Strong Competitive Effects Research Articles

Native tree promotes invasion when native grasses are absent

Despite the expected co‐occurrence of effects from resident species, the environment, and disturbance on non‐natives, these factors have largely been treated as acting separately. Co‐occurring factors may, however, act in combination to result in a powerful, yet little explored, mechanism of invasion. Here, we addressed three hypotheses to explain the localized invasion of the non‐native Chenopodium album (Chenopodium) under the canopy of the dominant native tree Neltuma caldenia (Neltuma) in central Argentina. First, we evaluated that Neltuma favors Chenopodium by modifying environmental conditions, and specifically assessed the importance of soil versus that of the microclimate created by Neltuma shade. Second, we tested that Neltuma benefits Chenopodium by promoting under its canopy (calden microsite) the dominance of a grass species, Nassella tenuissima (Nassella), that exerts weaker competitive effects on Chenopodium than those exerted by the dominant grass, Piptochaetium napostaense (Piptochaetium), in adjacent communities free of the tree (open microsite). Lastly, we explored that the invasion of Chenopodium is mediated by disturbance. Chenopodium displayed increased biomass and fecundity (performance) in soil from calden relative to that from open microsites, whereas it exhibited no response to shade treatments. Also, Chenopodium performance in pots with Nassella was similar to that in pots with Piptochaetium. Finally, Chenopodium performance was much greater in pots with no initial plants than in those with grasses. Importantly, in pots without plants, Chenopodium performed much better in calden than open microsites, but in pots with grasses, Chenopodium performance exhibited no differences between microsites. These findings suggest that disturbance mediates Chenopodium invasion in calden microsites. Specifically, disturbance may weaken strong competitive effects from native grasses on Chenopodium, allowing this non‐native herb to benefit from favorable soil conditions under Neltuma. The combined action of natives enhancing resource levels and disturbance providing access to them could be a general mechanism of invasion.

Multicomponent adsorption mechanism of CO2, SO2, NO, and C7H8 from flue gases on nitrogen-doped biochar: Experimental and computational insights

The comprehensive control of CO2 and gaseous pollutants in coal-fired flue gas is urgent and difficult. As a green low-cost adsorbent, nitrogen-doped biochar has potential application in the control technology of flue gas pollutants. Still, its multi-component adsorption characteristics for flue gas are unclear. In this study, the multi-component adsorption characteristics of CO2, SO2, NO, and C7H8 on nitrogen-doped biochar were explored at different temperatures (25–120 °C), and the competitive mechanism of multi-component adsorption was revealed through continuous adsorption experiments and numerical calculation. The adsorption capacities of CO2, SO2, NO, and C7H8 by nitrogen-doped biochar can reach 38.1, 78.9, 3.1, and 245.2 mg/g, among which CO2, SO2, and C7H8 show strong competitive effects. Their adsorption capacities are decreased by 42 % (CO2), 28 % (SO2), and 27 % (C7H8) respectively compared with the single-component adsorption. This is because there are not only more C7H8 adsorption sites on nitrogen-doped carbon, but also C7H8 can partially occupy the adsorption sites of SO2 and CO2 during multi-component adsorption. Combined with the calculation results of density functional theory, the competitive ability of the three gases can be ranked as follows: C7H8 > SO2 > CO2.

Comparing the abiotic removal of glyphosate by β-MnO2 and δ-MnO2 colloids: Insights into kinetics and mechanisms

