations during grassland succession since grazing exclusion

Grazing exclusion is proposed as an effective strategy for to recover degraded grasslands and increase carbon accumulation. However, few studies have explored the response of soil organic carbon (SOC) and its components to grazing exclusion during long-term succession. In this study, we collected soils from sites with a chronosequence of ~33 years after grazing exclusion with randomized and replicated experiments in the temperate grasslands of the Loess Plateau, China. The contents of SOC, free particulate organic carbon (fPOC), occluded particulate organic carbon (oPOC), and mineral-associated organic carbon (MOC) and their driving factors in the 0–60 cm soil layer were examined in each grassland. The results showed that fPOC, oPOC, and MOC contents were significantly affected (P < 0.05) by grazing exclusion duration and soil depth. Soil fPOC, oPOC, POC, and MOC contents increased with exclusion time, but decreased with soil depth. SOC content was significantly improved since grazing exclusion for more than 26 years compared with that for active grazing grasslands. The fPOC played critical roles in promoting the SOC formation within the entire soil profile (0–60 cm depth). Across the sampled areas, we found a positive association between the concentrations of SOC and its fractions, and the input of litter to the topsoil (0–40 cm), and soil extracellular enzymes at greater depths (40–60 cm). Our results indicate the potential of grazing exclusion for promoting SOC accumulation in semiarid regions, and highlight the need to understand soil carbon stabilization mechanisms in both top- and subsoil under future climate change scenarios.

Increased precipitation and nitrogen addition accelerate the temporal increase in soil respiration during 8-year old-field grassland succession.

Ecological succession after disturbance plays a vital role in influencing ecosystem structure and functioning. However, how global change factors regulate ecosystem carbon (C) cycling in successional plant communities remains largely elusive. As part of an 8-year (2012-2019) manipulative experiment, this study was designed to examine the responses of soil respiration and its heterotrophic component to simulated increases in precipitation and atmospheric nitrogen (N) deposition in an old-field grassland undergoing secondary succession. Over the 8-year experimental period, increased precipitation stimulated soil respiration by 11.6%, but did not affect soil heterotrophic respiration. Nitrogen addition increased both soil respiration (5.1%) and heterotrophic respiration (6.2%). Soil respiration and heterotrophic respiration linearly increased with time in the control plots, resulting from changes in soil moisture and shifts of plant community composition from grass-forb codominance to grass dominance in this old-field grassland. Compared to the control, increased precipitation significantly strengthened the temporal increase in soil respiration through stimulating belowground net primary productivity. By contrast, N addition accelerated temporal increases in both soil respiration and its heterotrophic component by driving plant community shifts and thus stimulating soil organic C. Our findings indicate that increases in water and N availabilities may accelerate soil C release during old-field grassland succession and reduce their potential positive impacts on soil C accumulation under future climate change scenarios.

Changes in rhizosphere-specific enzyme activity during secondary grassland succession in the Loess Plateau, China

ABSTRACT Dynamics of soil enzyme activity during plant restoration processes have been studied extensively; however, a general understanding of the rhizosphere-specific enzyme activity during plant secondary succession is limited. Rhizosphere samples were collected from the dominant and main companion species in farmlands abandoned for up to 32 years in the Loess Plateau. We determined soil chemical properties, phospholipid fatty acid (PLFA) profiles and activities of four enzymes (β-1,4-glucosidase, BG; β-1,4-N-acetylglucosaminidase, NAG; L-leucine aminopeptidase, LAP and alkaline phosphatase, AP), specific enzyme activity per soil organic carbon (SOC) and per PLFA unit. Specific BG, NAG, LAP and AP activities per SOC unit significantly decreased 77.1%, 53.2%, 83.0% and 49.2% with plant succession. Specific BG, NAG and LAP activities per PLFA unit significantly decreased 59.6%, 18.9% and 70.9% with plant succession. Furthermore, specific BG and LAP activities in the dominant species were lower than those in the companion species. Redundancy analysis revealed that variations in specific enzyme activities per SOC and per PLFA unit were explained 76.6% and 68.6% by soil chemical properties. SOC, total nitrogen (TN) and available phosphorus (aP) significantly influenced the rhizosphere-specific enzyme activities. This study improved the understanding of the element cycle at the root–soil interface under secondary succession ecosystems.

