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Evaluation of restoration activities is indispensable to assess the extent to which targets have been reached. Usually, the main goal of ecological restoration is to restore biodiversity and ecosystem functioning, but validation is often based on a single indicator, which may or may not cope with whole‐ecosystem dynamics. Network analyses are, however, powerful tools, allowing to examine both the recovery of various biotic and abiotic properties and the integrated response at community and ecosystem level.We used restoration sites where topsoil was removed from former intensively managed grassland and seeds were added. These sites were between 3 and 32 years old. We assessed how plants, soil biota, soil properties and correlation‐based interactions between biotic communities and their abiotic environment developed over time and compared the results with (i) intensively managed (not restored), and (ii) well‐preserved targeted semi‐natural grasslands.Plant, nematode, fungal and prokaryotic diversity and community structures of the restored grasslands revealed clear successional patterns and followed similar trajectories towards targeted semi‐natural grasslands. All biotic communities reached targeted diversity levels no later than 18 years post‐restoration.Ecological networks of intensively managed and short‐term (~4 years) restored grasslands were less tightly connected compared to those found in mid‐ and long‐term (~18–30 years) restored and target grasslands. Restoration specifically enhanced interactions among biotic communities, but reduced interactions between biotic communities and their abiotic environment as well as interactions among abiotic properties in the short‐ and mid‐term.Synthesis and applications: Overall, our study demonstrated that topsoil removal and seed addition were successful in restoring diverse, tightly coupled and well‐connected biotic communities above‐ and below‐ground similar to those found in the semi‐natural grasslands that were restoration targets. Network analyses proved to be powerful in examining the long‐term re‐establishment of functionally connected biotic communities in restored ecosystems. Thus, we provide an approach to holistically assess restoration activities by notably considering the complexity of ecosystems, much in contrast to most traditional approaches. [ABSTRACT FROM AUTHOR]

To evaluate how increased anthropogenic nutrient inputs alter carbon cycling in grasslands, we conducted a litter decomposition study across 20 temperate grasslands on three continents within the Nutrient Network, a globally distributed nutrient enrichment experimentWe determined the effects of addition of experimental nitrogen (N), phosphorus (P) and potassium plus micronutrient (Kμ) on decomposition of a common tree leaf litter in a long‐term study (maximum of 7 years; exact deployment period varied across sites). The use of higher order decomposition models allowed us to distinguish between the effects of nutrients on early‐ versus late‐stage decomposition.Across continents, the addition of N (but not other nutrients) accelerated early‐stage decomposition and slowed late‐stage decomposition, increasing the slowly decomposing fraction by 28% and the overall litter mean residence time by 58%.Synthesis. Using a novel, long‐term cross‐site experiment, we found widespread evidence that N enhances the early stages of above‐ground plant litter decomposition across diverse and widespread temperate grassland sites but slows late‐stage decomposition. These findings were corroborated by fitting the data to multiple decomposition models and have implications for N effects on soil organic matter formation. For example, following N enrichment, increased microbial processing of litter substrates early in decomposition could promote the production and transfer of low molecular weight compounds to soils and potentially enhance the stabilization of mineral‐associated organic matter. By contrast, by slowing late‐stage decomposition, N enrichment could promote particulate organic matter (POM) accumulation. Such hypotheses deserve further testing. [ABSTRACT FROM AUTHOR]

Increasing evidence suggests that remotely sensed spectral diversity is linked to plant species richness. However, a conflicting spectral diversity–biodiversity relationship in grasslands has been found in previous studies. In particular, it remains unclear how well the spectral diversity–biodiversity relationship holds in naturally assembled species‐rich grasslands. To address the linkage between spectral diversity and plant species richness in a species‐rich alpine grassland ecosystem, we investigated (i) the trade‐off between spectral and spatial resolution in remote sensing data; (ii) the suitability of three different spectral metrics to describe spectral diversity (coefficient of variation, convex hull volume and spectral species richness) and (iii) the importance of confounding effects of live plant biomass, dead plant biomass and plant life forms on the spectral diversity–biodiversity relationship. We addressed these questions using remote sensing data collected with consumer‐grade cameras with four spectral bands and 10 cm spatial resolution on an unmanned aerial vehicle (UAV), airborne imaging spectrometer data (AVIRIS‐NG) with 372 bands and 2.5 m spatial resolution, and a fused data product of both datasets. Our findings suggest that a fused dataset can cope with the requirement of both high spatial‐ and spectral resolution to remotely measure biodiversity. However, in contrast to several previous studies, we found a negative correlation between plant species richness and spectral metrics based on the spectral information content (i.e. spectral complexity). The spectral diversity calculated based on the spectral complexity was sensitive to live and dead plant biomass. Overall, our results suggest that remote sensing of plant species diversity requires a high spatial resolution, the use of classification‐based spectral metrics, such as spectral species richness, and awareness of confounding factors (e.g. plant biomass), which may be ecosystem specific. [ABSTRACT FROM AUTHOR]

Nutrients and herbivores are well‐known drivers of grassland diversity and stability in local communities. However, whether they interact to impact the stability of aboveground biomass and whether these effects depend on spatial scales remain unknown. It is also unclear whether nutrients and herbivores impact stability via different facets of plant diversity including species richness, evenness, and changes in community composition through time and space. We used a replicated experiment adding nutrients and excluding herbivores for 5 years in 34 global grasslands to explore these questions. We found that both nutrient addition and herbivore exclusion alone reduced stability at the larger spatial scale (aggregated local communities; gamma stability), but through different pathways. Nutrient addition reduced gamma stability primarily by increasing changes in local community composition over time, which was mainly driven by species replacement. Herbivore exclusion reduced gamma stability primarily by decreasing asynchronous dynamics among local communities (spatial asynchrony). Their interaction weakly increased gamma stability by increasing spatial asynchrony. Our findings indicate that disentangling the processes operating at different spatial scales may improve conservation and management aiming at maintaining the ability of ecosystems to reliably provide functions and services for humanity. [ABSTRACT FROM AUTHOR]