Glyphosate as an effective broad-spectrum herbicide is frequently detected in various water and soil resources. Given the ubiquity of β-MnO2 and δ-MnO2 colloids in groundwater and soil, the abiotic removal of glyphosate by MnO2 colloids was investigated. β-MnO2 colloids exhibited superior glyphosate removal efficiency, up to 37%, compared to 21% for δ-MnO2 colloids at a pH of 4.0. Glyphosate removal involved simultaneous adsorption and oxidation process, identified by HRTEM, NH3-TPD, XPS, LC-MS, FTIR analyses and the occurrence of aminomethylphosphonic acid (AMPA) and Mn2+. Moreover, adsorption dominated the removal of glyphosate by two MnO2 colloids. The solution pH had a substantial effect on glyphosate removal. Co-existing ions in the solution, such as carbonate (CO32−), phosphate (Na2HPO4, NaH2PO4) and humic acid (HA), were also found to impede glyphosate removal. Phosphate, in particular, exhibited a strong competitive effect for adsorption sites on both MnO2 colloids. Of them, the removal of glyphosate by β-MnO2 colloids was more prone to occur due to its higher specific surface area, abundant oxygen vacancies, and moderate acid sites. However, δ-MnO2 colloids presented a stronger oxidation capacity than that of β-MnO2 colloids due to the quicker generation rate of Mn2+. Finally, AMPA was the same products by two MnO2 colloids in the oxidation process, revealing the degradation pathway based on the cleavage of C–N bond. Therefore, by comparing kinetics and mechanisms of glyphosate removal by β- and δ-MnO2 colloids, this study improves us better understanding for the behavior of glyphosate in the environment.

Determinants and spatial spillover effects of inbound tourism in Chinese cities

PurposeBy using a wide range of macro and micro factors, this paper aims to provide a new assessment of the recent literature on inbound tourism demand models.Design/methodology/approachThis study examines the determinants and spatial effects of inbound tourism using Hausman–Taylor and spatial econometric models.FindingsSeveral important factors were identified, including local economic growth, openness to the outside world, regional size, geographic distance, foreign direct investment, level of innovation and average annual temperature. In addition, the study found strong cross-city competition effects on tourism resource endowment and hotel infrastructure.Originality/valueInbound tourism is a crucial link in achieving high-quality economic development. However, previous studies have mainly focused on the analysis of single influencing factors, ignoring the spatial spillover effects of factors.

Functional traits shape plant-plant interactions and recruitment in a hotspot of woody plant diversity.

Understanding and predicting recruitment in species-rich plant communities requires identifying functional determinants of both density-independent performance and interactions. In a common-garden field experiment with 25 species of the woody plant genus Protea, we varied the initial spatial and taxonomic arrangement of seedlings and followed their survival and growth during recruitment. Neighbourhood models quantified how six key functional traits affect density-independent performance, interaction effects and responses. Trait-based neighbourhood models accurately predicted individual survival and growth from the initial spatial and functional composition of species-rich experimental communities. Functional variation among species caused substantial variation in density-independent survival and growth that was not correlated with interaction effects and responses. Interactions were spatially restricted but had important, predominantly competitive, effects on recruitment. Traits increasing the acquisition of limiting resources (water for survival and soil P for growth) mediated trade-offs between interaction effects and responses. Moreover, resprouting species had higher survival but reduced growth, likely reinforcing the survival-growth trade-off in adult plants. Resource acquisition of juvenile plants shapes Protea community dynamics with acquisitive species with strong competitive effects suffering more from competition. Together with functional determinants of density-independent performance, this makes recruitment remarkably predictable, which is critical for efficient restoration and near-term ecological forecasts of species-rich communities.

Interspecific competitive effects and annual differences in predation of Empoasca onukii (Hemiptera: Cicadellidae) by wandering spiders.

Empoasca onukii Matsuda is an important pest widely distributed in tea areas in China, which greatly affects tea production and quality. The long-term use of chemical control measures will cause environmental pollution. To better utilize wandering spiders that have strong competitive effects on the predation of E. onukii, we conducted a path analysis between the populations of E. onukii and wandering spiders in 3 tea plantations in 2020 and 2021. The wandering spider species that had the greatest direct and indirect effects on the population of E. onukii were analyzed by the magnitude of the path coefficient. Then, a gray system analysis was conducted to determine the closeness of the populations of different wandering spiders to E. onukii by the magnitude of gray correlation coefficient. Finally, the competition coefficients were calculated to determine the competitiveness of wandering spiders. In addition, considering the influence of the number of E. onukii on the interspecific competition of wandering spiders, the gray correlation coefficient and competition coefficient were combined to derive the competition intensity index, which was used to analyze the competitiveness of wandering spiders in a comprehensive manner. The highest competition coefficients in 2020 and 2021 were found for Ebrechtella tricuspidata Fabricius (Araneae: Thomisidae) (X2, 0.5329) and Clubiona reichlini Fabricius (Araneae: Clubionidae) (X4, 0.8475), respectively. The magnitude of the competition intensity index showed that the most competitive wandering spider in 2020 and 2021 was E. tricuspidata (X2, 0.5692) and C. reichlini (X4, 0.8892), respectively. The least competitive spider in both years was Plexippus setipes Karsch (Araneae: Salticidae) (X7). The more competitive the wandering spider is, the closer it is to E. onukii in terms of numbers, and the more dominant it is in feeding on E. onukii. By reasonably protecting and utilizing the competitive E. tricuspidata (X2) and C. reichlini (X4), we can achieve sustainable and effective control of E. onukii.

