Grassland Restoration Research Articles

Grassland restoration benefits declining farmland birds: A landscape-scale before-after-control-impact experiment

The decline of farmland bird populations starting in the 1980s has induced intense research on farmland biodiversity conservation in Europe. Although many studies assessing the effectiveness of agri-environmental schemes have concentrated on birds, farmland birds, surprisingly, have not yet been targeted directly by permanent, landscape-scale restoration of grassland ecosystems on former croplands in Europe. We compared farmland bird responses to grassland restoration by grass sowing, alfalfa sowing followed by spontaneous grassland recovery, and hay transfer (impact sites) with responses to extensive, low-intensity cropland cultivation (controls) in a Before-After-Control-Impact design, and also compared extensive croplands against a baseline reference of intensive croplands. Point counts in 69 sites on 910 ha in at least two years before and three years after the interventions showed that farmland bird species richness increased in both restored grasslands and in extensive croplands, whereas abundance and Shannon diversity increased only in restored grasslands but not in extensive croplands. Abundance increased in restored grasslands for five farmland species and two species of conservation importance, and in extensive croplands for one farmland and one species of conservation importance. Active restoration by grass sowing increased both species richness and diversity and active restoration by hay transfer increased abundance, while passive restoration targeting spontaneous grassland recovery after alfalfa sowing increased richness and abundance. Extensive croplands had four-five times more species and individuals than intensive croplands. Our results suggest that landscape-scale grassland restoration can locally reverse regional farmland bird declines and can thus be a promising tool in farmland biodiversity conservation.

An integrated approach for the restoration of Australian temperate grasslands invaded by Nassella trichotoma

Invasive plants are considered to be one of the biggest threats to environmental assets, and once established, they can be immensely difficult to control. Nassella trichotoma is an aggressive, perennial grass species, and is considered to be one of the most economically damaging weeds to grazing systems due to its unpalatability, as well as being one of the leading causes of biodiversity loss in grassland communities. This species produces high density seedbanks that rapidly respond to disturbance events. Despite control programs being developing in Australia since the 1930s, this species is still widespread throughout south-east Australia, indicating that a new management approach is critical to control this Weed of National Significance at the landscape scale. The present study explored the effect of 12 different combinations of herbicide, fire, a second application of herbicide, grazing exclusion, tillage and broadcasting seeds in order to reduce the above and below-ground density of N. trichotoma. A control treatment was also included. The results were assessed using a Hierarchy analysis, whereby treatments of increasing complexity were compared for their efficacy in reducing N. trichotoma cover and seedbank density, while simultaneously increasing the establishment of the broadcast species. Whilst all integrated treatments effectively reduced N. trichotoma's seedbank, the treatments that included fire performed significantly better at simultaneously reducing N. trichotoma and increasing the establishment of broadcasted seeds. Overall, the integration of herbicide, fire and broadcasting native seeds was observed to provide the most economically feasible management strategy for the landscape scale restoration of a degraded temperate grassland dominated by N. trichotoma.

Co-seeding grasses and forbs supports restoration of species-rich grasslands and improves weed control in ex-arable land.

Sowing is widely used for the restoration of species-rich grasslands but still there are knowledge gaps regarding the most suitable application of different seed mixtures. We tested the effect of seed mixtures application timing on the establishment of sown forbs and weed control. 36 experimental plots with nine sowing treatments were established in an abandoned cropland in Hungary. Grass-seeds, diverse forb seed mixture and the combination of the two were applied: diverse forb mixture was sown simultaneously or 1, 2 or 3years after grass sowing, in plots sown previously with grass or in empty plots (fallows). All sowing treatments supported the rapid establishment of the sown species in large cover and hampered weed encroachment. Forbs performed better when sown into fallows than in grass-matrix and forbs establishment was worse in older fallows than in younger ones. Grasses expressed a strong priority effect, especially when forbs were sown at least two years later than grasses. We also investigated the relation between seed germinability, weather parameters and establishment success. Germination rate in the greenhouse could not predict the establishment success of forbs in the field and showed great differences between years, hence we recommend sowing target forbs in multiple years.