Human‐caused loss of vertebrate and invertebrate animals, defaunation, is increasing, and potentially affects plant community structure of diverse grassland ecosystems world‐wide.We experimentally simulated defaunation using size‐selective fences to progressively exclude large‐, medium‐ and small‐sized mammals, and invertebrates from two subalpine vegetation types in the Swiss National Park (SNP): intensively grazed short‐grass and moderately grazed tall‐grass vegetation. We assessed plant community properties yearly from 2009 to 2013, and examined treatment effects on plant community structure in the two grassland types.In the short‐grass vegetation, the exclusion of large mammals increased total plant biomass, while the exclusion of large and medium‐sized mammals increased total, grass and forb biomass compared to when all animals had access. These increases became stronger when invertebrates were also excluded. The exclusion of all mammals and invertebrates increased biomass of grasses by 205%, forbs by 100% and total plant biomass by 118% compared to when all animals had access, hence enhancing relative biomass of grasses from 43.6% to 60%, changing plant species composition and lowering richness of forbs by 16%, the number of plant families by 13% and family‐level Shannon diversity by 23%. In contrast to these significant community‐level responses found in the short‐grass vegetation, there was no evidence that the size‐selective exclusion of animals altered the plant community structure of the tall‐grass vegetation. The contrasting results were due to the difference in plant community composition prior to our experiment, which were related to differences in quantity and quality of forage and in grazing intensities of herbivores between the two grassland types.Synthesis. Our results showed that different‐sized animals, in particular large mammals and invertebrates, contributed to maintain the plant community structure in the short‐grass vegetation, highlighting the importance of multiple, functionally different animal groups for ecosystem functioning and stability. In contrast to the short‐grass vegetation, we could not detect such a top‐down control by animals in the tall‐grass vegetation. Our results suggest that potential defaunation effects on grassland plant community structure depend on the degree of grazing pressure release and grassland vegetation type. [ABSTRACT FROM AUTHOR]

It is generally assumed that restoring biodiversity will enhance diversity and ecosystem functioning. However, to date, it has rarely been evaluated whether and how restoration efforts manage to rebuild biodiversity and multiple ecosystem functions (ecosystem multifunctionality) simultaneously. Here, we quantified how three restoration methods of increasing intervention intensity (harvest only < topsoil removal < topsoil removal + propagule addition) affected grassland ecosystem multifunctionality 22 yr after the restoration event. We compared restored with intensively managed and targeted seminatural grasslands based on 13 biotic and abiotic, above‐ and belowground properties. We found that all three restoration methods improved ecosystem multifunctionality compared to intensively managed grasslands and developed toward the targeted seminatural grasslands. However, whereas higher levels of intervention intensity reached ecosystem multifunctionality of targeted seminatural grasslands after 22 yr, lower intervention missed this target. Moreover, we found that topsoil removal with and without seed addition accelerated the recovery of biotic and aboveground properties, and we found no negative long‐term effects on abiotic or belowground properties despite removing the top layer of the soil. We also evaluated which ecosystem properties were the best indicators for restoration success in terms of accuracy and cost efficiency. Overall, we demonstrated that low‐cost measures explained relatively more variation of ecosystem multifunctionality compared to high‐cost measures. Plant species richness was the most accurate individual property in describing ecosystem multifunctionality, as it accounted for 54% of ecosystem multifunctionality at only 4% of the costs of our comprehensive multifunctionality approach. Plant species richness is the property that typically is used in restoration monitoring by conservation agencies. Vegetation structure, soil carbon storage and water‐holding capacity together explained 70% of ecosystem multifunctionality at only twice the costs (8%) of plant species richness, which is, in our opinion, worth considering in future restoration monitoring projects. Hence, our findings provide a guideline for land managers how they could obtain an accurate estimate of aboveground‐belowground ecosystem multifunctionality and restoration success in a highly cost‐efficient way. [ABSTRACT FROM AUTHOR]

Soil nitrogen (N) availability is critical for grassland functioning. However, human activities have increased the supply of biologically limiting nutrients, and changed the density and identity of mammalian herbivores. These anthropogenic changes may alter net soil N mineralization (soil net Nmin), that is, the net balance between N mineralization and immobilization, which could severely impact grassland structure and functioning. Yet, to date, little is known about how fertilization and herbivore removal individually, or jointly, affect soil net Nmin across a wide range of grasslands that vary in soil and climatic properties. Here we collected data from 22 grasslands on five continents, all part of a globally replicated experiment, to assess how fertilization and herbivore removal affected potential (laboratory‐based) and realized (field‐based) soil net Nmin. Herbivore removal in the absence of fertilization did not alter potential and realized soil net Nmin. However, fertilization alone and in combination with herbivore removal consistently increased potential soil net Nmin. Realized soil net Nmin, in contrast, significantly decreased in fertilized plots where herbivores were removed. Treatment effects on potential and realized soil net Nmin were contingent on site‐specific soil and climatic properties. Fertilization effects on potential soil net Nmin were larger at sites with higher mean annual precipitation (MAP) and temperature of the wettest quarter (T.q.wet). Reciprocally, realized soil net Nmin declined most strongly with fertilization and herbivore removal at sites with lower MAP and higher T.q.wet. In summary, our findings show that anthropogenic nutrient enrichment, herbivore exclusion and alterations in future climatic conditions can negatively impact soil net Nmin across global grasslands under realistic field conditions. This is an important context‐dependent knowledge for grassland management worldwide. [ABSTRACT FROM AUTHOR]

