Native Grassland Communities Research Articles

A juhlegeltetési módok hatása a gyepen felvételezhető endoparazita populációra

Sampling for the occurrence of internal parasites of sheep was carried out in three extensively cultivated Achilleo - Festucetum pseudovinae grass communities with different grazing systems but with the same site conditions, in 2022 - 2023, at the MATE Research Institute in Karcag, Hungary. The sheep grazing regimes studied were: pastoral grazing, rotational grazing, and permanent, delta - forest grazing used on all grazing days. Microscopic analysis of the genomes and numbers of potentially infective oviposition and L3 larval stage endoparasites in sheep pastures was carried out on samples of faecal matter from grazed pastures and grass samples prepared using a 'larval feeder'. Our research objective was to clarify the effect of different sheep grazing practices on parasite infestation in a semi - natural grassland community with a solonyec soil composition.

Mowing increased community stability in semiarid grasslands more than either fencing or grazing.

A substantial body of empirical evidence suggests that anthropogenic disturbance can affect the structure and function of grassland ecosystems. Despite this, few studies have elucidated the mechanisms through which grazing and mowing, the two most widespread land management practices, affect the stability of natural grassland communities. In this study, we draw upon 9 years of field data from natural grasslands in northern China to investigate the effects of gazing and mowing on community stability, specifically focusing on community aboveground net primary productivity (ANPP) and dominance, which are two major biodiversity mechanisms known to characterize community fluctuations. We found that both grazing and mowing reduced ANPP in comparison to areas enclosed by fencing. Grazing reduced community stability by increasing the likelihood of single-species dominance and decreasing the relative proportion of nondominant species. In contrast, mowing reduced the productivity of the dominant species but increased the productivity of nondominant species. As a consequence, mowing improved the overall community stability by increasing the stability of nondominant species. Our study provides novel insight into understanding of the relationship between community species fluctuation-stability, with implications for ecological research and ecosystem management in natural grasslands.

Mechanical and biotic reclamation strategies for a post‐mine temperate grassland

AbstractGlobal energy production is in high demand and is expanding its development into new landscapes, including grasslands. This expansion has intensive impacts on aboveground and belowground components of grasslands which need to be addressed during reclamation to promote long‐term ecological integrity. This study was conducted to ascertain how alternative reclamation practices may improve soil structure (i.e., compaction) while aiding in the creation of conditions that are conducive to both the establishment and continued growth of native grassland plant species. The grassland was reclaimed with different combinations of seeding mixtures (grass or grass and forb), ripping techniques (subsoil ripping or topsoil ripping), and the integration of mulch into the soil profile. Year, seed mixtures, and ripping techniques and their interactions significantly affected community composition and species diversity. Topsoil‐ripping and grass‐forb treatment had a higher association with native, perennial grasses while subsoil‐ripping and grass treatment favor more short‐lived species. Similar trends persisted across penetration resistance and soil moisture readings where topsoil‐ripping and grass‐forb treatment were different from subsoil‐ripping and grass treatments (p ≤ 0.10). Additionally, Kentucky bluegrass, an invasive grass species, increased by 76% over 1 year and was more common in the topsoil‐ripping and grass‐forb treatments. While early in the reclamation process, results suggest topsoil‐ripping and grass‐forb treatment are promising combination reclamation practices that can establish a native grassland community and initiate the improvement of compacted soil conditions.

Life History Traits of Exotic and Native Species Determine Grassland Management Outcomes Following Prescribed Fire

<h3>ABSTRACT</h3> Disturbance regimes, including the historical timing of disturbance, are important components of natural ecosystems and greatly influence ecosystem structure and functioning. Consequently, disturbance timing can be an important component of biodiversity management. We evaluated the effect of prescribed fires ignited during the warm and cool seasons (summer and spring, respectively) on the plant community of a calcareous grassland in northern Mississippi (USA). We found that fire season influenced plant community composition by having differential impacts on species with different life history traits. Differences among species were primarily driven by the dichotomy between cool-season (C₃) and warm-season (C₄) plants, independent of species native status. Spring burns reduced the cover of cool-season C₃ graminoids, but had the opposite effect on C₄ graminoids, which likely benefited from increases in resource availability due to the reduction of C₃ species. However, summer burns decreased the abundance of C₄ graminoids, as summer burns were ignited during the active growing and reproductive period for the C₄ species. We found the same patterns for the number of inflorescences of the most abundant C₃ and C₄ graminoids. Summer burns also increased overall species diversity and the abundance of native C₃ graminoids, forbs, and vines, resulting in significant differences in plant community composition between spring- and summer-burned areas. Programs that aim to restore native grassland communities in the short-term using prescribed fire should consider the life history traits of target plants (including invasive species) to determine the best time for prescribed fire implementation.