Trend Analysis and Driving Factors of Vegetation Dynamics in Northern China from 1982 to 2015

Under the background of global warming, understanding the dynamic of vegetation plays a key role in revealing the structure and function of an ecosystem. Assessing the impact of climate change and human activities on vegetation dynamics is crucial for policy formulation and ecological protection. Based on the Global Inventory Monitoring and Modeling System (GIMMS) third generation of Normalized Difference Vegetation Index (NDVI3g), meteorological data and land cover data, this study analyzed the linear and nonlinear trends of vegetation in northern China from 1982 to 2015, and quantified the relative impact of climate change and human activities on vegetation change. The results showed that more than 53% of the vegetation had changed significantly, and 36.64% of the vegetation had a reverse trend. There were potential risks of vegetation degradation in the southwestern, northwestern and northeastern parts of the study’s area. The linear analysis method cannot disclose the reversal of the vegetation growth trend, which will underestimate or overestimate the risk of vegetation degradation or restoration. Climate change and human activities promoted 76.54% of the vegetation growth in the study area, with an average contribution rate of 51.22% and 48.78%, respectively, while the average contribution rate to the vegetation degradation area was 47.43% and 52.57%, respectively. Vegetation restoration of grassland and woodland was mainly affected by climate change, and human activities dominated their degradation, while cropland vegetation was opposite. The contribution rate of human activities to vegetation change in the southeastern and eastern parts of the study area was generally higher than that of climate change, but it was the opposite in the high altitude area, with obvious spatial heterogeneity. These results are helpful to understand the dynamic mechanism of vegetation in northern China, and provide a scientific basis for vegetation restoration and protection of regional ecosystems.

Deciphering factors driving soil microbial life-history strategies in restored grasslands.

In macroecology, the concept of r- and K-strategy has been widely applied, yet, there have been limited studies on microbial life-history strategies in temperate grasslands using multiple sequencing approaches. Total phospholipid fatty acid(PLFA) analysis, high-throughput meta-genomic sequencing, and GeoChip technologies were used to examine the changes in microbial life-history traits in a chronosequence of restored grasslands (1, 5, 10, 15, 25, and 30 years since restoration). Grassland restoration increased the relative abundances of Actinobacteria, Proteobacteria, and Bacteroidetes but reduced the relative abundances of Acidobacteria, Planctomycetes, and Chloroflexi. PLFA analysis revealed that grassland restoration reduced the fungi:bacteria and Gram-positive:Gram-negative bacteria ratios. Combined with the meta-genomic data, we found that grassland restoration shifted microorganisms from oligotrophic (K-) to copiotrophic (r-) groups, consistent with the increased rRNA operon copy number of the microbial community. Structural equation modeling showed that soil properties positively (p < 0.05) while plant properties negatively (p < 0.05) affected microbial life-history traits. We built a framework to highlight the importance of plant and soil properties in driving microbial life-history traits during grassland restoration. Finally, by incorporating meta-genomic and other microbiological data, this study showed that microbial life-history traits support the idea that rRNA operon copy number is a trait that reflects resource availability to soil microorganisms.

Identifying prioritized afforestation types in ecologically vulnerable zones of Northern China considering reducing water consumption and increasing carbon sequestration

Afforestation is one of the most important measures to control soil erosion and desertification in Northern China. Meanwhile, considering that afforestation in Northern China needs to increase carbon sequestration (CS) and reduce water consumption (WC), it is essential to select prioritized afforestation types in suitable regions. In this work, we identified ecologically vulnerable zones based on soil water and wind erosion assessment, evaluated tree and shrub afforestation suitability, and thus recognized potential afforestation regions. Further, we set four scenarios for different goals, and identified the prioritized afforestation types in each scenario. The results showed that potential afforestation regions are mainly distributed in the Loess Plateau, Western Liao River, Ordos Plateau, and Tarim Basin. Scenario 1 (aiming to minimize WC) is dominated by shrub afforestation and grassland restoration. This scenario will reduce WC by 3.1%-6.4% compared to other scenarios, but it will also decrease CS by 9.4%-56.1% and soil conservation (SC) by 7.7%-13.0%. Scenario 2 (aiming to maximize CS) is dominated by tree and shrub afforestation. This scenario will fix 41.8%-56.1% more carbon, and consume 3.0%-6.4% more water than the other scenarios. Meanwhile, this scenario can maximize SC, but also may reduce sand fixation (SF). Scenario 3 (aiming to maximize CS in humid region and minimize WC in arid region) and Scenario 4 (aiming to enhance both SC and SF) are dominated by shrub afforestation, tree afforestation and grassland restoration. The two scenarios can balance CS and WC, and have advantages in improving both SC and SF. In addition, Scenario 4 performs better than Scenario 3. In the future, it is better to implement tree afforestation mainly in sub-humid area, and conduct shrub afforestation mainly in arid and semi-arid regions. This study can provide guidance for the planning and management of afforestation projects in Northern China and other water scarcity areas.