Seminatural grasslands are important biodiversity hotspots, but they are increasingly degraded by intensive agriculture. Grassland restoration is considered to be promising in halting the ongoing loss of biodiversity, but this evaluation is mostly based on plant communities. Insect herbivores contribute substantially to grassland biodiversity and to the provisioning of a variety of ecosystem functions. However, it is unclear how they respond to different measures that are commonly used to restore seminatural grasslands from intensively used agricultural land. We studied the long‐term success of different restoration techniques, which were originally targeted at reestablishing seminatural grassland plant communities, for herbivorous insect communities on taxonomic as well as functional level. Therefore, we sampled insect communities 22 yr after the establishment of restoration measures. These measures ranged from harvest and removal of biomass to removal of the topsoil layer and subsequent seeding of plant propagules. We found that insect communities in restored grasslands had higher taxonomic and functional diversity compared to intensively managed agricultural grasslands and were more similar in composition to target grasslands. Restoration measures including topsoil removal proved to be more effective, in particular in restoring species characterized by functional traits susceptible to intensive agriculture (e.g., large‐bodied species). Our study shows that long‐term success in the restoration of herbivorous insect communities of seminatural grasslands can be achieved by different restoration measures and that more invasive approaches that involve the removal of the topsoil layer are more effective. We attribute these restoration successes to accompanying changes in the plant community, resulting in bottom‐up control of the herbivore community. Our results are of critical importance for management decisions aiming to restore multi‐trophic communities, their functional composition and consequently the proliferation of ecosystem functions. [ABSTRACT FROM AUTHOR]

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Successful restoration of semi‐natural grasslands on grasslands previously subject to intensive management needs to overcome manifold barriers. These include high soil fertility, the dominance of a few fast‐growing plant species, degraded soil faunal communities and missing propagules of the targeted above‐ and below‐ground flora and fauna. A combination of removing the topsoil and introducing propagules of target plants has become one of the major tools for nature conservation agencies and practitioners to reduce soil fertility and restore former species‐rich grasslands in various European countries.Using topsoil removal as a restoration measure has provoked an ongoing debate between supporting nature conservation and rejecting soil protection agencies. Although it favours species‐rich plant communities, it strongly disturbs soil communities and affects physical and chemical soil properties and processes. Currently, there is a lack of long‐term data to assess how restored grassland ecosystems develop and recover after topsoil removal. Here, we used two well‐established bioindicators, soil nematodes and plants, to quantify restoration success of topsoil removal in comparison with alternative restoration measures and target communities 22 years after intervention.The nematode community composition indicated reduced nutrient availability in the restored systems, as was aimed at by topsoil removal. Nevertheless, after this 22‐year period following topsoil removal, nematode composition and structure revealed successful recovery.Plant communities benefitted from the reduction of soil nutrients after topsoil removal as indicated by higher numbers of plant species and higher Shannon diversity. Furthermore, topsoil removal strongly promoted the re‐establishment of plant species of the target plant community.Synthesis and applications. Overall, our study demonstrates how a massive intervention by topsoil removal proved successful in converting intensively managed into species‐rich grasslands. This contrasts with the mild intervention of repeated mowing and removing of the harvested plant material. We show that, in the long run, potential negative effects of topsoil removal on the soil fauna can be successfully overcome and plant communities can develop into targeted species‐rich grassland. Overall, our study demonstrates how a massive intervention by topsoil removal proved successful in converting intensively managed into species‐rich grasslands. This contrasts with the mild intervention of repeated mowing and removing of the harvested plant material. We show that, in the long run, potential negative effects of topsoil removal on the soil fauna can be successfully overcome and plant communities can develop into targeted species‐rich grassland. [ABSTRACT FROM AUTHOR]

Mammalian grazing induces changes in vegetation properties in grasslands, which can affect a wide variety of other animals including many arthropods. However, the impacts may depend on the type and body size of these mammals. Furthermore, how mammals influence functional trait syndromes of arthropod communities is not well known. We progressively excluded large (e.g. red deer, chamois), medium (e.g. alpine marmot, mountain hare), and small (e.g. mice) mammals using size‐selective fences in two vegetation types (short‐ and tall‐grass vegetation) of subalpine grasslands. We then assessed how these exclusions affected the community composition and functional traits of ground beetles (Coleoptera, Carabidae), and which vegetation characteristic mediated the observed effects. Total carabid biomass, the activity densities of carabids with specific traits (i.e. small eyes, short wings), the richness of small‐eyed species and the richness of herbivorous species were significantly higher when certain mammals were excluded compared to when all mammals had access, regardless of vegetation type. Excluding large and medium mammals increased the activity density of herbivorous carabid species, but only in short‐grass vegetation. Similarly, excluding large mammals (ungulates) altered carabid species composition in the short‐, but not in the tall‐grass vegetation. All these responses were related to aboveground plant biomass, but not to plant Shannon diversity or vegetation structural heterogeneity. Our results indicate that changes in aboveground plant biomass are key drivers of mammalian grazers’ influence on carabids, suggesting that bottom–up forces are important in subalpine grassland systems. The exclusion of ungulates provoked the strongest carabid response. Our results, however, also highlight the ecological significance of smaller herbivorous mammals. Our study furthermore shows that mammalian grazing not only altered carabid community composition, but also caused community‐wide functional trait shifts, which could potentially have a wider impact on species interactions and ecosystem functioning. [ABSTRACT FROM AUTHOR]