Applicability of Grassland Production Estimation Using Remote Sensing for the Mongolian Plateau by Comparing Typical Regions in China and Mongolia

Grasslands on the Mongolian Plateau are critical for supporting local sustainable development. Sufficient measured sample information is the basis of remote sensing modeling and estimation of grassland production. Limited by field inventory costs, it is difficult to collect sufficient and widely distributed samples in the Mongolian Plateau, especially in transboundary areas, which affects the results of grassland production estimation. Here, considering that the measured sample points are sparse, this study took Xilingol League of Inner Mongolia Autonomous Region in China and Dornogovi Province in Mongolia as the study areas, introduced multiple interpolation methods for interpolation experiments, established a statistical regression model based on the above measured and interpolated samples combined with the normalized differential vegetation index, and discussed the applicability of grassland production estimation. The comparison results revealed that the point estimation biased sample hospital-based area disease estimation method and radial basis function showed the best interpolation results for grassland production in Xilingol League and Dornogovi Province, respectively. The power function model was suitable for grassland production estimation in both regions. By inversion, we obtained annual grassland production for 2010–2021 and the uneven spatial distribution of grassland production in both regions. In these two regions, the spatial change in grassland production showed a decreasing trend from northeast to southwest, and the interannual change generally showed a dynamic upward trend. The growth rate of grassland output was faster in Xilingol League than in Dornogovi Province with similar physical geography and climate conditions, indicating that the animal husbandry regulation policies play important roles beyond the influence of climate change. The study recommended grassland estimation methods for an area with sparse samples and the results can be used to support decision making for sustainable animal husbandry and grassland succession management.

Forest structure and seasonally inundated grassland shape tropical mammal communities under moderate disturbance

AbstractTropical biodiversity is threatened globally by anthropogenic disturbances, particularly forest degradation and overhunting. Where large mammals have been extirpated, smaller bodied “mesomammals” may play an important ecological role (e.g., as seed dispersers). However, these species are disproportionally affected by overhunting for wildlife trade markets and are routinely understudied as they tend to be rare, cryptic, and nocturnal. Few studies have examined spatiotemporal responses to anthropogenic disturbance by mesomammals at the community level, which may identify imbalances within an ecosystem that could threaten species persistence. We deployed camera traps throughout Cat Tien National Park (i.e., Nam Cat Tien area), southern Vietnam, to (1) identify long‐term changes in terrestrial mesomammal richness and (2) evaluate the effects of forest structure and anthropogenic disturbance on an 18‐species mesomammal community within a historically disturbed tropical forest using hierarchical Bayesian community occupancy models. We found that site occupancy was driven by the interaction between distance to seasonally inundated grassland and absolute forest cover (basal area per hectare). This may be due to the combination of intact forest benefits (refuge from predators and hunters, denning sites) and early successional grassland resources (forage quality), as well as high levels of tolerance for disturbed forest among the largely generalist mesomammal community of Nam Cat Tien. We found no negative effects of current anthropogenic factors at the community level. However, we did find that four disturbance‐tolerant small carnivores have been extirpated since the 1990s and continued human presence in the park suggests that hunting and snaring remain an acute threat to native mesomammals. Without continued efforts to address the unsustainable harvest of wildlife, Southeast Asian's remaining mesomammals are at risk of extirpation despite resilience to moderate levels of disturbance.

Mapping vegetation species succession in a mountainous grassland ecosystem using Landsat, ASTER MI, and Sentinel-2 data.

Vegetation species succession and composition are significant factors determining the rate of ecosystem biodiversity recovery after being disturbed and subsequently vital for sustainable and effective natural resource management and biodiversity. The succession and composition of grasslands ecosystems worldwide have significantly been affected by accelerated environmental changes due to natural and anthropogenic activities. Therefore, understanding spatial data on the succession of grassland vegetation species and communities through mapping and monitoring is essential to gain knowledge on the ecosystem and other ecosystem services. This study used a random forest machine learning classifier on the Google Earth Engine platform to classify grass vegetation species with Landsat 7 ETM+ and ASTER multispectral imager (MI) data resampled with the current Sentinel-2 MSI data to map and estimate the changes in vegetation species succession. The results indicate that ASTER MI has the least accuracy of 72%, Landsat 7 ETM+ 84%, and Sentinel-2 had the highest of 87%. The result also shows that other species had replaced four dominant grass species totaling about 49 km2 throughout the study.