Restoration of calcareous grasslands by natural recolonization after forest clearing and its impact on the genetic variation of three common herb species

Species-rich calcareous grasslands in Europe strongly declined during the twentieth century due to drastic land use changes. Many grasslands were converted into more productive pastures or are covered by shrubs or forests today, since they were overgrown after abandonment or afforested. Restoration of calcareous grasslands by shrub or forest clearing and subsequent recolonization of grassland species from adjacent grasslands is, therefore, an important conservation approach. Restored populations of calcareous grassland species may, however, differ from their source populations in genetic diversity and differentiation due to potential founder and bottleneck effects. In our study we analyzed, therefore, the impact of restoration by forest clearing and natural recolonization on the genetic variation of three common calcareous grassland species (Agrimonia eupatoria, Campanula rotundifolia, and Knautia arvensis) without a contribution of persistent seed bank, in South Western Germany. We used molecular markers AFLPs (Amplified fragment length polymorphisms) to compare genetic diversity within and differentiation between spontaneously recovered subpopulations with adjacent historically old, natural subpopulations at eight study sites. Restored parts of the grasslands have been re-established during the 1990s. Molecular markers revealed broadly similar levels of genetic diversity in source and restored subpopulations of the study species. Only A. eupatoria exhibited slightly higher diversity in restored subpopulations, which may be explained by higher dispersal potential due to the hooky fruits of the species. Genetic differentiation between source and restored subpopulations was not significant, indicating strong gene flow between the subpopulations. Our study underlines, therefore, that restoration of calcareous grasslands by natural recolonization after forest clearing is an efficient method to re-establish genetically variable subpopulations comparable to their sources.

A single application of fertilizer can affect semi-natural grassland vegetation over half a century.

Restoration of species-rich semi-natural grassland requires not only a seed source but also appropriate soil properties. In Europe, approximately 10 years are required for the properties of fertilized soils to reach suitable conditions and be considered successfully restored. However, restoration may require additional time in Japan because heavier precipitation causes leaching of basic cations from soils, resulting in soil acidification; volcanic ejecta also forms active Al and Fe hydroxides with high phosphate sorption. Within this context, we aimed to answer the following questions: i) whether and how the impacts of fertilization remain in the soil properties after half a century in Japan; and ii) how fertilization affects the restoration of semi-natural grasslands in Japan. We investigated the vegetation and soil properties of a Zoysia japonica pasture improved half a century ago with a single application of fertilizer and an adjacent semi-natural grassland (native pasture) in Japan, and found the following: (1) the two pastures had similar dominance of Z. japonica, but differed in the species composition; (2) the improved pasture exhibited lower species richness than the native pasture; (3) soil nutrients, including N, P, K, Mg, and Ca, were higher in the improved pasture than in the native pasture; and (4) many chemical properties of the soils were associated with species composition; namely, the vegetation on nutrient-rich soil had more alien species and fewer native species. We conclude that a single dose of fertilization can affect soil properties in semi-natural grasslands over half a century in Japan, leading to species loss and changing the species composition. We suggest that fertilized soils under grazing in Japan may require more than half a century to restore the nutrients to suitable levels for the establishment of a species-diverse grassland.

Biodiversity and soil pH regulate the recovery of ecosystem multifunctionality during secondary succession of abandoned croplands in northern China