A rigorous treatment of dynamical electron correlation in crystalline solids is one of the main challenges in today's materials quantum chemistry and theoretical solid state physics. In this study, we address this problem by using the local correlation approach and exploring a variety of methods, ranging from the full periodic treatment through embedded fragments to finite clusters. Apart from the computational advantages, the direct‐space local representation for the occupied space allows one to partition the system into fragments and thus forms a natural basis for a hierarchy of embedding models. Furthermore, a subset of localized orbitals in a cluster or a fragment can be chosen to mimic the unit cell of the reference periodic system. Introduction of such subsets allows one to define a formal quantity “the correlation energy per unit cell”, which is directly related to the correlation energy per unit cell in the crystal. The orbital pairs, where neither of the two localized orbital indices belongs to the “unit cell” do not explicitly contribute to the “energy per cell”: Their role is to provide correlated embedding via the couplings in the amplitude equations. The periodic, fragment and finite‐cluster approaches can be combined in a form of high precision computational protocols, where progressively higher‐level corrections are evaluated using lower‐level embedding models. We apply these techniques to investigate the importance of Coulomb screening in dispersively interacting systems on the examples of the phosphorene bilayer and the adsorption of water on 2D silica. This article is categorized under: Structure and Mechanism > Computational Materials Science Electronic Structure Theory > Ab Initio Electronic Structure Methods Software > Quantum Chemistry [ABSTRACT FROM AUTHOR]

Abstract: Plant stoichiometry, the relative concentration of elements, is a key regulator of ecosystem functioning and is also being altered by human activities. In this paper we sought to understand the global drivers of plant stoichiometry and compare the relative contribution of climatic vs. anthropogenic effects. We addressed this goal by measuring plant elemental (C, N, P and K) responses to eutrophication and vertebrate herbivore exclusion at eighteen sites on six continents. Across sites, climate and atmospheric N deposition emerged as strong predictors of plot‐level tissue nutrients, mediated by biomass and plant chemistry. Within sites, fertilization increased total plant nutrient pools, but results were contingent on soil fertility and the proportion of grass biomass relative to other functional types. Total plant nutrient pools diverged strongly in response to herbivore exclusion when fertilized; responses were largest in ungrazed plots at low rainfall, whereas herbivore grazing dampened the plant community nutrient responses to fertilization. Our study highlights (1) the importance of climate in determining plant nutrient concentrations mediated through effects on plant biomass, (2) that eutrophication affects grassland nutrient pools via both soil and atmospheric pathways and (3) that interactions among soils, herbivores and eutrophication drive plant nutrient responses at small scales, especially at water‐limited sites. [ABSTRACT FROM AUTHOR]

Abstract: Theory predicts that mammalian herbivores affect the quantity and quality of plants on which they preferentially feed in the short term. In the longer term, they can promote either preferred or less preferred plants, depending on whether preferred plants are adapted or sensitive to grazing. Less clear are the short‐ and long‐term responses of herbivorous insects to mammalian herbivory, and how these responses depend on the specific plants or plant functional types on which the insects feed. We progressively excluded large, medium and small mammals for five growing seasons in two subalpine vegetation types with long‐term differences in mammalian grazing intensity. Short‐grass vegetation has a history of intensive grazing, while tall‐grass vegetation has been grazed less intensively. We tested whether mammals altered the abundance and body size of leafhoppers specialized on specific plant functional types (grasses, sedges, forbs, or legumes/forbs), distinguishing between short‐term (exclosures) and long‐term (vegetation types) differences in mammalian grazing pressure. Furthermore, we assessed whether leafhoppers’ responses were explained by changes in biomass or quality of the plant functional types on which they feed. In the short term, mammal exclosures increased the abundance of grass‐ and forb‐feeding leafhoppers via increases in the biomass of grasses and forbs, regardless of vegetation type. Both grasses and forbs are preferred food plants of mammals. In the long term, the biomass of sedges, which are less preferred by mammals, increased in the less intensively grazed tall‐grass vegetation. This resulted in a higher abundance of sedge‐feeding leafhoppers. The small size of these sedge feeders lowered the average leafhopper body size in the tall‐grass vegetation. Plant nutritional quality did not explain any effects of exclusions or vegetation types. Our results demonstrate that both short‐ and long‐term effects of mammalian herbivores on the biomass of specific plant functional types caused concurrent changes in the abundance of specialized herbivorous insects, which scaled up to community‐wide shifts in insect body size, a key life‐history trait. A plant‐functional‐type approach can thus help to predict how overabundance or extinction of mammalian herbivores impacts on other components of the food web at various timescales. A plain language summary is available for this article. [ABSTRACT FROM AUTHOR]

Even though mammalian herbivores can exert strong indirect effects on other animals by altering the vegetation, the study of trophic cascades retains a focus on apex predators and their top-down forces. Bottom-up trophic interaction chains induced by mammalian herbivores, particularly in invertebrate food webs, remain largely unexplored., We tested whether effects of mammalian herbivores on the vegetation ricochet back up several trophic levels of the invertebrate food web. We further tested two alternative hypotheses: the strength of herbivore-induced indirect interactions either increases with plant productivity because of a concurrent higher grazing intensity, or it decreases because of a higher plant tolerance to grazing., We progressively excluded large, medium and small herbivorous mammals from replicated plots of 6 m2 in productive, intensively grazed short-grass vegetation and less productive, less intensively grazed tall-grass vegetation of subalpine grasslands. We measured vegetation quantity, quality, structure and composition, and determined the abundance of invertebrate herbivores, detritivores, omnivores and predators. We used structural equation modelling to test vegetation-mediated cascading effects of the different mammalian herbivores across different trophic groups of invertebrates., In the short-grass vegetation, mammals caused changes in vegetation quantity and thickness. These changes directly affected detritivorous and predatory invertebrate abundance, yet indirectly affected predatory and omnivorous invertebrates through a bottom-up trophic cascade via changes in herbivorous invertebrate abundance. In the tall-grass vegetation, mammal-induced changes in vegetation quality and composition affected detritivorous invertebrates and in turn omnivorous invertebrates, but these cascading effects were weaker than those in the short-grass vegetation. Smaller mammals were at least as important as large mammals in structuring the invertebrate food web., Our results demonstrate that differently sized mammalian herbivores can trigger trophic cascades in the local invertebrate food web. Our findings further support the hypothesis that herbivore-induced indirect interactions are stronger in more productive systems because of higher foraging intensity, as opposed to the hypothesis that a higher grazing tolerance of plants should dampen herbivore-induced indirect interactions in productive systems. [ABSTRACT FROM AUTHOR]