Restoration of insect communities after land use change is shaped by plant diversity: a case study on carabid beetles (Carabidae)

There is no doubt about the insect decline currently taking place in ecosystems with large anthropogenic impacts. Thus, there is a need for practices that avoid insect decline and or help to recover insect communities that have already suffered. Plant diversity has been shown to be positively related to insect abundance and diversity and to ecosystem functions provided by insects. However, it remains open if increased plant diversity can help to recover decreased populations. Here, we tested over one decade the effects of plant diversity on the carabid community in a large grassland biodiversity experiment and how plant diversity fostered the establishment of a natural grassland community after conversion of an arable field. There was a dramatic decline in carabid abundance from 2003, the first year after establishing the diversity experiment, to 2005. However, subsequently, the abundance increased constantly. One year after the land use change most individuals and species were those commonly found in agricultural fields. In subsequent years the community was dominated by grassland species. While plant diversity did not affect the abundance and richness of the carabid community, the turnover to a more native grassland community was accelerated by plant diversity in the first years after the land use change. In contrast, in later years plant diversity stabilized the community assemblage. Our study shows that high plant diversity can contribute to a faster transition of insect populations towards naturally occurring community assemblages and at later stages to more stabilized assemblages.

内蒙古高原植物气孔性状的空间变异及其适应机制

PDF HTML阅读 XML下载 导出引用 引用提醒 内蒙古高原植物气孔性状的空间变异及其适应机制 DOI: 10.5846/stxb202204090934 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家科技基础调查项目(2019FY101300);国家自然科学基金项目(31872683,31988102,31961143022) Spatial variations and adaptive mechanisms of plant stomatal traits on the Inner Mongolian Plateau Author: Affiliation: Fund Project: National Science and Technology Basic Survey Project(2019FY101300) ；The National Natural Science Foundation of China (31872683,31988102,31961143022) 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:气孔是植物与大气进行水气交换的阀门,调节着植物的蒸腾与光合作用。 因此,气孔性状的变异影响着植物功能,并能够反映植物对环境的适应。目前,内蒙古高原草地植物气孔性状的空间变异及其对环境的响应尚未被探究。于2018年在内蒙古高原草原区沿降水梯度设置了10个受人为干扰较少的天然草地样地,采集每个样地及周围的植物,并对每个物种叶片上、下表皮的气孔性状进行了测量和计算。结果表明:(1)气孔密度(SD)、气孔大小(SS)和气孔相对面积(SRA)的均值分别为262.29个/mm2、378.84 μm2和8.10%;下表皮与上表皮的气孔密度比(R.SD)、大小比(R.SS)和相对面积比(R.SRA)的均值分别为1.54、1.04和1.61。(2)由于草地生境开阔,气孔形态性状在不同生活型(草本与木本植物、一二年生与多年生草本)间没有显著差异(P>0.05)。(3)从草甸草原到荒漠草原,叶片SD和SRA减小,SS增大,气孔性状变异的主要驱动因素是年降水。(4)气孔综合指标SRA主要受SD驱动,降低叶片SD是内蒙古高原草地植物提高耐旱性的重要机制之一。(5)植物还可以通过降低气孔比来适应干旱胁迫,下表皮气孔是内蒙古高原植物气孔比降低的主要贡献者。研究结果有助于进一步了解草地植物叶片气孔独特的气候适应机制,还可为生态预测模型提供基础数据。 Abstract:Stomata are the valves for water and CO2 exchange between plants and the surrounding environment, regulating plant transpiration as well as photosynthesis to some extent. Therefore, the spatial variation of stomatal traits affects plant functions and reflects the adaptation of plants to their environments. The stomatal traits have attracted scientists' attention for a long time. However, spatial variation in the stomatal traits of grassland plants on the Inner Mongolia Plateau and their responses to the environment has not yet been explored. In this study, we set up 10 study sites, with low levels of human disturbance, along the precipitation gradient on the Inner Mongolian Plateau. In 2018, we collected nearly all the plant species that were present within a 1 km×1 km area of each site. The stomatal density (SD), stomatal size (SS), and the stomatal relative area (SRA) of the adaxial and abaxial epidermis of each species were measured. Meanwhile, the ratio of stomatal traits between the abaxial and adaxial epidermis was calculated. Results showed that the mean SD, SS, and the SRA were 262.29 stomata/mm2, 378.84 μm2, and 8.10%, respectively. The mean stomatal density ratio (R.SD), the stomatal size ratio (R.SS), and the stomatal relative area ratio (R.SRA) were 1.54, 1.04, and 1.61, respectively. Due to the open grassland habitat, there were no significant differences in leaf stomatal morphological traits among the different life forms, namely herbs vs woody plants and annual or biennial herbs vs perennial herbs (P>0.05). With the increase in the degree of drought, the leaf SD and SRA decreased, and the SS increased. The mean annual precipitation was the main driving factor of stomatal variation, and the mean annual temperature and photosynthetically active radiation had no significant effect on stomatal traits. The SRA was mainly driven by the SD, and it was one of the most important mechanisms of reducing leaf SD to improve the drought tolerance of grassland plants on the Inner Mongolian Plateau. Plants can also adapt to drought by reducing the stomatal ratio. The stomata in the abaxial epidermic were the main contributor to the decrease in the stomatal ratio on the Inner Mongolian Plateau. These new findings help us further understand the unique climate adaptation mechanisms of plant stomata in natural grassland communities and provide these ecological process models as baseline data. 参考文献 相似文献 引证文献