Ectomycorrhizal effects on decomposition are highly dependent on fungal traits, climate, and litter properties: A model-based assessment

It has been proposed that competition between ectomycorrhizal (ECM) fungi and free-living saprotrophs for resources like nitrogen (N) slows decomposition and increases the soil carbon storage in ECM ecosystems compared to arbuscular (AM) ecosystems. However, empirical evidence for the generality of such ECM effects is equivocal, and confounding mechanisms have been proposed that affect the magnitude and direction of ECM effects on soil carbon. Here we conduct a theoretical modeling experiment, where we explicitly incorporate mycorrhizal processes into the Carbon, Organisms, Rhizosphere, and Protection in the Soil Environment (CORPSE) model. We use the model to explore the conditions under which ECM N acquisition processes can induce stronger saprotrophic N limitation and result in slower decomposition rates and greater soil organic carbon accumulation compared to AM processes. We found that the ECM fungi more strongly inhibited decomposition when litter inputs were N-depleted and relatively recalcitrant and when ECM fungi possessed a strong capacity to mine N from both recalcitrant soil organic matter and microbial necromass. Climate and seasonality also played a role as the ECM competition effect was strongest at low mean annual temperatures and when litterfall peaked seasonally. Priming effects driven by high root exudation rates in ECM-dominated systems could overwhelm the competition effect and reduce soil carbon under some circumstances. The ECM effect on decomposition in our simulations was highly context dependent. Based on our model results, we expect to see a strong ECM competition effect in temperate deciduous and boreal forests with relatively recalcitrant litter inputs, and with ECM fungi that produce oxidases and necromass-degrading enzymes. However, even a relatively strong ECM competition effect on decomposition only increased soil organic carbon accumulation by ∼10%.

The Effects of Foreign Acquisitions on the Value of Industry Peers

Abstract This article studies how industry peers’ stock prices respond when another firm in the industry is acquired by a foreign firm. The average stock price reactions of industry peers in horizontal foreign acquisitions around deal announcements are significantly negative. Peers’ returns are more negative in growing, less specialized, and competitive industries. Moreover, the negative stock price reactions of industry peers are related to future decreases in their operating performance. Overall, these results suggest that foreign acquisitions have strong competitive effects for the industry peers of U.S. target companies.

Competitive Removal of Perchlorate Ions by Quaternary Amine Modified Reed in the Presence of Nitrate and Phosphate

We report a kinetic and equilibrium study in which we examined the removal of perchlorate anions from water by adsorption onto modified reed (MR), an adsorption material constituted by giant reed (GR) particles whose anion adsorption properties have been enhanced by quaternary amine (QA) crosslinking. In particular, we examined how MR adsorption of perchlorate interacts competitively with concomitant adsorption of agriculture-derived phosphate and nitrate contaminants. Equilibrium and pH experiments were first conducted in single-component systems, the results of which were best described by the Langmuir-Freundlich (L-F) isotherm. Subsequent analyses of competitive effects on adsorption showed that although MR had a higher adsorption capacity for perchlorate alone than for nitrate or phosphate alone, the addition of either phosphate or nitrate to a perchlorate solution had a diminishing effect on MR adsorption of perchlorate within a natural-water pH range, with phosphate having the stronger competitive effect. Perchlorate adsorption on MR varied inversely with competing ion concentrations, providing direct evidence of the perchlorate diminution effect being attributable to anion competition. Finally, we developed a multicomponent isotherm model that describes the binary adsorption of perchlorate in the presence of each of these competing anions. The results of this work provide perchlorate removal efficiency information that is directly applicable to the design of water treatment systems.