The ‘Grain-for-Green’ program in China provides a valuable opportunity to investigate whether spontaneous restoration can reverse the deterioration of grassland ecosystem functions. Previous studies have focused on individual ecosystem functions, but the response of and mechanisms driving variation in ecosystem multifunctionality (EMF) during restoration are poorly understood. Here, we quantified EMF using productivity, nutrient cycling, and water regulation functions along abandoned croplands in a recovery chronosequence (5, 15 and 20 years) and in natural grasslands in the desert steppe and typical steppe. We also analyzed the effects of plant and microbial diversity and an abiotic factor (soil pH) on EMF. Our results showed that EMF increased gradually concomitant with recovery time, shifting toward EMF values comparable to those in natural grasslands in both desert and typical steppe. Similar results were found for the productivity function, the water regulation function, and soil organic carbon. However, even after 20 years of restoration, EMF did not reach the levels observed in natural grasslands. Structural equation modeling showed that the driving mechanisms of EMF differed between the two steppe types. Specifically, in the desert steppe, plant diversity, especially the diversity of perennial graminoids and perennial herbs, had a positive effect on EMF, but in the typical steppe, soil bacterial diversity had a negative effect, while soil pH had a positive effect on EMF. Our results demonstrated that spontaneous grassland restoration effectively enhanced EMF, and emphasized the importance of biodiversity and soil pH in regulating EMF during secondary succession. This work provides important insights for grassland ecosystem management in arid and semi-arid regions.

Effects of different management practices on soil microbial community structure and function in alpine grassland

Management practices, such as grazing exclusion and reseeding, have been implemented to mitigate the degradation of grassland. Low grazing intensities and reseeding increase grass production. Nevertheless, few studies have investigated the effects of these measures on the soil microbial community structure and function in the Qinghai Tibetan Plateau (QTP). To reveal the effects of management practices on soil microbes and give a reference to assess and improve ecosystems functions, we here evaluated the impact of various types of grazing (exclusion, seasonal, and traditional), reseeding (annual oat (Avena fatua) grassland (RO) and perennial artificial grassland cultivated >10 y), and integrated restoration (weed control and no-tillage reseeding) measures on soil microbial community structure and function in the QTP. The Shannon-Wiener diversity indices were highest for prokaryotes under RO and for fungi under integrated grassland restoration. Relative Actinobacteria abundance was higher under seasonal grazing than that under integrated grassland restoration. The latter had relatively higher abundances of Betaproteobacteria, Alphaproteobacteria, and Deltaproteobacteria and comparatively lower abundance of Thermoleophilia. There were significantly higher abundances of plant pathogens under seasonal grazing than those under other managements. There were significantly high proportions of pathotrophs and saprotrophs (10.0%) under seasonal and traditional grazing, respectively. The proportion of pathotrophs under integrated restoration (10.0%) was about seven-fold greater than that under grazing exclusion (1.5%). The relative differences among treatments in terms of soil water content, plant biomass, and soil C:N partially explained the differences in their prokaryotic community compositions. Increases in soil organic carbon and C:N may explain the observed changes in the soil fungal communities. The management practices affected soil microorganisms mainly by altering the soil nutrient profile. Grazing attracted specific pathotrophs and saprotrophs while repelling certain plant pathogens. Hence, modulations in soil microbial community structure and function must be considered in the process of planning for the implementation of grassland degradation management measures.

Toward diverse seed sourcing to upscale ecological restoration in the Brazilian Cerrado

Seed markets are vital to scaling up ecosystem restoration in the Brazilian Cerrado, home of the world’s most species-rich grasslands and savannas. We compiled lists of species traded by four major Cerrado seed supply systems to investigate the representativeness of the species currently available for seed-based restoration. We also identified whether dominant ground-layer species are being sourced for seed production. Seeds from 263 Cerrado species can be purchased for restoration, of which 68% are trees, particularly legumes (24%). 63% of the traded species were found in only one seed supply system. The five most dominant graminoids of the Cerrado ground layer were available for sale, but two additional species uncommon in old-growth areas represented 44% of the sales of a key seed trader in Central Brazil. The expansion of Cerrado seed supply systems should be supported to further increase the number of species on the market. Sourcing seeds from a diversity of herbaceous species is central to facilitating the restoration of species-rich grasslands and savannas in the Cerrado. Recovering the diversity and functioning of old-growth open ecosystems through seeds will depend on increasing the supply and demand for species typical of Cerrado’s ground layer.