Applying a participatory methodology to evaluate ecosystem services in the Pampa biome: lessons learned from the Tessa methodology in Uruguay

Identifying and measuring ecosystem services involving local stakeholders has been characterised as a novel approach in the literature. This article describes the methodology used in the participatory workshops, the lessons learned, and the specific results of applying the Tessa method. The methodology was piloted with 56 researchers and technicians, more than 22 institutions, and 54 livestock producers involved with the grassland conservation initiative, Alianza del Pastizal. Identified change agents with the most significant impact include the absence of a rural workforce, the lack of family succession, and weeding and overgrazing of grasslands. The primary ecosystem services identified included the production of fodder, meat/wool, wildlife forage, way of life/culture, and medicinal plants. The methodology presented here is replicable, capable of expansion to more groups, contributes to a better understanding, by the producers, of their problems and points to the need for the development of public incentive policies.

Plant Functional and Phylogenetic Diversity Regulate Ecosystem Multifunctionality in Semi-Arid Grassland During Succession

The relationship between biodiversity and ecosystem multifunctionality (EMF) is crucial for understanding the processes of ecological restoration in semi-arid regions. However, partitioning the relative influence of various biodiversity attributes, namely taxonomic, functional, and phylogenetic diversity, on EMF during secondary succession is still unclear. This study aimed to bridge the gap by employing field measurements and the chronosequence approach at 21 plots with different stand ages and precipitation conditions on the Loess Plateau of China. For diversity indices, we calculated the Shannon–Wiener diversity index, Simpson’s dominance index, Pielou evenness index, community weighted mean (CWM), functional variance (FDvar), and Faith’s phylogenetic diversity (PD) based on the empirically measured composition and traits of plant species. The EMF was expressed as the averaged value of eight function variables (including aboveground biomass, root biomass, soil total carbon, total nitrogen, and total phosphorus content, soil organic carbon, available nitrogen and available phosphorus content). The results showed that species evenness and CWM of leaf dry matter content (LDMC) significantly increased yet the CWM of specific leaf area (SLA) decreased with stand age, indicating the resource-use strategy of the plants became more conservative through succession into its later stages. The EMF increased with both stand age and mean annual precipitation. The structural equation model revealed that stand age, soil water content (SWC), and the multiple diversity indices altogether accounted for 56.0% of the variation in the EMF. PD and the CWMs of plant height and LDMC had positive effects on the EMF, and the FDvar of leaf nitrogen had negative effects on EMF. However, the Shannon Wiener diversity had no significant effect on the EMF. Our results suggest that functional and phylogenetic diversity are more important than taxonomic diversity in predicting EMF, and that multidimensional biodiversity indices should be jointly considered to better predict EMF during the succession of semiarid grasslands.