Dissimilarity effects on house prices: what is the value of similar neighbours?

Residential choice does not only depend on properties of the dwelling, neighbourhood amenities and affordability, but is also affected by the population composition within a neighbourhood. All these attributes are capitalised in the house price. Empirically, it is not easy to disentangle the effect of the neighbourhood on house prices from the effects of the dwelling attributes. We implement an agent-based model of an urban housing market that allows us to analyse the interaction between residential choice, population composition in a neighbourhood and house prices. Agents differ in terms of education, income and group affiliation (majority vs. minority). Whereas rich agents can afford to move to preferred places, roughly 13.01% of poor minorities and 8.02% of poor majority agents are locked in their current neighbourhood. We show that a preference to live among similar neighbours has a strong competitive effect on rich households and drives up their house prices. This is not the case with a preference for status. By introducing a policy that provides agents more access to credit, we find that all population groups denote higher satisfaction levels. Poor agents show the largest improvements. The general satisfaction level across all population groups increases. However, the extra credit accessibility also drives up house prices and leads to higher wealth inequality within the city. If agents have a preference for status rather than for similarity, the effect of the overall inequality is smaller, since agents become more satisfied living in areas with less similar agents.

Loose nanofiltration membranes for selective rejection of natural organic matter and mineral salts in drinking water treatment

Loose nanofiltration (LNF) is a promising technology for advanced treatment of drinking water, primarily owing to the potentially high rejection of natural organic matter (NOM) and high passage of mineral salts, particularly divalent cations, along with the low operating pressure. This study was devoted to relating the performance with the properties of LNF membranes, and obtaining the membrane properties most suitable for drinking water treatment. Cluster analysis indicated that the commercially available LNF membranes would behave quite differently, mainly depending on the molecular weight cut-off (MWCO). By using a treated natural water as the feed, a best-performing membrane had a mineral salts rejection lower than 30% and an NOM rejection higher than 70%, with the membrane water permeance at ∼17 L/m2/h/bar. The LNF membranes with high mineral salts/NOM selectivity should have an MWCO of around 1000 Da, sufficiently uniform pore sizes, and high surface negative charge density. The rejection characteristics for mineral ions by LNF membranes were similar with the relatively dense conventional NF membranes, but with a lower rejection difference among the ions, manifesting less strong co-ion and counter-ion competition effects. The LNF membranes with an MWCO of ∼1000 Da could satisfactorily remove (>80%) disinfection byproduct precursors, with small-sized protein-like and other substances remaining in the permeate water. This study helps to understand the rejection characteristics and mechanisms of LNF membranes, which will benefit the synthesis of high-performance LNF membranes for drinking water treatment and other applications.

Competition and Facilitation Co-Regulate Spatial Patterns and Coexistence in a Coniferous and Broad-Leaved Mixed Forest Community in Zhejiang, China

Plant interactions have long been the subject of intense research and debate in ecology. Competition and facilitation are known to be the basic drivers of community structure, species coexistence, and forest succession dynamics; however, there remains a lack of understanding of how spatial patterns affect these in the mixed forest community of coniferous and broad-leaved species. In the present study, we studied the roles of competition and facilitation in a mixed forest community in the Zhejiang Province, China. For this, we divided plants measured at a study site according to the size of the diameter at breast height (DBH) into three levels of saplings as follows: saplings (1 cm ≤ DBH < 5 cm), juveniles (5 cm ≤ DBH < 15 cm), and adults (DBH ≥ 15 cm). We used the spatial point pattern method to explore the raw number, spatial distribution, and both intra- and inter-specific correlations of coniferous and broad-leaved species at these different diameter levels. The corresponding findings were as follows. First, the DBH and structure of coniferous and broad-leaved species were similar, showing a distinct distribution in an inverted “J” shape as the number of individuals with a particular diameter declined as DBH increased. Second, when all individuals of a similar diameter range were pooled, coniferous species were clustered at all size scales; however, in this situation, broad-leaved species (evergreen and deciduous) showed a clumped distribution at small scales, and this decreased as spatial scale increased. Third, there were small, but significant positive correlations between large-diameter trees and small-diameter trees of coniferous species and between evergreen broad-leaved species at different diameter levels; however, as the scale increased, the correlation diminished. On any scale, individual deciduous broad-leaved species at different diameter ranges did not have any significant correlation. Fourth, coniferous species had a strong competitive effect on broad-leaved species, and there was a weak promoting effect between deciduous and evergreen broad-leaved species as well. In summary, different tree species occupy similar living spaces, and through competition and facilitation, regulate the spatial pattern and community stability of coniferous and broad-leaved species in mixed forest communities.