Plant community productivity is associated with multiple ecological stoichiometry in restoration grasslands

Ecological stoichiometry links the growth of living organisms at the organ level through the strict elemental ratio (carbon [C], nitrogen [N] as well as phosphorus [P]). And this is conducive to maintaining plant productivity in terrestrial ecosystems. Yet, the identification about the significance of multiple ecological stoichiometry (including leaves, roots, soil and microbial biomass) in shaping plant productivity remains unknown. Here, we evaluated the ecological stoichiometry contributions to plant productivity in restoration grasslands on the Loess Plateau (1-, 5-, 10-, 15-, 25-, 30-years restoration grasslands). We found that grassland restoration for 30 years enhanced plant community productivity by 67.34%, which showed the synchronous increase trend with C and N contents in leaves, roots, soil as well as microbial biomass. However, leaves, roots, soil and microbial biomass P contents displayed the opposite change trend with no significant difference in these restoration grasslands (p > 0.05). Microbial biomass C/N/P ratios exhibited thesignificant correlations with leaves, roots, soil C/N/P ratios, as well as plant community productivity (p < 0.01), indicating that stoichiometry of soil microbial biomass is greatly restricted, with the potential to influence plant community productivity. These findings emphasized the crucial role of microbial biomass stoichiometry as a primary regulator on plant community productivity, providing the important data to improve the parameterization of plant growth models in natural grassland of China.

Agricultural and Forestry Biomass for Meeting the Renewable Fuel Standard: Implications for Land Use and GHG Emissions

Agricultural land and forestland are considered as two largest potential biomass sources for meeting the Renewable Fuel Standard (RFS) mandate for cellulosic biofuels. However, the land use change and greenhouse gas (GHG) savings with both agricultural and forest biomass production are yet to be examined systematically. This paper examines the effects of implementing a 16-billion gallon (60 billion liters) cellulosic biofuel mandate by 2035 on the mix of agricultural and forest biomass, land use change and GHG emissions by using a dynamic partial equilibrium model of the agricultural, forestry and transportation sectors in the US. Our results show that crop residues play a significant role in supplying cellulosic ethanol before 2030, while energy crops are the major feedstocks used for meeting the RFS cellulosic mandate after 2030. Milling and logging residues are economically viable supplements to agricultural biomass for cellulosic ethanol production, though their role in total biomass is small. Across different scenarios of cellulosic ethanol mandate that can be met with either agricultural biomass only or with both agricultural and forest biomass, we find GHG savings from displacing the gasoline range from 0.61 to 0.82 B MgCO2e over the 2015–2035 period. Induced land use change effects associated with expanded feedstock production are modest between and within the agricultural and forestry sectors. We conclude that a mixed feedstock base maximizes the economic and environmental benefits of cellulosic biofuel production. The mitigation potential of cellulosic biofuels is severalfold larger than natural-based solutions such as grassland restoration.

Aboveground Biomass in China’s Managed Grasslands and Their Responses to Environmental and Management Variations

Aboveground biomass (AGB) in managed grasslands can vary across a suite of environmental and management conditions; however, there lacks a quantitative assessment at the national scale of China. Although the potential effects of individual drivers (e.g., species, nutrient fertilization, and water management) have been examined in China’s managed grasslands, no attempts have been made to comprehensively assess the effects of multiple variables on AGB. Using a meta-data analysis approach, we created a database composed of AGB and associated attributes of managed grasslands in China. The database was used to assess the responses of AGB to anthropogenic factors, in addition to a suite of natural variables including climate, soil, and topography. The average AGB in managed grasslands of China is approximately 630 g m−2 of dry matter, ranging from 55 to 2172 g m−2 (95% confidence interval). Medicago sativa is the most widely planted species in China’s managed grasslands, followed by Elymus dahuricus and Bromus japonicus. The national average AGB of these three species was around 692, 530, and 856 g m−2, respectively. For each species, AGB shows a large discrepancy across different places. In general, grassland AGB depends substantially on species, environments, and management practices. The dependence can be well described by a linear mixed-effects regression in which a series of biotic and abiotic factors are used as predictors. We highlight that establishing managed grassland can potentially contribute to not only AGB enhancement, but also grassland restoration on degraded natural grasslands.