While the ecological importance of bioturbation is well recognized and the prevalence of aquatic foraging by terrestrial ungulates is increasingly appreciated, research linking how terrestrial ungulates function as disturbance mechanisms via bioturbation in freshwater systems is lacking. The purpose of this study was to quantify potential nutrient pulses released from benthic sediments into the water column when moose Alces alces feed on aquatic plants. We also determined if we could experimentally mimic the benthic disturbance and the expected nutrient pulse created when moose feed aquatically. When moose foraged aquatically, significant releases of both total and dissolved phosphorus (P) and nitrogen (N) resulted in the waters that were disturbed in foraging areas compared to adjacent undisturbed waters. Nutrient concentrations for total P and N ranged from 42.5 × and 2.7 × greater in disturbed than undisturbed, respectively. Dissolved P and N were 26.8 × and 1.5 × greater, respectively, in disturbed versus undisturbed waters. Our experimental mimic created increases of total and dissolved P and N that were equivalent to pulses created by moose. This indicates that it is possible to experimentally test by proxy the potential impact of moose bioturbation on other ecosystem processes. This study is the first quantification of moose foraging as a consumer mechanism that influences the release of limiting nutrients in aquatic systems, thereby emphasizing the potential cascading importance for nutrient uptake and productivity of plants and microbes. [ABSTRACT FROM AUTHOR]

Ungulates, smaller mammals, and invertebrates can each affect soil biota through their influence on vegetation and soil characteristics. However, direct and indirect effects of the aboveground biota on soil food webs remain to be unraveled. We assessed effects of progressively excluding aboveground large-, medium- and small-sized mammals as well as invertebrates on soil nematode diversity and feeding type abundances in two subalpine grassland types: short- and tall-grass vegetation. We explored pathways that link exclusions of aboveground biota to nematode feeding type abundances via changes in plants, soil environment, soil microbial biomass, and soil nutrients. In both vegetation types, exclusions caused a similar shift toward higher abundance of all nematode feeding types, except plant feeders, lower Shannon diversity, and lower evenness. These effects were strongest when small mammals, or both small mammals and invertebrates were excluded in addition to excluding larger mammals. Exclusions resulted in a changed abiotic soil environment that only affected nematodes in the short-grass vegetation. In each vegetation type, exclusion effects on nematode abundances were mediated by different drivers related to plant quantity and quality. In the short-grass vegetation, not all exclusion effects on omni-carnivorous nematodes were mediated by the abundance of lower trophic level nematodes, suggesting that omni-carnivores also depended on other prey than nematodes. We conclude that small aboveground herbivores have major impacts on the soil food web of subalpine short- and tall-grass ecosystems. Excluding aboveground animals caused similar shifts in soil nematode assemblages in both subalpine vegetation types, however, mechanisms turned out to be system-specific. [ABSTRACT FROM AUTHOR]

Vertebrate and invertebrate herbivores alter plant communities directly by selectively consuming plant species; and indirectly by inducing morphological and physiological changes to plant traits that provide competitive or survivorship advantages to some life forms over others. Progressively excluding aboveground herbivore communities (ungulates, medium and small sized mammals, invertebrates) over five growing seasons, we explored how leaf morphology (specific leaf area or SLA) and nutrition (nitrogen, carbon, phosphorous, potassium, sodium, and calcium) of different plant life forms (forbs, legumes, grasses, sedges) correlated with their dominance. We experimented in two subalpine grassland types with different land-use histories: (1) heavily grazed, nutrient-rich, short-grass vegetation and (2) lightly grazed, lower nutrient tall-grass vegetation. We found differences in leaf traits between treatments where either all herbivores were excluded or all herbivores were present, showing the importance of considering the impacts of both vertebrates and invertebrates on the leaf traits of plant species. Life forms responses to the progressive exclusion of herbivores were captured by six possible combinations: (1) increased leaf size and resource use efficiency (leaf area/nutrients) where lower nutrient levels are invested in leaf construction, but a reduction in the number of leaves, for example, forbs in both vegetation types, (2) increased leaf size and resource use efficiency, for example, legumes in short grass, (3) increased leaf size but a reduction in the number of leaves, for example, legumes in the tall grass, (4) increased number of leaves produced and increased resource use efficiency, for example, grasses in the short grass, (5) increased resource use efficiency of leaves only, for example, grasses and sedges in the tall grass, and (6) no response in terms of leaf construction or dominance, for example, sedges in the short grass. Although we found multiple possible responses by life forms to progressive exclusion of herbivores, we also found some important generalities. Changes in leaf traits of legumes and grasses correlated with their increasing dominance in the short-grass vegetation and plants were more efficient at constructing photosynthetic tissue when herbivores are present with few exceptions. These results demonstrate that vertebrate and invertebrate herbivores are essential to maintain plant species richness and resource-use efficiency. [ABSTRACT FROM AUTHOR]