Encroachment order and spatial patterns of broad-leaf tree species in the naturalization of a Cunninghamia lanceolata plantation

The aim of this study was to understand the encroachment order, spatial patterns, interspecific associations, and species diversity of a Cunninghamia lanceolata plantation and to provide context for how to improve the spatial structure of C. lanceolata plantations. We investigated a Guanshan (C. lanceolata) Plantation in the Jiangxi Province. The C. lanceolata plantation was divided into three developmental stages (early, middle and late), with a space-for-time substitution method, according to their diameter at breast height (DBH) measurements. Across these plots, we analyzed encroachment patterns of the species and their interspecific associations with C. lanceolata according to the coordinates of trees in the plot, as well as the variation of species diversity after the encroachment of broad-leaf tree species. Our results show that the encroachment of broad-leaf trees into the C. lanceolata plantation followed a clear successional sequence of tree community assembly: intolerant tree species encroachment first, such as Alniphyllum fortunei and Liquidambar formosana, encroached; neutral tree species then encroachment, such as Daphniphyllum oldhamii and Schima superba, and shade-tolerant tree species encroachment last, such as Castanopsis eyrei and Castanopsis tibetana. Further, the spatial pattern of species establishment differed based upon when they encroached on the plantation. Intolerant and neutral tree species of early and middle developmental stages were distributed randomly. However, intolerant and some shade-tolerant tree species of the late developmental stage were aggregated on a scale of about 0–3 m. In addition, the interspecific associations between broad-leaf species encroachment into the C. lanceolata plantation were mainly negative, among which the most competitive ones were A. fortunei, D. oldhamii and Machilus thunbergii. However, with the development of the community, some species with negative correlations changed to having no correlation with C. lanceolata. We found that species diversity in the plantation gradually increased by nearly-five times from the early to the late developmental stage. Based on our collective results, we conclude that the encroachment and assembly of tree species show obvious order and pattern, which has a strong competitive effect with C. lanceolata in the naturalized plantation. Additionally, the community biodiversity has been significantly improved. Therefore, this successional process is important in the transformation of the C lanceolata plantation and different tree species should be replanted according to C. lanceolata plantation developmental stages with priority given to competitive species, such as A. fortunei, D. oldhamii, and M. thunbergii, so as to promote the C. lanceolata plantation change to C. lanceolata and broadleaf mixed forest.

Hydrogeochemistry mechanism contrasts between low and high sulfate in limestone aquifers at the massive coalfield in Anhui province, China

Abstract High sulfate mine groundwater at the Huaibei coalfield has exceeded the permissible limit (250 mg/l) of World Health Organization, posing serious threat to nearby water resource. A total of 28 samples were collected from Taiyuan formation aquifer (TA) and Ordovician aquifer (QA). In view of the mean concentration in two aquifers, the TA and OA were identified as high sulfate group and low sulfate group. The contrast on hydrochemical characterization and water-rock interactions were analyzed to reveal the mechanism of sulfate enrichment in mine groundwater. Compared with low sulfate groundwater, the high sulfate groundwater possess a higher content of TDS, Na+ and Cl−, which elevated by 3.83, 4.0 and 3.29 times, respectively. The low sulfate groundwater is controlled by Ca-Na-HCO3 type (82%), whereas the high sulfate groundwater is dominated by Na-SO4-HCO3 type (88%). The geochemical process of low sulfate groundwater is influenced by dissolution of carbonate minerals and weak ion exchange. The mechanism of sulfate enrichment in mine groundwater are predominately controlled by both silicate and carbonate minerals weathering, strong ion exchange interaction and competitive effect. The outcomes enhance understanding of the mechanism of high sulfate mine water and provide theoretical support for mine wastewater treatment. HIGHLIGHTS Hydrogeochemistry mechanism contrasts between low and high sulfate in limestone aquifers were studied. Water environment for high sulfate mine groundwater was revealed from comparative analysis with low sulfate mine groundwater. Corresponding minerals dissolution dominated the hydro-chemistry process together with ion exchange and competitive effect.