Evaluating the Melbourne Strategic Assessment—Elegant on process, currently failing on implementation

SummaryThis paper provides a critical analysis of the development and current outcomes of Australia's first endorsed strategic assessment under the Environment Protection and Biodiversity Conservation Act 1999, namely, the Melbourne Strategic Assessment. It covers progress towards protection of a number of Nationally Significant Species and Ecological Communities – most notably, the native grassland communities immediately adjacent to Melbourne's Urban Growth Boundary. The Commonwealth approval to protect biodiversity and allow urban development was made in 2010 and it aimed to achieve its outcomes by 2020. These outcomes included providing new land for homes, for new transport corridors, and for conservation of biodiversity. Natural Temperate Grassland (4,667 ha), Grassy Eucalypt Woodland (709 ha) and seven other Matters of National Environmental Significance will be impacted. Mitigation for this is establishment of 15,000 ha of grassland reserves, 1,200 ha of grassy woodland reserves, over 4,000 ha of other land zoned for conservation and 300 ha of wetland restoration. We conclude that the Melbourne Strategic Assessment has been a success in terms of the elegance and comprehensiveness of the approach, in cooperation between the levels of government, in the economic benefits, and in some aspects of social engagement of the agreement. However, the achievement of environmental outcomes must be currently considered a failure due to poor implementation. This failure includes not meeting the agreed 10 year deadline for land acquisition and management, poor monitoring and protection of set‐aside areas, and in reporting. We offer suggestions for how these current shortcomings could be overcome. These align well with the recommendations of the review of the Environment Protection and Biodiversity Conservation Act 1999 (The independent statutory review of the Act in 2020) and include the establishment of the proposed Office of Compliance and Enforcement, the adoption of National Environmental Standards and the reforms regarding the role of Indigenous Australians in strategic assessments. If these were adopted, we conclude that the strategic assessment approach should be more widely used because of the more holistic approach and efficiencies that it envisages compared with site by site approaches.

Efficacy of strip seeding to restore grassland plant communities

Strip seeding is a novel restoration practice of strategically planting in strips, resulting in alternating seeded and unseeded areas to target efforts and reduce costs while achieving ecological outcomes similar to conventional methods of seeding entire sites. However, there has been limited work testing the efficacy of this method, including how strip width and percent seeded area affect restoration outcomes. We evaluated four native grass strip seed treatments (33%, 50% narrow, 50% wide, and 66% of area seeded), an unseeded control, and a conventional 100% seeded control to investigate: (1) how plant communities in seeded and unseeded strips change over time; (2) how initial strip width affect native species biomass, invasive species biomass, and plant species diversity; and (3) cost‐effectiveness of strip seeding in terms of management costs and benefits accrued. Four years post‐seeding, seeded and unseeded strips exhibited unique plant communities; seeded strips were characterized by native perennial grasses while unseeded strips had a higher abundance of annual forbs (majority non‐native) and non‐native annual grasses. Plant communities were similar within strips across strip seeding treatments. Invasion resistance and productivity scaled with percent area initially seeded, but by year four all strip seed treatments (33–66%) provided similar benefits to conventional seeding (100%). Overall, this suggests strip seeding is a promising, cost‐effective method to restore targeted species and maintain native grassland communities. Further research is needed on long‐term effects, ecological and economic barriers and opportunities, and provisioning of a broad suite of ecosystem services across different environmental contexts and management practices.