The comparable and integrated nature of plant functional types and advances in high-spectral-resolution remote sensing techniques (i.e. imaging spectroscopy) make their combination highly interesting for spatially continuous and repeatable large-scale ecosystem monitoring. Depending on physical environment and stress, plants invest in covarying biochemical and structural traits, influencing spectral characteristics of vegetation. These traits are assumed to bear a more direct causal relationship to plant functional types than to plant life/growth forms. However, the connection between a vegetation community's functional and spectral response remains to be established., We assessed the correlation structure between (i) biochemical and structural vegetation traits (biomass, dry matter content, nitrogen content, neutral detergent fibre content), (ii) plant life/growth forms and (iii) seven plant functional types of two categories (strategy types, indicator values) collected in heterogeneous alpine grassland. We then used airborne imaging spectroscopy data from the same area to model and predict plant life/growth forms and plant functional types at the vegetation community level using partial least squares regression and validated our models based on an independent data set., We found high correlations between many of the biochemical and structural vegetation traits, plant life/growth forms and plant functional types tested. Using airborne imaging spectroscopy data, we successfully modelled and predicted most plant life/growth forms ( R2 max. = 0·56) and all plant functional types ( R2 max. = 0·62). However, model performance for plant life/growth forms decreased substantially during external validation and overall model consistency was low (average change in R2 = 72%), while plant functional type models were much more consistent (average change in R2 = 20%). Based on our findings, we developed a conceptual framework using the theory and methodology of vegetation ecology and imaging spectroscopy to link the vegetation community's functional to its spectral signature., Our results encourage the use of plant functional types in imaging spectroscopy in order to aid the large-scale monitoring of ecosystems, which is particularly important given the increased availability of airborne data and the prospective launches of spaceborne instruments in the near future. [ABSTRACT FROM AUTHOR]

Aboveground herbivores have strong effects on grassland nitrogen (N) cycling. They can accelerate or slow down soil net N mineralization depending on ecosystem productivity and grazing intensity. Yet, most studies only consider either ungulates or invertebrate herbivores, but not the combined effect of several functionally different vertebrate and invertebrate herbivore species or guilds. We assessed how a diverse herbivore community affects net N mineralization in subalpine grasslands. By using size-selective fences, we progressively excluded large, medium, and small mammals, as well as invertebrates from two vegetation types, and assessed how the exclosure types (ET) affected net N mineralization. The two vegetation types differed in long-term management (centuries), forage quality, and grazing history and intensity. To gain a more mechanistic understanding of how herbivores affect net N mineralization, we linked mineralization to soil abiotic (temperature; moisture; NO3- NH44+, and total inorganic N concentrations/pools; C, N, P concentrations; pH; bulk density), soil biotic (microbial biomass; abundance of collembolans, mites, and nematodes) and plant (shoot and root biomass; consumption; plant C, N, and fiber content; plant N pool) properties. Net N mineralization differed between ET, but not between vegetation types. Thus, short-term changes in herbivore community composition and, therefore, in grazing intensity had a stronger effect on net N mineralization than long-term management and grazing history. We found highest N mineralization values when only invertebrates were present, suggesting that mammals had a negative effect on net N mineralization. Of the variables included in our analyses, only mite abundance and aboveground plant biomass explained variation in net N mineralization among ET. Abundances of both mites and leaf-sucking invertebrates were positively correlated with aboveground plant biomass, and biomass increased with progressive exclusion. The negative impact of mammals on net N mineralization may be related partially to (1) differences in the amount of plant material (litter) returned to the belowground subsystem, which induced a positive bottom-up effect on mite abundance, and (2) alterations in the amount and/or distribution of dung, urine, and food waste. Thus, our results clearly show that short-term alterations of the aboveground herbivore community can strongly impact nutrient cycling within ecosystems independent of long-term management and grazing history. [ABSTRACT FROM AUTHOR]

Aims Imaging spectroscopy enables measurement of vegetation optical properties to predict vegetation characteristics that are important for a wide range of ecological applications. Our aim was to predict fresh above-ground biomass of heterogeneous alpine grasslands in two areas and at two ecological scales. We assessed model plausibility for an intensively studied alpine grassland site (plant community scale) having distinct biomass and ungulate grazing patterns. Location Alpine grasslands in the Swiss National Park. Methods Biomass data were collected in 51 plots and combined with imaging spectroscopy data to establish simple ratio models. We analysed the predictive power and transferability of models developed in two areas (Val Trupchun, Il Fuorn) and at two ecological scales (regional, local). In a next step, we compared our results to the broadband normalized difference vegetation index ( NDVI). Finally, we assessed the correlations between model predictions and plant biomass distribution at the plant community scale. Results The best local simple ratio models yielded a model fit of R2 = 0.60 and R2 = 0.30, respectively, the best regional model a fit of R2 = 0.44. NDVI model performance was weaker for the regional and one local area, but slightly better for the other local area. However, at the plant community scale only the local model showed a significant positive correlation ( RS = 0.39) with the known biomass distribution. Further, predictive power decreased when models were transferred from one local area to another or from one ecological scale to another. Conclusions Our study demonstrated that imaging spectroscopy is generally useful to predict above-ground plant biomass in alpine grasslands with distinct grazing patterns. Site-specific local models based on simple ratio indices performed better than the NDVI or regional models, suggesting that standardized approaches might not be adequate, particularly in heterogeneous grasslands inhabited by large ungulates. We emphasize the importance of collecting ground reference data covering the expected range of productivity and plant species composition. Moreover, plant community-scale data from a previous study proved to be extremely valuable to test model plausibility. [ABSTRACT FROM AUTHOR]