Tree logs for grassland restoration? Lessons from an unintentional experiment

For subtropical Brazilian grasslands, few restoration techniques are established, and seeds of native grassland species are not available on the market. Here, we evaluated the effect of physical barriers (PB) on vegetation recovery in a degraded grassland. We considered species that exhibit attributes in their diaspores that facilitate dispersal as well‐dispersed species (WDS) and compared the proportion of WDS at our site to their proportion in the regional species pool. To analyze plots near and distant from the PB, we calculated the extrapolated metrics by an asymptotic estimator (double sample size of each distance). We found 74 species in the degraded area, with higher richness and Shannon diversity values closer to logs, but higher Simpson values with larger distance from logs. Almost half of the species in the degraded area are WDS, more than in the regional species pool. While effects of logs on microsite conditions may also play a role (e.g. logs accumulating organic material or increasing soil moisture, providing shade), our data indicates that the PB works as a seed trap favoring the occurrence of WDS. It seems promising to develop applications in restoration, especially when associating PB with other restoration techniques to increase availability of adequate germination and establishment conditions.

Attractiveness of Drought-tolerant Plants to Insect Pollinators in the Southern High Plains Region

Urban and rural landscapes are important for providing floral resources to pollinating insects, yet determining the attractiveness of specific plants to a variety of pollinators remains a need in many regions. The objective of this study was to determine the attractiveness of 30 different plants to foraging insects. On 14 dates in 2016 and 2017, floral abundances were measured and the number of insect visitors recorded. A total of 57 insect morphospecies were recorded, with bees (Apoidea: Anthophila) the most abundant pollinator and honey bees the most frequently observed forager. Russian sage (Salvia farinacea) and Catmint (Nepeta × faassenii ‘Walker’s Low’) attracted the greatest number of pollinators. Native plants adapted to the region attracted the highest diversity of pollinators. Thirteen plants, some that are considered good pollinator plants, attracted low numbers of insects. Five pollinator taxa (Anthophora californica/urbana, Apis mellifera, Agapostemon angelicus/texanus, Lasioglossum spp., and Bombyliidae) were attracted to 10 or more different plants, while approximately 65 percent of the taxa were attracted to three or fewer plants. Results support strategies for both grassland restoration and the selection of plants when resources and habitat for pollinators are considered in the management of urban green spaces.

Effects of artificial restoration on vertical distribution of soil carbon storage following revegetation in a semiarid grassland of North China

AbstractArtificial restoration is an important strategy to restore plant communities and soil nutrients in degraded grassland ecosystems. Despite that research has been extensive on the impacts of vegetation restoration on soil carbon storage, little work has been tried to examine the impacts of artificial restoration on the vertical distribution of soil organic carbon (SOC) storage following revegetation in grassland ecosystems. In this paper, the responses of plant species diversity, litter biomass (LB), aboveground biomass (AGB), the relative biomass of three dominant plant species, and the belowground biomass (BGB) were quantified under five different restoration regimes (natural recovery, harrowing, harrowing plus fertilization, harrowing plus irrigation, harrowing plus fertilization and irrigation), to explore the direct and indirect effects of artificial restoration, mediated by changes in the plant properties following revegetation, on SOC storage in Leymus chinensis steppe, North China. We found that artificial restoration greatly facilitated the recovery of Leymus chinensis but lowered the plant diversity. Irrigation treatment, particularly harrowing plus irrigation, was associated with both higher BGB and LB, which had positive effects on SOC storage at the 30–60 cm soil layer when compared with natural restoration. In addition, artificial restoration had positive but not significant effects on SOC storage in the surface soil layer (0–10 cm) mediated directly by changes in BGB, while it exerted negative indirect effects on SOC storage at the 10–30 cm soil layer through low level of plant species diversity. The loss of two dominant species (Stipa krylovii and Cleistogenes squarrosa) could greatly impact SOC storage not only due to lowered species diversity but also the reduced quality of litter input into soil. It is therefore proposed that maintaining high levels of plant species diversity could help sustain higher soil carbon storage through producing high‐quality root and litter. Our findings from the 9‐year restoration experiment suggested that natural restoration is a sustainable grassland restoration regime to conserve both plant diversity and soil nutrients over short timescales in semi‐arid grasslands in North China. In the long term, SOC storage can be substantially enhanced by artificial restoration, especially under treatments that include irrigation.