Functional assembly of grassland plant species in native communities in Spain and recipient communities in California

Abstract A major aim in invasion ecology is to understand the role of exotic species in plant communities. Whereas most studies have explored the traits of exotic species in the context of the introduced community, functional comparisons of entire assemblages of species in their native and introduced communities have rarely been analysed. Taking advantage of the unidirectional invasion of plant species of European origin (i.e. colonizers) into California, this study aims to investigate the relative importance of plant traits, environmental factors and invasion status in biological invasions. We compared the functional structure (i.e. trait composition and diversity) along resource availability gradients in recipient and native Mediterranean grassland communities in California and Spain, respectively. Traits were related to resource use in above‐ground and below‐ground organs and reproductive strategy. We also investigated how niche differences vary along environmental gradients between coexisting colonizer and native species assemblages within communities. There were clear differences in the functional structure of Mediterranean grassland communities between regions, which were associated with the resource availability gradient. Paradoxically, the most acquisitive communities occurred in resource‐poor sites, highlighting that rapid acquisition and use of resources permit species to cope with environmental stress through stress avoidance. In Spain, colonizer species had greater specific leaf area than non‐colonizers. Yet, differences between colonizer and non‐colonizer species in Spain for other traits were mostly absent and did not change along the gradient. This might be a result of the greater native species richness as a consequence of the agricultural practices that have taken place in Europe for millennia and reflect that the entire species pool of grasslands is adapted to agricultural landscapes. In comparison, in California, colonizer species were more acquisitive in their use of resources than natives under favourable conditions, but functionally converged in resource‐limited sites. Synthesis. These results underscore that the importance of niche differences between native and colonizer species as a community assembly mechanism is strongly subjected to the influence of habitat filtering. Trait comparisons are context dependent, and a correct interpretation of filtering processes in community assembly requires a regional perspective.

Post-Invasion Recovery of Plant Communities Colonised by Gunnera tinctoria after Mechanical Removal or Herbicide Application and Its Interaction with an Extreme Weather Event.

The interventions that are required for both the control and post-invasion restoration of native plant communities depends on several factors, including the efficacy of the measures that are used and how these interact with environmental factors. Here, we report on the results of an experiment on the effects of mechanical removal and herbicide application on the invasive plant Gunnera tinctoria and how an extreme weather event impacted on the invader and on the recovery of native coastal grassland communities. Both removal protocols were largely effective in eradicating mature plants, but the mechanical removal treatment resulted in a major increase in the number of G. tinctoria seedlings, which was exacerbated by the extreme event. Nine months after removal, the number of native species had recovered to c. 80% of that in uninvaded grasslands. In contrast to seedlings, mature plants of G. tinctoria showed a significant reduction in above-ground production after the extreme weather event, although these had largely recovered after six months. Overall, our results indicate that post-control restoration of the plant community may be possible without further significant management interventions. Nevertheless, since some invasive plants survived, further monitoring is required to ensure that recolonisation does not occur.

Competitive size asymmetry, not intensity, is linked to species loss and gain in a native grassland community.

Competition is often highlighted as a major force influencing plant species diversity. However, there are multiple facets of competition (e.g., strength, intransitivity, and size asymmetry) that may have independent and differential impacts on diversity, making understanding the degree to which competition structures communities difficult. Unfortunately, field-based experiments that decouple multiple facets of competition are lacking, limiting our ability to test theoretical frameworks and reducing understanding of the actual linkages among competition and coexistence. Here, we experimentally manipulate the size structure of local grassland communities to examine the relative impacts of competitive size asymmetry (i.e., competitive advantage based on relative size) and intensity (i.e., mean effect of neighbors on plant growth) on species loss and gain. Increased competitive size asymmetry was associated with increased species loss and decreased species gain, while no relationship was found between competitive intensity and species loss and gain. Furthermore, the probability of loss was not dependent on a species initial size, suggesting that small species may not always be the losers of size-asymmetric interactions. Instead, loss was dependent on species rarity, where loss was higher for rare species. Overall, these results suggest that competitive size asymmetry may be more important for species loss than intensity in some plant communities and demonstrates the importance of decoupling different aspects of competition to better understand their drivers and ecological consequences.