Questions How do rates of endozoochory change across gradients of environmental variation, grazing intensity and herbivore body size? Is there evidence that plants experience a trade-off in successful germination in dung vs soil, and if so, are opposing strategies associated with traits indicative of evolutionary grazing history? Location Serengeti National Park, Tanzania and a greenhouse in Birmensdorf, Switzerland. Methods We compared rates of seedling emergence from the dung of six grazing herbivore species and soil collected across an environmental gradient in the Serengeti; we experimentally exposed both dung and soil to smoke to test for the effects of breaking seed dormancy. We analysed overlap in plant composition of seedlings germinated from dung and soil and asked whether species found in dung (but not soil) or soil (but not dung) differed in traits that are associated with evolutionary grazing history, such as leaf height and seed head height. Results Spatially, dung samples collected in the heavily grazed Serengeti plains contained more seeds than more northern sites. Median seedling emergence from dung varied among herbivores: hartebeest and wildebeest had the most, topi and zebra had intermediate numbers and Thomson's and Grant's gazelle the fewest, with Grant's gazelle dung being composed almost entirely of herbaceous dicots. Smoke failed to induce a germination response when applied to dung, but the composition of plant species germinating in 'dung only' or 'soil only' was surprisingly distinct. Moreover, seed head heights and leaf heights were shorter for plant species that germinated from dung compared to those that germinated from soil. Finally, the abundance of seeds germinating in dung and soil showed opposite patterns across the transition from short-grass, historically grazed sites in the south to tall-grass, fire-prone sites in to the north. Conclusions Together, our results suggest that some Serengeti plant species may be specialized to disperse via the dung of large herbivores. Consequently, endozoochory may be an important, and thus far overlooked, ecological process in Serengeti and in tropical savannas dominated by large herbivores more generally. [ABSTRACT FROM AUTHOR]

We investigate the torsional vibrations in biphenyl-like molecular junctions and transport properties in the presence of an external THz field. Ab initio calculations including external electric fields show that the torsional angle [ABSTRACT FROM AUTHOR]

. 1. Grasslands cover approximately 40% of the Earth's terrestrial landscape, supporting large communities of vertebrate and invertebrate herbivores. Orthoptera play an important role, consuming relatively large amounts of biomass. Their occurrence can be strongly affected by habitat diversity and structure, which can be shaped by large herbivores. Several studies have focused on the impact of livestock on Orthoptera communities, but little is known about how wild ungulates influence the abundance and diversity of these insects in grassland ecosystems. 2. We studied Orthoptera abundance and diversity in subalpine grasslands in the Swiss Alps, where grazing by red deer and chamois has created a mosaic of short- and tall-grass patches. Data on vegetation structure, habitat diversity and plant nitrogen (N) content allowed us to consider how these parameters affected the occurrence of Orthoptera at our study sites. 3. We found a total of nine Orthoptera species with an average density of 2.6 individuals m−2. Neither Orthoptera abundance nor diversity differed between short- and tall-grass patches created by large ungulates. Both Orthoptera abundance and diversity were, however, positively influenced by increasing vegetation height, but negatively by increasing habitat diversity within patches. Increasing plant N content promoted a more even spread of species within the insect assemblage on short- but not on tall-grass patches. 4. Large-scale habitat alteration by wild ungulates had no direct effect on the abundance and diversity of Orthoptera. However, we observed that they indirectly affected Orthoptera abundance and diversity by altering plant N content and the structure of the habitat at small scales. [ABSTRACT FROM AUTHOR]

Molpro (available at ) is a general-purpose quantum chemical program. The original focus was on high-accuracy wave function calculations for small molecules, but using local approximations combined with explicit correlation treatments, highly accurate coupled-cluster calculations are now possible for molecules with up to approximately 100 atoms. Recently, multireference correlation treatments were also made applicable to larger molecules. Furthermore, an efficient implementation of density functional theory is available. © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Soil seed banks are an important source of new individuals for many plant populations and contribute to future genetic variability. In general, the size and persistence of soil seed banks is predicted to be greater where growth occurs in unpredictable pulses, where opportunities for disturbance-related recruitment are frequent and where the probability of recruitment failure is high. In savanna ecosystems, characterized by disturbance from fire and unpredictable water availability, soil seed banks should be relatively important sources of recruitment. However, the few studies conducted in savannas are inconclusive about the importance of soil seed banks and, more specifically, how seed banks should change across environmental gradients. We determined the number of viable seeds in the soil seed bank across savanna-grasslands in the Serengeti, an ecosystem characterized by frequent fire and seasonal drought. Soils were exposed to a combination of smoke and heat, cues which may be required to break seed dormancy in such ecosystems. Our a priori expectation was to observe large seed banks in regions characterized by seasonal drought and comparatively smaller seed banks in regions of higher moisture availability and high fire frequencies. In contrast to our hypothesis, seed germination increased strongly with precipitation and fire frequency. In addition, there was a significant interaction effect between fire and rainfall: low rainfall sites with frequent fire had greater seed germination than low rainfall sites with low fire frequency. Moreover, in laboratory experiments, heat had a negative, smoke a positive effect on final seed germination numbers. Together, these findings suggest that fire may be a key factor in driving herbaceous seed bank dynamics in tropical savannas. [ABSTRACT FROM AUTHOR]

A computational technique for solving the MP2 equations for periodic systems using a local-correlation approach and implemented in the CRYSCOR code is presented. The Hartree-Fock solution provided by the CRYSTAL program is used as a reference. The motivations for the implementation of the new code are discussed, and the techniques adopted are briefly recalled. With respect to the original formulation (Pisani et al., J Chem Phys 2005, 122, 094113), many new features have been introduced in CRYSCOR to improve its efficiency and robustness. In particular, an adaptation of the density fitting scheme to translationally periodic systems is described, based on Fourier transformation techniques. Three examples of application are provided, concerning the CO2 crystal, proton transfer in ice XI, and the adsorption of methane on MgO (001). The results obtained with the periodic LMP2 method for these systems appear more reliable than the ones obtained using density functional theory. © 2008 Wiley Periodicals, Inc. J Comput Chem, 2008 [ABSTRACT FROM AUTHOR]