Coarsened soil reduces drought resistance of fibrous-rooted species on degraded steppe

Grassland degradation is often accompanied by coarsened soil, which could change water and nutrient uptake by plant roots. Studying the effects of soil coarsening on species performance with different root systems under manipulated irrigation has important practical significance in grassland restoration under changing climate. We conducted a common garden experiment with three water treatments (control, drought stressed and water addition) and two soil texture (loamy soil which is fine and sandy soil which is coarse) under a rainout shelter to explore the effects of degradation on the growth and drought response of tap-rooted species and fibrous-rooted species. Three fibrous-rooted species (Setaira viridis, Cleistogenes squarrosa and Leymus chinensis) and three tap-rooted species (Medicago ruthenica, Artemisia frigida and Potentilla bifurca) were used in the study (P. bifurca failed to germinate). The results showed that three of the five selected species tended to have higher aboveground biomass, greater belowground biomass, larger height and longer root length in sandy soil than in loamy soil. For fibrous-rooted species, drought had negative influence on several plant traits in sandy soil, and had no influence on plant traits in loamy soil. For tap-rooted species, drought had negative influence on plant traits both in loamy soil and in sandy soil, and the influence was larger in loamy soil than in sandy soil. The results showed that loamy soil might provide a buffer against drought for fibrous-rooted species, but make tap-rooted species more sensitive to drought. Our results implied that degraded grasslands with coarsened soil might change community composition in the grassland, making tap-rooted species take the place of fibrous-rooted species. Thus, soil coarsening is an important factor in predicting drought resistance as well as composition of the community, and should be given more attention under future climate changes.

Study on Soil Desalination Process of Saline-Alkaline Grassland along the Yellow River in Western Inner Mongolia under Subsurface Drainage

This study aimed to explore the characteristics of water and salt transport in saline-alkali grassland, effectively guide the ecological construction of saline-alkali grassland along the Yellow River in western Inner Mongolia, and provide a theoretical basis and technical support for the ecological restoration of saline-alkali grassland and regional environmentally sustainable development. The desalination process of saline-alkali soil under the condition of subsurface pipe drainage was simulated using an indoor soil tank test. The variation in soil leaching water consumption, the salinity of the leaching filtrate with time, the accumulation of the filtrate, and the desalination rate of the filtrate under the condition of continuous leaching with a 25 mm head were analyzed. At the same time, the variation process of soil conductivity at 0~40 cm (upper layer), 40~80 cm (middle layer), and 80~120 cm (lower layer) was analyzed. Subsurface pipe drainage can reduce the soil salt content, while reducing the control area of the subsurface pipes can accelerate the soil desalination rate, thus improving the quality of saline-alkali soil. In addition, the leaching effect under 30 cm partition spacing was better than that under 35, 40, and 45 cm partition spacing, and the corresponding desalination rate was higher. Under stable continuous leaching with a 25 mm head, the entire leaching process can be divided into three stages: the rapid desalination, moderate desalination, and stable stages. During the desalination process, the upper, middle, and lower layers were desalinated synchronously, and the desalination rate of the upper layer was the highest, followed by the desalination rate of the middle and lower layers.

Early sowing is more effective in the long-term for restoring sandy grassland than six years of mowing or carbon amendment

In order to find the best and most reliable practices for ecological restoration of degraded lands, longer time scales should be considered when evaluating restoration efforts. We assessed the long-term (16 years) effects of different grassland restoration treatments – seeding, mowing, and carbon amendment – in the Pannonian sand grasslands. After re-plowing in 1 m × 1 m plots, treatments were carried out in two abandoned croplands. Seeding was applied only initially (2002) while mowing and carbon amendment were carried out for six years (2003–2008). Vegetation was surveyed yearly from 2003 to 2008 and re-sampled in 2019 in each permanent treatment plot. We used principal coordinates analysis to describe the trajectories of vegetation development and linear mixed-effects models to test changes in the relative cover of native sand grassland (target) and invasive (neophyte) species with time and treatments. Relative cover of target species increased while neophyte species decreased with time in both sites. There was a higher relative cover of target species from the first or third year on and a lower relative cover of neophyte species from the third year on in one site in seeded plots compared to other treatments. Seeded species also spread into non-seeded plots by 2019, obscuring the differences between treatments 16 years after sowing. Carbon amendment proved to be beneficial in the early and mowing in the later phases of restoration. Based on the long-term results, initial seeding is the best method for restoring sand grasslands in old fields by favoring the establishment of target species and controlling non-native invasion. As a supplement to seeding, carbon amendment can be suggested in the initial phases and/or low-intensity mowing in the later phases of the restoration after land abandonment. Although the spread from seeded plots obscured the long-term differences between treatments, it optimized the restoration process, suggesting that the use of small seed introduction units can be enough to restore the whole degraded area.