Interspecific trait variability and local soil conditions modulate grassland model community responses to climate.

Medium‐to‐high elevation grasslands provide critical services in agriculture and ecosystem stabilization, through high biodiversity and providing food for wildlife. However, these ecosystems face elevated risks of disruption due to predicted soil and climate changes. Separating the effects of soil and climate, however, is difficult in situ, with previous experiments focusing largely on monocultures instead of natural grassland communities. We experimentally exposed model grassland communities, comprised of three species grown on either local or reference soil, to varied climatic environments along an elevational gradient in the European Alps, measuring the effects on species and community traits. Although species‐specific biomass varied across soil and climate, species' proportional contributions to community‐level biomass production remained consistent. Where species experienced low survivorship, species‐level biomass production was maintained through increased productivity of surviving individuals; however, maximum species‐level biomass was obtained under high survivorship. Species responded directionally to climatic variation, spatially separating differentially by plant traits (including height, reproduction, biomass, survival, leaf dry weight, and leaf area) consistently across all climates. Local soil variation drove stochastic trait responses across all species, with high levels of interactions occurring between site and species. This soil variability obscured climate‐driven responses: we recorded no directional trait responses for soil‐corrected traits like observed for climate‐corrected traits. Our species‐based approach contributes to our understanding of grassland community stabilization and suggests that these communities show some stability under climatic variation.

Biodiversity–productivity relationships in a natural grassland community vary under diversity loss scenarios

Abstract Understanding the biodiversity–productivity relationship and underlying mechanisms in natural ecosystems under realistic diversity loss scenarios remains a major challenge for ecologists despite its importance for predicting impacts of rapid loss of biodiversity worldwide. Here we report the results of a plant functional group (PFG) removal experiment conducted on the Mongolian Plateau, the largest remaining natural grassland in the world. Our results demonstrated that the biodiversity–productivity relationship varied among positive linear, neutral and unimodal forms under different PFG loss patterns. Moreover, the form of this relationship with the same PFG loss pattern sometimes changed through time. The abundance of the remaining PFG(s) before removal and their compensation following the loss of other PFGs were two major mechanisms affecting the biodiversity–productivity relationship under diversity loss scenarios. The abundance effect promoted positive responses of productivity to biodiversity, but the compensation effect caused several biodiversity–productivity relationships, hinging on its direction (positive or negative) and strength. As indicated by the values of the compensation index, negative, zero and partial compensations contributed to the positive relationships, while full compensation resulted in a neutral relationship. Overcompensation at intermediate PFG richness levels created a unimodal curve in our system, but it could also lead to a negative linear relationship. Synthesis. Our experiment provides a vivid picture of how the form of the biodiversity–productivity relationship varies among different diversity loss patterns in a natural ecosystem. We argue that compensation by the remaining species, which is not revealed by synthesized biodiversity experiments, plays a critical role in shaping the form of this relationship when diversity is lost from existing systems. The direction and strength of compensation are highly dependent on extirpation scenarios. Thus, impacts of biodiversity loss on natural ecosystems are likely more complex than predicted by the canonical positive saturating curve obtained from the synthesized biodiversity experiments. We suggest that models forecasting the consequences of biodiversity declines on natural ecosystems should take into account diversity loss patterns and the ensuing compensation.

Streetlights positively affect the presence of an invasive grass species.

Anthropogenic disturbances associated with urban ecosystems can create favorable conditions for populations of some invasive plant species. Light pollution is one of these disturbances, but how it affects the growth and establishment of invasive plant populations is unknown. Cheatgrass (Bromus tectorum) is a problematic invasive species where it has displaced native grassland communities in the United States, but to our knowledge, there have been no studies of the ecological factors that affect cheatgrass presence in urban ecosystems. We conducted field surveys in urban alleys in Denver, Colorado, to compare the presence of cheatgrass at sites with and without artificial light at night (hereafter artificial light) from streetlights. These streetlights are mounted on utility poles, which cause ground disturbance when installed in alleys; we were able to test the independent effect of poles on cheatgrass establishment because not all poles have streetlights on them. We found that cheatgrass was positively associated with the presence of streetlights and to a lesser extent poles. In addition to cheatgrass, we also found that other plants were positively associated with the presence of both poles and streetlights. Our results suggest that artificial light may benefit the occurrence of cheatgrass and other plant species in urban settings. While invasive populations of cheatgrass in wild habitats attract the most attention from managers, we suggest more consideration for this grass in urban environments where its growth and establishment benefit from anthropogenic changes.