放牧管理模式对高原鼢鼠(Eospalax baileyi)鼠丘形态特征的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 放牧管理模式对高原鼢鼠(Eospalax baileyi)鼠丘形态特征的影响 DOI: 10.5846/stxb202012253273 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31760706）；甘肃省陇原青年创新创业人才项目（LYRC2018-02）和甘肃省科技计划项目（20JR10RA564） Effects of grazing management regimes on mound morphological characteristics of plateau zokors (Eospalax baileyi) Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为明晰放牧对高原鼢鼠（Eospalax baileyi）造丘活动的影响，于2019年5月、8月和10月分别对禁牧（No grazing，NG）、生长季休牧（Rest grazing in growing season，RG）、传统放牧（Traditional grazing，TG）和连续放牧（Continuous grazing，CG）4种放牧管理模式样地下高原鼢鼠的新鼠丘（2个月内形成）半径、高度、表面积和体积等进行测定，并分析其表面积、体积与土壤和植被生物量间的关系。结果发现：放牧管理模式显著影响了高原鼢鼠鼠丘形态特征，且具有季节性差异。NG下鼠丘的半径、表面积和体积最大，而CG下鼠丘的体积和表面积显著变小（P<0.05），在8月和10月，鼠丘半径在CG样地显著小于其他3种放牧模式样地（P<0.05）；8月TG下鼠丘高度最高，而5月和10月NG下鼠丘高度最高，鼠丘高度在CG样地显著小于NG样地（P<0.05）。冗余分析2个排序轴几乎全部解释了土壤因子及地下生物量与鼠丘特征之间的关系，但各放牧管理模式下影响因子不同，NG样地的土壤容重（P<0.05）、土壤紧实度（P<0.01）和莎草科植物的地上生物量（P<0.01），RG样地的地下生物量（P<0.01）、土壤紧实度（P<0.01）和豆科植物的地上生物量（P<0.01），TG样地的禾本科和豆科植物的地上生物量（P<0.01），CG样地的土壤水分、地下生生物量、土壤紧实度（P<0.05）和莎草科植物的地上生物量（P<0.01）均显著影响了鼠丘的形态特征。可见，放牧会影响高原鼢鼠的鼠丘形态特征，进而对草地的演替产生不同的影响。 Abstract:The rodent damage by plateau zokor in the process of alpine meadow grazing is a key problem in its utilization and management. Grazing is one of the most important ways to use grassland. Grazing management regimes, as a utilization system index to control grazing intensity, maintain livestock quantity and grassland ecosystem balance, which have different influences on grassland community structure, grassland productivity, soil structure, and nutrient properties. The plateau zokor (Eospalax baileyi) is a kind of underground rodent endemic to the Qinghai-Tibet Plateau, the embodiment of their different functions is the key to judge the "benefit and harm". Their continuous earthmoving and mound building is also one of the important manifestations of their harm,and the size of the mound building and the change of the excavated soil properties are the key factors affecting the grassland. Therefore, it is of great significance for rodent control and grassland management and utilization by elucidating the changes of mound characteristics in alpine meadow under different grazing management systems. In order to clarify the effect of grazing management regimes on the mound-building activity of plateau zokors, the radius, height, surface area and volumes of new mounds (formed within 2 months) under four kinds of grazing management regimes, namely no grazing (NG), rest grazing in the growing season (RG), traditional grazing (TG), and continuous grazing (CG) plots, were measured in May, August, and October 2019, and the relationship between surface area and volume and soil and vegetation biomass was analyzed. The results showed that the grazing management regimes significantly affected the morphological characteristics of mounds with seasonal differences. The radius, surface area and volume of mounds under no grazing regime were the largest, while the volume and surface area of mounds under continuous grazing regime decreased significantly (P<0.05), and the radius of mounds under the continuous grazing regime was significantly less than that of other three grazing regimes in August and October (P<0.05); the height of mounds under traditional grazing regime was the largest in August, while they were the largest under no grazing regime in May and October, and they were significantly less under continuous grazing regime than that under no grazing regime (P<0.05). The two sequencing axes of redundancy analysis almost entirely explained the relationship of mounds with environmental factors and underground biomass. However, the influencing factors were different under different grazing management regimes. There were great effects on the characteristics of zokor mounds from soil bulk density (P<0.05), soil compactness (P<0.01) and aboveground biomass of cyperaceae plants (P<0.01) under no grazing regimes. There were great effects on the characteristics of zokor mounds from underground biomass (P<0.01), soil compactness (P<0.01) and aboveground biomass of leguminosae plants(P<0.01) under rest grazing in growing season regime. There were great effects on the characteristics of zokor mounds from aboveground biomass of gramineae and leguminosae plants (P<0.01) under traditional grazing regimes, and there were great effects on the characteristics of zokor mounds from soil moisture, underground biomass, soil compactness (P<0.05) and aboveground biomass of cyperaceae plants(P<0.01) under continuous grazing regimes. Grazing can affect the mound-building activity of plateau zokors, and then had different effects on the succession of grassland. 参考文献 相似文献 引证文献

Nutrients and consumers impact tree colonization differently from performance in a successional old field.

Successful colonization and growth of trees within herbaceous communities may result from different interactions with the herbaceous community. First, colonizing trees compete against larger, established herbs, while subsequent growth occurs among similarly sized or smaller herbs. This shift from colonization to growth may lead three drivers of community dynamics-nutrients, consumers, and herbaceous diversity-to differentially affect tree colonization and, later, tree performance. Initially, these drivers should favor larger, established herbs, reducing tree colonization. Later, when established trees can better compete with herbs, these drivers should benefit trees and increase their performance. In a 4-year study in a southeastern US old field, we added nutrients to, excluded aboveground consumers from, and manipulated initial richness of, the herbaceous community, and then allowed trees to naturally colonize these communities (from intact seedbanks or as seed rain) and grow. Nutrients and consumers had opposing effects on tree colonization and performance: adding nutrients and excluding consumers reduced tree colonization rate, but later increased the size of established trees (height, basal diameter). Adding nutrients and excluding consumers also restricted tree colonization to earlier years of study, which partially explained the effect of nutrient addition on plant size. Together, this shows differing impacts of nutrients and consumers: factors that initially limited tree colonization also resulted in larger established trees. This suggests that succession of grasslands that are either eutrophied or have diminished consumer pressure may experience lags and pulses in woody encroachment, leading to an extended period of herbaceous dominance followed by accelerated woody growth.