Using imagery from unmanned aerial vehicles to investigate variation in snag frequency among forest stands

Advances in unmanned aerial vehicle (UAV) technology have opened new opportunities for measuring canopy mortality processes through high-resolution aerial imagery. Unlike traditional plot-based sampling, UAVs can easily survey areas several hectares in size that encompass hundreds of canopy trees. The resulting imagery provides extensive data on the number and locations of dead trees (snags), which can be related to neighbourhood conditions and environmental factors that vary among stands. Here, we used a UAV to measure the relative proportions of live and dead canopy trees in stands varying in soil moisture across a mixed forest landscape. Crowns of live trees and snags were first segmented and classified to species from high-resolution canopy imagery. We then modeled whether crowns of each species were alive or dead as a function of tree height, neighbourhood competition, soil moisture, and the relative abundance of conspecifics. Short lodgepole pine (Pinus contorta var. latifolia) trees were more likely to be dead when surrounded by a tall canopy in sites with greater soil moisture, reflecting effects of competition on this shade-intolerant species. Trembling aspen (Populus tremuloides) was more likely to be alive when surrounded by tall neighbours, perhaps because this clonal species can benefit from facilitation through root connections with neighbouring aspen stems. There was a higher frequency of white spruce (Picea glauca) snags in sites where it had a high relative abundance, suggesting strong effects of intraspecific competition for this species. Soil moisture did not appear to have a direct effect on the snag frequency of any of these species, despite pronounced niche partitioning along an elevation-driven moisture gradient. Our models explained 39% and 33% of the variation in white spruce and lodgepole pine snag frequency, respectively, but did not have much predictive power for trembling aspen or total snag frequency. Our results reflect the important role of competition in determining tree mortality, but also indicate that stochastic or unexplained processes account for considerable variation in snag frequency among stands. As UAV technology becomes more widely used by ecologists, it may enable a better understanding of how biotic and abiotic processes produce local variation in canopy mortality.

Social Welfare Analysis under Different Levels of Consumers’ Privacy Regulation

With the rapid development of information technology, digital platforms can collect, utilize, and share large amounts of specific information of consumers. However, these behaviors may endanger information security, thus causing privacy concerns among consumers. Considering the information sharing among firms, this paper constructs a two-period duopoly price competition Hotelling model, and gives insight into the impact of three different levels of privacy regulations on industry profit, consumer surplus, and social welfare. The results show that strong privacy protection does not necessarily make consumers better off, and weak privacy protection does not necessarily hurt consumers. Information sharing among firms will lead to strong competitive effects, which will prompt firms to lower the price for new customers, thus damaging the profits of firms, and making consumers’ surplus higher. The level of social welfare under different privacy regulations depends on consumers’ product-privacy preference, and the cost of information coordination among firms. With the cost of information coordination among firms increasing, it is only in areas where consumers have greater privacy preferences that social welfare may be optimal under the weak regulation.

In-situ sequestration of perfluoroalkyl substances using polymer-stabilized ion exchange resin

Remediation of groundwater impacted by per- and polyfluoroalkyl substances (PFAS) is challenging due to the strength of the carbon-fluorine bond and the need to achieve nanogram per liter drinking water targets. Previous studies have shown that ion exchange resins can serve as effective sorbents for the removal of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) in conventional water treatment systems. The objectives of this study were to evaluate the in situ delivery and PFAS sorption capacity of a polymer-stabilized ion exchange resin (S-IXR) consisting of Amberlite® IRA910 beads and Pluronic® F-127 in a quartz sand. At concentrations below 100 µg/L, individual and mixed PFAS adsorption on resin beads exhibited linear isotherms with no apparent competitive effects. However, at concentrations up to 100 mg/L, PFAS adsorption isotherms were non-linear and a mixture of six PFAS exhibited strong competitive effects. In columns packed with 40–50 mesh Ottawa sand, injection of the S-IXR suspension created a uniform sorptive zone that increased PFOA or PFOS retention by more than five orders-of-magnitude compared to untreated control columns. Multi-solute column studies revealed earlier breakthrough of shorter-chain length PFAS, which was consistent with the mixed PFAS adsorption data. These findings indicate that injectable ion exchange resins could provide an effective in situ remediation strategy for PFAS-impacted groundwater plumes.