Spatial variation of stomatal morphological traits in grassland plants of the Loess Plateau

The stomata control carbon and water vapor exchange between the leaves and atmosphere and may reflect plant adaptation to climate change to some extent. However, the spatial variation of stomatal traits on different sides of the leaves’ epidermis and their response to environmental changes remain unclear. Here, we measured stomatal density (SD), stomatal size (SS), and stomatal relative area (SRA) on both leaf surfaces of 181 plant species across an environmental gradient on the Loess Plateau. We calculated the proportion of stomatal traits between different epidermis surfaces of the leaves (abaxial and adaxial) and measured the total SD (SDtot), total SS (SStot), and total SRA (SRAtot) of the leaves as a whole. The SDtot, SStot, and SRAtot showed a log-normal distribution, differing across grassland types and plant functional groups, with a range of 22.57–890.09 stomata mm−2, 84.61–2022.81 μm2, and 0.51–43.71%, respectively. The SDtot, SStot, and SRAtot differed significantly between different grassland types. Meadow plants had larger SDtot, desert plants had larger SStot, and typical grassland plants had relatively larger SRAtot. The abaxial SD and SRA of the woody plants were significantly higher than those of herbaceous plants, but no significant differences were observed at the adaxial surface or for the overall leaf. A higher SDtot was correlated with a larger stomatal density ratio (R.SD) and smaller stomatal size ratio (R.SS). The R.SD, abaxial SD, abaxial SS, and adaxial SS were significantly correlated with environmental factors, but no such correlations were observed for the adaxial SD. These findings highlight the strong associations of stomatal traits with plant functional group and climate at a regional scale, representing the climatic adaptation strategies of stomatal traits across natural grassland communities.

Exotic oryx interact with shrub encroachment in the Chihuahuan Desert

Biotic invasions can interact with ongoing landscape transitions in introduced ranges, acting synergistically to accelerate landscape change. The African oryx (Oryx gazella), a large ungulate native to the Kalahari Desert in southern Africa, was intentionally released into the Chihuahuan Desert of southern New Mexico to provide increased hunting opportunities. Oryx have subsequently dispersed widely, including into the adjacent Jornada Basin Long Term Ecological Research site, which contains native grassland communities imperiled due to shrub encroachment. We examined how landscape use and diel activity of oryx interacts with shrub encroachment at Jornada Basin. We hypothesized that oryx would be more common on unencroached grasslands that provide preferred forage, and that oryx would be most active at dawn and dusk (crepuscular) when ambient temperatures were favorable and predator surveillance was possible. We sampled 24 sites across a broad gradient of shrub encroachment from 2014 to 2018 using camera traps to evaluate our hypotheses. Oryx relative abundances were higher on unencroached grasslands, especially in years of low to moderate precipitation. We found oryx were most active during crepuscular periods, and this behavior was consistent across the shrub encroachment gradient. Our research suggests exotic oryx could contribute to shrub encroachment by focusing their foraging on remaining grasslands, especially during drier years, which may adversely affect livestock production and other ecosystem services.

An experimental study on potential changes in plant community evapotranspiration due to the invasion of Hydrocotyle vulgaris

Alien plant invasion has caused severe ecological problems in many places around the world. The introduction of exotic species may significantly alter the community composition and has a potential to change water cycle in the local ecosystem. Hydrocotyle vulgaris L. (H. vulgaris) is an introduced species, widely spreading in both aquatic and terrestrial habitats as a potentially invasive plant in humid region of China. A greenhouse experiment was conducted to investigate the impact of H. vulgaris invasion on the evapotranspiration of the native grassland community during the establishment period. Three gradients (none, one, and five seedlings) of the introduced species were established either in bare soil or in an experimental plant community consisting of four grassland species. A bare soil treatment without any plants was conducted as a control. The results showed that H. vulgaris did not affect the evapotranspiration when growing alone in any gradient treatment, while the native grassland community exhibited more rapid evapotranspiration when growing along with H. vulgaris. Moreover, the evapotranspiration of the native grassland community was higher as the introduced species settlers increased in number, but the initial H. vulgaris ramets with different gradient did not significantly affect the growth of native plant community. A reoccurrence experiment was conducted and yielded identical results. The results indicated that H. vulgaris could cause the native grassland community to have higher evapotranspiration, and that such an effect becomes more significant with increasing numbers of invasive propagules. This study may have profound implications for understanding the regional eco-hydrological alteration caused by alien plants invasion.