Significant changes in arbuscular mycorrhizal community and soil physicochemical properties during the saline-alkali grassland vegetation succession

Arbuscular mycorrhizal (AM) fungi are widely distributed in various habitats, and the community composition varies in response to the changing environmental conditions. To explore the response of community composition to the succession of saline-alkali land, soil samples were collected from three succession stages of Songnen saline-alkali grassland. Subsequently, the soil characteristics were determined and the AM fungi in soil samples were analyzed by high-throughput sequencing. Then, the response relationship between community composition and soil characteristics was studied by Canonical correlation and Pearson analyses. The soil properties improved with the succession of saline-alkali grassland. There was no significant difference in alpha diversity between the first and second succession stage (Suaeda glauca and Puccinellia tenuiflora, respectively), and the microbial community had a dense association network at the third stage (Leymus chinensis); in addition, each succession stage had significantly enriched amplicon sequence variants (ASVs) and functional pathways. All the soil properties except cellulase activity had significant effects on community composition. Furthermore, the pH, organic carbon, organic matter, and sucrase activity significantly correlated with alpha diversity indices. These results provide a theoretical basis for realizing the significant changes in AM fungal community and soil properties during the saline-alkali grassland vegetation succession.

Impact of Secondary Succession in the Xerothermic Grassland on the Population of the Eastern Pasque Flower (Pulsatilla patens)—Preliminary Studies

We studied the impact of secondary succession in xerothermic grasslands on a population of Pulsatilla patens, a species of European Community interest. We established two permanent plots with a high number of individuals of P. patens in a xerothermic grassland in Southern Poland. We compared two areas, the first in open grassland (plot A), and the second with overgrowing vegetation (plot B). We assessed the population structure as well as the individual traits of the species. The total abundance of P. patens in the open xerothermic grassland was five times higher than in the overgrowing xerothermic grassland. A randomly clustering distribution was noted only in plot A; in plot B a random type of distribution occurred. The density structure of the rosettes was higher in plot A. The mean number of leaves in rosettes of P. patens as well as dimensions of intermediate stems and leaves of the species is strongly correlated with habitat conditions. The shadowing caused by shrubs and trees and high weeds observed in the overgrowing xerothermic grassland negatively impacted on the number of individuals, distribution, structure and morphology of P. patens.

Possibilities of restoration of natural or seminatural grasslands

The number of natural grassland restoration projects increased in the last decade in Hungary, and probably the area of restored grasslands will be significantly extended in the next years due to New National Rural Development Program. To contribute to the success of this activity, in this paper we review the most important theoretical and practical aspects of natural grassland restoration methods. In the course of grassland restoration, habitats dominated by grasses and/or sedges have been restored in place of arable lands. In order to perform “natural” restoration, we should consider the ecological conditions of the landscape, and reconstruct natural or seminatural grasslands including of native plant species. Essentially, rehabilitation of natural landscape is supported also by creating new seminatural grassland patches. The basic principles of the natural grassland restoration are:&#x0D; 1. When a spontaneous secondary succession starts to proceed on an abandoned field without invasion of any alien plant species, the re-ploughing of the abandoned field has to be ignored.&#x0D; 2. Generally, the old fields surrounded by species-rich natural or seminatural grassland pathes can succesfully be restorated. Then, as a consequence of newly restored vegetation patches the recovery of the whole landscape can be accelerated. Furthermore, by restoring isolated grassland patches surrounded by arable lands a more diverse landscape pattern could be developed.&#x0D; 3. Spontaneous secondary succession of grasslands should be assisted.&#x0D; 4. The development of typical species composition of a seminatural grassland can be promoted by methods of spreaded hay. For successful process the hay has to be cut in a habitat type similar to ones that will be restored.&#x0D; 5. Applying seed-mix for sowing can be useful to prevent spreading weeds drastically in the early stages of succession.&#x0D; 6. Ideally, the seed-mix is originated from own harvesting or gathering from similar (or the same) habitats. If it is not possible, commercially available seed-mix can be applied, in which the dominant species is the same as in the restored habitat, with similar proportion.&#x0D; 7. Seed-mix consists of alien species has to be avoided.&#x0D; 8. If the composition or structure of the restored grassland is not appropriate after some years, the renewal of the grassland could be necessary. During the improvement process the reploughing of the restored grassland is avoided, but spreading seeds or hay, and direct sowing can be applied.&#x0D; 9. The loading of nutrient is not necessary in any stages of grassland restoration.&#x0D; 10. Applying chemicals is avoided; any herbicides can be used only when extensive invasion of alien plant species occurs.&#x0D; 11. The mechanical intrusions on soil are also avoided.&#x0D; 12. The restored grasslands is required regular or continuous management, which could be a preserving mowing or moderate grazing. The aspects of nature conservation should be considered.