Questions: Is change in cover of dominant species driving the velocity of succession or is it species turnover (1)? Is the length of the time-step chosen in sampling affecting our recognition of the long-term rate of change (2)? Location: 74 permanent plots located in the Swiss National Park, SE Switzerland, ca. 1900 m a.s.1. Methods: We superimpose several time-series from permanent plots to one single series solely based on compositional dissimilarity. As shown earlier (Wildi & Schütz 2000) this results in a synthetic series covering about 400 to 650 yr length. Continuous power transformation of cover-percentage scores is used to test if the dominance or the presence-absence of species is governing secondary succession from pasture to forest. The effect of time step length is tested by sub-samples of the time series. Results: Altering the weight of presence-absence versus dominance of species affects the emerging time frame, while altering time step length is uncritical. Where species turnover is fast, different performance scales yield similar results. When cover change in dominant species prevails, the solutions vary considerably. Ordinations reveal that the synthetic time series seek for shortest paths of the temporal pattern whereas in the real system longer lasting alternatives exist. Conclusions: Superimposing time series differs from the classical space-for-time substitution approach. It is a computation-based method to investigate temporal patterns of hundreds of years fitting between direct monitoring (usually limited to decades) and the analysis of proxy-data (for time spans of thousands of years and more). [ABSTRACT FROM AUTHOR]

Questions: How do species diversity, frequency and composition in tussocks differ from those in similar sized plots outside tussocks? Does the extent of the differences depend on community types or environmental conditions? Location: A sub-alpine grassland in the Swiss National Park. Methods: In each of the two communities (short grass and tall graminoid) differing in species composition, grazing intensity and soil nutrient availability, relevés were made in 40 pairs of small circular plots, with one plot located inside a randomly selected Carex sempervirens tussock and the other outside. Results: We found 92 vascular species, of which 46 had a frequency higher than 5%. Species richness (S), pooled cover, Shannon's diversity (H) and cumulative species number (CS) were higher outside than inside the C. sempervirens tussocks, but evenness (J) was lower. S, H and CS differed more in the tall graminoid community than in the short grass community. However, dissimilarity between the paired relevés inside and outside tussocks did not differ between the two communities. Of the 46 most frequent species, 12 were statistically more and only one less frequent outside than inside the tussocks. Vegetation inside and outside tussocks could be clearly distinguished in the ordination space. Conclusion: Vegetation inside C. sempervirens tussocks is different from that in the surrounding area and represents an impoverished but homogenized version of the surrounding vegetation. Although tussocks of C. sempervirens were systematically avoided by grazers, there is little evidence that tussocks facilitate the species growing inside them. [ABSTRACT FROM AUTHOR]

Current understanding of plant–herbivore interactions postulates that forest understory species are less tolerant to herbivory by large mammals than grassland species. As yet, research on forest species has focused on extensive biomass loss. However, forest dwelling ungulates are often selective browsers, hence biomass loss experienced by forage species is mostly limited to specific plant modules. We investigated the impact of herbivory on common forage species of roe deer Capreolus capreolus by simulating browsing on wild transplants of the two herbs Geum urbanum and Prenanthes purpurea, and the two graminoids Carex sylvatica and Luzula luzuloides. Two clipping regimes simulated different browsing frequencies, whereas shading and full day light represented light conditions in closed forests and gaps, respectively. Single clipping did not affect above ground biomass production of any species, independent of light conditions. Repeated biomass loss led to undercompensation in L. luzuloides, marginal compensation in C. sylvatica, and full compensation in G. urbanum and P. purpurea measured as above ground biomass production. The change in root biomass after clipping was positively correlated with the change in above ground biomass production in all four species. In contrast, nitrogen concentration was negatively correlated with above ground biomass in the graminoids, whereas no relationship between nitrogen and biomass was found in the herbs. Although light conditions and plant provenance affected biomass production, we found no effect of light conditions on plant reactions to herbivory. These results suggest that forest understory species, graminoids as well as herbs, are tolerant to herbivory by selective browsers such as roe deer. As in grassland ecosystems, the degree of compensatory growth depends on amount and frequency of biomass loss. [ABSTRACT FROM AUTHOR]

Little information is available regarding red wood ant (RWA; Formica rufa group) impacts on soil carbon (C) and nitrogen (N) cycling in forest ecosystems. We found that RWA mound density (number per ha) was linked to forest tree species composition, slope aspect, and canopy closure. The size of RWA mounds was positively correlated with successional age of the stands. C and N concentrations of mound material were significantly higher than in the forest floor, while C:N ratios were not. RWA mound C and N pools were found to be significantly lower (≤990 kg C/ha and ≤21 kg N/ha) than in the forest floor. RWA mounds were "hot spots" for CO, emissions ranging from 12.4 (mid July) to 3.5 (early September) times higher than the adjacent forest floor. Overall, they contributed 0.7- 2.5% to total forest soil CO, emissions. Consequently, the contribution of RWA to total forest soil C and N pools and forest CO, emission is minor and likely not important when calculating or modeling C and N pools or C fluxes. Yet, RWAs increase the spatial heterogeneity of soil C and nutrients and alter the flow of energy within their habitat. [ABSTRACT FROM AUTHOR]

The cover image, by Denis Usvyat et al., is based on the Advanced Review Periodic and fragment models based on the local correlation approach, DOI: 10.1002/wcms.1357. [ABSTRACT FROM AUTHOR]