Manipulation of vegetation with activated carbon reveals the role of root exudates in shaping native grassland communities

AbstractQuestionPlant community assembly has traditionally been viewed from the perspective of plant resource niches and competition and, more recently, facilitation in stressful environments. However, plants also engage in biotic interactions with neighbours and soil microbiome by producing chemically diverse root exudates. Root exudates have the potential to affect plant community productivity and composition by mediating plant interactions, fostering beneficial microbial interactions and affecting nutrient cycling. However, empirical evidence for the role of root exudates in plant community dynamics is still lacking, particularly under field conditions.LocationTwo calcareous grasslands in Western Estonia, Europe.MethodsWe tested the role of root exudates in shaping plant community productivity and composition by applying activated carbon powder, known to adsorb root exudates from soil solution, to two intact species‐rich grasslands. The experiment continued for four years and was combined with fertiliser application.ResultsWe found that the application of activated carbon triggered significant changes in root morphology, plant productivity and growth form composition that were distinct from the effects of fertilisation. Community responses were site‐specific and varied with the duration of activated carbon application. Activated carbon addition increased the production of finer roots in a community with shallow soil in the first year of the experiment and significantly reduced above‐ground productivity at both sites by the end of the fourth growth season. The application of activated carbon promoted legume abundance at both sites and suppressed forb dominance at the site with shallow soil.ConclusionOur findings suggest that chemical interactions in the plant rhizosphere may play an important role in shaping grassland productivity and plant community composition. We also show that activated carbon can be used as an effective tool for manipulating plant interactions in intact grasslands occupied by long‐lived individuals.

The effect of fire on terrestrial amphipods (Crustacea: Amphipoda) in a natural grassland community

Fire is known to cause severe and protracted reductions in some invertebrate communities. Amphipods are prone to desiccation and, therefore, litter removal through fire could be expected to have a significant adverse impact on their populations. We aimed to determine the temporal and spatial response patterns in density of amphipods following seasonal fires in a natural grassland site in southern South Island, New Zealand. Fires lit for management purposes in spring are generally cooler and considered less detrimental to the ecosystem than those occurring in hot dry summer conditions. Annual quantitative sampling was used to measure amphipod density in tussock grassland communities before and after single fire treatments were carried out in either spring or summer. Three samples were taken annually before each of the experimental fires, and for 12 years post-treatment. In general, amphipod populations took 7–9 years after treatment to recover to pre-burn densities although densities in spring burnt plots recovered more slowly. Eleven years post-burn, the spatial distribution of amphipods in relation to microhabitat was also examined. Two amphipod species were present, and they were distributed differently in tussock and inter-tussock vegetation and responded differently to fire but not to fire season. A protracted period of recovery from fire for an important member of the detritivore community is likely to have negative impacts on nutrient cycling, and therefore on primary production in grassland systems. The implication for land managers is to avoid burning in spring if soil conditions are relatively dry.

Semi-polar root exudates in natural grassland communities.

In the rhizosphere, plants are exposed to a multitude of different biotic and abiotic factors, to which they respond by exuding a wide range of secondary root metabolites. So far, it has been unknown to which degree root exudate composition is species‐specific and is affected by land use, the local impact and local neighborhood under field conditions. In this study, root exudates of 10 common grassland species were analyzed, each five of forbs and grasses, in the German Biodiversity Exploratories using a combined phytometer and untargeted liquid chromatography‐mass spectrometry (LC‐MS) approach. Redundancy analysis and hierarchical clustering revealed a large set of semi‐polar metabolites common to all species in addition to species‐specific metabolites. Chemical richness and exudate composition revealed that forbs, such as Plantago lanceolata and Galium species, exuded more species‐specific metabolites than grasses. Grasses instead were primarily affected by environmental conditions. In both forbs and grasses, plant functional traits had only a minor impact on plant root exudation patterns. Overall, our results demonstrate the feasibility of obtaining and untargeted profiling of semi‐polar metabolites under field condition and allow a deeper view in the exudation of plants in a natural grassland community.