Long-term development of species richness in a central European beech (Fagus sylvatica) forest affected by windthrow-Support for the intermediate disturbance hypothesis?

On the basis of long‐term surveys of permanent plots and traps, we examined the communities of saproxylic beetles, fungi, herbs, and trees on an untreated 22 ha large beech forest windthrow and asked whether the results lend support to the intermediate disturbance hypothesis (IDH). We studied species richness and the similarity of community composition. Additionally, we grouped species by their frequency trend over time to successional model types to examine whether, corresponding to the IDH, the diversity of these groups explained peak richness at intermediate intervals after the disturbance. In line with the IDH, species richness showed a hump‐backed temporal course for alpha and gamma diversity. We found evidence for a linear succession directly after the disturbance. This, however, did not continue, and in all species groups, a partial recovery of the initial community was observed. In the case of fungi, herbs, and trees, but not for saproxylic beetles, alpha diversity was driven by the diversity of the successional model types. Our results underline that the mechanisms driving species richness after disturbances are more complex than the IDH suggests and that these mechanisms vary with species group. We assumed that, besides competition, legacy effects, facilitation, habitat heterogeneity, and random saturation of the species pool are important. In case of trees and herbs, we found indications for strong legacy and competition effects. For fungi and beetles, substrate heterogeneity and microclimate were assumed to be important. We concluded that disturbances contribute to increasing species richness not only by reducing the effectiveness of competitors but also by increasing the amount and diversity of resources, as well as their rate of change over time.

Using sensitivity analysis to identify factors promoting higher versus lower infection prevalence in multi-host communities

Relationships between host species richness and levels of disease in a focal host are likely to be context-dependent, depending on the characteristics of which particular host species are present in a community. I use a multi-host epidemiological model with environmental transmission to explore how the characteristics of the host species (e.g., competence and competitive ability), host density, and the pathogen transmission mechanism affect the proportion of infected individuals (i.e., infection prevalence) in a focal host. My sensitivity-based approach identifies the indirect pathways through which specific ecological and epidemiological processes affect focal host infection prevalence. This in turn yields predictions about the context-dependent rules governing whether increased host species richness increases (amplifies) or decreases (dilutes) infection prevalence in a focal host. For example, in many cases, amplification and dilution are predicted to occur when added host species are sources or sinks of infectious propagules, respectively. However, if the added host species have strong and asymmetric competitive effects on resident host species, then amplification and dilution are predicted to occur when the added host species have stronger competitive effects on resident host species that are sources or sinks of infectious propagules, respectively. My results also predict that greater dilution and less amplification is more likely to occur under frequency-dependent direct transmission than density-dependent direct transmission when (i) the added hosts have lower competence than resident host species and (ii) interspecific competition between the added host species and resident host species is lower; the opposite conditions promote greater amplification and less dilution under frequency-dependent direct transmission. This work helps identify and explain the mechanisms shaping the context-dependent relationships between host species richness and disease in multi-host communities.

Tuning the Properties of MOF-808 via Defect Engineering and Metal Nanoparticle Encapsulation.

Defect engineering and metal encapsulation are considered as valuable approaches to fine‐tune the reactivity of metal–organic frameworks. In this work, various MOF‐808 (Zr) samples are synthesized and characterized with the final aim to understand how defects and/or platinum nanoparticle encapsulation act on the intrinsic and reactive properties of these MOFs. The reactivity of the pristine, defective and Pt encapsulated MOF‐808 is quantified with water adsorption and CO2 adsorption calorimetry. The results reveal strong competitive effects between crystal morphology and missing linker defects which in turn affect the crystal morphology, porosity, stability, and reactivity. In spite of leading to a loss in porosity, the introduction of defects (missing linkers or Pt nanoparticles) is beneficial to the stability of the MOF‐808 towards water and could also be advantageously used to tune adsorption properties of this MOF family.