Manipulating plant microbiomes in the field: Native mycorrhizae advance plant succession and improve native plant restoration

Abstract The plant microbiome is critical to plant health and is degraded with anthropogenic disturbance. However, the value of re‐establishing the native microbiome is rarely considered in ecological restoration. Arbuscular mycorrhizal (AM) fungi are particularly important microbiome components, as they associate with most plants, and later successional grassland plants are strongly responsive to native AM fungi. With five separate sites across the United States, we inoculated mid‐ and late successional plant seedlings with one of three types of native microbiome amendments: (a) whole rhizosphere soil collected from local old‐growth, undisturbed grassland communities in Illinois, Kansas or Oklahoma, (b) laboratory cultured AM fungi from these same old‐growth grassland sites or (c) no microbiome amendment. We also seeded each restoration with a diverse native seed mixture. Plant establishment and growth was followed for three growing seasons. The reintroduction of soil microbiome from native ecosystems improved restoration establishment. Including only native arbuscular mycorrhizal fungal communities produced similar improvements in plant establishment as what was found with whole soil microbiome amendment. These findings were robust across plant functional groups. Inoculated plants (amended with either AM fungi or whole soil) also grew more leaves and were generally taller during the three growing seasons. Synthesis and applications. Our research shows that mycorrhizal fungi can accelerate plant succession and that the reintroduction of both whole soil and laboratory cultivated native mycorrhizal fungi can be used as tools to improve native plant restoration following anthropogenic disturbance.

Reasonable management of perennial planting grassland contributes to positive succession of soil microbial community in Sanjiangyuan of Qinghai-Tibetan Plateau, China

AbstractGrassland reconstruction is a major approach to alleviate the ‘black beach’ in Sanjiangyuan of the Qinghai-Tibetan Plateau. It is vital to understand how to manage the planting grassland after reconstruction. And which artificial grassland management pattern is more likely to restore the degraded grassland of ‘black beach?’ To provide the scientific basis for the restoration of ‘black beach’, we investigated the changes in vegetation characteristics, soil physicochemical properties and soil microbial community structure of planting grassland under different management patterns, and explored the effect of the management patterns on community succession of planting grassland. In this study, vegetation characteristics and soil physicochemical properties were measured by field investigation and laboratory analyses, respectively. Soil microbial community composition was determined by high-throughput sequencing techniques. The results showed that there were significant differences in vegetation characteristics, soil physicochemical properties and soil microbial community structure of the planting grassland under different management patterns. Actinobacteria and Basidiomycota were mainly controlled by vegetation plant species diversity, aboveground biomass (AGB) and soil organic carbon (SOC). Shannon-Wiener index, AGB and SOC peaked and the relative abundance of amplicon sequence variants annotated by Actinobacteria and Basidiomycota were significantly enriched under the management pattern of the planting once treatment. Additionally, the soil had the highest bacterial diversity and the lowest fungal diversity under the planting once treatment, becoming a ‘bacterial’ soil. These vegetation characteristics and soil environment were more conducive to overall positive community succession, indicating that the planting once treatment is the most reasonable management pattern for restoring the ‘black beach’.

Soil nutrients increase long-term soil carbon gains threefold on retired farmland.

Abandoned agricultural lands often accumulate soil carbon (C) following depletion of soil C by cultivation. The potential for this recovery to provide significant C storage benefits depends on the rate of soil C accumulation, which, in turn, may depend on nutrient supply rates. We tracked soil C for almost four decades following intensive agricultural soil disturbance along an experimentally imposed gradient in nitrogen (N) added annually in combination with other macro- and micro-nutrients. Soil %C accumulated over the course of the study in unfertilized control plots leading to a gain of 6.1MgCha-1 in the top 20cm of soil. Nutrient addition increased soil %C accumulation leading to a gain of 17.8MgCha-1 in fertilized plots, nearly a threefold increase over the control plots. These results demonstrate that substantial increases in soil C in successional grasslands following agricultural abandonment occur over decadal timescales, and that C gain is increased by high supply rates of soil nutrients. In addition, soil %C continued to increase for decades under elevated nutrient supply, suggesting that short-term nutrient addition experiments underestimate the effects of soil nutrients on soil C accumulation.